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 VCO or Voltage Controlled Oscillator was found in a Popular Electronics from 1991 but can be...
This simple circuit was found in Popular Electronics from 1992. The transistor is a...
This type of circuit is widely used in old cassette recorders and tape players, regulating the...