This circuit with two operating modes was found in the September 1989 issue of Radio Electronics magazine. Other operational amplifiers can be used. The power supply must be dual.
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
This circuit was found in a Poptronics of the 90's. The circuit limits the load current to 0.6 A....
Incandescent lamps and heaters can be controlled by a low power switch using this circuit. The...