Found in a September 1992 Radio Electronics magazine article, this circuit generates a pulse as shown in the graph below the diagram. The timings can be changed by swapping C3 and C7.
This old slide projector control circuit was found in an 80s Hands On. The circuit uses modern...
In the figure we have a circuit that uses unusual components, being indicated for low frequency...
The sensor of this circuit found in Popular Electronics can be formed by a piece of fabric between two...