Found in a 90s Popular Electronics, this circuit uses a simple 9 V source. The power can be used from the circuit with which it works.
This simple electroscope with bipolar transistors is not the most sensitive, but can detect static...
This oscillator for various frequencies was obtained from a 1980s telecom documentation. The...
This circuit is from a July 1970 Radio Electronics magazine. The sensors are metal probes. The 18 V...