Inspired by Mike Gould’s “Lunchbox Laser Shows” project in MAKE, Volume 20, Karl Lunt made his own, more simplified version, scaling down the mechanics and changing up the motor and control scheme:
Since I didn’t have a 1 RPM motor and I wanted to use something about that speed, I took the slowest, smallest gearhead motor in my junk box and powered it with a pulse-width-modulated (PWM) drive signal from the ATtiny13A MCU. Though the motor started out at about 10 RPM when driven with 5 VDC, I was able to get very smooth 1 RPM motion using PWM. If you aren’t comfortable using an MCU for what is admittedly a simple function, you could substitute a suitable 555 timer circuit; check the web for pages that will help you design such a circuit.
From MAKE magazine:
Want to know how to build a hydrogen rocket? How about a laser light show in a lunchbox? Or a simple remote-controlled videocam car? Or maybe you want to go old-school and build a wooden mini sailboat or toy car launcher? All this and tons more, plus revealing photos of Adam Savage’s maker childhood, can all be found in MAKE, Volume 20, “For Kids of All Ages.” Get your individual copy in the Maker Shed, or subscribe now.