This circuit emits a warning sound when night falls. The circuit is from a Hands On Electronics from the 90s. The Sensor is a common LDR and R6 adjusts the trigger point.
The simple touch of the fingers on a sensor causes this circuit to drive a motor that goes into...
Motorola's MC1456 integrated circuit used in this application is not very common today. The...
This circuit of an old publication produces the insect-like noise that drives them away. The...