This circuit was found in a 73 magazine for radio amateurs from the 90s. The circuit uses high voltage transistors and the relay is high voltage as well.
T This circuit produces an audible signal when someone touches the sensor, or even approaches. The...
We found this circuit in a 1994 publication. It makes use of a divider for 16 384 CMOS type 4060. By...
Using germanium transistors, this amplifier provides a 540mW output power when powered by 9V. We...