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 is from a 1977 publication for radio amateurs presenting a crowbar protection. The...
Found in a 1965 Motorola documentation, this circuit uses a neon lamp as a trigger element. The SCR...
Twin-T oscillators can be used to produce sinusoidal signals in the audio track with good...