This circuit with TTL output was found in a 1968 EEE. The transistor can be of general use. The tunnel diode is an uncommon component today.
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...