This additional bell circuit was found in the February 1994 Electronics Now magazine. The transistors are common, and the circuit is for analog lines.
The TBA810 integrated circuit used in this 1982 project is not very common today, but if found it...
This regulated power supply can provide currents up to 1 A to a load. The transformer may actually have...
Found in a Popular Electronics from the 90s, this circuit can be made with current equivalent...