# Electrical

## General

big mess

### Learning

• Electronics Club - learn about electronics, how to solder and build simple projects

Physics Videos by Eugene Khutoryansky:

• Electrical Age - a Minecraft mod offering the ability to perform large-scale in-game electrical simulations.

### Formulae

• P=I²R
• E=Pt
• Energy = power x time
• Q=It
• Charge = current (Amps) x time (Seconds)

• Rt (series) = R1 + R2 + R3 ...
• Rt (parallel x2) = R1xR2 / R1+R2
• Rt (parallel x2+) = 1 / 1/Ra + 1/R2 + 1/R3
• v=f x λ
• Velocity = frequency x wavelength (lambda)

### Basics

• https://en.wikipedia.org/wiki/Coupling_(electronics) - the desirable or undesirable transfer of energy from one medium, such as a metallic wire or an optical fiber, to another medium. Coupling is also the transfer of electrical energy from one circuit segment to another. For example, energy is transferred from a power source to an electrical load by means of conductive coupling, which may be either resistive or hard-wire.  An AC potential may be transferred from one circuit segment to another having a DC potential by use of a capacitor.  Electrical energy may be transferred from one circuit segment to another segment with different impedance by use of a transformer. This is known as impedance matching. These are examples of electrostatic and electrodynamic inductive coupling.

• https://en.wikipedia.org/wiki/Direct_coupling - or DC coupling (also called conductive coupling) is the transfer of electrical energy by means of physical contact via a conductive medium, in contrast to inductive coupling and capacitive coupling. It is a way of interconnecting two circuits such that, in addition to transferring the AC signal (or information), the first stage[clarification needed] also provides DC bias to the next. Thus, there is no need for a DC blocking capacitor to be used in order to interconnect the circuits. Conductive coupling passes the full spectrum of frequencies including direct current.Such coupling may be achieved by a wire, resistor, or common terminal, such as a binding post or metallic bonding.

"Passive circuit theory can be thought of as a set of relationships between electromagnetic quantities:

1. Voltage v - Volts, defined as the change magnetic flux Φ with respect to time t
2. Current i - Amperes, defined as the change in electric charge q with respect to time
3. Resistor R - Ohms, defined as a linear relationship between voltage and current (dv = Rdi )
4. Capacitor C - Farads, defined as a linear relationship between voltage and electric charge (dq = Cdv)
5. Inductor L - Henrys, defined as a linear relationship between magnetic flux Φ and current i (dΦ = Ldi).

"Of the six possible relationships, the only two electromagnetic quantities for which there are no pairings are magnetic flux and electric charge. However, in 1971 Leon Chua hypothesized that mathematically, a fourth fundamental passive circuit element could exist, proposing the fourth component, called memristor, that binds the charge q to the linkage flux Φ." [3]

• Two-terminal non-linear circuit elements.svg - Relations between the four fundamental electronic variables (voltage, charge, current, flux) and devices that implement these relations (resistor, capacitor, inductor, memristor).

### Resistance

• https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance - The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor. The inverse quantity is electrical conductance, and is the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with the notion of mechanical friction. The SI unit of electrical resistance is the ohm (Ω), while electrical conductance is measured in siemens (S). An object of uniform cross section has a resistance proportional to its resistivity and length and inversely proportional to its cross-sectional area. All materials show some resistance, except for superconductors, which have a resistance of zero.

• https://en.wikipedia.org/wiki/Equivalent_series_resistance - Practical capacitors and inductors as used in electric circuits are not ideal components with only capacitance or inductance. However, they can be treated, to a very good degree of approximation, as being ideal capacitors and inductors in series with a resistance; this resistance is defined as the equivalent series resistance (ESR). If not otherwise specified, the ESR is always an AC resistance[vague] measured at specified frequencies, 100 kHz for switched-mode power supply components, 120 Hz for linear power-supply components, and at the self-resonant frequency for general-application components. Audio components may report "Q factor", incorporating ESR among other things, at 1000 Hz.

• https://en.wikipedia.org/wiki/Electrical_impedance - the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be used interchangeably. Quantitatively, the impedance of a two-terminal circuit element is the ratio of the complex representation of a sinusoidal voltage between its terminals to the complex representation of the current flowing through it. In general, it depends upon the frequency of the sinusoidal voltage. Impedance is a complex number, with the same units as resistance, for which the SI unit is the ohm (Ω). Its symbol is usually Z, and it may be represented by writing its magnitude and phase in the form |Z|∠θ. However, cartesian complex number representation is often more powerful for circuit analysis purposes. The reciprocal of impedance is admittance, whose SI unit is the siemens, formerly called mho

Impedance extends the concept of resistance to AC circuits, and possesses both magnitude and phase, unlike resistance, which has only magnitude. When a circuit is driven with direct current (DC), there is no distinction between impedance and resistance; the latter can be thought of as impedance with zero phase angle. The notion of impedance is useful for performing AC analysis of electrical networks, because it allows relating sinusoidal voltages and currents by a simple linear law. In multiple port networks, the two-terminal definition of impedance is inadequate, but the complex voltages at the ports and the currents flowing through them are still linearly related by the impedance matrix.

• Z = sqr rt of (resistance² x impedence²)
• Impedance (Z) = the square root of (resistance squared plus reactance squared).

• https://en.wikipedia.org/wiki/Electrical_reactance - the opposition of a circuit element to a change in current or voltage, due to that element's inductance or capacitance. The notion of reactance is similar to electrical resistance, but it differs in several respects. In phasor analysis, reactance is used to compute amplitude and phase changes of sinusoidal alternating current going through a circuit element. It is denoted by the symbol X. An ideal resistor has zero reactance, whereas ideal inductors and capacitors have zero resistance – that is, respond to current only by reactance. The magnitude of the reactance of an inductor rises in proportion to a rise in frequency, while the magnitude of the reactance of a capacitor decreases in proportion to a rise in frequency. As frequency goes up, inductive reactance also goes up and capacitive reactance goes down.

Reactance = resistance to alternating current flow, depends on frequency.

Impedence of pure resistor = resistance, impedence of pure capacitor = reactance

Reactence of capacitor = 1/(2pie x f x c)

• https://en.wikipedia.org/wiki/Susceptance - the imaginary part of admittance, where the real part is conductance. The inverse of admittance is impedance, where the imaginary part is reactance and the real part is resistance. In SI units, susceptance is measured in siemens. Oliver Heaviside first defined this property in June 1887.

• https://en.wikipedia.org/wiki/Resistor - a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity.

Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds and forms. Resistors are also implemented within integrated circuits. The electrical function of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than nine orders of magnitude. The nominal value of the resistance falls within the manufacturing tolerance, indicated on the component.

• https://en.wikipedia.org/wiki/Resistance_wire - wire intended for making electrical resistors (which are used to control the amount of current in a circuit).[1] It is better if the alloy used has a high resistivity, since a shorter wire can then be used. In many situations, the stability of the resistor is of primary importance, and thus the alloy's temperature coefficient of resistivity and corrosion resistance play a large part in material selection.When resistance wire is used for heating elements (in electric heaters, toasters, and the like), high resistivity and oxidation resistance is important.Sometimes resistance wire is insulated by ceramic powder and sheathed in a tube of another alloy. Such heating elements are used in electric ovens and water heaters, and in specialized forms for cooktops.

• https://en.wikipedia.org/wiki/Varistor - an electronic component with an electrical resistance that varies with the applied voltage. Also known as a voltage-dependent resistor (VDR), it has a nonlinear, non-ohmic current–voltage characteristic that is similar to that of a diode. In contrast to a diode however, it has the same characteristic for both directions of traversing current. At low voltage it has a high electrical resistance which decreases as the voltage is raised. Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive transient voltages. When used as protection devices, they shunt the current created by the excessive voltage away from sensitive components when triggered. The name varistor is a portmanteau of varying resistor. The term is only used for non-ohmic varying resistors. Variable resistors, such as the potentiometer and the rheostat, have ohmic characteristics.
• YouTube: How a Surge Protector Works (Metal Oxide Varistor) - How a common surge strip works explained by GE Global Research Engineer Bill Morris. The GEMOV surge suppressor was developed first in 1973 by John D. Harnden Jr., François Martzloff, and William G. Morris in Schenectady, NY. This revolutionized power control for all computers and semiconductor devices. The device was put into production by 1976. Hundreds of millions were produced within a few years. Morris investigated the relationship of crystal size to volts and resistance. Work started with the Thyristor and Zener Diode (varistor works in both polarities).

• https://en.wikipedia.org/wiki/Thermistor - a type of resistor whose resistance is dependent on temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors (negative temperature coefficient or NTC type typically), self-resetting overcurrent protectors, and self-regulating heating elements (positive temperature coefficient or PTC type typically). Thermistors are of two opposite fundamental types: With NTC thermistors, resistance decreases as temperature rises. An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current limiter. With PTC thermistors, resistance increases as temperature rises. PTC thermistors are commonly installed in series with a circuit, and used to protect against overcurrent conditions, as resettable fuses.

### Inductance

• https://en.wikipedia.org/wiki/Inductance - the property of a conductor by which a change in current flowing through it "induces" (creates) a voltage (electromotive force) in both the conductor itself (self-inductance) and in any nearby conductors (mutual inductance).
• https://en.wikipedia.org/wiki/Faraday's_law_of_induction - a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF)—a phenomenon called electromagnetic induction. It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids. The Maxwell–Faraday equation is a generalization of Faraday's law, and is listed as one of Maxwell's equations.

• https://en.wikipedia.org/wiki/Inductor - also called a coil, choke or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core. When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, described by Faraday's law of induction. According to Lenz's law, the direction of induced electromotive force (e.m.f.) opposes the change in current that created it. As a result, inductors oppose any changes in current through them.

An inductor is characterized by its inductance, which is the ratio of the voltage to the rate of change of current. In the International System of Units (SI), the unit of inductance is the henry (H) named for 19th century American scientist Joseph Henry. In the measurement of magnetic circuits, it is equivalent to weber/ampere. Inductors have values that typically range from 1 µH (10−6 H) to 20 H. Many inductors have a magnetic core made of iron or ferrite inside the coil, which serves to increase the magnetic field and thus the inductance. Along with capacitors and resistors, inductors are one of the three passive linear circuit elements that make up electronic circuits. Inductors are widely used in alternating current (AC) electronic equipment, particularly in radio equipment. They are used to block AC while allowing DC to pass; inductors designed for this purpose are called chokes. They are also used in electronic filters to separate signals of different frequencies, and in combination with capacitors to make tuned circuits, used to tune radio and TV receivers.

• https://en.wikipedia.org/wiki/Inductive_coupling - two conductors are referred to as inductively coupled or magnetically coupled when they are configured such that a change in current through one wire induces a voltage across the ends of the other wire through electromagnetic induction. The amount of inductive coupling between two conductors is measured by their mutual inductance. The coupling between two wires can be increased by winding them into coils and placing them close together on a common axis, so the magnetic field of one coil passes through the other coil. Coupling can also be increased by a magnetic core of a ferromagnetic material like iron or ferrite in the coils, which increases the magnetic flux. The two coils may be physically contained in a single unit, as in the primary and secondary windings of a transformer, or may be separated. Coupling may be intentional or unintentional. Unintentional inductive coupling can cause signals from one circuit to be induced into a nearby circuit, this is called cross-talk, and is a form of electromagnetic interference.

### Insulator

• https://en.wikipedia.org/wiki/Insulator_(electricity) - material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field. This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors.

• Glass Insulators Collectors Reference Site - Glass insulators were first produced in the 1850's for use with telegraph lines. As technology developed insulators were needed for telephone lines, electric power lines, and other applications. In the mid 1960's a few people began collecting these antique glass insulators. Today there are over 3,000 insulator collectors. Insulator clubs, local and national shows, and good reference books are available.

• https://en.wikipedia.org/wiki/Electrical_insulation_paper - paper types that are used as electrical insulation in many applications due to pure cellulose having outstanding electrical properties. Cellulose is a good insulator and is also polar, having a dielectric constant significantly greater than one. Electrical paper products are classified by their thickness, with tissue considered papers less than 1.5 mils (0.0381 mm) thickness, and board considered more than 20 mils (0.508 mm) thickness.

### Dielectric

• https://en.wikipedia.org/wiki/Dielectric - an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor but only slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive charges are displaced in the direction of the field and negative charges shift in the opposite direction. This creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axes align to the field. The study of dielectric properties concerns storage and dissipation of electric and magnetic energy in materials. Dielectrics are important for explaining various phenomena in electronics, optics, solid-state physics, and cell biophysics.

• https://en.wikipedia.org/wiki/Electret - a dielectric material that has a quasi-permanent electric charge or dipole polarisation. An electret generates internal and external electric fields, and is the electrostatic equivalent of a permanent magnet. Although Oliver Heaviside coined this term in 1885, materials with electret properties were already known to science and had been studied since the early 1700s. One particular example is the electrophorus, a device consisting of a slab with electret properties and a separate metal plate. The electrophorus was originally invented by Johan Carl Wilcke in Sweden and again by Alessandro Volta in Italy.The name derives from "electron" and "magnet"; drawing analogy to the formation of a magnet by alignment of magnetic domains in a piece of iron. Historically, electrets were made by first melting a suitable dielectric material such as a polymer or wax that contains polar molecules, and then allowing it to re-solidify in a powerful electrostatic field. The polar molecules of the dielectric align themselves to the direction of the electrostatic field, producing a dipole electret with a permanent electrostatic bias. Modern electrets are usually made by embedding excess charges into a highly insulating dielectric, e.g. by means of an electron beam, corona discharge, injection from an electron gun, electric breakdown across a gap, or a dielectric barrier.

### Capacitance

• https://en.wikipedia.org/wiki/Capacitor - layers of insulators and conductors. AC will jump the gap because of inductance. Smaller caps block lower frequencies because bass frequencies are closer to DC.

• https://en.wikipedia.org/wiki/Farad - he SI derived unit of electrical capacitance, the ability of a body to store an electrical charge. It is named after the English physicist Michael Faraday.

• https://en.wikipedia.org/wiki/Mutual_capacitance - intentional or unintentional capacitance that occurs between two charge-holding objects or conductors, in which the current passing through one passes over into the other. In transmission lines, when conductors are closely spaced together, the air or material separating the lines acts as a dielectric, and the conductors act as a capacitors plates. All objects in the universe, conducting or non-conducting, that hold charge with respect to another exhibit capacitance. An object's capacitance increases when another object is brought closer to it. The human body is a great charge-holding object (capacitor) (this biological property is called body capacitance), and sensitive capacitive detectors can be made to function as proximity detectors. The capacitive property of the human body is also helpful in making touch switches, such as those used in touch-activated lamps. The lamp constantly charges and discharges its metal exterior, measuring a change in capacitance. When mutual capacitance occurs adversely (unintentionally) between transmission lines, this is an example of crosstalk.

• https://en.wikipedia.org/wiki/Parasitic_capacitance - or stray capacitance is an unavoidable and usually unwanted capacitance that exists between the parts of an electronic component or circuit simply because of their proximity to each other. When two electrical conductors at different voltages are close together, the electric field between them causes electric charge to be stored on them; this effect is parasitic capacitance. All actual circuit elements such as inductors, diodes, and transistors have internal capacitance, which can cause their behavior to depart from that of 'ideal' circuit elements. Additionally, there is always non-zero capacitance between any two conductors; this can be significant at higher frequencies with closely spaced conductors, such as wires or printed circuit board traces. The parasitic capacitance between the turns of an inductor or other wound component is often described as self-capacitance. However, self-capacitance of a conductive object is a different phenomenon, referring to the capacitance of the object without reference to another object.

• https://en.wikipedia.org/wiki/Capacitive_coupling - the transfer of energy within an electrical network or between distant networks by means of displacement current between circuit(s) nodes, induced by the electric field. This coupling can have an intentional or accidental effect. Capacitive coupling with high-voltage power lines can light a lamp continuously at low intensity. In its simplest implementation, capacitive coupling is achieved by placing a capacitor between two nodes. Where analysis of many points in a circuit is carried out, the capacitance at each point and between points can be described in a matrix form.

### to sort

• https://en.wikipedia.org/wiki/Terminal_(electronics) - the point at which a conductor from an electrical component, device or network comes to an end and provides a point of connection to external circuits. A terminal may simply be the end of a wire or it may be fitted with a connector or fastener. In network analysis, terminal means a point at which connections can be made to a network in theory and does not necessarily refer to any real physical object. In this context, especially in older documents, it is sometimes called a pole.

• https://en.wikipedia.org/wiki/Electrical_ballast - a device placed in line with the load to limit the amount of current in an electrical circuit. It may be a fixed or variable resistor. Ballasts vary greatly in complexity. They may be as simple as a resistor, inductor or capacitor (or a combination of these) wired in series with the lamp; or as complex as the electronic ballasts used in compact fluorescent lamps and high-intensity discharge lamps.

• https://en.wikipedia.org/wiki/Electrical_junction - may be either a thermoelectricity junction, a metal–semiconductor junction or a p–n junction (p-type semiconductor–n-type semiconductor junction). Junctions are either rectifying or non-rectifying. Non-rectifying junctions are called ohmic contacts. Electronic components employing rectifying junctions include p–n diodes, Schottky diodes and bipolar junction transistors.

• https://en.wikipedia.org/wiki/Coulomb - a fundamental unit of electrical charge, and is also the SI derived unit of electric charge (symbol: Q or q). It is equal to the charge of approximately 6.241×1018 electrons. Its SI definition is the charge transported by a constant current of one ampere in one second. One coulomb is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt.

• https://en.wikipedia.org/wiki/Ampère's_force_law - In magnetostatics, the force of attraction or repulsion between two current-carrying wires (see first figure below) is often called Ampère's force law. The physical origin of this force is that each wire generates a magnetic field, following the Biot–Savart law, and the other wire experiences a magnetic force as a consequence, following the Lorentz force law.
• https://en.wikipedia.org/wiki/Ammeter - from Ampere Meter, is a measuring instrument used to measure the current in a circuit. Electric currents are measured in amperes (A), hence the name.

• https://en.wikipedia.org/wiki/Ampacity - a portmanteau for ampere capacity defined by National Electrical Safety Codes, in some North American countries. Ampacity is defined as the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration. Also described as current rating or current-carrying capacity, ampacity is the RMS electric current which a device or conductor can continuously carry while remaining within its temperature rating.

• https://en.wikipedia.org/wiki/Permittivity - In electromagnetism, absolute permittivity, often simply called permittivity, usually denoted by the Greek letter ε (epsilon), is the measure of resistance that is encountered when forming an electric field in a particular medium. More specifically, permittivity describes the amount of charge needed to generate one unit of electric flux in a particular medium. Accordingly, a charge will yield more electric flux in a medium with low permittivity than in a medium with high permittivity. Thus, permittivity is the measure of a material's ability to resist an electric field, not its ability to ‘permit’ it (as the name ‘permittivity’ might seem to suggest).

The SI unit for permittivity is farad per meter (F/m or F·m−1).

• https://en.wikipedia.org/wiki/Relative_permittivity - a material is its (absolute) permittivity expressed as a ratio relative to the permittivity of vacuum. Permittivity is a material property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as dielectric constant, a term deprecated in physics and engineering as well as in chemistry.

• https://en.wikipedia.org/wiki/Direct_current - the unidirectional flow of electric charge. A battery is a good example of a DC power supply. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current. The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage. Direct current may be obtained from an alternating current supply by use of a rectifier, which contains electronic elements (usually) or electromechanical elements (historically) that allow current to flow only in one direction. Direct current may be converted into alternating current with an inverter or a motor-generator set. Direct current is used to charge batteries and as power supply for electronic systems. Very large quantities of direct-current power are used in production of aluminum and other electrochemical processes. It is also used for some railways, especially in urban areas. High-voltage direct current is used to transmit large amounts of power from remote generation sites or to interconnect alternating current power grids.

• https://en.wikipedia.org/wiki/Alternating_current - an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans and electric lamps into a wall socket. A common source of DC power is a battery cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage. The usual waveform of alternating current in most electric power circuits is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. These types of alternating current carry information such as sound (audio) or images (video) sometimes carried by modulation of an AC carrier signal. These currents typically alternate at higher frequencies than those used in power transmission.

• https://en.wikipedia.org/wiki/AC_power - the rate of flow of energy past a given point of the circuit. In alternating current circuits, energy storage elements such as inductors and capacitors may result in periodic reversals of the direction of energy flow. The portion of power that, averaged over a complete cycle of the AC waveform, results in net transfer of energy in one direction is known as active power (more commonly called real power to avoid ambiguity especially in discussions of loads with non-sinusoidal currents). The portion of power due to stored energy, which returns to the source in each cycle, is known as reactive power.

• https://en.wikipedia.org/wiki/Inrush_current - input surge current or switch-on surge is the maximal instantaneous input current drawn by an electrical device when first turned on. Alternating-current electric motors and transformers may draw several times their normal full-load current when first energized, for a few cycles of the input waveform. Power converters also often have inrush currents much higher than their steady-state currents, due to the charging current of the input capacitance. The selection of overcurrent-protection devices such as fuses and circuit breakers is made more complicated when high inrush currents must be tolerated. The overcurrent protection must react quickly to overload or short-circuit faults but must not interrupt the circuit when the (usually harmless) inrush current flows.

• https://en.wikipedia.org/wiki/Leading_and_lagging_current - phenomena that occur as a result of alternating current. In a circuit with alternating current, the value of voltage and current vary sinusoidally. In these types of circuits, the terms lead, lag, or in phase are used to describe current with reference to voltage. Current is in phase with voltage when there is no phase shift between the sinusoids describing their time varying behavior. This generally occurs when the load drawing the current is resistive. In electric power flow, it is important to know whether current is leading or lagging because it can be used to describe how much circulating reactive power flow is occurring in the system, and whether that power is inductive or capacitative. It can also play an important role in the operation of three-phase power systems.

• https://en.wikipedia.org/wiki/Power_factor - of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit, and is a dimensionless number in the closed interval of −1 to 1. A power factor of less than one means that the voltage and current waveforms are not in phase, reducing the instantaneous product of the two waveforms (V × I). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power. A negative power factor occurs when the device (which is normally the load) generates power, which then flows back towards the source, which is normally considered the generator.

In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor. Linear loads with low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Non-linear loads, such as rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over a distribution system, or built into power-consuming equipment.

• https://en.wikipedia.org/wiki/Volt-ampere_reactive - a unit by which reactive power is expressed in an AC electric power system. Reactive power exists in an AC circuit when the current and voltage are not in phase. Per EU directive 80/181/EEC (the "metric directive"), the correct symbol is lower-case "var", although the spellings "Var" and "VAr" are commonly seen, and "VAR" is widely used throughout the power industry. The term var was proposed by the Romanian electrical engineer Constantin Budeanu and introduced in 1930 by the IEC in Stockholm, which has adopted it as the unit for reactive power.Special instruments called varmeters are available to measure the reactive power in a circuit.

• https://en.wikipedia.org/wiki/Kirchhoff's_circuit_laws - are two equalities that deal with the current and potential difference (commonly known as voltage) in the lumped element model of electrical circuits. They were first described in 1845 by German physicist Gustav Kirchhoff. This generalized the work of Georg Ohm and preceded the work of James Clerk Maxwell. Widely used in electrical engineering, they are also called Kirchhoff's rules or simply Kirchhoff's laws. Both of Kirchhoff's laws can be understood as corollaries of Maxwell's equations in the low-frequency limit. They are accurate for DC circuits, and for AC circuits at frequencies where the wavelengths of electromagnetic radiation are very large compared to the circuits.

Current law = At any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node

Voltate law = The directed sum of the electrical potential differences (voltage) around any closed network is zero.

• https://en.wikipedia.org/wiki/Electrical_element - conceptual abstractions representing idealized electrical components, such as resistors, capacitors, and inductors, used in the analysis of electrical networks. All electrical networks can be analyzed as multiple electrical elements interconnected by wires. Where the elements roughly correspond to real components the representation can be in the form of a schematic diagram or circuit diagram. This is called a lumped element circuit model. In other cases infinitesimal elements are used to model the network in a distributed element model.

These ideal electrical elements represent real, physical electrical or electronic components but they do not exist physically and they are assumed to have ideal properties, while actual electrical components have less than ideal properties, a degree of uncertainty in their values and some degree of nonlinearity. To model the nonideal behavior of a real circuit component may require a combination of multiple ideal electrical elements in order to approximate its function. For example, an inductor circuit element is assumed to have inductance but no resistance or capacitance, while a real inductor, a coil of wire, has some resistance in addition to its inductance. This may be modeled by an ideal inductance element in series with a resistance.

• https://en.wikipedia.org/wiki/Counter-electromotive_force - abbreviated counter EMF or simply CEMF, also known as back electromotive force (or back EMF), is the electromotive force or "voltage" that opposes the change in current which induced it. CEMF is the EMF caused by magnetic induction (see Faraday's law of induction, electromagnetic induction, Lenz's Law).

• https://en.wikipedia.org/wiki/Biot–Savart_law - an equation describing the magnetic field generated by a stationary electric current. It relates the magnetic field to the magnitude, direction, length, and proximity of the electric current. The Biot–Savart law is fundamental to magnetostatics, playing a similar role to Coulomb's law in electrostatics. When magnetostatics does not apply, the Biot–Savart law should be replaced by Jefimenko's equations. The law is valid in the magnetostatic approximation, and is consistent with both Ampère's circuital law and Gauss's law for magnetism. It is named after Jean-Baptiste Biot and Félix Savart who discovered this relationship in 1820.

• WaveDrom is Free and Open Source online digital timing diagram (waveform) rendering engine that uses javascript, HTML5 and SVG to convert WaveJSON input text description into SVG vector graphics. WaveJSON is an application of the JSON format. The purpose of WaveJSON is to provide a compact exchange format for digital timing diagrams utilized by digital HW / IC engineers.

• https://en.wikipedia.org/wiki/Electromigration - the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. The effect is important in applications where high direct current densities are used, such as in microelectronics and related structures. As the structure size in electronics such as integrated circuits (ICs) decreases, the practical significance of this effect increases.

### Switch

• https://en.wikipedia.org/wiki/Switch - an electrical component that can "make" or "break" an electrical circuit, interrupting the current or diverting it from one conductor to another. The mechanism of a switch removes or restores the conducting path in a circuit when it is operated. It may be operated manually, for example, a light switch or a keyboard button, may be operated by a moving object such as a door, or may be operated by some sensing element for pressure, temperature or flow. A switch will have one or more sets of contacts, which may operate simultaneously, sequentially, or alternately. Switches in high-powered circuits must operate rapidly to prevent destructive arcing, and may include special features to assist in rapidly interrupting a heavy current. Multiple forms of actuators are used for operation by hand or to sense position, level, temperature or flow. Special types are used, for example, for control of machinery, to reverse electric motors, or to sense liquid level. Many specialized forms exist. A common use is control of lighting, where multiple switches may be wired into one circuit to allow convenient control of light fixtures.

• https://en.wikipedia.org/wiki/Multiway_switching - the interconnection of two or more electrical switches to control an electrical load (often, but not always, lighting) from more than one location. For example, this allows lighting in a hallway, stairwell or large room to be controlled from multiple locations. While a "normal" light switch needs to be only a single pole, single throw (SPST) switch, multiway switching requires the use of switches that have one or more additional contacts and two or more wires must be run between the switches. When the load is controlled from only two points, single pole, double throw (SPDT) switches are used. Double pole, double throw (DPDT) switches allow control from three or more locations.

In alternative designs, low-voltage relay or electronic controls can be used to switch electrical loads, sometimes without the extra power wires.

• https://en.wikipedia.org/wiki/Relay - an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a separate low-power signal, or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.

A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays".

• https://en.wikipedia.org/wiki/Transfer_switch - an electrical switch that switches a load between two sources. Some transfer switches are manual, in that an operator effects the transfer by throwing a switch, while others are automatic and trigger when they sense one of the sources has lost or gained power. An Automatic Transfer Switch (ATS) is often installed where a backup generator is located, so that the generator may provide temporary electrical power if the utility source fails.

• https://en.wikipedia.org/wiki/Disconnector - disconnect switch or isolator switch is used to ensure that an electrical circuit is completely de-energized for service or maintenance. Such switches are often found in electrical distribution and industrial applications, where machinery must have its source of driving power removed for adjustment or repair. High-voltage isolation switches are used in electrical substations to allow isolation of apparatus such as circuit breakers, transformers, and transmission lines, for maintenance. The disconnector is usually not intended for normal control of the circuit, but only for safety isolation. Disconnectors can be operated either manually or automatically.

### Protection

• https://en.wikipedia.org/wiki/Electrical_bonding - the practice of intentionally electrically connecting all exposed metallic items not designed to carry electricity in a room or building as protection from electric shock. If a failure of electrical insulation occurs, all bonded metal objects in the room will have substantially the same electrical potential, so that an occupant of the room cannot touch two objects with significantly different potentials. Even if the connection to a distant earth ground is lost, the occupant will be protected from dangerous potential differences.

• https://en.wikipedia.org/wiki/Overcurrent - or excess current is a situation where a larger than intended electric current exists through a conductor, leading to excessive generation of heat, and the risk of fire or damage to equipment. Possible causes for overcurrent include short circuits, excessive load, incorrect design, or a ground fault. Fuses, circuit breakers, temperature sensors and current limiters are commonly used protection mechanisms to control the risks of overcurrent.

• https://en.wikipedia.org/wiki/Inrush_current_limiter - a component used to limit inrush current to avoid gradual damage to components and avoid blowing fuses or tripping circuit breakers. Negative temperature coefficient (NTC) thermistors and fixed resistors are often used to limit inrush current. NTC thermistors can be used as inrush-current limiting devices in power supply circuits when added in series with the circuit being protected. They present a higher resistance initially, which prevents large currents from flowing at turn-on. As current continues to flow, NTC thermistors heat up, allowing higher current flow during normal operation. NTC thermistors are usually much larger than measurement type thermistors, and are purposely designed for power applications.

• https://en.wikipedia.org/wiki/Resettable_fuse - a polymeric positive temperature coefficient (PPTC) device that is a passive electronic component used to protect against overcurrent faults in electronic circuits. The device is also known as a polyfuse or polyswitch. They are similar in function to PTC thermistors in certain situations but operate on mechanical changes instead of charge carrier effects in semiconductors.

• https://en.wikipedia.org/wiki/Circuit_breaker - an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect low-current circuits or individual household appliance, up to large switchgear designed to protect high voltage circuits feeding an entire city. The generic function of a circuit breaker, RCD or a fuse, as an automatic means of removing power from a faulty system is often abbreviated as OCPD (Over Current Protection Device).

• https://en.wikipedia.org/wiki/Earth_leakage_circuit_breaker - a safety device used in electrical installations with high Earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected. Once widely used, more recent installations instead use residual current circuit breakers which instead detect leakage current directly.
• https://en.wikipedia.org/wiki/Residual-current_device - RCD, or residual-current circuit breaker (RCCB), is a device that instantly breaks an electric circuit to prevent serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a human falls after receiving a shock. Also Known As, United States and Canada: the device is more commonly known as a ground fault circuit interrupter (GFCI), ground fault interrupter (GFI) or an appliance leakage current interrupter (ALCI).

- United Kingdom: these are better known by their initials RCD, and a combined RCD+MCB (miniature circuit breaker) is known as a RCBO (residual-current circuit breaker with overcurrent protection). - Australia: they are best known singularly as a Safety Switch or otherwise known as an RCD. An earth leakage circuit breaker (ELCB) may be a residual-current device, although an older type of voltage-operated earth leakage circuit breaker also exists.

### Ground

• https://en.wikipedia.org/wiki/Earthing_system - or grounding system connects specific parts of that installation with the Earth's conductive surface for safety and functional purposes. The point of reference is the Earth's conductive surface. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Regulations for earthing systems vary considerably among countries, though many follow the recommendations of the International Electrotechnical Commission. Regulations may identify special cases for earthing in mines, in patient care areas, or in hazardous areas of industrial plants.

In addition to electric power systems, other systems may require grounding for safety or function. Tall structures may have lightning rods as part of a system to protect them from lightning strikes. Telegraph lines may use the Earth as one conductor of a circuit, saving the cost of installation of a return wire over a long circuit. Radio antennas may require particular grounding for operation, as well as to control static electricity and provide lightning protection.

• https://en.wikipedia.org/wiki/Floating_ground - Most electrical circuits have a ground which is electrically connected to the Earth, hence the name "ground". The ground is said to be floating when this connection does not exist. Conductors are also described as having a floating voltage if they are not connected electrically to another non-floating conductor. Without such a connection, voltages and current flows are induced by electromagnetic fields or charge accumulation within the conductor rather than being due to the usual external potential difference of a power source.

• https://en.wikipedia.org/wiki/Ground_loop_(electricity) - or earth loop occurs when two points of a circuit both intended to be at ground reference potential have a potential between them. This can be caused, for example, in a signal circuit referenced to ground, if enough current is flowing in the ground to cause two points to be at different potentials. Ground loops are a major cause of noise, hum, and interference in audio, video, and computer systems. Wiring practices that protect against ground loops include ensuring that all vulnerable signal circuits are referenced to one point as ground. The use of differential connections can provide rejections of ground-induced interference. Removal of safety ground connections to equipment in an effort to eliminate ground loops also eliminates the protection the safety ground connection is intended to provide.

### Generation

• https://en.wikipedia.org/wiki/Electric_generator - a device that converts motive power (mechanical energy) into electrical power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines and even hand cranks. The first electromagnetic generator, the Faraday disk, was built in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable manual generators.

• https://en.wikipedia.org/wiki/Distributed_generation - also distributed energy, on-site generation (OSG) or district/decentralized energy is electrical generation and storage performed by a variety of small, grid-connected devices referred to as distributed energy resources (DER). Conventional power stations, such as coal-fired, gas and nuclear powered plants, as well as hydroelectric dams and large-scale solar power stations, are centralized and often require electric energy to be transmitted over long distances. By contrast, DER systems are decentralized, modular and more flexible technologies, that are located close to the load they serve, albeit having capacities of only 10 megawatts (MW) or less. These systems can comprise multiple generation and storage components; in this instance they are referred to as hybrid power systems.

DER systems typically use renewable energy sources, including small hydro, biomass, biogas, solar power, wind power, and geothermal power, and increasingly play an important role for the electric power distribution system. A grid-connected device for electricity storage can also be classified as a DER system, and is often called a distributed energy storage system (DESS). By means of an interface, DER systems can be managed and coordinated within a smart grid. Distributed generation and storage enables collection of energy from many sources and may lower environmental impacts and improve security of supply.

• https://en.wikipedia.org/wiki/Electrostatic_generator - electrostatic machine, is an electromechanical generator that produces static electricity, or electricity at high voltage and low continuous current. The knowledge of static electricity dates back to the earliest civilizations, but for millennia it remained merely an interesting and mystifying phenomenon, without a theory to explain its behavior and often confused with magnetism. By the end of the 17th century, researchers had developed practical means of generating electricity by friction, but the development of electrostatic machines did not begin in earnest until the 18th century, when they became fundamental instruments in the studies about the new science of electricity. Electrostatic generators operate by using manual (or other) power to transform mechanical work into electric energy. Electrostatic generators develop electrostatic charges of opposite signs rendered to two conductors, using only electric forces, and work by using moving plates, drums, or belts to carry electric charge to a high potential electrode. The charge is generated by one of two methods: either the triboelectric effect (friction) or electrostatic induction.

• https://en.wikipedia.org/wiki/Van_de_Graaff_generator - an electrostatic generator which uses a moving belt to accumulate electric charge on a hollow metal globe on the top of an insulated column, creating very high electric potentials. It produces very high voltage direct current (DC) electricity at low current levels. It was invented by American physicist Robert J. Van de Graaff in 1929. The potential difference achieved by modern Van de Graaff generators can be as much as 5 megavolts. A tabletop version can produce on the order of 100,000 volts and can store enough energy to produce a visible spark. Small Van de Graaff machines are produced for entertainment, and for physics education to teach electrostatics; larger ones are displayed in some science museums.

The Van de Graaff generator was developed as a particle accelerator for physics research; its high potential is used to accelerate subatomic particles to great speeds in an evacuated tube. It was the most powerful type of accelerator of the 1930s until the cyclotron was developed. Van de Graaff generators are still used as accelerators to generate energetic particle and x-ray beams for nuclear research and nuclear medicine.

• https://en.wikipedia.org/wiki/Thermoelectric_effect - the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. At the atomic scale, an applied temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side.
• https://en.wikipedia.org/wiki/Thermoelectric_generator - TEG, also called a Seebeck generator, is a solid state device that converts heat flux (temperature differences) directly into electrical energy through a phenomenon called the Seebeck effect (a form of thermoelectric effect). Thermoelectric generators function like heat engines, but are less bulky and have no moving parts. However, TEGs are typically more expensive and less efficient. Thermoelectric generators could be used in power plants in order to convert waste heat into additional electrical power and in automobiles as automotive thermoelectric generators (ATGs) to increase fuel efficiency. Another application is radioisotope thermoelectric generators which are used in space probes, which has the same mechanism but use radioisotopes to generate the required heat difference.

### Semiconductor

• https://en.wikipedia.org/wiki/Semiconductor - A semiconductor material has an electrical conductivity value falling between that of a conductor – such as copper, gold etc. – and an insulator, such as glass. Their resistance decreases as their temperature increases, which is behavior opposite to that of a metal. Their conducting properties may be altered in useful ways by the deliberate, controlled introduction of impurities ("doping") into the crystal structure. Where two differently-doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers which include electrons, ions and electron holes at these junctions is the basis of diodes, transistors and all modern electronics.

• https://en.wikipedia.org/wiki/Semiconductor_device - electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide, as well as organic semiconductors. Semiconductor devices have replaced thermionic devices (vacuum tubes) in most applications. They use electronic conduction in the solid state as opposed to the gaseous state or thermionic emission in a high vacuum. Semiconductor devices are manufactured both as single discrete devices and as integrated circuits (ICs), which consist of a number—from a few (as low as two) to billions—of devices manufactured and interconnected on a single semiconductor substrate, or wafer.

• https://en.wikipedia.org/wiki/Extrinsic_semiconductor - is one that has been doped; during manufacture of the semiconductor crystal a trace element or chemical called a doping agent has been incorporated chemically into the crystal, for the purpose of giving it different electrical properties than the pure semiconductor crystal, which is called an intrinsic semiconductor. In an extrinsic semiconductor it is these foreign dopant atoms in the crystal lattice that mainly provide the charge carriers which carry electric current through the crystal. The doping agents used are of two types, resulting in two types of extrinsic semiconductor. An electron donor dopant is an atom which, when incorporated in the crystal, releases a mobile conduction electron into the crystal lattice. An extrinsic semiconductor which has been doped with electron donor atoms is called an n-type semiconductor, because the majority of charge carriers in the crystal are negative electrons. An electron acceptor dopant is an atom which accepts an electron from the lattice, creating a vacancy where an electron should be called a hole which can move through the crystal like a positively charged particle. An extrinsic semiconductor which has been doped with electron acceptor atoms is called a p-type semiconductor, because the majority of charge carriers in the crystal are positive holes.Doping is the key to the extraordinarily wide range of electrical behavior that semiconductors can exhibit, and extrinsic semiconductors are used to make semiconductor electronic devices such as diodes, transistors, integrated circuits, semiconductor lasers, LEDs, and photovoltaic cells. Sophisticated semiconductor fabrication processes like photolithography can implant different dopant elements in different regions of the same semiconductor crystal wafer, creating semiconductor devices on the wafer's surface. For example a common type of transistor, the n-p-n bipolar transistor, consists of an extrinsic semiconductor crystal with two regions of n-type semiconductor, separated by a region of p-type semiconductor, with metal contacts attached to each part.

• https://en.wikipedia.org/wiki/P–n_junction - a boundary or interface between two types of semiconductor materials, p-type and n-type, inside a single crystal of semiconductor. The "p" (positive) side contains an excess of holes, while the "n" (negative) side contains an excess of electrons in the outer shells of the electrically neutral atoms there. This allows electrical current to pass through the junction only in one direction. The p-n junction is created by doping, for example by ion implantation, diffusion of dopants, or by epitaxy (growing a layer of crystal doped with one type of dopant on top of a layer of crystal doped with another type of dopant). If two separate pieces of material were used, this would introduce a grain boundary between the semiconductors that would severely inhibit its utility by scattering the electrons and holes.

p–n junctions are elementary "building blocks" of semiconductor electronic devices such as diodes, transistors, solar cells, LEDs, and integrated circuits; they are the active sites where the electronic action of the device takes place. For example, a common type of transistor, the bipolar junction transistor, consists of two p–n junctions in series, in the form n–p–n or p–n–p; while a diode can be made from a single p-n junction. A Schottky junction is a special case of a p–n junction, where metal serves the role of the p-type semiconductor.

• https://en.wikipedia.org/wiki/Depletion_region - also called depletion layer, depletion zone, junction region, space charge region or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile charge carriers have been diffused away, or have been forced away by an electric field. The only elements left in the depletion region are ionized donor or acceptor impurities.

The depletion region is so named because it is formed from a conducting region by removal of all free charge carriers, leaving none to carry a current. Understanding the depletion region is key to explaining modern semiconductor electronics: diodes, bipolar junction transistors, field-effect transistors, and variable capacitance diodes all rely on depletion region phenomena.

• https://en.wikipedia.org/wiki/Diode - a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. A vacuum tube diode has two electrodes, a plate (anode) and a heated cathode. Semiconductor diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today, most diodes are made of silicon, but other materials such as selenium and germanium are sometimes used.

• https://en.wikipedia.org/wiki/P–n_diode - a type of semiconductor diode based upon the p–n junction. The diode conducts current in only one direction, and it is made by joining a p-type semiconducting layer to an n-type semiconducting layer. Semiconductor diodes have multiple uses including rectification of alternating current to direct current, detection of radio signals, emitting light and detecting light.

• https://en.wikipedia.org/wiki/Crystal_detector - an electronic component used to rectify radio frequency alternating current. The "asymmetric conduction" of crystals was discovered in 1874 by Karl Ferdinand Braun and the first crystal detectors were used in wireless research by Braun and Jagadish Chandra Bose in 1894. Development of these detectors began to significantly advance around 1904 when Henry H. C. Dunwoody and G. W. Pickard commenced research on the performance of many crystalline and metallic materials as detectors. Crystal detectors became very commonly used in early 20th century wireless receivers and crystal radios. The crystal detector was the first type of semiconductor diode, and in fact, one of the first semiconductor electronic devices (after photoconductors).

• https://en.wikipedia.org/wiki/Zener_diode - a particular type of diode that, unlike a normal one, allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the Zener voltage is reached. Zener diodes have a highly doped p-n junction. Normal diodes will also break down with a reverse voltage but the voltage and sharpness of the knee are not as well defined as for a Zener diode. Also normal diodes are not designed to operate in the breakdown region, but Zener diodes can reliably operate in this region.

The device was named after Clarence Melvin Zener, who discovered the Zener effect. Zener reverse breakdown is due to electron quantum tunnelling caused by a high-strength electric field. However, many diodes described as "Zener" diodes rely instead on avalanche breakdown. Both breakdown types are used in Zener diodes with the Zener effect predominating under 5.6 V and avalanche breakdown above. Zener diodes are widely used in electronic equipment of all kinds and are one of the basic building blocks of electronic circuits. They are used to generate low power stabilized supply rails from a higher voltage and to provide reference voltages for circuits, especially stabilized power supplies. They are also used to protect circuits from overvoltage, especially electrostatic discharge (ESD).

• https://en.wikipedia.org/wiki/Transistor - a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

• https://en.wikipedia.org/wiki/Field-effect_transistor - a transistor that uses an electric field to control the electrical behaviour of the device. FETs are also known as unipolar transistors since they involve single-carrier-type operation. Many different implementations of field effect transistors exist. Field effect transistors generally display very high input impedance at low frequencies. The conductivity between the drain and source terminals is controlled by an electric field in the device, which is generated by the voltage difference between the body and the gate of the device.
• https://en.wikipedia.org/wiki/JFET - JFET or JUGFET, is the simplest type of field-effect transistor. They are three-terminal semiconductor devices that can be used as electronically-controlled switches, amplifiers, or voltage-controlled resistors.
• https://en.wikipedia.org/wiki/MOSFET - metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of transistor used for amplifying or switching electronic signals. Although the MOSFET is a four-terminal device with source (S), gate (G), drain (D), and body (B) terminals, the body (or substrate) of the MOSFET is often connected to the source terminal, making it a three-terminal device like other field-effect transistors. Because these two terminals are normally connected to each other (short-circuited) internally, only three terminals appear in electrical diagrams. The MOSFET is by far the most common transistor in both digital and analog circuits, though the bipolar junction transistor was at one time much more common.
• https://en.wikipedia.org/wiki/Dennard_scaling - also known as MOSFET scaling, is a scaling law based on a 1974 paper co-authored by Robert H. Dennard, after whom it is named. Originally formulated for MOSFETs, it states, roughly, that as transistors get smaller their power density stays constant, so that the power use stays in proportion with area: both voltage and current scale (downward) with length.

• https://en.wikipedia.org/wiki/Bipolar_junction_transistor - bipolar transistor or BJT, is a type of transistor that uses both electron and hole charge carriers. In contrast, unipolar transistors, such as field-effect transistors, only use one kind of charge carrier. For their operation, BJTs use two junctions between two semiconductor types, n-type and p-type. BJTs are manufactured in two types, NPN and PNP, and are available as individual components, or fabricated in integrated circuits, often in large numbers. The basic function of a BJT is to amplify current. This allows BJTs to be used as amplifiers or switches, giving them wide applicability in electronic equipment, including computers, televisions, mobile phones, audio amplifiers, industrial control, and radio transmitters.

• https://en.wikipedia.org/wiki/CMOS - abbreviated as CMOS /ˈsiːmɒs/, is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for several analog circuits such as image sensors (CMOS sensor), data converters, and highly integrated transceivers for many types of communication.

• https://en.wikipedia.org/wiki/Metal–semiconductor_junction - a type of junction in which a metal comes in close contact with a semiconductor material. It is the oldest practical semiconductor device. M–S junctions can either be rectifying or non-rectifying. The rectifying metal–semiconductor junction forms a Schottky barrier, making a device known as a Schottky diode, while the non-rectifying junction is called an ohmic contact. (In contrast, a rectifying semiconductor–semiconductor junction, the most common semiconductor device today, is known as a p–n junction.)

Metal–semiconductor junctions are crucial to the operation of all semiconductor devices. Usually an ohmic contact is desired, so that electrical charge can be conducted easily between the active region of a transistor and the external circuitry. Occasionally however a Schottky barrier is useful, as in Schottky diodes, Schottky transistors, and metal–semiconductor field effect transistors.

• https://en.wikipedia.org/wiki/MESFET - stands for metal–semiconductor field-effect transistor. It is quite similar to a JFET in construction and terminology. The difference is that instead of using a p-n junction for a gate, a Schottky (metal-semiconductor) junction is used. MESFETs are usually constructed in compound semiconductor technologies lacking high quality surface passivation such as GaAs, InP, or SiC, and are faster but more expensive than silicon-based JFETs or MOSFETs. Production MESFETs are operated up to approximately 45 GHz, and are commonly used for microwave frequency communications and radar. The first MESFETs were developed in 1966, and a year later their extremely high frequency RF microwave performance was demonstrated.

• https://en.wikipedia.org/wiki/Nonlinear_junction_detector - or an NLJD, is a device that illuminates a small region of space with high-frequency RF energy. Any "non linear junction" in the vicinity—for example, and particularly, the p-n junction—will receive this energy, and because of the asymmetric response of the junction to an electric field, it will rectify it, re-emitting some of it on multiples of the illumination frequency (see harmonic). The detector has a sensitive receiver tuned to these harmonics, as well as appropriate processing and displays to make their presence known to the user of the device. Because the basis of almost all semiconductor electronics is the p-n junction, an NLJD is correspondingly capable of detecting almost any unshielded electronic device containing semiconductors, whether the electronics are actively powered or not.

In its basic form, an NLJD can also detect things that are not themselves electronic in nature, so the use of the device requires a modicum of skill and experience. For example, a rusty nail inside a wall can give a false positive. For this reason, most modern NLJDs examine the ratio between the second and the third harmonic of the illumination frequency. When a true (electronic) p-n junction is encountered, the second harmonic will generally be stronger than the third.

• https://en.wikipedia.org/wiki/Silicon_controlled_rectifier - or semiconductor controlled rectifier is a four-layer solid-state current-controlling device. The principle of four-layer p–n–p–n switching was developed by Moll, Tanenbaum, Goldey and Holonyak of Bell Laboratories in 1956. The practical demonstration of silicon controlled switching and detailed theoretical behavior of a device in agreement with the experimental results was presented by Dr Ian M. Mackintosh of Bell Laboratories in January 1958. The name "silicon controlled rectifier" is General Electric's trade name for a type of thyristor. The SCR was developed by a team of power engineers led by Gordon Hall and commercialized by Frank W. "Bill" Gutzwiller in 1957.Some sources define silicon-controlled rectifiers and thyristors as synonymous, other sources define silicon-controlled rectifiers as a proper subset of the set of thyristors, those being devices with at least four layers of alternating n- and p-type material. According to Bill Gutzwiller, the terms "SCR" and "controlled rectifier" were earlier, and "thyristor" was applied later, as usage of the device spread internationally.

• https://en.wikipedia.org/wiki/Thyristor - a solid-state semiconductor device with four layers of alternating P- and N-type materials. It acts exclusively as a bistable switch, conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reversed biased, or until the voltage is removed (by some other means). A three-lead thyristor is designed to control the larger current of the Anode to Cathode path by controlling that current with the smaller current of its other lead, known as its Gate. In contrast, a two-lead thyristor is designed to switch on if the potential difference between its leads is sufficiently large (breakdown voltage).

• https://en.wikipedia.org/wiki/TRIAC - from triode for alternating current, is a generic trademark for a three terminal electronic component that conducts current in either direction when triggered. Its formal name is bidirectional triode thyristor or bilateral triode thyristor. A thyristor is analogous to a relay in that a small voltage and current can control a much larger voltage and current.

### Power electronics

• https://en.wikipedia.org/wiki/Power_electronics - the application of solid-state electronics to the control and conversion of electric power. The first high power electronic devices were mercury-arc valves. In modern systems the conversion is performed with semiconductor switching devices such as diodes, thyristors and transistors, pioneered by R. D. Middlebrook and others beginning in the 1950s. In contrast to electronic systems concerned with transmission and processing of signals and data, in power electronics substantial amounts of electrical energy are processed.

• https://en.wikipedia.org/wiki/Transmission_line - a specialized cable or other structure designed to conduct alternating current of radio frequency, that is, currents with a frequency high enough that their wave nature must be taken into account. Transmission lines are used for purposes such as connecting radio transmitters and receivers with their antennas (they are then called feed lines or feeders), distributing cable television signals, trunklines routing calls between telephone switching centres, computer network connections and high speed computer data buses.

#### Testing

• https://en.wikipedia.org/wiki/Electronic_test_equipment - used to create signals and capture responses from electronic devices under test (DUTs). In this way, the proper operation of the DUT can be proven or faults in the device can be traced. Use of electronic test equipment is essential to any serious work on electronics systems.Practical electronics engineering and assembly requires the use of many different kinds of electronic test equipment ranging from the very simple and inexpensive (such as a test light consisting of just a light bulb and a test lead) to extremely complex and sophisticated such as automatic test equipment (ATE). ATE often includes many of these instruments in real and simulated forms.Generally, more advanced test gear is necessary when developing circuits and systems than is needed when doing production testing or when troubleshooting existing production units in the field.

• https://en.wikipedia.org/wiki/Electrical_measurements - the methods, devices and calculations used to measure electrical quantities. Measurement of electrical quantities may be done to measure electrical parameters of a system. Using transducers, physical properties such as temperature, pressure, flow, force, and many others can be converted into electrical signals, which can then be conveniently measured and recorded. High-precision laboratory measurements of electrical quantities are used in experiments to determine fundamental physical properties such as the charge of the electron or the speed of light, and in the definition of the units for electrical measurements, with precision in some cases on the order of a few parts per million. Less precise measurements are required every day in industrial practice.

• https://en.wikipedia.org/wiki/Metrology - the science of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France, when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th Conference Generale des Poids et Mesures (CGPM) in 1960. Metrology is divided into three basic overlapping activities. The first being the definition of units of measurement, second the realisation of these units of measurement in practice, and last traceability, which is linking measurements made in practice to the reference standards. These overlapping activities are used in varying degrees by the three basic sub-fields of Metrology. The sub-fields are scientific or fundamental metrology, which is concerned with the establishment of units of measurement, Applied, technical or industrial metrology, the application of measurement to manufacturing and other processes in society, and Legal metrology, which covers the regulation and statutory requirements for measuring instruments and the methods of measurement.

• https://en.wikipedia.org/wiki/Electricity_meter - electric meter, electrical meter, or energy meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device.Electric utilities use electric meters installed at customers' premises for billing purposes. They are typically calibrated in billing units, the most common one being the kilowatt hour (kWh). They are usually read once each billing period.When energy savings during certain periods are desired, some meters may measure demand, the maximum use of power in some interval. "Time of day" metering allows electric rates to be changed during a day, to record usage during peak high-cost periods and off-peak, lower-cost, periods. Also, in some areas meters have relays for demand response load shedding during peak load periods.

• https://en.wikipedia.org/wiki/Shunt_(electrical) - a device which allows electric current to pass around another point in the circuit by creating a low resistance path]The term is also widely used in photovoltaics to describe an unwanted short circuit between the front and back surface contacts of a solar cell, usually caused by wafer damage. The origin of the term is in the verb 'to shunt' meaning to turn away or follow a different path. An ammeter shunt allows the measurement of current values too large to be directly measured by a particular ammeter. In this case the shunt, a manganin resistor of accurately known resistance, is placed in parallel with the moving coil galvanometer, thus all of the current to be measured will flow through it. In order not to disrupt the circuit, the resistance of the shunt is normally very low. The voltage drop across the shunt is proportional to the current flowing through it and as its resistance is known, a voltmeter connected across the shunt can be scaled to directly display the current value.

• https://github.com/oxesoft/energymeter - aims to measure the AC in kWh (kilowatt-hour) on a single, two or three-phase power supply for home use (less than 100A), using the Arduino Uno platform and some cheap components. The voltage is measured using a 200mA transformer and a resistive voltage divider. The current is measured using a non-invasive sensor. The power factor is measured in software. The output can be shown in a LCD display or sent to a server on internet. The possibilities are endless.

#### Regulation

• https://en.wikipedia.org/wiki/Electric_power_quality - or simply power quality, involves voltage, frequency, and waveform. Good power quality can be defined as a steady supply voltage that stays within the prescribed range, steady a.c. frequency close to the rated value, and smooth voltage curve waveform (resembles a sine wave). In general, it is useful to consider power quality as the compatibility between what comes out of an electric outlet and the load that is plugged into it. The term is used to describe electric power that drives an electrical load and the load's ability to function properly. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality and many more causes of such poor quality power. While "power quality" is a convenient term for many, it is the quality of the voltage—rather than power or electric current—that is actually described by the term. Power is simply the flow of energy and the current demanded by a load is largely uncontrollable.

• https://en.wikipedia.org/wiki/Power_conditioner - also known as a line conditioner or power line conditioner, is a device intended to improve the quality of the power that is delivered to electrical load equipment. The term most often refers to a device that acts in one or more ways to deliver a voltage of the proper level and characteristics to enable load equipment to function properly. In some uses, power conditioner refers to a voltage regulator with at least one other function to improve power quality (e.g. power factor correction, noise suppression, transient impulse protection, etc.) The terms "power conditioning" and "power conditioner" can be misleading, as the word "power" here refers to the electricity generally rather than the more technical electric power. Conditioners specifically work to smooth the sinusoidal A.C. wave form and maintain a constant voltage over varying loads.

• https://en.wikipedia.org/wiki/Voltage_regulator - an electronic circuit that provides a stable DC voltage independent of the load current, temperature and AC line voltage variations. A voltage regulator may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages. Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators control the output of the plant. In an electric power distribution system, voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.

• https://en.wikipedia.org/wiki/Linear_regulator - a system used to maintain a steady voltage. The resistance of the regulator varies in accordance with the load resulting in a constant output voltage. The regulating device is made to act like a variable resistor, continuously adjusting a voltage divider network to maintain a constant output voltage and continually dissipating the difference between the input and regulated voltages as waste heat. By contrast, a switching regulator uses an active device that switches on and off to maintain an average value of output. Because the regulated voltage of a linear regulator must always be lower than input voltage, efficiency is limited and the input voltage must be high enough to always allow the active device to drop some voltage.

Linear regulators may place the regulating device in parallel with the load (shunt regulator) or may place the regulating device between the source and the regulated load (a series regulator). Simple linear regulators may only contain a Zener diode and a series resistor; more complicated regulators include separate stages of voltage reference, error amplifier and power pass element. Because a linear voltage regulator is a common element of many devices, integrated circuit regulators are very common. Linear regulators may also be made up of assemblies of discrete solid-state or vacuum tube components.

• https://en.wikipedia.org/wiki/Low-dropout_regulator - or LDO regulator is a DC linear voltage regulator that can regulate the output voltage even when the supply voltage is very close to the output voltage. The advantages of a low dropout voltage regulator over other DC to DC regulators include the absence of switching noise (as no switching takes place), smaller device size (as neither large inductors nor transformers are needed), and greater design simplicity (usually consists of a reference, an amplifier, and a pass element). The disadvantage is that, unlike switching regulators, linear DC regulators must dissipate power, and thus heat, across the regulation device in order to regulate the output voltage.

#### Reference

• https://en.wikipedia.org/wiki/Voltage_reference - an electronic device that ideally produces a fixed (constant) voltage irrespective of the loading on the device, power supply variations, temperature changes, and the passage of time. Voltage references are used in power supplies, analog-to-digital converters, digital-to-analog converters, and other measurement and control systems. Voltage references vary widely in performance; a regulator for a computer power supply may only hold its value to within a few percent of the nominal value, whereas laboratory voltage standards have precisions and stability measured in parts per million.

• https://en.wikipedia.org/wiki/Rubber_diode - or VBE multiplier is a Bipolar junction transistor circuit that serves as a voltage reference. It consists of one transistor and two resistors, and the reference voltage across the circuit is determined by the selected resistor values and the base-to-emitter voltage (VBE) of the transistor. The circuit behaves as a voltage divider, but with the voltage across the base-emitter resistor determined by the forward base-emitter junction voltage. It is commonly used in the biasing of push-pull output stages of amplifiers, where one benefit is thermal compensation: The temperature-dependent variations in the multiplier's VBE, can be made to match variations occurring in the VBE of the power transistors by mounting to the same heat sink. In this context, it is sometimes called a bias servo.

#### Conversion

• https://en.wikipedia.org/wiki/Electric_power_conversion - converting electric energy from one form to another such as converting between AC and DC; or just changing the voltage or frequency; or some combination of these. A power converter is an electrical or electro-mechanical device for converting electrical energy. This could be as simple as a transformer to change the voltage of AC power, but also includes far more complex systems. The term can also refer to a class of electrical machinery that is used to convert one frequency of alternating current into another frequency. Power conversion systems often incorporate redundancy and voltage regulation. One way of classifying power conversion systems is according to whether the input and output are alternating current (AC) or direct current (DC).

The power conversion systems can be classified according to the type of the input and output power:

• AC to DC (rectifier)
• DC to AC (inverter)
• DC to DC (DC-to-DC converter)
• AC to AC (AC-to-AC converter)

• https://en.wikipedia.org/wiki/Diode_bridge - an arrangement of four (or more) diodes in a bridge circuit configuration that provides the same polarity of output for either polarity of input. When used in its most common application, for conversion of an alternating-current (AC) input into a direct-current (DC) output, it is known as a bridge rectifier. A bridge rectifier provides full-wave rectification from a two-wire AC input, resulting in lower cost and weight as compared to a rectifier with a 3-wire input from a transformer with a center-tapped secondary winding. The essential feature of a diode bridge is that the polarity of the output is the same regardless of the polarity at the input. The diode bridge circuit was invented by Polish electrotechnician Karol Pollak and patented in December 1895 in Great Britain and in January 1896 in Germany. In 1897, the German physicist Leo Graetz independently invented and published a similar circuit. Today the circuit is still often referred to as a Graetz circuit or Graetz bridge. Prior to the availability of integrated circuits, a bridge rectifier was constructed from "discrete components", i.e., separate diodes. Since about 1950, a single four-terminal component containing the four diodes connected in a bridge configuration became a standard commercial component and is now available with various voltage and current ratings.

• https://en.wikipedia.org/wiki/Rectifier - an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.

• https://en.wikipedia.org/wiki/Ripple_(electrical) - specifically ripple voltage) in electronics is the residual periodic variation of the DC voltage within a power supply which has been derived from an alternating current (AC) source. This ripple is due to incomplete suppression of the alternating waveform after rectification. Ripple voltage originates as the output of a rectifier or from generation and commutation of DC power. Ripple (specifically ripple current or surge current) may also refer to the pulsed current consumption of non-linear devices like capacitor-input rectifiers. Ripple is wasted power, and has many undesirable effects in a DC circuit: it heats components, causes noise and distortion, and may cause digital circuits to operate improperly. Ripple may be reduced by an electronic filter, and eliminated by a voltage regulator.

As well as these time-varying phenomena, there is a frequency domain ripple that arises in some classes of filter and other signal processing networks. In this case the periodic variation is a variation in the insertion loss of the network against increasing frequency. The variation may not be strictly linearly periodic. In this meaning also, ripple is usually to be considered an incidental effect, its existence being a compromise between the amount of ripple and other design parameters.

• https://en.wikipedia.org/wiki/DC-to-DC_converter - an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission).

• https://en.wikipedia.org/wiki/Transformer - a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. A varying current in one coil of the transformer produces a varying magnetic field, which in turn induces a varying electromotive force (emf) or "voltage" in a second coil. Power can be transferred between the two coils through the magnetic field, without a metallic connection between the two circuits. Faraday's law of induction discovered in 1831 described this effect. Transformers are used to increase or decrease the alternating voltages in electric power applications.
• https://en.wikipedia.org/wiki/Tap_changer - a mechanism in transformers which allows for variable turn ratios to be selected in discrete steps. Transformers with this mechanism obtain this variable turn ratio by connecting to a number of access points known as taps along either the primary or secondary winding. These systems usually possess 33 taps (one at centre "Rated" tap and sixteen to increase and decrease the turn ratio) and allow for ±10% variation (each step providing 0.625% variation) from the nominal transformer rating which, in turn, allows for stepped voltage regulation of the output.

• https://en.wikipedia.org/wiki/Isolation_transformer - a transformer used to transfer electrical power from a source of alternating current (AC) power to some equipment or device while isolating the powered device from the power source, usually for safety reasons. Isolation transformers provide galvanic isolation and are used to protect against electric shock, to suppress electrical noise in sensitive devices, or to transfer power between two circuits which must not be connected. A transformer sold for isolation is often built with special insulation between primary and secondary, and is specified to withstand a high voltage between windings.

Isolation transformers block transmission of the DC component in signals from one circuit to the other, but allow AC components in signals to pass. Transformers that have a ratio of 1 to 1 between the primary and secondary windings are often used to protect secondary circuits and individuals from electrical shocks between energized conductors and earth ground. Suitably designed isolation transformers block interference caused by ground loops. Isolation transformers with electrostatic shields are used for power supplies for sensitive equipment such as computers, medical devices, or laboratory instruments.

• https://en.wikipedia.org/wiki/Charge_pump - a kind of DC to DC converter that uses capacitors for energetic charge storage to raise or lower voltage. Charge-pump circuits are capable of high efficiencies, sometimes as high as 90–95%, while being electrically simple circuits.

• https://en.wikipedia.org/wiki/Buck_converter - step-down converter, is a DC-to-DC power converter which steps down voltage (while stepping up current) from its input (supply) to its output (load). It is a class of switched-mode power supply (SMPS) typically containing at least two semiconductors (a diode and a transistor, although modern buck converters frequently replace the diode with a second transistor used for synchronous rectification) and at least one energy storage element, a capacitor, inductor, or the two in combination. To reduce voltage ripple, filters made of capacitors (sometimes in combination with inductors) are normally added to such a converter's output (load-side filter) and input (supply-side filter). Switching converters (such as buck converters) provide much greater power efficiency as DC-to-DC converters than linear regulators, which are simpler circuits that lower voltages by dissipating power as heat, but do not step up output current.

• https://en.wikipedia.org/wiki/Boost_converter - step-up converter, is a DC-to-DC power converter that steps up voltage (while stepping down current) from its input (supply) to its output (load). It is a class of switched-mode power supply (SMPS) containing at least two semiconductors (a diode and a transistor) and at least one energy storage element: a capacitor, inductor, or the two in combination. To reduce voltage ripple, filters made of capacitors (sometimes in combination with inductors) are normally added to such a converter's output (load-side filter) and input (supply-side filter).

• https://en.wikipedia.org/wiki/Buck–boost_converter - a type of DC-to-DC converter that has an output voltage magnitude that is either greater than or less than the input voltage magnitude. It is equivalent to a flyback converter using a single inductor instead of a transformer. Two different topologies are called buck–boost converter. Both of them can produce a range of output voltages, ranging from much larger (in absolute magnitude) than the input voltage, down to almost zero; The inverting topology, and A buck (step-down) converter combined with a boost (step-up) converter, sometimes called a "four-switch buck-boost converter"

• https://en.wikipedia.org/wiki/Flyback_converter - used in both AC/DC and DC/DC conversion with galvanic isolation between the input and any outputs. The flyback converter is a buck-boost converter with the inductor split to form a transformer, so that the voltage ratios are multiplied with an additional advantage of isolation. When driving for example a plasma lamp or a voltage multiplier the rectifying diode of the boost converter is left out and the device is called a flyback transformer. When driving for example a plasma lamp or a voltage multiplier the rectifying diode of the boost converter is left out and the device is called a flyback transformer.
• https://en.wikipedia.org/wiki/Flyback_transformer - FBT, also called a line output transformer (LOPT), is a special type of electrical transformer. It was initially designed to generate high voltage sawtooth signals at a relatively high frequency. In modern applications, it is used extensively in switched-mode power supplies for both low (3 V) and high voltage (over 10 kV) supplies.

• https://en.wikipedia.org/wiki/Push–pull_converter - a type of DC-to-DC converter, a switching converter that uses a transformer to change the voltage of a DC power supply. The distinguishing feature of a push-pull converter is that the transformer primary is supplied with current from the input line by pairs of transistors in a symmetrical push-pull circuit. The transistors are alternately switched on and off, periodically reversing the current in the transformer. Therefore, current is drawn from the line during both halves of the switching cycle. This contrasts with buck-boost converters, in which the input current is supplied by a single transistor which is switched on and off, so current is only drawn from the line during half the switching cycle. During the other half the output power is supplied by energy stored in inductors or capacitors in the power supply. Push–pull converters have steadier input current, create less noise on the input line, and are more efficient in higher power applications.

• https://en.wikipedia.org/wiki/Gain_(electronics) - a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port by adding energy converted from some power supply to the signal. It is usually defined as the mean ratio of the signal amplitude or power at the output port to the amplitude or power at the input port. It is often expressed using the logarithmic decibel (dB) units ("dB gain"). A gain greater than one (greater than zero dB), that is amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one.

The term gain alone is ambiguous, and can refer to the ratio of output to input voltage (voltage gain), current (current gain) or electric power (power gain). In the field of audio and general purpose amplifiers, especially operational amplifiers, the term usually refers to voltage gain, but in radi... to power gain. Furthermore, the term gain is also applied in systems such as sensors where the input and output have different units; in such cases the gain units must be specified, as in "5 microvolts per photon" for the responsivity of a photosensor. The "gain" of a bipolar transistor normally refers to forward current transfer ratio, either hFE ("Beta", the static ratio of Ic divided by Ib at some operating point), or sometimes hfe (the small-signal current gain, the slope of the graph of Ic against Ib at a point). The gain of an electronic device or circuit generally varies with the frequency of the applied signal. Unless otherwise stated, the term refers to the gain for frequencies in the passband, the intended operating frequency range, of the equipment.

• https://en.wikipedia.org/wiki/Backfeeding - flow of electrical energy in the reverse direction from its normal flow. For example, backfeeding may occur when electrical power is injected into the local power grid from a source other than a utility company generator.

• https://en.wikipedia.org/wiki/Differential_signaling - a method for electrically transmitting information using two complementary signals. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conductors can be wires (typically twisted together) or traces on a circuit board. The receiving circuit responds to the electrical difference between the two signals, rather than the difference between a single wire and ground. The opposite technique is called single-ended signaling. Differential pairs are usually found on printed circuit boards, in twisted-pair and ribbon cables, and in connectors.

• https://en.wikipedia.org/wiki/Balanced_circuit - circuitry for use with a balanced line or the balanced line itself. Balanced lines are a common method of transmitting many types of electrical communication signals between two points on two wires. In a balanced line the two signal lines are of a matched impedance to help ensure that interference induced in the line is common-mode and can be removed at the receiving end by circuitry with good common-mode rejection. To maintain the balance, circuit blocks which interface to the line, or are connected in the line, must also be balanced.
• https://en.wikipedia.org/wiki/Balanced_line - or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits. The chief advantage of the balanced line format is good rejection of external noise when fed to a differential amplifier. Common forms of balanced line are twin-lead, used for radio frequency signals and twisted pair, used for lower frequencies. They are to be contrasted to unbalanced lines, such as coaxial cable, which is designed to have its return conductor connected to ground, or circuits whose return conductor actually is ground. Balanced and unbalanced circuits can be interconnected using a transformer called a balun. Circuits driving balanced lines must themselves be balanced to maintain the benefits of balance. This may be achieved by transformer coupling or by merely balancing the impedance in each conductor.

• https://en.wikipedia.org/wiki/Common-mode_rejection_ratio - of a differential amplifier (or other device) is a metric used to quantify the ability of the device to reject common-mode signals, i.e., those that appear simultaneously and in-phase on both inputs. An ideal differential amplifier would have infinite CMRR, however this is not achievable in practice. A high CMRR is required when a differential signal must be amplified in the presence of a possibly large common-mode input, such as strong electromagnetic interference (EMI). An example is audio transmission over balanced line in sound reinforcement or recording.

• https://en.wikipedia.org/wiki/Balun - for balanced to unbalanced, is an electrical device that converts between a balanced signal (two signals working against each other where ground is irrelevant) and an unbalanced signal (a single signal working against ground or pseudo-ground). A balun can take many forms and may include devices that also transform impedances but need not do so. Transformer baluns can also be used to connect lines of differing impedance. Sometimes, in the case of transformer baluns, they use magnetic coupling but need not do so. Common-mode chokes are also used as baluns and work by eliminating, rather than ignoring, common mode signals. A variation of this device is the unun, which transfers signal from one unbalanced line to another.

• https://en.wikipedia.org/wiki/Motor–generator - an M–G set, is a device for converting electrical power to another form. Motor–generator sets are used to convert frequency, voltage, or phase of power. They may also be used to isolate electrical loads from the electrical power supply line. Large motor–generators were widely used to convert industrial amounts of power while smaller motor–generators (such as the one shown in the picture) were used to convert battery power to higher DC voltages. These motor-generators should not be confused with "motor generator", which is a term occasionally used to describe a portable generator powered by an internal combustion engine.

• https://en.wikipedia.org/wiki/Power_inverter - an electronic device or circuitry that changes direct current (DC) to alternating current (AC). The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source. A power inverter can be entirely electronic or may be a combination of mechanical effects (such as a rotary apparatus) and electronic circuitry. Static inverters do not use moving parts in the conversion process.

### Delivery

• https://en.wikipedia.org/wiki/Electricity_delivery - the process that goes from generation of electricity in the power station to the use by the consumer. The main processes in electricity delivery are, by order: Generation, Transmission, Distribution, Retailing

• https://en.wikipedia.org/wiki/Electrical_grid - an interconnected network for delivering electricity from producers to consumers. It consists of generating stations that produce electrical power, high voltage transmission lines that carry power from distant sources to demand centers, and distribution lines that connect individual customers. Power stations may be located near a fuel source, at a dam site, or to take advantage of renewable energy sources, and are often located away from heavily populated areas. They are usually quite large to take advantage of economies of scale. The electric power which is generated is stepped up to a higher voltage at which it connects to the electric power transmission net. The bulk power transmission network will move the power long distances, sometimes across international boundaries, until it reaches its wholesale customer (usually the company that owns the local electric power distribution network).

• https://en.wikipedia.org/wiki/Electric_power_transmission - the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines which facilitate this movement are known as a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is known as the "power grid" in North America, or just "the grid". In the United Kingdom, India, Malaysia and New Zealand, the network is known as the "National Grid".A wide area synchronous grid, also known as an "interconnection" in North America, directly connects a large number of generators delivering AC power with the same relative frequency to a large number of consumers. For example, there are four major interconnections in North America (the Western Interconnection, the Eastern Interconnection, the Quebec Interconnection and the Electric Reliability Council of Texas (ERCOT) grid). In Europe one large grid connects most of continental Europe.

• https://en.wikipedia.org/wiki/High-voltage_direct_current - also called a power superhighway or an electrical superhighway) uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current (AC) systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses. For underwater power cables, HVDC avoids the heavy currents required to charge and discharge the cable capacitance each cycle. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may still be justified, due to other benefits of direct current links. HVDC uses voltages between 100 kV and 1,500 kV.HVDC allows power transmission between unsynchronized AC transmission systems. Since the power flow through an HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power. HVDC also allows transfer of power between grid systems running at different frequencies, such as 50 Hz and 60 Hz. This improves the stability and economy of each grid, by allowing exchange of power between incompatible networks.

• https://en.wikipedia.org/wiki/HVDC_converter - converts electric power from high voltage alternating current (AC) to high-voltage direct current (HVDC), or vice versa. HVDC is used as an alternative to AC for transmitting electrical energy over long distances or between AC power systems of different frequencies. HVDC converters capable of converting up to two gigawatts (GW) and with voltage ratings of up to 1,100 kilovolts (kV) have been built, and even higher ratings are technically feasible. A complete converter station may contain several such converters in series and/or parallel.
• https://en.wikipedia.org/wiki/HVDC_converter_station - a specialised type of substation which forms the terminal equipment for a high-voltage direct current (HVDC) transmission line. It converts direct current to alternating current or the reverse. In addition to the converter, the station usually contains: three-phase alternating current switch gear, transformers, capacitors or synchronous condensers for reactive power filters for harmonic suppression, and direct current switch gear.

• https://en.wikipedia.org/wiki/Electric_power_distribution - the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers. Distribution substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between 2 kV and 35 kV with the use of transformers. Primary distribution lines carry this medium voltage power to distribution transformers located near the customer's premises. Distribution transformers again lower the voltage to the utilization voltage used by lighting, industrial equipment or household appliances. Often several customers are supplied from one transformer through secondary distribution lines. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the subtransmission level.

• https://en.wikipedia.org/wiki/Busbar - a busbar (also bus bar, and sometimes misspelled as buss bar or bussbar) is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution. They are also used to connect high voltage equipment at electrical switchyards, and low voltage equipment in battery banks. They are generally uninsulated, and have sufficient stiffness to be supported in air by insulated pillars. These features allow sufficient cooling of the conductors, and the ability to tap in at various points without creating a new joint.

### Storage

• Battery University - a free educational website offering hands-on battery information to engineers, educators, media, students and battery users alike. The tutorials evaluate the advantages and limitations of battery chemistries, advise on best battery choice and suggest ways to extend battery life.

• Battery calculator - Capacity, C-rating, ampere, charge and discharge run-time calculator (energy storage)

UPG 12V 55Ah Sealed

• https://en.wikipedia.org/wiki/Electric_vehicle_battery - EVB or traction battery is a battery used to power the propulsion of battery electric vehicles (BEVs). Vehicle batteries are usually a secondary (rechargeable) battery. Traction batteries are used in forklifts, electric golf carts, riding floor scrubbers, electric motorcycles, electric cars, trucks, vans, and other electric vehicles.

Electric-vehicle batteries differ from starting, lighting, and ignition (SLI) batteries because they are designed to give power over sustained periods of time. Deep-cycle batteries are used instead of SLI batteries for these applications. Traction batteries must be designed with a high ampere-hour capacity. Batteries for electric vehicles are characterized by their relatively high power-to-weight ratio, energy-to-weight ratio and energy density; smaller, lighter batteries reduce the weight of the vehicle and improve its performance. Compared to liquid fuels, most current battery technologies have much lower specific energy, and this often impacts the maximal all-electric range of the vehicles. However, metal-air batteries have high specific energy because the cathode is provided by the surrounding oxygen in the air. Rechargeable batteries used in electric vehicles include lead–acid ("flooded", deep-cycle, and VRLA), NiCd, nickel–metal hydride, lithium-ion, Li-ion polymer, and, less commonly, zinc–air and molten-salt batteries. The amount of electricity (i.e. electric charge) stored in batteries is measured in ampere hours or in coulombs, with the total energy often measured in watt hours.

• https://en.wikipedia.org/wiki/Lead–acid_battery - invented in 1859 by French physicist Gaston Planté and is the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by automobile starter motors.

As they are inexpensive compared to newer technologies, lead–acid batteries are widely used even when surge current is not important and other designs could provide higher energy densities. Large-format lead–acid designs are widely used for storage in backup power supplies in cell phone towers, high-availability settings like hospitals, and stand-alone power systems. For these roles, modified versions of the standard cell may be used to improve storage times and reduce maintenance requirements. Gel-cells and absorbed glass-mat batteries are common in these roles, collectively known as VRLA (valve-regulated lead–acid) batteries.

• https://en.wikipedia.org/wiki/VRLA_battery - valve-regulated lead-acid battery ('VRLA battery) sometimes called sealed lead-acid (SLA), gel cell, or maintenance free battery. Due to their construction, the gel and absorbent glass mat (AGM) types of VRLA can be mounted in any orientation, and do not require constant maintenance. The term "maintenance free" is a misnomer as VRLA batteries still require cleaning and regular functional testing. They are widely used in large portable electrical devices, off-grid power systems and similar roles, where large amounts of storage are needed at a lower cost than other low-maintenance technologies like lithium-ion.

There are three primary types of VRLA batteries, sealed VR wet cell, AGM and gel cells. Gel cells add silica dust to the electrolyte, forming a thick putty-like gel. These are sometimes referred to as "silicone batteries". AGM (absorbent glass mat) batteries feature fiberglass mesh between the battery plates which serves to contain the electrolyte. Both designs offer advantages and disadvantages compared to conventional batteries and sealed VR wet cells, as well as each other.

#### Lithium

• https://en.wikipedia.org/wiki/Lithium_battery - are primary batteries that have lithium as an anode. These types of batteries are also referred to as lithium-metal batteries. They stand apart from other batteries in their high charge density (long life) and high cost per unit. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V (comparable to a zinc–carbon or alkaline battery) to about 3.7 V. Lithium batteries are widely used in portable consumer electronic devices, and in electric vehicles ranging from full sized vehicles to radio controlled toys.

Disposable primary lithium batteries must be distinguished from secondary lithium-ion and lithium-polymer, which are rechargeable batteries. Lithium is especially useful, because its ions can be arranged to move between the anode and the cathode, using an intercalated lithium compound as the cathode material but without using lithium metal as the anode material. Pure lithium will instantly react with water, or even moisture in the air; the lithium in lithium ion batteries is in a less reactive compound. Mistreatment during charging or discharging can cause outgassing of some of their contents, which can cause explosions or fire.

#### Lithium-ion

• https://en.wikipedia.org/wiki/Lithium-ion_battery - or Li-ion battery (abbreviated as LIB) is a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, compared to the metallic lithium used in a non-rechargeable lithium battery. The electrolyte, which allows for ionic movement, and the two electrodes are the constituent components of a lithium-ion battery cell. Lithium-ion batteries are common in home electronics. They are one of the most popular types of rechargeable batteries for portable electronics, with a high energy density, tiny memory effect and low self-discharge. LIBs are also growing in popularity for military, battery electric vehicle and aerospace applications.

• https://en.wikipedia.org/wiki/Lithium_polymer_battery - or more correctly lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly and others), is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid one. High conductivity semisolid (gel) polymers form this electrolyte. These batteries provide a higher specific energy than other lithium battery types and are being used in applications where weight is a critical feature - like tablet computers, cellular telephone handsets or radio-controlled aircraft.

• https://en.wikipedia.org/wiki/Lithium_ion_manganese_oxide_battery - a lithium ion cell that uses manganese dioxide, MnO2, as the primary cathode material. They function through the same intercalation/de-intercalation mechanism as other commercialized secondary battery technologies, such as LiCoO2. They are a promising technology as their manganese-oxide components are earth-abundant, inexpensive, non-toxic, and provide better thermal stability

• https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery - LiFePO4, battery, also called LFP battery (with "LFP" standing for "lithium ferrophosphate"), is a type of rechargeable battery, specifically a lithium-ion battery, which uses LiFePO4 as a cathode material, and a graphitic carbon electrode with a metallic current collector grid as the anode. The specific capacity of LiFePO4 is higher than that of the related lithium cobalt oxide (LiCoO2) chemistry, but its energy density is slightly lower due to its low operating voltage. The main problem of LiFePO4 is its low electrical conductivity. Therefore, all the LiFePO4 cathodes under consideration are actually LiFePO4/C. Because of low cost, low toxicity, well-defined performance, long-term stability, etc. LiFePO4 is finding a number of roles in vehicle use, utility scale stationary applications, and backup power.

##### 18650 cells

Nominal Voltage: 3.6V, 3.7V

Capacity: ~3Ah

4S (4 in serial) = 14.4V, 14.8V

• 40 cells for 30Ah (4S10P)
• 160 cells for 120Ah (4S40P)

##### Suppliers
• NKON - Wholesale in batteries, chargers and LED flashlights

##### Holders / modules

• N.E.S.E module - cell format module born in Endless-Sphere community. It was long debated and awaited product for easy 18650 cell termination and assembly into battery packs. The main goal of this module was to make it simple, easy to assemble, modular and replaceable.

##### BMS

LightHarvest Solar

#### Ultrabattery

• https://en.wikipedia.org/wiki/UltraBattery - a hybrid energy storage device invented by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO). UltraBattery combines ultracapacitor technology with lead-acid battery technology in a single cell with a common electrolyte.

#### BMS

• https://en.wikipedia.org/wiki/Battery_management_system - any electronic system that manages a rechargeable battery (cell or battery pack), such as by protecting the battery from operating outside its Safe Operating Area, monitoring its state, calculating secondary data, reporting that data, controlling its environment, authenticating it and / or balancing it. A battery pack built together with a battery management system with an external communication data bus is a smart battery pack. A smart battery pack must be charged by a smart battery charger.

• https://en.wikipedia.org/wiki/Battery_balancing - and battery redistribution refer to techniques that maximize the capacity of a battery pack with multiple cells (usually in series) to make all of capacity available for use and increase each cell's longevity. A battery balancer or battery regulator is a device in a battery pack that performs battery balancing. Balancers are often found in lithium-ion battery packs for cell phones and laptop computers. They can also be found in battery electric vehicle battery packs. Typically, the individual cells in a battery have somewhat different capacities and may be at different levels of state of charge (SOC). This is due to manufacturing variances, assembly variances (e.g., cells from one production run mixed others), different histories experienced amongst the cells in a battery pack (e.g., charging/discharging, heat exposures, etc.) and must be accounted for to maximize life and service of the particular battery pack in use. Each b...tive and appropriate balancing, discharging during use must stop when the cell with the lowest capacity is empty (even though other cells aren't); this limits the energy that can be taken from and returned to the battery.

Without balancing, the smallest capacity cell is a problem, and potentially a serious one. It can be easily overcharged or over-discharged whilst cells with higher capacities are only partial charged. The balance circuit should arrange for higher capacity cells to fully charge/discharge, while smaller capacity cells are charged/discharged suitably—which will necessarily be rather different. In a properly balanced battery pack, the cell with the largest capacity will be filled without overcharging any other (i.e., weaker, smaller) cell, and it can be discharged in use without over-discharging any other cell. Battery balancing is done by transferring energy from or to individual cells, until the SOC of the cell with the lowest capacity is equal to the battery's SOC.

• BMS chips options - A comparison of commercially available Integrated Circuits (ICs) for BMSs for large Li-Ion battery packs

### Circuits

• https://en.wikipedia.org/wiki/Network_analysis_(electrical_circuits) - A network, in the context of electronics, is a collection of interconnected components. Network analysis is the process of finding the voltages across, and the currents through, every component in the network. There are many different techniques for calculating these values. However, for the most part, the applied technique assumes that the components of the network are all linear. The methods described in this article are only applicable to linear network analysis, except where explicitly stated.

• https://en.wikipedia.org/wiki/Topology_(electrical_circuits) - of an electronic circuit is the form taken by the network of interconnections of the circuit components. Different specific values or ratings of the components are regarded as being the same topology. Topology is not concerned with the physical layout of components in a circuit, nor with their positions on a circuit diagram. It is only concerned with what connections exist between the components. There may be numerous physical layouts and circuit diagrams that all amount to the same topology.

Strictly speaking, replacing a component with one of an entirely different type is still the same topology. In some contexts, however, these can loosely be described as different topologies. For instance, interchanging inductors and capacitors in a low-pass filter results in a high-pass filter. These might be described as high-pass and low-pass topologies even though the network topology is identical. A more correct term for these classes of object (that is, a network where the type of component is specified but not the absolute value) is prototype network.

• https://en.wikipedia.org/wiki/Biasing - means establishing predetermined voltages or currents at various points of an electronic circuit for the purpose of establishing proper operating conditions in electronic components. Many electronic devices such as transistors and vacuum tubes, whose function is processing time-varying (AC) signals also require a steady (DC) current or voltage to operate correctly — a bias. The AC signal applied to them is superposed on this DC bias current or voltage. The operating point of a device, also known as bias point, quiescent point, or Q-point, is the steady-state (DC) voltage or current at a specified terminal of an active device (a transistor or vacuum tube) with no input signal applied. A bias circuit is a portion of the device's circuit which supplies this steady current or voltage.

• https://en.wikipedia.org/wiki/Bridge_circuit - a topology of electrical circuitry in which two circuit branches (usually in parallel with each other) are "bridged" by a third branch connected between the first two branches at some intermediate point along them. The bridge was originally developed for laboratory measurement purposes and one of the intermediate bridging points is often adjustable when so used. Bridge circuits now find many applications, both linear and non-linear, including in instrumentation, filtering and power conversion.

• https://en.wikibooks.org/wiki/Signals_and_Systems - This book is about the study of engineering signals and systems, from a discipline-neutral approach. It is a fundamental starting point in the field of engineering, and serves as the basic material that other advanced books in the engineering subject area are based. This book looks at the concepts of systems, serving as an introduction to systems theory. Also, this book examines signals, and the way that signals interact with physical systems. While this book strives to be discipline-neutral, it currently is focused strongly on electrical engineering concepts. It is hoped that this book will be expanded to include information from other disciplines as well.

• https://en.wikipedia.org/wiki/Galvanic_isolation - a principle of isolating functional sections of electrical systems to prevent current flow; no direct conduction path is permitted. Energy or information can still be exchanged between the sections by other means, such as capacitance, induction or electromagnetic waves, or by optical, acoustic or mechanical means. Galvanic isolation is used where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor. Galvanic isolation is also used for safety, preventing accidental current from reaching ground through a person's body.

• xDevs.com - dedicated to electronics engineering, involving, but not limited to digital and analog circuit design, PCB layout, field programmable devices and gate array applications and firmware development for embedded systems. All data presented here is free for grabs and use, without any warranties. There are no login, registration, email forms or anything else needed to view articles and referenced files. You are free to share and copy content, if links to source pages are added. This way you support our efforts to keep everything online.

• https://en.wikipedia.org/wiki/Chip_select - or slave select (SS) is the name of a control line in digital electronics used to select one (or a set) of integrated circuits (commonly called "chips") out of several connected to the same computer bus, usually utilizing the three-state logic.

### Connectors and cable

• https://en.wikipedia.org/wiki/DIN_rail - a metal rail of a standard type widely used for mounting circuit breakers and industrial control equipment inside equipment racks. These products are typically made from cold rolled carbon steel sheet with a zinc-plated or chromated bright surface finish. The term derives from the original specifications published by Deutsches Institut für Normung (DIN) in Germany, which have since been adopted as European (EN) and international (IEC) standards.

• https://en.wikipedia.org/wiki/IEC_60309 - an international standard from the International Electrotechnical Commission (IEC) for "plugs, socket-outlets and couplers for industrial purposes". The maximum voltage allowed by the standard is 1000 V DC or AC; the maximum current, 800 A; and the maximum frequency, 500 Hz. The ambient temperature range is −25 °C to 40 °C.

There is a range of plugs and sockets of different sizes with differing numbers of pins, depending on the current supplied and number of phases accommodated. The fittings are popular in open-air conditions, as they include IP44 weather-proofing. They are also sometimes used in situations where their special capabilities (such as high current rating or three-phase facilities) are not needed, to discourage potential users from connecting domestic appliances to the sockets, as 'normal' domestic plugs will not fit.

The cable connectors and sockets are keyed and colour-coded, according to the voltage range and frequency used; common colours for 50–60 Hz AC power are yellow for 100–130 volts, blue for 200–250 volts, and red for 380–480 volts. The blue fittings are often used for providing weather-proofed exterior sockets for outdoor apparatus. In camping situations, the large 32 A blue fittings provide power to static caravans, whilst the smaller blue 16 A version powers touring caravans and tents. The yellow fittings are used to provide transformer isolated 110 V supplies for UK construction sites to reduce the risk of electric shock, and this use spills over into uses of power tools outside of the construction site environment. The red three-phase versions are used for three-phase portable equipment.

• https://wiki.pierobotics.org/wiki/XT60 - used to make secure connections when high currents will be used. It will be usually found with one black and red wire coming out it. For most electrical components you will attach to the robot, you will need an XT60. There are two variants of the XT60 connector, both male and female.

• https://en.wikipedia.org/wiki/JST_connector - are electrical connectors manufactured to the design standards originally developed by J.S.T. Mfg. Co. (Japan Solderless Terminal). JST manufactures numerous series (families) and pitches (pin-to-pin distance) of connectors. JST connectors are used in many types of products, and commonly used by electronics hobbyists and consumer products for rechargeable battery packs, battery balancers, battery eliminator circuits, and radio controlled servos. The term "JST" is incorrectly used as a vernacular term meaning any small white electrical connector mounted on PCBs. JST-XH.

• https://en.wikipedia.org/wiki/DC_connector - or DC plug, for one common type of connector) is an electrical connector for supplying direct current (DC) power. Compared to domestic AC power plugs and sockets, DC connectors have many more standard types that are not interchangeable. The dimensions and arrangement of DC connectors can be chosen to prevent accidental interconnection of incompatible sources and loads. Types vary from small coaxial connectors used to power portable electronic devices from AC adapters, to connectors used for automotive accessories and for battery packs in portable equipment.

• https://en.wikipedia.org/wiki/Socapex - a brand of electrical connectors, known in the entertainment industry primarily for their 19-pin electrical connectors, commonly known as Socapex connectors, and used in film, television, and stage lighting to terminate the ends of a multicable. They are wired with six hot/live pins, six neutral pins, six ground/earth pins, and a final central pin used to aid alignment of the male end of the connector with a female receptacle. The Socapex was first created by a company called Socapex in 1961, which later on became Amphenol Socapex. "Socapex" became a brand name owned by Amphenol Socapex, the term is now often applied to similar off-brand connectors as a genericized trademark.

• https://en.wikipedia.org/wiki/RF_connector - (radio frequency connector) is an electrical connector designed to work at radio frequencies in the multi-megahertz range. RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission line impedance at the connection in order to reduce signal reflection and power loss. As the frequency increases, transmission line effects become more important, with small impedance variations from connectors causing the signal to reflect rather than pass through. An RF connector must not allow external signals into the circuit through electromagnetic interference and capacitive pickup.Mechanically, RF connectors may provide a fastening mechanism (thread, bayonet, braces, blind mate) and springs for a low ohmic electric contact while sparing the gold surface, thus allowing very high mating cycles and reducing the insertion force. Research activity in the area of radio-frequency (RF) circuit design has surged in the 2000s in direct response to the enormous market demand for inexpensive, high-data-rate wireless transceivers. Common types of RF connectors are used for television receivers, two-way radio, certain Wi-Fi devices with removable antennas, and industrial or scientific measurements instruments using radio frequencies.

• https://en.wikipedia.org/wiki/TV_aerial_plug - a colloquial name for a connector used to connect coaxial cables with each other and with terrestrial VHF/UHF roof antennas, antenna signal amplifiers, CATV distribution equipment, TV sets and FM / DAB-radio receivers.
• https://en.wikipedia.org/wiki/UHF_connector - a dated name for a threaded RF connector. The connector design was invented in the 1930s for use in the radio industry, and is a shielded form of the "banana plug". It is a widely-used standard connector for HF transmission lines on full-sized radio equipment, with BNC connectors predominating for smaller, hand-held equipment.

• https://en.wikipedia.org/wiki/N_connector - aka type-N connector, is a threaded, weatherproof, medium-size RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave-frequency signals, and was invented in the 1940s by Paul Neill of Bell Labs, after whom the connector is named.
• https://en.wikipedia.org/wiki/SMA_connector - connectors are semi-precision coaxial RF connectors developed in the 1960s as a minimal connector interface for coaxial cable with a screw-type coupling mechanism. The connector has a 50 Ω impedance. SMA is designed for use from DC (0 Hz) to 18 GHz, and is most commonly used in microwave systems, hand-held radio and mobile telephone antennas, and more recently with WiFi antenna systems and USB software-defined radio dongles[citation needed]. It is also commonly used in radio astronomy, particularly at higher frequencies (5 GHz+).SMA connectors can be visually confused with the standard household 75-ohm type F coax connector (diameters: Male 7⁄16 inch (11 mm) circular or hex; female 3⁄8 in (9.5 mm) external threads), as there is only about a 2 mm difference overall in the specifications. Type F cannot be mated with SMA connectors without the use of an adapter.

• KPSE 26482-Style Series I / VG95328 | ITT Cannon - Cannon's KPSE miniature circular connectors are designed to be comparable with the specifications for MIL-DTL-26482 (formerly MIL-C-26482) with a positive three point bayonet coupling, five-keyway polarization and high insert arrangement contact density. The KPSE series are high performance crimp connectors that feature “clip-in” contact and insulator design and are optimized for fast assembly and high volume production environments. KPSE connectors are intermateable with most connectors and accessories manufactured in accordance with MIL-DTL-26482 and VG95328 standards. These highly engineered, ruggedized connectors are designed for durability and reliability in harsh environment applications such as military vehicles and helicopters, industrial transports and commercial aerospace in-flight entertainment systems.

### Signal

• https://en.wikipedia.org/wiki/Signal - as referred to in communication systems, signal processing, and electrical engineering is a function that "conveys information about the behaviour or attributes of some phenomenon". In the physical world, any quantity exhibiting variation in time or variation in space (such as an image) is potentially a signal that might provide information on the status of a physical system, or convey a message between observers, among other possibilities. The IEEE Transactions on Signal Processing states that the term "signal" includes audio, video, speech, image, communication, geophysical, sonar, radar, medical and musical signals.

In nature, signals can take the form of any action by one organism able to be perceived by other organisms, ranging from the release of chemicals by plants to alert nearby plants of the same type of a predator, to sounds or motions made by animals to alert other animals of the presence of danger or of food. Signaling occurs in organisms all the way down to the cellular level, with cell signaling. Signaling theory, in evolutionary biology, proposes that a substantial driver for evolution is the ability for animals to communicate with each other by developing ways of signaling. In human engineering, signals are typically provided by a sensor, and often the original form of a signal is converted to another form of energy using a transducer. For example, a microphone converts an acoustic signal to a voltage waveform, and a speaker does the reverse.

Engineering disciplines such as electrical engineering have led the way in the design, study, and implementation of systems involving transmission, storage, and manipulation of information. In the latter half of the 20th century, electrical engineering itself separated into several disciplines, specialising in the design and analysis of systems that manipulate physical signals; electronic engineering and computer engineering as examples; while design engineering developed to deal with functional design of man–machine interfaces.

• https://en.wikipedia.org/wiki/Signaling_(telecommunications) - has the following meanings: the use of signals for controlling communications, the information exchange concerning the establishment and control of a telecommunication circuit and the management of the network, in contrast to manual setup of circuits by users or administrators, the sending of a signal from the transmitting end of a telecommunication circuit to inform a user at the receiving end that a message is to be sent.

• https://en.wikipedia.org/wiki/Line_code - a pattern of voltage, current, or photons used to represent digital data transmitted down a transmission line. This repertoire of signals is usually called a constrained code in data storage systems. Some signals are more prone to error than others when conveyed over a communication channel as the physics of the communication or storage medium constrains the repertoire of signals that can be used reliably. Common line encodings are unipolar, polar, bipolar, and Manchester code.

• https://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio - often abbreviated PSNR, is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. Because many signals have a very wide dynamic range, PSNR is usually expressed in terms of the logarithmic decibel scale.

• GTKWave - a fully featured GTK+ based wave viewer for Unix, Win32, and Mac OSX which reads LXT, LXT2, VZT, FST, and GHW files as well as standard Verilog VCD/EVCD files and allows their viewing.

• https://en.wikipedia.org/wiki/Continuous_wave - or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, almost always a sine wave, that for mathematical analysis is considered to be of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a sinusoidal carrier wave is switched on and off. Information is carried in the varying duration of the on and off periods of the signal, for example by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves were also known as "undamped waves", to distinguish this method from damped wave signals produced by earlier spark gap type transmitters.

• https://en.wikipedia.org/wiki/Frequency-division_multiplexing - a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands, each of which is used to carry a separate signal. This allows a single transmission medium such as a cable or optical fiber to be shared by multiple independent signals. Another use is to carry separate serial bits or segments of a higher rate signal in parallel.The most natural example of frequency-division multiplexing is radio and television broadcasting, in which multiple radio signals at different frequencies pass through the air at the same time. Another example is cable television, in which many television channels are carried simultaneously on a single cable. FDM is also used by telephone systems to transmit multiple telephone calls through high capacity trunklines, communications satellites to transmit multiple channels of data on uplink and downlink radio beams, and broadband DSL modems to transmit large amounts of computer data through twisted pair telephone lines, among many other uses.

• https://en.wikipedia.org/wiki/Diplexer - a passive device that implements frequency-domain multiplexing. Two ports (e.g., L and H) are multiplexed onto a third port (e.g., S). The signals on ports L and H occupy disjoint frequency bands. Consequently, the signals on L and H can coexist on port S without interfering with each other.

### Noise

• https://en.wikipedia.org/wiki/Electromagnetic_compatibility - the branch of electrical engineering concerned with the unintentional generation, propagation and reception of electromagnetic energy which may cause unwanted effects such as electromagnetic interference (EMI) or even physical damage in operational equipment. The goal of EMC is the correct operation of different equipment in a common electromagnetic environment. EMC pursues three main classes of issue. Emission is the generation of electromagnetic energy, whether deliberate or accidental, by some source and its release into the environment. EMC studies the unwanted emissions and the countermeasures which may be taken in order to reduce unwanted emissions. The second class, susceptibility, is the tendency of electrical equipment, referred to as the victim, to malfunction or break down in the presence of unwanted emissions, which are known as Radio frequency interference (RFI). Immunity is the opposite of susceptibility, being the ability of equipment to function correctly in the presence of RFI, with the discipline of "hardening" equipment being known equally as susceptibility or immunity. A third class studied is coupling, which is the mechanism by which emitted interference reaches the victim. Interference mitigation and hence electromagnetic compatibility may be achieved by addressing any or all of these issues, i.e., quieting the sources of interference, inhibiting coupling paths and/or hardening the potential victims. In practice, many of the engineering techniques used, such as grounding and shielding, apply to all three issues.

• https://en.wikipedia.org/wiki/Spurious_emission - any radio frequency not deliberately created or transmitted, especially in a device which normally does create other frequencies. A harmonic or other signal outside a transmitter's assigned channel would be considered a spurious emission. From ITU, 1.145 Spurious emission: Emission on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequency conversion products but exclude out-of-band emissions.

• https://en.wikipedia.org/wiki/Title_47_CFR_Part_15 - an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions. It is a part of Title 47 of the Code of Federal Regulations (CFR), and regulates everything from spurious emissions to unlicensed low-power broadcasting. Nearly every electronics device sold inside the United States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.

• https://en.wikipedia.org/wiki/Noise_(electronics) - an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. In communication systems, noise is an error or undesired random disturbance of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources. Noise is, however, typically distinguished from interference,[a] for example in the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise plus interference ratio (SNIR) measures. Noise is also typically distinguished from distortion, which is an unwanted systematic alteration of the signal waveform by the communication equipment, for example in signal-to-noise and distortion ratio (SINAD) and total harmonic distortion plus noise (THD+N) measures. While noise is generally unwanted, it can serve a useful purpose in some applications, such as random number generation or dither.

• https://en.wikipedia.org/wiki/Johnson–Nyquist_noise - thermal noise, Johnson noise, or Nyquist noise, is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied voltage. The generic, statistical physical derivation of this noise is called the fluctuation-dissipation theorem, where generalized impedance or generalized susceptibility is used to characterize the medium. Thermal noise in an ideal resistor is approximately white, meaning that the power spectral density is nearly constant throughout the frequency spectrum (however see the section below on extremely high frequencies). When limited to a finite bandwidth, thermal noise has a nearly Gaussian amplitude distribution.

• https://en.wikipedia.org/wiki/Electromagnetically_excited_acoustic_noise_and_vibration - audible sound directly produced by materials vibrating under the excitation of electromagnetic forces. Some examples of electromagnetically excited acoustic noise include the hum of transformers, the whine of some rotating electric machines, or the buzz of fluorescent lamps. The hissing of high voltage transmission lines is due to corona discharge, not magnetism. The phenomenon is also called audible magnetic noise, electromagnetic acoustic noise, or electromagnetically-induced acoustic noise, or more rarely, electrical noise, "coil noise", or " coil whine", depending on the application. The term electromagnetic noise is generally avoided as the term is used in the field of electromagnetic compatibility, dealing with radio frequencies. The term electrical noise describes electrical perturbations occurring in electronic circuits, not sound. For the later use, the terms electromagnetic vibrations or magnetic vibrations, focusing on the structural phenomenon are less ambiguous.

• https://en.wikipedia.org/wiki/Mains_hum - electric hum, or power line hum is a sound associated with alternating current at the frequency of the mains electricity. The fundamental frequency of this sound is usually 50 Hz or 60 Hz, depending on the local power-line frequency. The sound often has heavy harmonic content above 50–60 Hz. Because of the presence of mains current in mains-powered audio equipment as well as ubiquitous AC electromagnetic fields from nearby appliances and wiring, 50/60 Hz electrical noise can get into audio systems, and is heard as mains hum from their speakers. Mains hum may also be heard coming from powerful electric power grid equipment such as utility transformers, caused by mechanical vibrations induced by the powerful AC current in them.

### Distortion

• Total harmonic distortion - Wikipedia - a measurement of the harmonic distortion present in a signal and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. Distortion factor, a closely related term, is sometimes used as a synonym.

• https://en.wikipedia.org/wiki/Intermodulation - the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency components will form additional components at frequencies that are not just at harmonic frequencies (integer multiples) of either, like harmonic distortion, but also at the sum and difference frequencies of the original frequencies and at sums and differences of multiples of those frequencies.Intermodulation is caused by non-linear behaviour of the signal processing (physical equipment or even algorithms) being used. The theoretical outcome of these non-linearities can be calculated by generating a Volterra series of the characteristic, or more approximately by a Taylor series.

### Shielding

• https://en.wikipedia.org/wiki/Electromagnetic_shielding - the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF shielding. The shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. A conductive enclosure used to block electrostatic fields is also known as a Faraday cage. The amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic field.

• YouTube: Pigtail Demo - This video explains why pigtailed shield connections can cause shielded I/O cables to radiate and potentially fail EMI.

• https://en.wikipedia.org/wiki/Electromagnetic_interference - also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data. Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares, and auroras (Northern/Southern Lights). EMI frequently affects AM radios. It can also affect mobile phones, FM radios, and televisions, as well as observations for radio astronomy. EMI can be used intentionally for radio jamming, as in electronic warfare.

1. Interference that appears on both signal leads (signal and circuit return), or the terminals of a measuring circuit, and ground.
2. A form of coherent interference that affects two or more elements of a network in a similar manner (i.e., highly coupled) as distinct from locally generated noise or interference that is statistically independent between pairs of network elements.

• https://en.wikipedia.org/wiki/Choke_(electronics) - an inductor used to block higher-frequency alternating current (AC) in an electrical circuit, while passing lower-frequency or direct current (DC). A choke usually consists of a coil of insulated wire often wound on a magnetic core, although some consist of a doughnut-shaped "bead" of ferrite material strung on a wire. The choke's impedance increases with frequency. Its low electrical resistance passes both AC and DC with little power loss, but its reactance limits the amount of AC passed. The name comes from blocking—"choking"—high frequencies while passing low frequencies. It is a functional name; the name "choke" is used if an inductor is used for blocking or decoupling higher frequencies, but is simply called an "inductor" if used in electronic filters or tuned circuits. Inductors designed for use as chokes are usually distinguished by not having the low-loss construction (high Q factor) required in inductors used in tuned circuits and filtering applications.

• https://en.wikipedia.org/wiki/Ferrite_bead - or ferrite choke is a passive electric component that suppresses high frequency noise in electronic circuits. It is a specific type of electronic choke. Ferrite beads employ high frequency current dissipation in a ferrite ceramic to build high frequency noise suppression devices. Ferrite beads may also be called blocks, cores, rings, EMI filters, or chokes.

### Filters

• Design LC Filters (V 4.0 June 15, 2018 ) - web based application allows the user to design simple radio frequency filters with inductors and capacitors. These filters are most effective between 50 kHz and 500 mHz. Below 50 kHz active filters are usually more cost effective and above 500 mHz strip lines are generally used.

• OSH Park ~ - For use with USB to VGA adapters and Osmo-fl2k.

### Actuator

• https://en.wikipedia.org/wiki/Actuator - a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover". An actuator requires a control signal and a source of energy. The control signal is relatively low energy and may be electric voltage or current, pneumatic or hydraulic pressure, or even human power. Its main energy source may be an electric current, hydraulic fluid pressure, or pneumatic pressure. When it receives a control signal, an actuator responds by converting the signal's energy into mechanical motion. An actuator is the mechanism by which a control system acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input.

• https://en.wikipedia.org/wiki/Linear_actuator - an actuator that creates motion in a straight line, in contrast to the circular motion of a conventional electric motor. Linear actuators are used in machine tools and industrial machinery, in computer peripherals such as disk drives and printers, in valves and dampers, and in many other places where linear motion is required. Hydraulic or pneumatic cylinders inherently produce linear motion. Many other mechanisms are used to generate linear motion from a rotating motor.

### Motor

• https://en.wikipedia.org/wiki/Electric_motor - an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of mechanical energy into electrical energy and is done by an electric generator, which has much in common with a motor. Most electric motors operate through the interaction between an electric motor's magnetic field and winding currents to generate force. In certain applications, such as in regenerative braking with traction motors in the transportation industry, electric motors can also be used in reverse as generators to convert mechanical energy into electric power.

Found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives, electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as from the power grid, inverters or generators. Small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use. The largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, and so on. Electric motors are used to produce linear or rotary force (torque), and should be distinguished from devices such as magnetic solenoids and loudspeakers that convert electricity into motion but do not generate usable mechanical powers, which are respectively referred to as actuators and transducers.

• https://en.wikipedia.org/wiki/AC_motor - an electric motor driven by an alternating current (AC). The AC motor commonly consists of two basic parts, an outside stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft producing a second rotating magnetic field. The rotor magnetic field may be produced by permanent magnets, reluctance saliency, or DC or AC electrical windings. Less common, AC linear motors operate on similar principles as rotating motors but have their stationary and moving parts arranged in a straight line configuration, producing linear motion instead of rotation.

• https://en.wikipedia.org/wiki/Induction_motor - or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor. An induction motor's rotor can be either wound type or squirrel-cage type.

Three-phase squirrel-cage induction motors are widely used as industrial drives because they are rugged, reliable and economical. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans. Although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives (VFDs) in variable-speed service. VFDs offer especially important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan, pump and compressor load applications. Squirrel cage induction motors are very widely used in both fixed-speed and variable-frequency drive (VFD) applications.

• https://en.wikipedia.org/wiki/Variable-frequency_drive - VFD; also termed adjustable-frequency drive, “variable-voltage/variable-frequency (VVVF) drive”, variable speed drive, AC drive, micro drive or inverter drive, is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage. VFDs are used in applications ranging from small appliances to large compressors. About 25% of the world's electrical energy is consumed by electric motors in industrial applications, which can be more efficient when using VFDs in centrifugal load service; however, VFDs' global market penetration for all applications is relatively small. Over the last four decades, power electronics technology has reduced VFD cost and size and has improved performance through advances in semiconductor switching devices, drive topologies, simulation and control techniques, and control hardware and software. VFDs are made in a number of different low- and medium-voltage AC-AC and DC-AC topologies.

• https://en.wikipedia.org/wiki/Reluctance_motor - a type of electric motor that induces non-permanent magnetic poles on the ferromagnetic rotor. The rotor does not have any windings. Torque is generated through the phenomenon of magnetic reluctance.

### Oscillator

• https://en.wikipedia.org/wiki/Electronic_oscillator - an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal. They are widely used in many electronic devices. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games.

Oscillators are often characterized by the frequency of their output signal:

• A low-frequency oscillator (LFO) is an electronic oscillator that generates a frequency below approximately 20 Hz. This term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator.
• An audio oscillator produces frequencies in the audio range, about 16 Hz to 20 kHz.
• An RF oscillator produces signals in the radio frequency (RF) range of about 100 kHz to 100 GHz.

Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters. There are two main types of electronic oscillator – the linear or harmonic oscillator and the nonlinear or relaxation oscillator.

• https://en.wikipedia.org/wiki/Crystal_oscillator - an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency. This frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.

• https://en.wikipedia.org/wiki/Crystal_oven - a temperature-controlled chamber used to maintain the quartz crystal in electronic crystal oscillators at a constant temperature, in order to prevent changes in the frequency due to variations in ambient temperature. An oscillator of this type is known as an oven-controlled crystal oscillator (OCXO, where "XO" is an old abbreviation for "crystal oscillator".) This type of oscillator achieves the highest frequency stability possible with a crystal. They are typically used to control the frequency of radio transmitters, cellular base stations, military communications equipment, and for precision frequency measurement.

### Amplifier

• https://en.wikipedia.org/wiki/Amplifier - electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current). An amplifier uses electric power from a power supply to increase the amplitude of a signal. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. An amplifier is a circuit that has a power gain greater than one.

An amplifier can either be a separate piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment. Amplifiers can be categorized in different ways. One is by the frequency of the electronic signal being amplified. For example, audio amplifiers amplify signals in the audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz, and servo amplifiers and instrumentation amplifiers may work with very low frequencies down to direct current. Amplifiers can also be categorized by their physical placement in the signal chain; a preamplifier may precede other signal processing stages, for example. The first practical electrical device which could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912.

• https://en.wikipedia.org/wiki/Open-loop_gain - an amplifier is the gain obtained when no overall feedback is used in the circuit. Open loop gain, in some amplifiers, can be exceedingly high. An ideal operational amplifier has infinite open-loop gain. Typically an op-amp may have a maximal open-loop gain of around 10^5. The very high open-loop gain of the op-amp allows a wide range of feedback levels to be applied to achieve the desired performance. Normally, feedback is applied around an amplifier with high open loop gain so that the effective gain circuit is defined and kept to a desired figure.

• https://en.wikipedia.org/wiki/Differential_amplifier - a type of electronic amplifier that amplifies the difference between two input voltages but suppresses any voltage common to the two inputs. It is an analog circuit with two inputs and one output in which the output is ideally proportional to the difference between the two voltages.

• https://en.wikipedia.org/wiki/Magnetic_amplifier - colloquially known as a "mag amp", is an electromagnetic device for amplifying electrical signals. The magnetic amplifier was invented early in the 20th century, and was used as an alternative to vacuum tube amplifiers where robustness and high current capacity were required. World War II Germany perfected this type of amplifier, and it was used in the V-2 rocket. The magnetic amplifier was most prominent in power control and low-frequency signal applications from 1947 to about 1957, when the transistor began to supplant it. The magnetic amplifier has now been largely superseded by the transistor-based amplifier, except in a few safety critical, high-reliability or extremely demanding applications. Combinations of transistor and mag-amp techniques are still used.

• https://en.wikipedia.org/wiki/Operational_amplifier - often op-amp or opamp, is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals. Operational amplifiers had their origins in analog computers, where they were used to perform mathematical operations in many linear, non-linear, and frequency-dependent circuits.

The popularity of the op-amp as a building block in analog circuits is due to its versatility. By using negative feedback, the characteristics of an op-amp circuit, its gain, input and output impedance, bandwidth etc. are determined by external components and have little dependence on temperature coefficients or manufacturing variations in the op-amp itself. Op-amps are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices. Many standard IC op-amps cost only a few cents in moderate production volume; however, some integrated or hybrid operational amplifiers with special performance specifications may cost over US\$100 in small quantities. Op-amps may be packaged as components or used as elements of more complex integrated circuits.

• https://en.wikipedia.org/wiki/Operational_amplifier_applications - A non-ideal operational amplifier's equivalent circuit has a finite input impedance, a non-zero output impedance, and a finite gain. A real op-amp has a number of non-ideal features as shown in the diagram, but here a simplified schematic notation is used, many details such as device selection and power supply connections are not shown. Operational amplifiers are optimised for use with negative feedback, and this article discusses only negative-feedback applications. When positive feedback is required, a comparator is usually more appropriate. See Comparator applications for further information.

• https://en.wikipedia.org/wiki/Comparator - a device that compares two voltages or currents and outputs a digital signal indicating which is larger. It has two analog input terminals and one binary digital output. A comparator consists of a specialized high-gain differential amplifier. They are commonly used in devices that measure and digitize analog signals, such as analog-to-digital converters (ADCs), as well as relaxation oscillators.
• https://en.wikipedia.org/wiki/Comparator_applications - closely related to operational amplifiers, but a comparator is designed to operate with positive feedback and with its output saturated at one power rail or the other. An op-amp can be pressed into service as a poorly performing comparator if necessary, but its slew rate will be impaired.

• https://en.wikipedia.org/wiki/Common_collector - amplifier, also known as an emitter follower, is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a voltage buffer. In this circuit the base terminal of the transistor serves as the input, the emitter is the output, and the collector is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous field-effect transistor circuit is the common drain amplifier and the analogous tube circuit is the cathode follower.

• https://en.wikipedia.org/wiki/Common_drain - amplifier, also known as a source follower, is one of three basic single-stage field effect transistor (FET) amplifier topologies, typically used as a voltage buffer. In this circuit (NMOS) the gate terminal of the transistor serves as the input, the source is the output, and the drain is common to both (input and output), hence its name. The analogous bipolar junction transistor circuit is the common-collector amplifier. This circuit is also commonly called a "stabilizer."

In addition, this circuit is used to transform impedances. For example, the Thévenin resistance of a combination of a voltage follower driven by a voltage source with high Thévenin resistance is reduced to only the output resistance of the voltage follower (a small resistance). That resistance reduction makes the combination a more ideal voltage source. Conversely, a voltage follower inserted between a driving stage and a high load (i.e. a low resistance) presents an infinite resistance (low load) to the driving stage—an advantage in coupling a voltage signal to a large load.

### Analog electronics

• https://en.wikipedia.org/wiki/Common-mode_signal - the component of an analog signal which is present with one sign on all considered conductors. In telecommunication, common-mode signal on a transmission line is known as longitudinal voltage. In electronics where the signal is transferred by differential voltage, the common-mode signal is a half-sum of voltages. When referenced to the local common or ground, a common-mode signal appears on both lines of a two-wire cable, in-phase and with equal amplitudes. Technically, a common-mode voltage is one-half the vector sum of the voltages from each conductor of a balanced circuit to local ground or common. Such signals can arise from one or more of the following sources: Radiated signals coupled equally to both lines, An offset from signal common created in the driver circuit, or A ground differential between the transmitting and receiving locations.

Noise induced into a cable, or transmitted from a cable usually occurs in the common mode; i.e. the same signal tends to be picked up by both conductors in a two wire cable. Likewise, RF noise transmitted from a cable tends to emanate from both conductors. Elimination of common mode signals on cables entering or leaving electronic equipment is important to ensure electromagnetic compatibility. Unless the intention is to transmit or receive radio signals, an electronic designer will generally design electronic circuits to minimise or eliminate common mode effects.

### Digital

• https://en.wikipedia.org/wiki/Flip-flop_(electronics) - or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems.

• https://en.wikipedia.org/wiki/Shift_register - a cascade of flip flops, sharing the same clock, in which the output of each flip-flop is connected to the "data" input of the next flip-flop in the chain, resulting in a circuit that shifts by one position the "bit array" stored in it, "shifting in" the data present at its input and 'shifting out' the last bit in the array, at each transition of the clock input. More generally, a shift register may be multidimensional, such that its "data in" and stage outputs are themselves bit arrays; this is implemented simply by running several shift registers of the same bit-length in parallel. Shift registers can have both parallel and serial inputs and outputs. These are often configured as "serial-in, parallel-out" (SIPO) or as "parallel-in, serial-out" (PISO). There are also types that have both serial and parallel input and types with serial and parallel output. There are also "bidirectional" shift registers which allow shifting in both directions: L→R or R→L. The serial input and last output of a shift register can also be connected to create a "circular shift register". One register is PIPO (parellar in parellar out),which is very fast,within single clock pulse ,it is giving output.

#### Logics

• https://en.wikipedia.org/wiki/Logic_family - may refer to one of two related concepts. A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply characteristics within a family. Many logic families were produced as individual components, each containing one or a few related basic logical functions, which could be used as "building-blocks" to create systems or as so-called "glue" to interconnect more complex integrated circuits. A "logic family" may also refer to a set of techniques used to implement logic within VLSI integrated circuits such as central processors, memories, or other complex functions. Some such logic families use static techniques to minimize design complexity. Other such logic families, such as domino logic, use clocked dynamic techniques to minimize size, power consumption and delay.

• https://en.wikipedia.org/wiki/7400_series - of transistor–transistor logic (TTL) integrated circuits are the most popular family of TTL integrated circuit logic. Quickly replacing diode–transistor logic, it was used to build the mini and mainframe computers of the 1960s and 1970s. Several generations of pin-compatible descendants of the original family have since become de facto standard electronic components.

• https://en.wikipedia.org/wiki/Logic_level - one of a finite number of states that a digital signal can inhabit. Logic levels are usually represented by the voltage difference between the signal and ground, although other standards exist. The range of voltage levels that represents each state depends on the logic family being used.

#### Simulation

• BOOLR - a digital logic simulator. BOOLR works with Windows, Mac OS and Linux and it is completely free. BOOLR is created with JavaScript, HTML5, CSS3 and runs in Electron. The simulation and rendering are running (yet) on the same thread. The simulation runs asynchronously and in ticks, so complex simulations won't freeze your screen. [15]

### Logic

• https://en.wikipedia.org/wiki/Functional_completeness - means that every possible logic gate can be realized as a network of gates of the types prescribed by the set. In particular, all logic gates can be assembled from either only binary NAND gates, or only binary NOR gates.

• https://en.wikipedia.org/wiki/Logic_synthesis - a process by which an abstract form of desired circuit behavior, typically at register transfer level (RTL), is turned into a design implementation in terms of logic gates, typically by a computer program called a synthesis tool. Common examples of this process include synthesis of HDLs, including VHDL and Verilog. Some synthesis tools generate bitstreams for programmable logic devices such as PALs or FPGAs, while others target the creation of ASICs. Logic synthesis is one aspect of electronic design automation.

See Signal

### Integrated circuits

• WikiChip - the preeminent resource for computer architectures and semiconductor (logic) engineering. WikiChip covers historical and contemporary electronic systems and technologies as well as related topics.

• https://github.com/enjoy-digital/litex - a Migen/MiSoC based Core/SoC builder that provides the infrastructure to easily create Cores/SoCs (with or without CPU). The common components of a SoC are provided directly: Buses and Streams (Wishbone, AXI, Avalon-ST), Interconnect, Common cores (RAM, ROM, Timer, UART, etc...), CPU wrappers/integration, etc... and SoC creation capabilities can be greatly extended with the ecosystem of LiteX cores (DRAM, PCIe, Ethernet, SATA, etc...) that can be integrated/simulated/build easily with LiteX. It also provides build backends for open-source and vendors toolchains.Think of Migen as a toolbox to create FPGA designs in Python and LiteX as a SoC builder to create/develop/debug FPGA SoCs in Python.

• https://en.wikipedia.org/wiki/Footprint_(electronics) - or land pattern is the arrangement of pads (in surface-mount technology) or through-holes (in through-hole technology) used to physically attach and electrically connect a component to a printed circuit board. The land pattern on a circuit board matches the arrangement of leads on a component.

• https://en.wikipedia.org/wiki/Programmable_logic_controller - PLC, or programmable controller is an industrial digital computer which has been ruggedised and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis. They were first developed in the automobile industry to provide flexible, ruggedised and easily programmable controllers to replace hard-wired relays and timers. Since then they have been widely adopted as high-reliability automation controllers suitable for harsh environments. A PLC is an example of a "hard" real-time system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result.

• https://en.wikipedia.org/wiki/Very-large-scale_integration - the process of creating an integrated circuit by combining thousands of transistors into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed. The microprocessor is a VLSI device. Before the introduction of VLSI technology most ICs had a limited set of functions they could perform. An electronic circuit might consist of a CPU, ROM, RAM and other glue logic. VLSI lets IC makers add all of these into one chip.

#### Through-hole

• https://en.wikipedia.org/wiki/Through-hole_technology - tht, also spelled "thru-hole", refers to the mounting scheme used for electronic components that involves the use of leads on the components that are inserted into holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side either by manual assembly (hand placement) or by the use of automated insertion mount machines

#### Surface mount

• https://en.wikipedia.org/wiki/Surface-mount_technology - SMT, is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD). In industry, it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board. Both technologies can be used on the same board, with the through-hole technology used for components not suitable for surface mounting such as large transformers and heat-sinked power semiconductors.

• https://en.wikipedia.org/wiki/Contact_pad - or bond pads are designated surface areas of a printed circuit board or die of an integrated circuit. Possibilities to contact to pads include soldering, wirebonding, flip chip mounting, or probe needles.

#### Wire bonding

• https://en.wikipedia.org/wiki/Wire_bonding - the method of making interconnections (ATJ) between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Although less common, wire bonding can be used to connect an IC to other electronics or to connect from one printed circuit board (PCB) to another. Wire bonding is generally considered the most cost-effective and flexible interconnect technology and is used to assemble the vast majority of semiconductor packages. If properly designed, wire bonding can be used at frequencies above 100 GHz.

#### Flip chip

• https://en.wikipedia.org/wiki/Flip_chip - also known as controlled collapse chip connection or its abbreviation, C4, is a method for interconnecting semiconductor devices, such as IC chips and microelectromechanical systems (MEMS), to external circuitry with solder bumps that have been deposited onto the chip pads. The technique was developed by General Electric's Light Military Electronics Dept., Utica, N.Y. The solder bumps are deposited on the chip pads on the top side of the wafer during the final wafer processing step. In order to mount the chip to external circuitry (e.g., a circuit board or another chip or wafer), it is flipped over so that its top side faces down, and aligned so that its pads align with matching pads on the external circuit, and then the solder is reflowed to complete the interconnect. This is in contrast to wire bonding, in which the chip is mounted upright and wires are used to interconnect the chip pads to external circuitry.

### Low power

• LowPowerLab - Exploring and building low power IoT systems

## Design

to rework

• https://en.wikipedia.org/wiki/Electronic_design_automation - a category of software tools for designing electronic systems such as printed circuit boards and integrated circuits. The tools work together in a design flow that chip designers use to design and analyze entire semiconductor chips. EDA is also referred to as electronic computer-aided design (ECAD).
• https://en.wikipedia.org/wiki/Design_flow_(EDA) - the explicit combination of electronic design automation tools to accomplish the design of an integrated circuit. Moore's law has driven the entire IC implementation RTL to GDSII design flows from one which uses primarily stand-alone synthesis, placement, and routing algorithms to an integrated construction and analysis flows for design closure. The challenges of rising interconnect delay led to a new way of thinking about and integrating design closure tools.

• Open Collector - carries listings and news for free EDA software and circuit designs. Open Collector supports gEDA.

• TinyCAD - a program for drawing electrical circuit diagrams commonly known as schematic drawings. It supports standard and custom symbol libraries. It supports PCB layout programs with several netlist formats and can also produce SPICE simulation netlists. It is also often used to draw one-line diagrams, block diagrams, and presentation drawings.

#### gEDA

• gEDA project has produced and continues working on a full GPL'd suite and toolkit of Electronic Design Automation tools. These tools are used for electrical circuit design, schematic capture, simulation, prototyping, and production. Currently, the gEDA project offers a mature suite of free software applications for electronics design, including schematic capture, attribute management, bill of materials (BOM) generation, netlisting into over 20 netlist formats, analog and digital simulation, and printed circuit board (PCB) layout. The gEDA project was started because of the lack of free EDA tools for POSIX systems with the primary purpose of advancing the state of free hardware or open source hardware. The suite is mainly being developed on the GNU/Linux platform with some development effort going into making sure the tools run on other platforms as well.

#### XCircuit

• XCircuit - a UNIX/X11 (and Windows, or Windows using Cygwin and the Cygwin X-Server) program for drawing publishable-quality electrical circuit schematic diagrams and related figures, and produce circuit netlists through schematic capture. XCircuit regards circuits as inherently hierarchical, and writes both hierarchical PostScript output and hierarchical SPICE netlists. Circuit components are saved in and retrieved from libraries which are fully editable. XCircuit does not separate artistic expression from circuit drawing; it maintains flexiblity in style without compromising the power of schematic capture. XCircuit is flexible enough to be used as a generic program for drawing just about anything, and is competitive with powerful programs such as "xfig". It is especially good for any task requiring repeated use of a standard set of graphical objects, including architectural drawing, printed circuit board layouts, and (my personal favorite) music typography (see my Music Page for examples).

#### FreePCB

• FreePCB - a free, open-source PCB editor for Microsoft Windows, released under the GNU General Public License. It was designed to be easy to learn and easy to use, yet capable of professional-quality work.

• KiCad EDA - A Cross Platform and Open Source Electronics Design Automation Suite [19]

#### Yosys

• Yosys Open SYnthesis Suite - a framework for Verilog RTL synthesis. It currently has extensive Verilog-2005 support and provides a basic set of synthesis algorithms for various application domains. Yosys can be adapted to perform any synthesis job by combining the existing passes (algorithms) using synthesis scripts and adding additional passes as needed by extending the Yosys C++ code base. Yosys is free software licensed under the ISC license (a GPL compatible license that is similar in terms to the MIT license or the 2-clause BSD license).

### Gerber

• https://en.wikipedia.org/wiki/Gerber_format - an open, ASCII, vector format for printed circuit board (PCB) designs. It is the de facto standard used by PCB industry software to describe the printed circuit board images: copper layers, solder mask, legend, drill data, etc. The official website contains the specification, test files, notes and the Reference Gerber Viewer to support users and especially developers of Gerber software.

Gerber is used in PCB fabrication data. PCBs are designed on a specialized electronic design automation (EDA) or a computer-aided design (CAD) system. The CAD systems output PCB fabrication data to allow fabrication of the board. This data typically contains a Gerber file for each image layer (copper layers, solder mask, legend or silk...). Gerber is also the standard image input format for all bare board fabrication equipment needing image data, such as photoplotters, legend printers, direct imagers or automated optical inspection (AOI) machines and for viewing reference images in different departments. For assembly the fabrication data contains the solder paste layers and the central locations of components to create the stencil and place and bond the components.

### Services

#### EveryCircuit

• EveryCircuit - You can build and simulate circuits right on your phone or tablet, animate and understand how they work, check homework and test your designs. Best of all, you can join and interact with EveryCircuit's large online community of fellow circuit enthusiasts. [22]

#### CircuitBee

• CircuitBee provides a platform for you to share live versions of your circuit schematics on your websites, blogs or forums.

#### CircuitLab

• CircuitLab - Build and simulate circuits right in your browser. Design with our easy-to-use schematic editor. Analog & digital circuit simulations in seconds. Professional schematic PDFs, wiring diagrams, and plots. No installation required! Launch it instantly with one click.

#### upverter

• upverter - Create hardware better, faster. Design open source and private projects as a team. Draw schematics, layout PCBs and review designs together.

#### CircuitJS1

• CircuitJS1 - This electronic circuit simulator is highly interactive giving the feeling of playing with real components. It's very helpful for experimentation and visualization. Best of all, thanks to the power of HTML5, no plug-ins are required! The original implementation, in Java, belongs to Paul Falstad who kindly gave his permission for me to build this port.

### Simulation

#### Qucs

• Qucs - Quite Universal Circuit Simulator, an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit. After that simulation has finished you can view the simulation results on a presentation page or window.

#### LTspice

• LTspice | Design Center | Analog Devices - a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits. Included in the download of LTspice are macromodels for a majority of Analog Devices switching regulators, amplifiers, as well as a library of devices for general circuit simulation.
• https://en.wikipedia.org/wiki/LTspice - is freeware computer software implementing a SPICE electronic circuit simulator, produced by semiconductor manufacturer Linear Technology, now part of Analog Devices. It is used in-house at Linear Technology for IC design, and the most widely distributed and used SPICE program in the industry. LTspice isn't artificially crippled to limit its capabilities (no node limits, no component limits, no subcircuit limits).

#### Ngspice

• Ngspice - the open source spice simulator for electric and electronic circuits. Such a circuit may comprise of JFETs, bipolar and MOS transistors, passive elements like R, L, or C, diodes, transmission lines and other devices, all interconnected in a netlist. Digital circuits are simulated as well, event driven and fast, from single gates to complex circuits. And you may enter the combination of both analog and digital as a mixed-signal circuit. ngspice offers a wealth of device models for active, passive, analog, and digital elements. Model parameters are provided by the semiconductor manufacturers. The user add her circuits as a netlist, and the output is one or more graphs of currents, voltages and other electrical quantities or is saved in a data file. ngspice does not provide schematic entry. Its input is command line or file based. There are however third party interfaces available.

#### spicesound

• spicesound - Simulating Analog Audio Cicuits, an extension to ngspice that provides a libsndfile voltage source and the possibility to write ngspice's output in audio-file format. Ngspice is a mixed-level/mixed-signal circuit simulator, based on Berkeley Spice3F5 and developed openly as ngspice sourceforge project. Libsndfile is a C library for reading and writing files containing sampled sound; released in source code format under the GNU Lesser General Public License.

#### LiveSPICE

• LiveSPICE - a circuit simulator that attempts to run in real time with minimal latency for audio signals. It processes signals from audio input devices attached to your computer, and plays the results to the speakers.

#### Gnucap

• Gnucap - the Gnu Circuit Analysis Package. The primary component is a general purpose circuit simulator. It performs nonlinear dc and transient analyses, fourier analysis, and ac analysis. Spice compatible models for the MOSFET (level 1-8), BJT, and diode are included in this release. Gnucap is not based on Spice, but some of the models have been derived from the Berkeley models.Unlike Spice, the engine is designed to do true mixed-mode simulation. Most of the code is in place for future support of event driven analog simulation, and true multi-rate simulation.If you are tired of Spice and want a second opinion, you want to play with the circuit and want a simulator that is interactive, you want to study the source code and want something easier to follow than Spice, or you are a researcher working on modeling and want automated model generation tools to make your job easier, try Gnucap.

#### ICemu

• https://github.com/hsoft/icemu - a C library that emulates integrated circuits at the logic level. Its goal is to facilitate the debugging of software being written for microcontrollers being plugged into the emulated circuit.

#### PointToPoint_LT

• https://github.com/HackAudio/PointToPoint_LT - a software tool for modeling analog circuits. It is intended for audio signal processing applications. Component-level circuit analysis is automated, allowing for arbitrary circuits to be easily implemented based on the available components. An example JUCE plug-in project is included for demonstration.

#### EEsim

• EEsim - a circuit simulator based on ngspice and it runs inside the browser using WebAssembly technology. The input is spice based netlist, and the output is results of the analysis that you're doing in the simulations. You are able to plot and view the results directly in the browser using high-performance WebGL plotting library webgl-plot, or download the data in CSV format for further analysis. Notice that your netlist and results are processed locally and always remain inside your browser and are never uploaded to network. The focus of this implementation is rapid analysis, sharing circuits ideas and results in VLSI and chip-design communities.

## Testing

• https://github.com/GlasgowEmbedded/Glasgow - a tool for exploring digital interfaces, aimed at embedded developers, reverse engineers, digital archivists, electronics hobbyists, and everyone else who wants to communicate to a wide selection of digital devices with high reliability and minimum hassle. It can be attached to most devices without additional active or passive components, and includes extensive protection from unexpected conditions and operator error.

## Enclosures

• https://en.wikipedia.org/wiki/Electrical_enclosure - a cabinet for electrical or electronic equipment to mount switches, knobs and displays and to prevent electrical shock to equipment users and protect the contents from the environment. The enclosure is the only part of the equipment which is seen by users; in many cases it is designed not only for its utilitarian requirements, but also to be pleasing to the eye. Regulations may dictate the features and performance of enclosures for electrical equipment in hazardous areas, such as petrochemical plants or coal mines. Electronic packaging may place many demands on an enclosure for heat dissipation, radio frequency interference and electrostatic discharge protection, as well as functional, esthetic and commercial constraints.

• https://en.wikipedia.org/wiki/IP_Code - International Protection Marking, IEC standard 60529, sometimes interpreted as Ingress Protection Marking, classifies and rates the degree of protection provided against intrusion (body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures. It is published by the International Electrotechnical Commission (IEC). The equivalent European standard is EN 60529.

The standard aims to provide users more detailed information than vague marketing terms such as waterproof. The first digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects. The second digit indicates the level of protection that the enclosure provides against harmful ingress of water. The ratings for water ingress are not cumulative beyond IPX6. A device which is compliant with IPX7, covering immersion in water, need not be compliant with IPX5 or IPX6, covering exposure to water jets. A device which meets both tests is indicated by listing both tests separated by a slash, e.g. IPX5/IPX7.Similarly, an electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for indoor use.

• https://en.wikipedia.org/wiki/NEMA_enclosure_types - defines standards used in North America for various grades of electrical enclosures typically used in industrial applications. Each is rated to protect against personal access to hazardous parts, and additional type-dependent designated environmental conditions. A typical NEMA enclosure might be rated to provide protection against environmental hazards such as water, dust, oil or coolant or atmospheres containing corrosive agents such as acetylene or gasoline. A full list of NEMA enclosure types is available from the NEMA website.

## 12/24v system

"Leisure batteries differ in construction from vehicle starter batteries because they are designed for different jobs, and consequently require a different charging regime.

"Fixed voltage battery chargers won't achieve full re-charging of a leisure battery because the lead plates are thicker, so charging has to take place in controlled stages with the voltage level being automatically adjusted throughout to ensure full charge absoprtion. This is where dedicated multi-stage or 'intelligent' chargers need to be used to ensure your battery receives a full, deep charge and its serviceable lifetime is maximised.

"As a rule of the thumb the charger output current should be around 10-15% of your battery's Ah capacity."

• Capacitor

"you'll find that the spec says you need a BIG electrolytic cap across your battery, you don't need one for a portable system; it is recommended because class D amplifiers can backfeed current. Deep Cycle batteries cope with this; the capacitor is for car setups where the deep cycle battery for the amp is split charged and is only there to run the system full blast for an hour without the engine running."

## Projects

• https://github.com/szczys/pid_balancer - A couple years back Electronoobs built a very simple PID example that balanced a ping-pong ball. (Of course it was covered on Hackaday which is how it grabbed my attention.) I've always wanted to give it a try and have just taken the plunge. It's not so much the physical build I'm interested in, but I really want to write the PID code from scratch to ensure a thorough understanding of the concepts.

### Fan

• https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box - also called Corsi–Rosenthal Cube, is a design for a do-it-yourself air purifier that can be built comparatively inexpensively. It was popularized during the COVID-19 pandemic, with the goal of reducing the levels of airborne viral particles in indoor settings. It consists of four[1] or five[2][3] HVAC particulate air filters and a box fan.

### Tutorials

• Hackster.io gives professionals and hobbyists the resources they need to build hardware, the easy way.
• EEVblog Electronics Resource Wiki - This resource site contains useful links and information related to all aspects of Electronics Engineering and associated electronics design.

• Basic Electronics Tutorials provides students and beginners alike studying Electronics a good Basic Electronics Tutorials and information to help develop a knowledge and understanding of the subject of Electronics.

## Wearable

• HOW TO GET WHAT YOU WANT - Welcome to the KOBAKANT DIY Wearable Technology DocumentationThis website aims to be a comprehensible, accessible and maintainable reference resource, as well as a basis for further exploration and contribution.