This circuit was found in documentation for radio amateurs of the 1980s. This is the so-called roger-beep, which is the beep that is transmitted when the talk-listen function is changed.
This circuit can be used with motors or resistive loads, such as heaters and incandescent lamps....
The output of this circuit can be coupled to a radio control transmitter to perform a...
Using an RCA integrated circuit, this instrumentation amplifier was found in a November 1970 Radio...