After I hacked up a green laser pointer so I could access the driver board directly (see here), I built a simple light show using the pointer, a junk gearhead motor, and some simple code in an Atmel ATtiny13A microcontroller.

This project is based on the Lunchbox Laser Shows article from Volume 20 of MAKE magazine.  However, I've scaled down the mechanics quite a bit and simplified the electronics somewhat.  One major difference between the original design and my project is the motor used.

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.

Here are a few pictures of the unit.  I haven't mounted it in a box yet; that's next.



Here is an overview of the light show assembly; the ruler at the bottom of the frame is six inches long.  The laser pointer is on the right and is aimed at a shiny, new quarter taped to the end of the shaft of the gearhead motor.  Both the motor and the laser pointer are held in place by artistically arranged pieces of 12 AWG copper wire purchased at the local hardware store.  After bending the wires to the appropriate shapes, I fastened them to the black Sintra base using lots of hot glue.  I power the whole assembly with 5 VDC, applied through the power connector on the far right.





Here's a closer look.  The small breadboard holds the ATtiny13A MCU and a Maxim MAX4427 MOSFET driver chip.  The '4427 is an excellent low-current motor driver that I have used in small robotics for years.  On the upper right edge of the breadboard, you can see a black TO-92 device; that is a Microchip MCP1702 low-dropout linear regulator.  The electronics runs on 5 VDC but the laser pointer wants 3 VDC, so I use the '1702 solely for providing 3 VDC to the pointer.  Note that the pointer, a 20 mW green laser, draws right at the maximum of the '1702 regulator, so the little regulator runs pretty warm; I'll add a heatsink in the future.



Here are a few pictures of the light show, though frankly, they don't begin to do justice to how awesome this display appears.



This is taken about three feet from the ceiling.  The center of the image overpowered the camera.




Another shot from about three feet.  (I didn't get the camera very steady on this one.)




This is from about eight feet away and shows more of the extended effects that spray across the ceiling.




Another shot from about eight feet, showing some of the intricate details that are generated.

Unbelievably cool and one of the best visual projects I've ever done.


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