This 6W amplifier with 4 tubes was indicated in an American documentation from 1947 to operate with recorders. The circuit uses a source with a transformer.
Found on a 1969 EDN this circuit switches a current from a digital control signal. The impedance...
The Toshiba TLP577x series consists of an infrared photo-emitter (IR) and a sensor integrated circuit...
This conventional 4 channel circuit with the 4017 and 555 was found in the November 1991 Radio...