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 excellent wireless microphone circuit for the varicap-modulated FM band came out in...
The simple low voltage source that can be used as a battery eliminator, shown in the figure was...
This asymmetrical crossover filter was obtained from an 80s integrated circuit manual. The...