This 600 kHz circuit is designed to locate a lost boat anchor. The circuit has a range of up to 10 meters. The transistor admits equivalent.
This sensitive voltage measuring circuit has a very high input resistance, of the order of Mohms,...
The presented circuit monitors a line indicating if it is busy if there is an extension. The...
This circuit with germanium transistors was found in a 1980s documentation. The circuit makes use...