This TV remote control receiver uses a ratchet system to activate an old drum-type selector to change channels. A common system at the time. The circuit is from a Radio Electronics from February 1961.
This circuit is from the SGS manual of linear integrated circuits of 1982. The L78xx is equivalent to...
This low displacement circuit was found in American documentation from the 90s. Operational...
The purpose of this circuit is to maintain the liquid level of a reservoir between two values...