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Ampere. The basic unit of electrical current. Applying one volt across a one ohm resistor will cause a current of one ampere to flow. The letter 'I' is used to denote current.
A positive electrode of an electrochemical device (such as a primary or secondary electric cell) toward which the negative ions are drawn. The semiconductor-diode terminal that is positive with respect to the other terminal when the diode is biased in the forward direction.
An open source (both free to use and source code freely distributed) digital audio manipulation application. It is available for Windows, Mac OS X, Linux and BSD. It can record audio, provide editing functions for shortening the length of audio files or handle mixing, spectrum analysis or change in pitch and/or speed. It imports and exports WAV, AIFF, MP3, FLAC and — with plugins — WMA, AAC, AMR and AC3. With certain plug-ins it can be used to export beats of a piece of music that can be imported into certain sequencing software. It is available at and instructions are at
American Wire Gauge. The standards adopted in the United States for the measurement of wire sizes. AWG Chart


The region between the emitter and collector of a transistor that receives minority carriers injected from the emitter. The element in a transistor that controls the flow of current carriers. It is the element that corresponds to the control grid of an electron tube.
A measurement of data transmission speed based on the number of code elements or units per second.
Bayonet Nut Connection. A type of connector typically used on coaxial cables.
Bill of Material. A listing all the parts required to assemble a project or to populate a circuit board.


An electrical component that stores an electric charge and releases it when its needed.
The general name for any negative electrode. The negative terminal of a forward-biased semiconductor diode, which is the source of the electrons.
Center Tap 
A connection made to a point half way along a winding of a transformer or inductor, or along the element of a resistor or a potentiometer.
In DIYC, a channel refers to an individual line that can be independently controlled. As an example, the Grinch can control 64 channels, that is 64 independent lines that it can control.
A co-operative effort by participating DIYC members to pool their resources together to make a purchase of an item(s) in large quantity in an attempt to reduce the cost to the individual participants.
Coop Olsen 595 
This light controller is based on the Olsen 595 design. It is a 64 channel controller with basic ON/OFF capabilities. Normally gets its input from the parallel port of the controlling computer. On-board status LED for each channel. Developed by Brian Bresocnik (Macrosill). More info here. AKA - Brian's Olsen 595 board.
A DIYC design for a SSR PCB. Contains circuitry equal to four separate solid state relays. Provides independent control of four channels of lights. Designed by Sean Bowf. AKA - Sean's SSR.
Coaxial Cable 
A cable with one conductor completely surrounded by another conductor, separated by a dielectric. The two conductors being coaxial. Some types of coax cables use multiple conductors surrounding each other. Normally only the inner conductor carries a signal. The outer conductors [Braid] are used as a shield, or grounded. Coaxial Cable is normally used in RF transmission. The term Coaxial is normally shortened to Coax. Types of Coaxial Cable include: RG-6, RG-8, RG-11, RG-58, RG-59.
The electrode in a transistor through which a primary flow of carriers leaves the region between the electrodes.
An uninterrupted, complete path for current flow. When checking for continuity you are usually looking for a short.
The movement of electrons past a reference point. The passage of electrons through a conductor. Measured in amperes.


decibel. A unit of relative sound or radio transmission intensity.
Decoupling capacitor 
A capacitor that is included in circuits with integrated circuits to insure that overall circuit voltage doesn't dip or spike elsewhere in the circuit due to the demands of the integrated circuit. When the integrated circuit needs a burst of energy, the decoupling capacitor provides the needed energy without causing a drop in the voltage for the rest of the circuit.
An insulating (nonconducting) medium. A substance in which an electric field may be maintained with zero or near-zero power dissipation, i.e., the electrical conductivity is zero or near zero. An insulator; a term applied to the insulating material between the plates of a capacitor.
An electrical device that will allow current to pass in only one direction. Consists of a cathode and an anode. A two-terminal semiconductor device used chiefly as a rectifier.
Dual In-line Package. An IC package having two parallel rows of leads. Sometimes called "through-hole package," because holes are drilled in the PC boards and the package is soldered to the board on the side opposite the package.
A basic radio antenna that consists of two elements, each of equal length. The length of the elements is an algorithmic function of the frequency over which the broadcast is being made.
Do It Yourself
DMX (or DMX512) 
Digital Multiplex. A lighting control protocol standard developed to handle communications between commercial (usually entertainment, such as theater or music events) lighting control boards and the individual devices, such as lekos (elliposoidals), fresnels, moving lights, strip lights or DJ effect lights. DMX allows up to 512 devices to be attached, daisy-chain, to one wire, each controlled individually. More information on DMX is available here.


The terminal at which electricity passes from one medium into another, such as in an electrical cell where the current leaves or returns to the electrolyte.
A solution of a substance that is capable of conducting electricity. An electrolyte may be in the form of either a liquid or a paste.
Electrolytic Capacitor 
A capacitor that normally uses two aluminum foils separated by an insulating paper. The paper and foils are rolled and impregnated with a liquid electrolyte. Aluminum Electrolytic Capacitors are polarized, and may be used DC circuits.
Electrostatic Discharge Sensitive (ESDS) 
The level of susceptibility of devices to damage by static electricity, found by classification testing, is used as the basis for assigning an ESDS class. Electronic parts having sensitive characteristics (e.g., thin-layered internal composition) and delicate, miniaturized construction which are susceptible to damage or degradation, in various degrees, from environmental field forces (electrostatic, electromagnetic, magnetic, or radioactive). This susceptibility also extends to the standard electronic modules, printed circuit boards, printed wiring boards, and circuit card assemblies containing one or more of these sensitive electronic parts.
The element in a transistor that emits current carriers (electrons or holes).
Electrically connected to a source of potential difference, or electrically charged so as to have a potential significantly different from that of earth in the vicinity. A "live" circuit.
Electrostatic Discharge. More info on ESD is available here.


The basic unit of capacitance. A capacitor has a capacitance of 1 farad when a voltage potential of 1 volt across it produces a charge of 1 coulomb. Most capacitors used on DIYC boards are in the microfarad (labeled mF or uF) or picofarad (labeled pF) range.
The Federal Communications Commission. The FCC was established by the Communications Act of 1934 and is charged with regulating interstate and international communications by radio, television, wire (telegraph, telephone), satellite and cable.
Field-Effect Transistor. A transistor consisting of a source, a gate, and a drain. Current flow is controlled by the transverse electric field under the gate.
A set of instructions (software program) installed into a microprocessor. It provides the necessary instructions for how the device is supposed to operate.
A solution or paste that removes surface oxides from metals being soldered.
Full-Wave Rectifier 
A circuit that uses both positive and negative alternations in an alternating current to produce direct current; it changes alternating current to direct current.
A device that has as its critical component a metal wire or strip that will melt when heated by a prescribed (design) amperage, creating an open in the circuit of which it is a part, thereby protecting the circuit from an over current condition. It protects wiring from over-heating and causing fire.


Ground Fault Circuit Interrupter. An electrical safety device installed in a power panel, sub-panel or outlet box that instantly shuts off the electricity when there is an imbalance in the flow of electricity from hot to neutral. This imbalance can indicate that that an individual is getting an electrical shock. A GFCI should be used in all outdoor high-voltage environments (regular household current) and the device should be tested on a regular basis.
A 64 channel controller with basic ON/OFF capabilities. Normally gets its input from the parallel port of the controlling computer. No status LEDs, inexpensive/simple to build. Developed by Robert Jordan (RJ). More info here.
The point in a circuit used as a common reference point for measuring purposes. To connect some point of an electrical circuit or some item of electrical equipment to earth or to the conducting medium used in lieu thereof.


Half-Wave Rectifier 
A rectifier using only one-half of each cycle to change AC to pulsating DC.
Heat Shunt 
A device (preferably a clip-on type) used to absorb heat and protect heat-sensitive components during soldering.
Heat Sink 
A piece of metal attached to an electronic component (such as triac, transistor, or voltage regulator) that serves to dissipate or absorb unwanted heat. Many electronics components have two ratings, a lower one when a heat sink is not used and a higher one where a heat sink is in place. Also called a dissipator.


The property of a circuit that tends to oppose a change in the existing current flow. The symbol for inductance is L.
The act or process of producing voltage and current by the relative motion of a magnetic field across a conductor.
Separated from other conducting surfaces by a dielectric (including air space) offering a high resistance to the passage of current. Note: When any object is said to be insulated, it is understood to be insulated for the conditions to which it is normally subjected. Otherwise, it is, uninsulated.
A material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support as protection against accidental contact with the conductor.
Insulation Resistance 
The resistance offered by an insulating material to current leakage.
Material of such low conductivity that the flow of current through it can usually be neglected. A device having high electrical resistance; used for supporting or separating conductors so as to prevent undesired flow of current from the conductors to other objects.
Integrated Circuit (IC) 
A circuit in which many elements are fabricated and interconnected by a single process (into a single chip), as opposed to a "nonintegrated" circuit in which the transistors, diodes, resistors, and other components are fabricated separately and then assembled. Elements inseparably associated and formed on or within a single substrate.
A circuit with one input and one output. Its function is to invert or reverse the input. When the input is high, the output is low, and vice versa. The inverter is sometimes called a NOT circuit, since it produces the reverse of the input.


A short length of wire used to complete a circuit.



Light Emitting Diode. A solid-state, semiconductor device that converts electrical energy directly into light. LEDs show up in Christmas lighting in two contexts: the first is as a power or signal indicator in controllers or SSRs, while the second is their use as a substitute for incandescent lamps. LED Christmas light strings use about one-tenth the energy of an incandescent lamp and have a crystal-clear color brightness that incandescents cannot achieve.


A computer-on-a-chip that emphasizes high integration, low power consumption, self-sufficiency and relatively low cost. Typically, a microcontroller has flash-type read-write memory allowing a programming station (usually called a PIC programmer) to enter in task-specific programs, which can be written in programming languages such as C, C++, BASIC or even in assembly code (which, of course, is the most efficient).
Incandescent bulbs that are about 7/32nds of an inch in diameter, they come in strings as short as 35 bulbs and as long as 400 bulbs. Officially known as the T1-3/4, the strings are wired in series and parallel, usually in 50-bulb groups (the 50 bulbs are in series which are then wired parallel to the others, making 100-, 150-, 200-, 250-, 300-, 350- or 400-bulb strings). Pretty universally, strings that are grouped by 50 bulbs can be cut down to 50-bulb strings. Mini-lights that are grouped by 50s use 2.5-volt, 170 mA bulbs, while 35-bulb strings use 3.5-volt bulbs. Mini-light bulbs are traditionally painted with a transparent paint, which can under severe or extended weather begin to chip or fade.
A 6-Pin DIP 400V Random Phase Triac Driver Output Optocoupler. It provides both triac driver and optoisolator services in one package.
A semiconductor device that contains diffused source and drain regions on either side of a P- or N-channel area. Also contains a gate insulated from the channel area by silicon-oxide. Operates in either the depletion or the enhancement mode.
Metal Oxide Varistor. A resistor that changes value with applied voltage. A varistor may also be called a VDR [Voltage Dependent Resistor]. Varistors will have a negative voltage coefficient. MOV devices are used in parallel with the load.
A single meter combining the functions of an ammeter, a voltmeter, and an ohmmeter.


A type of transistor; it is formed by introducing a thin region of P-type material between two regions of N-type material.


The unit of electrical resistance. That value of electrical resistance through which a constant potential difference of 1 volt across the resistance will maintain a current flow of 1 ampere through the resistance.
Ohm's Law 
The current in an electrical circuit is directly proportional to the electromotive force in the circuit. The most common form of the law is E = IR, where E is the electromotive force or voltage across the circuit, I is the current flowing in the circuit, and R is the resistance of the circuit.
Olsen 595 
This is a popular light controller based on an approach first popularized on the ComputerChristmas and/or PlanetChristmas forums by Peter Olsen. In its first incarnation it used 8-bit 74HC595 logic chips, often with external buffers. More info on the original Olsen 595 design can be found here.
Open or Open Circuit 
The condition of an electrical circuit caused by the breaking of continuity of one or more conductors of the circuit; usually an undesired condition. A circuit that does not provide a complete path for the flow of current.
Optoisolator (opto, optocoupler) 
A semiconductor device that allows signals to be transferred between circuits or systems, while keeping those circuits or systems electrically isolated from each other. In its simplest form, an optoisolator consists of an light-emitting diode (LED), IRED (infrared-emitting diode), or laser diode for signal transmission, and a photosensor for signal reception.
A device that produces electrical oscillations at a frequency determined by its unique physical characteristics.


Parallel Port 
A port through which two or more data bits are passed simultaneously, such as all the bits of an 8-bit byte, and that requires as many input channels as the number of bits that are to be handled simultaneously. Typically found on a computer and used as the printer port.
Printed Circuit Board. An electronics board that contains layers of circuitry that connect the various components of a system. A PCB can be mass manufactured or can be "home etched," where a hobbyist transfers the design of the PCB to a copper-clad board, uses caustic chemicals to etch away the areas not needed and then drills the holes him or herself.
A registered trademark name for microcontrollers produced by Microchip Technology Inc. At DIYC, PIC has become a generic term for microcontrollers.
A term traditionally used in computer graphics to identify a picture element, it has been adapted by the Christmas-lights community to refer to a tri-color (red-green-blue) LED that has an internal controller and is manufactured as a string, a strip (either rigid or flexible) or as modules. Pixels require three channels of sequencing software each, so 10 pixels are 30 channels and 50 pixels are 150 channels. Pixels can be based on any of a variety of controllers, including the TM18xx series, the LPD-6803, the WS2801, the 3001 and the GE ColorEffects chips. Further, pixels can be driven at either 5-volts or 12-volts DC and can have a variety of color orders. For strings, strips or modules of pixels to interoperate, they must have the same controller chip, the same voltage and the same color order (which usually means they must have the exact same manufacturer).
The condition in an electrical circuit by which the direction of the flow of current can be determined. Usually applied to batteries and other direct voltage sources. Two opposite charges, one positive and one negative.
A variable resistor having a terminal connected to each end of a resistive element and a third terminal connected to a wiper contact. The output is a voltage that is variable depending upon the position of the wiper contact.
The rate of doing work or the rate of expending energy. The unit of electrical power is the watt.
A device that connects a personal computer to a microcontroller. Used to download software (firmware) from the PC to the microcontroller.
A formal set of conventions governing the format and control of interaction between the computer and attached hardware.
Pulse-Width Modulation (PWM) 
Pulse modulation in which the duration of the pulses is varied by the modulating voltage. A useful technique for dimming lights.



The section in a basic power supply that maintains the output of the power supply at a constant level in spite of large changes in load current or input line voltage.
An electromagnetic device with one or more sets of contacts that change position by the magnetic attraction of a coil to an armature.
A unique serial communication protocol developed solely for allowing Vixen to communicate to DIYC light controllers. Also applies to the dimming firmware used by many DIYC light controllers.
The opposition a device or material offers to the flow of current. The effect of resistance is to raise the temperature of the material or device carrying the current. A resistance of 1 ohm will allow a current of 1 ampere to flow through it when a potential of 1 volt is applied.
An electrical component that offers resistance to the flow of current. It may be a coil of fine wire or a composition rod.
RJ-45 (or RJ45) 
Registered Jack 45. A data plug or jack standard that allows for the connection of eight wires. It is similar to the modular plug on telephones (which are usually RJ11), though bigger. It is commonly used in Ethernet cabling and so its components (cable, female connectors, male connectors) are readily available and inexpensive.
Restriction of Hazardous Substances Directive. A directive by the European Union that is designed to keep harmful chemicals and materials to a minimum. It is used by electronics manufacturers to denote components that meet the EU requirements.
A telecommunications protocol, Recommended Standard 232 was originally designed to connect teletypes with modems; it has survived to this day as the way computer serial ports send out data. RS232 is implemented in a variety of connectors, but is most commonly seen in the DB9 and DB25 devices. It uses nine wires and supports transmitted data, received data, request to send, carrier detect and ring indicator. It is used in Christmas lights by as the physical layer between PC serial ports and Christmas lights controllers.
A telecommunications protocol, Recommended Standard 485 is typically used in building automation, the programming of logic controllers, sound system control, lighting control and video surveillance camera control. It is a two-wire system that uses a differential form of signaling that supports the transmission of data packets. It can be used over a long distance and supports multi-point connections. It is used in Christmas lights as a distribution system for light controllers signaling devices, sometimes using the DMX512 protocol.


A diagram which shows, by means of graphic symbols, the electrical connections and functions of a specific circuit arrangement.
Short Circuit 
An unintentional current path between two components in a circuit or between a component and ground; usually caused by a circuit malfunction.
A term used interchangeably with jumper. A device used to connect two pins and "jumper" them together.
Silicon-Controlled Rectifier (SCR) 
A semiconductor device that functions as an electrically controlled switch.
Silk Screen 
The printed information on a PCB. Typcially yellow or white, it outlines the components and shows the part reference numbers.
Sink Current 
An integrated circuit sinks current when current is flowing from a load [another device] into the circuits output. This is considered negative current to the IC. Basically happens when the integrated circuit output goes to ground [low].
SMT (or SMD) 
Surface mount technology (surface mount device). A method of mounting integrated circuits, microcontrollers and other electronics on printed circuit boards. The method mounts the devices on the top of a PC board rather than using holes through the board. Compare this with DIP.
Signal to Noise Ratio. A measure of signal strength relative to background noise.
Source Current 
An integrated circuit sources current when current is flowing from the IC into another device [Load]. Source-ing current is considered to be positive current flow from the ICs prospective. Source current is the opposite to Sink Current.
Service Parallel Thermoplastic. Commonly referred to as zip cord. There is SPT1, SPT2, and SPT3. The number refers to the thickness of the insulation in 64ths of an inch. SPT1 is often called lamp cord. SPT1 usually has 18 gauge wire. SPT2 is commonly available in 16 or 18 gauge. SPT3 is available as large as 10 gauge.
Solid State Relay. An electronic switch, which, unlike an electromechanical relay, contains no moving parts.
DIYC definition
Generally refers to a PCB that contains the circuitry that acts like four separate solid state relays. It receives data from the controller board and uses that information to control the power going to the attached lights. The key components of a DIYC SSR are the Optocoupler and the Triac. More information on SSRs can be found here.
Solid State Relay from Oz. A DIYC design for a SSR PCB. Contains circuitry equal to four separate solid state relays. Provides independent control of four channels of lights. Designed by John Wilson (wjohn).
Standing Wave Ratio. The ratio of the maximum (voltage, current) to the minimum (voltage, current) points of a transmission line. Indicates the impedance matching quality of the termination of the line.


The process of applying a thin coat of solder to materials prior to their being soldered; for example, application of a light coat of solder to the filaments of a conductor to hold the filaments in place prior to soldering of the conductor.
A device composed of two or more coils, linked by magnetic lines of force, used to transfer energy from one circuit to another.
A basic solid-state semiconductor that has three terminals and can be used for amplification, switching and/or detection.
TRIode for Alternating Current. This is an electronic component approximately equivalent to two silicon-controlled rectifiers (SCRs/thyristors) joined in inverse parallel (paralleled but with the polarity reversed) and with their gates connected together. This results in a bidirectional electronic switch which can conduct current in either direction when it is triggered (turned on).
Twisted Pair 
A line consisting of two insulated wires twisted together to form a flexible line without the use of spacers.


An array of eight Darlington transistors (which themselves are arrays of two transistors) that amplify current. Often used in Christmas lights as devices to increase the current coming from a microcontroller to an SSR so that there is enough power to turn on (or off) the SSR.
A collection of 512 channels of lighting control. Based on the DMX-512 standard, it is the output of a single USB-DMX device, such as an Enttec Pro, Enttec Open, Lynx USB-DMX Dongle or an RPM USB-DMX Dongle. The word was coined when stage-lighting consoles needed to expand beyond 512-channel output; the output ports on the consoles were given the name. Also see this.
Universal Serial Bus, a computer bus which provides two-way communication between the PC and peripheral devices, over a differential 4-wire serial interface cable.


A plated-thru hole in a printed circuit board. A via may may exist between one or more adjacent board layers, or through the entire board. A blind via runs vertically between the top [or bottom] side and through one or more adjacent board layers, but not through the entire board.
The term used to signify electrical pressure. Voltage is a force that causes current to flow through an electrical conductor. The voltage of a circuit is the greatest effective difference of potential between any two conductors of the circuit.
Voltage Drop 
The difference in voltage between two points. It is the result of the loss of electrical pressure as a current flows through a resistance.
Voltage regulator 
An electronic device designed to take a higher voltage and make it conform to a specific lower voltage. Provide a 5-volt regulator with 12 volts as an input and it will put out a steady 5 volts; provide a 12-volt regulator with 14.5 volts and it will output a steady 12 volts. While some regulators are designed for specific voltages, others can provide a range of voltages depending upon resistance applied; variable voltage regulators can be controlled by potentiometers (i.e.: volume control), so that you can turn a knob and get various voltages depending on where the knob is.


The unit of electrical power that is the product of voltage and current.


XLR Connector 
A shielded 5-conductor plug/jack used for DMX connections. Also can be a 3-conductor plug generally used for microphones.
Short for crystal.



Zener Diode 
A PN-junction diode designed to operate in the reverse-bias breakdown region. It is designed to conduct in the reverse [bias] direction: with a precise breakdown voltage [Vz].
Zero Crossing 
In alternating current, the zero crossing is the instantaneous point at which there is no voltage present. In a sine wave or other simple waveform, this normally occurs twice during each cycle.