For experiments with a disk rotating at various speeds, the April 1998 Electronics Now magazine suggests this PWM motor control. The current with the LM317 is 1.5A maximum.
This battery circuit provides a charging current of 500 mA depending on the solar panel. The...
This circuit was found in an Analog Devices manual and can supply a 3 mA current or drain a 10 mA...
This circuit has its application suggested in an alarm system. The circuit is from an old RCA...