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.
Operated directly from the power grid, this detector was found in an 80's RCA documentation. The sensor is...
This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are...
The purpose of this circuit is to 'produce a beam of infrared rays modulated at a frequency that...