Shoo Dog!

We’ve all had occasion to be annoyed at inconsiderate dog owners whose animals relieve themselves on the private property of others. This problem can hardly be solved in a lasting manner using verbal (or even physical) means, so recourse to an electronic remedy is better and friendlier.The starting point for this circuit is a ready-made passive infrared sensor (PIR), such as can be found in inexpensive movement detectors. The relay contact of the PIR energises the power supply of the circuit shown here. The power supply generates a voltage of around 15 V after rectification by D1-D4 and filtering by R1/C3 and R2/C2.