This circuit is from a March 1978 Radio Electronics magazine article that showed how to build it. The circuit is TTL based and is powered. The components used can still be found.
This circuit provides a signal of higher frequency the greater the intensity of the light incident on...
This circuit was obtained from a 1978 Practical Wireless. It generates a low frequency, low...
This circuit can be used as a lockable shield. A pulse activates the relay that remains on even...