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 a publication in the 1950s, mainly applying to germanium transistors of the...
This simple 3-channel passive mixer can be used with low-intensity signal sources but requires...
We find this circuit in a 1974 Motorola PUTs (Unijunction Programmable Transistors) documentation. The circuit...