Based on the 4017 integrated circuit, this circuit of a European 303 Circuits from the 90s, generates a pulse train in a relay that mimics the dialing of a telephone.
Here we show how two 4017s can be cascaded to count above 10. The circuits are driven by a square...
The circuit in the figure represents a typical application of a phototransistor exciting a relay...
This circuit, in fact, what it does is a reactivation of the batteries through a brief pulsating...