Found in an American circuit manual from the 1970s, this circuit can use any general-purpose transistor. The operating frequency range is from 600 to 4000 Hz.
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...