This circuit produces the sound of a motorcycle or an outboard motor. The frequency is adjusted in the pot. For supplies above 9 V the BD136 must be equipped with a small heat sink.
This simple low-power circuit uses, in the original version of 1965, germanium transistors. The...
This circuit was found in a 1989 publication. The operational amplifier supports equivalents. The...
This circuit from a 1967 publication turns a short pulse into a square signal whose duration...