Freon. The registered trade name for a fluorinated hydrocarbon compound used as a refrigerant and a fire extinguishing agent. There are a number of Freon compounds identified with numbers. Each compound having different characteristics.
Freon-12 has been the most commonly used refrigerant in aircraft air conditioning systems, but because of environmental considerations it is being phased out and replaced by R-134a which is more environmentally friendly.
frequency. The number of complete cycles of a recurring event that take place in one unit of time.
frequency converter (electronic circuit). A circuit which changes the frequency of alternating current. Alternating current with a frequency of 1,000 hertz, for example, can be changed to 200 hertz by combining it with an AC signal having a frequency of 1,200 hertz.
When alternating currents having these two frequencies are combined, or mixed, two more alternating currents are produced: one having a frequency which is the sum of the two, 2,200 hertz, and the other a frequency which is the difference between the two — in this case, 200 hertz, the desired frequency.
frequency divider (electronic circuit). An electronic circuit whose output has a frequency that is an exact divisor of the frequency at the input. If a signal of 100 kilohertz is placed on the input of a frequency divider that divides by two, the frequency at the output will be 50 kilohertz.