Arduino Laser Show: I

So, this popular German computer magazine called C't now also publishes "C't hacks", and I got a copy. Anton and I were immediately drawn to the Arduino-controlled low-cost laser light show. The main ingredient - besides the Arduino and the laser - are the read/write mechanics of two old hard disks. So I got some junk 2.5" HDs from work and we opened them up. After removing the platters we found that the galvos (the electromagnetic drivers of the read/write head unit) were pinned out over  ribbon cable to a little connector, and we didn't know which pins were data and which galvo power. First useful job for the new lab power source! After trying all possible combinations we found them, but they  were different for the two little drives. What was also interesting and useful for later was that 0.1 V would already drive them to center, so I am not sure we'll even need a motor driver for that. A simple Mosfet would probably do. Since Arduino Analog Write is PWM at 900Hz, we might need a Low-pass RC element as well, we'll see. For this first stage, we needed to solder wire to the tiny pins - glad we had that giant magnifying lamp from the San Jose lab! We put plumber's putty over the pins to keep everything protected.  The green laser was ordered tonight as well, and we cut little mirrors from the HD platters. Intense excitement!