Found in a 70s RCA manual, this circuit uses transistors from the era. Equivalent types can be used such as TIP31 for Q1 and BD135 for Q2.
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...