This circuit, which can be seen elsewhere on this website, was obtained from a 90’s English documentation. The circuit drives a small speaker, but for greater volume an external amplifier must be used.
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...