This circuit was found in an old American documentation. It can operate with signals from 40 Hz to 50 Hz and the input voltage range is from 0 to 200 mV.
This circuit came out in a 1978 American publication, but can be assembled with transistors BC547 or...
The trigger signal for this circuit is an audio tone. Tones up to close to 100 kHz can be used. The...
This circuit was found in a 70s documentation. The transistor is from that time. L1 has 4 turns of...