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 of1994, originally obtained from the National...
This circuit was found in a 1977 Radio Shack documentation. The circuit is TTL, which must be...
This circuit was found in an American 1980s documentation. It analyzes the exhaust gas of a...