Volume expander amplifier (T364E)

This circuit was found in the 1961 RCA tube manual. The circuit includes a power supply stage.

Automatic Telephone Recorder (CB5992E)
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
6V Charger (CB4790E)
This circuit was found in a Poptronics of the 90's. The circuit limits the load current to 0.6 A....
High Power Switch Using SCR (CB540E)
Incandescent lamps and heaters can be controlled by a low power switch using this circuit. The...