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Digital To Analog Converter (DAC) - A Digital To Analog Converter (DAC) is a device that takes a digital input (in either parallel or serial form) and outputs an analog voltage. DACs are used in many older sound cards (newer cards use DSPs, or digital signal processors) and anywhere else a computer must output an analog voltage. The DAC symbol shows the digital inputs usually on the top. The symbol "points" toward the analog output.

Generic IC - Integrated Circuits, or ICs, are entire circuits formed on a small silicon chip. The individual transistors, resistors, diodes, etc. are made depositing different layers of N and P type silicon on the chip's surface. Some ICs have special symbols on schematics, but for those that don't the standard square with connection pins is the representation of choice. This symbol can represent timers, decoders, processors, etc. What it actually represents will be on either the schematic or parts list.

orOperational Amplifier (Op-Amp) - Operational Amplifiers, or Op-Amps, amplify the difference in voltage between their two inputs. In this way, they are used to compare and amplify voltages. Many audio amplifiers are based on op-amps. Op-amps have two inputs, an inverting input and a non-inverting input. The polarity of a voltage applied to the inverting input gets reversed at the output. The inverting input is represented by the - symbol on the schematic. The non-inverting input is the + symbol.

Opto Isolator - An opto isolator allows two circuits to exchange signals yet remain electrically isolated. This is usually accomplished by using light to relay the signal. The standard opto isolator uses an LED shining on a phototransistor. The signal is applied to the LED, which then shines on the transistor. The light is proportional to the signal, so the signal is thus transferred to the phototransistor. Opto isolators may also use photodiodes, SCRs, TRIACs of other semiconductor switch as an output, and incandescent lamps, neon bulbs or other light source.

Voltage Regulator - A voltage regulator is an integrated circuit whose function is to keep a voltage at a specific level. Some regulators are adjustable, others are not. Voltage regulators come in both positive and negative voltages. They have three pins, the input, output and reference. The input is usually on the left side of the square and is where the unregulated input voltage is applied. The reference is usually on the bottom of the square and is where the reference voltage is applied. For fixed regulators, this reference is usually ground. For variable regulators, this reference is usually a small variable voltage just above ground. The last connection is the output, and is usually located on the right side of the square. This is where the regulated output voltage is taken from. On most schematics, the connections are numbered and labeled.