With this circuit it is possible to use a pair of old telephones in a wired communication system. The circuit is from a Popular Electronics from the 90s.
This circuit was found in the December 1995 issue of Electronics Now magazine. The circuit...
The basic idea of this 1989 circuit is to trigger a relay for a while when a call signal occurs on...
Found in Radio Electronics from the 90s, this circuit uses a 741 and can be changed to other...