This circuit simulates an American siren and can be found elsewhere on this website and section. The circuit is from a 90s documentation. Preferably, the signal should be applied to an amplifier.
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...