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 circuit trips when a negative pulse is applied to its input or when the voltage drops below a...
This is an old 1988 circuit consisting of a timer or time control for exposing silk-screen arrays. The...
This circuit was taken from an old American documentation. It can be built with modern op amps. The...