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.
This circuit was found in an 80's Electronic Engineering. The circuit uses operatives of the time...
The selected circuit was obtained in a Texas Instruments opto-electronics manual. The transistors can be...
In short wave receivers or in the recovery of signals from scratched discs this circuit can be...