Found in an American documentation from 1969, this astounding circuitry makes a relay operate on 3 Hz cycles. The relay is of the high voltage type of the time.
This circuit makes use of older operational amplifiers, but can be designed on the basis of modern...
Equivalent operational amplifiers can be used in this circuit of the 1990 Linear Databook,...
This switched, switched or PWM amplifier was obtained in the 1972 RCA linear integrated circuit...