This circuit is from a Radio Electronics from the 90's. The integrated circuit is from the time and the boost gain is 20 dB.
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...