This telephone recording circuit was found in the June 1979 issue of Radio Electronics magazine. The components are common at the time and the power is supplied by the power grid.
This circuit from a Radio Electronics from February 1976 activates the relay in two different ways...
The integrated circuit used in this project is unusual and it includes internal transistors that...
This circuit is quite old, from 1964, but can still be mounted with BC558 transistors. The circuit is...