This small control for DC motors up to approximately 1 A uses an operational amplifier that admits equivalent. The transistor can be TIP29 for currents up to 1 A or BD135 for 500 mA.
We found this circuit in a 1977 Radio Shack manual. The light bands are given by the operating gain...
The circuit in the figure is a current regulator with adjustment in the range of 0 to 3 amps. The...
This stage for JFETs was found in a 1965 US publication, but is valid for modern components. |...