This circuit that generates signals between 1.5 and 2 kHz was found in a documentation from the 90's. The capacitor C1 can be changed to obtain other frequencies.
This simple circuit imitates the sound of a machine gun and, when using a larger capacitor, a...
Hughes suggests this circuit in a 1968 documentation. The circuit uses old transistors that can be...
This series sensor circuit is from 1995 Popular Electronics. The circuit can use any SCR and the...