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.
The relay of this circuit closes when the position set in P2 is reached by the sensor...
This circuit is intended to monitor the flame of gas heating systems that must always have a small...
This circuit makes use of an old operational one to generate clock signals that depend on the...