This circuit was obtained in an Electronics Now from the 90s. The circuit uses operational amplifiers from the time and the indicator is of the Sonalert type with internal oscillator.
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...