Jukebox color wheel synchronizer

I built a system to synchronize the two color wheel motors in a Wurlitzer Model 1015 jukebox. Originally, the jukebox used two synchronous clock motors, and the designers assumed that the motors would stay synchronous and keep the colors wheels at the same orientation after manually setting it. As it turns out, the torque required to spin the color wheels is enough to cause the motors to slip. Eventually, the color wheels get out of sync, and the left and right side of the jukebox do not match in color.

My upgraded system uses two small DC gearmotors that interface with the original drive mechanics via a nylon gear from McMaster. I drive the two motors via a PN2222A transistor and sense the position of the color wheels with the optical sensors from an old computer mouse. An arduino controls the motors via PWM (20 or 30 KHz), and runs a phase-locked-loop routine with P-I control. This system could use a little tuning, but it's pretty close.

Universal motor speed control by a microcontroller

I am showing a method of using a CdS photoresistor to control a standard triac dimmer circuit that is wired to an electric drill motor (a universal motor). The CdS photoresistor is driven by an LED that is controlled by a PWM pin an an arduino microcontroller. This system provides a very easy way to control 120V AC devices with a single PWM pin, and not use any timing code or worry about zero-crossing of the AC power since this is done intrinsically in the circuit. It also offers true electrical isolation between the AC line voltage and microcontroller.