Found in an American documentation from the 90s, this circuit uses small low voltage lamps (6 to 12 V0. The circuit can be adapted to use LED indicators.
This circuit is intended for underwater communications. Of course, the critical point is the...
This circuit triggers an LED when the input signal exceeds the peak, or the value set in RV1. The...
This small FM transmitter was found in a Radio Electronics magazine in 1991. The magazine no...