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 originally appeared in a publication of 1997. With the changes, the circuit can be...
This circuit was found in the February 1992 Radio Electronics magazine. The circuit drives 5 LEDs...
This circuit can be used in instrumentation to obtain a very high input impedance for measurement of...