With this simple circuit it is possible to simulate a telephone line for carrying out repairs on telephone sets. The transformer must be 36 V and the diode can also be 1N4004.
This circuit is the conventional use of the 7805 as a constant current source up to 1 A. The...
The integrated circuit used in this application is not currently common. The circuit is from an...
This circuit is from a Radio Electronics from February 1966. The circuit is of a type that was...