It actually consists of a tunable field strength meter. The circuit is of an old documentation and the circuit must be tuned to the frequency to be monitored. The circuit offers the option to use a headset.
This circuit was found in an 80's General Electric documentation. The circuit uses components from the...
This oscillator can be used as a signal generator in a workshop, generating sinusoidal signals from...
This circuit is from a 1970 General Electric documentation. It can be found with variations on this...