Using an analog microamperimeter this circuit has a phototransistor adapted to the wheel as a sensor. The circuit is from American documentation from the 1980s, but the components are common today.
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...