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 was obtained from General Electric documentation from the 1980s. FET operations are from...
This circuit is from an American documentation from 1976. The FET can be the BF245 or MPF102 and...
This amplifier has a few Watt output, using old transistors. The speaker is 45 ohms, but with...