This highly sensitive light sensor was found in a 1970 General Electric documentation. The circuit can use the 2N2646 for the UJT and the phototransistor can be of any type.
This circuit is from 1990 documentation. When we press D1 the lamp remains on for a time interval that...
Some old multimeters have a high resistance scale that has an internal circuit powered by a 22.5 V...
This circuit, from a 2001 documentation, appears elsewhere on this site. Its purpose is to obtain a...