This simple circuit for motors that depends on the MOSFET used was found in the January 1998 Electronics Now magazine. The motor voltage does not need to be the same as the oscillator.
In the figure we have the typical circuit of a Baxandall tone control applied to an operational...
This circuit makes use of older operational amplifiers, but can be designed on the basis of modern...
This circuit that can be assembled in an “aspirin box” was found in the Radio Electronics magazine of...