This is the receiver from the previous alarm system. The circuit is from Radio Electronics, April 1989, and has an LDR as the sensor. Optical devices should be used to improve performance.
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...