This physical line servo control uses components that are not currently common. The circuit is from an 80's documentation and is powered by a voltage according to the servo.
Using an analog microamperimeter this circuit has a phototransistor adapted to the wheel as a...
This two-transistor MW radio was found in a publication from 1958. It uses one of the oldest type...
With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of...