This circuit recognizes a tone determined by the tuned input circuit (R3 / R4 / C2). The circuit was found in Radio Electronics from the 90s. The 4046 is not a common component today.
This 32 A circuit uses SCRs of the time. We found it in a 90s General Electric documentation. The...
This amplifier stage with 1 power transistor was found in the Radio Electronics magazine of...
This transceiver is also low power, but this time, it can generate signals in the 144 MHz band. In the...