This circuit is from an American documentation from 1975. The single junction transistors can be 2N2646 and the signal must be applied to the input of a good amplifier.
This circuit was found in a 1986 publication. The speed of the effect is determined by the 555,...
This preamp version uses BC109 transistors that are older versions of the current BC549 in plastic...
This simple voltage-controlled oscillator generates signals from 300 Hz to 1,500 Hz with voltages from...