This additional bell circuit was found in the February 1994 Electronics Now magazine. The transistors are common, and the circuit is for analog lines.
This circuit with integrated TTL 7400 has a good teaching purpose, drawing one of two LEDs. The...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...
This circuit makes use of a diac to stop the activation of a sensitive reed relay 1 mA. The trip...