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 circuit is from 1985 documentation. The integrated circuit is not very common today, but...
This power supply is protected from shorts in the load. The BD135 must be mounted on a heatsink...
This receiver for the police band, which at the time was 45 MHz, was found in a publication by...