The circuit shown in Fig. 1 provides a mechanical means of striking two gongs or chimes in sequence -- one when the doorbell is pressed, the other when it is released. This it does by briefly activating two solenoids in succession -- or even two motors to which suitable hammers are attached. It is a circuit which was rejected by a publisher, for the reason that it was thought to be too complex -- which really it is. I had been designing various embodiments of the same idea, and this embodiment was not the most elegant. Having said this, it works perfectly well. The circuit is unusual from the point of view that it is based on two pulse shorteners, IC1a and IC1b. These are essentially two monostable timers with special arrangements at their inputs. Of critical importance, in these circuits, is that the potential between S1 and R1 should change fairly rapidly when S1 is pressed, and that the trigger inputs of IC1a and IC1b should be suitably biased. Universal Ding-Dong Circuit Diagram C2...