This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational amplifiers. Power MOSFETs and inverted zeners support equivalents.
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...