This circuit was obtained from Linear Technology documentation from the 80's. Powered by 5 V it can be used as a shield. The components are from the era.
This circuit was obtained in a 1967 General Electric documentation. It is a relaxation oscillator...
This circuit detects when a powered circuit suffers a malfunction, lighting an LED. The supply...
Other versions exist on this site from various publications. This one is from the Radio...