With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of the 555. The circuit was found in the November 1989 Radio Electronics magazine.
The circuit shown in the figure has elements for maximum gain at maximum speed. By setting the...
This circuit was originally designed to drive an engine with a small flower that dances when the...
The circuit is from the Texas Instruments optoelectronics manual. The capacitor depends on the...