Hard Drive Laser Oscilloscope

This project was inspired by Aftotech’s Hard Drive Speakers (page 4). Basically the voice coil drive circuit was located on the hard drive controller board and disconnected by cutting a trace. The voice coil was metered and was found to be 10 ohms, this was within range to be driven directly from my stereo speaker output. A laser was mounted to the hard drive body, the laser output bounces off a mirror that is mounted at the edge of the hard drive body. The first mirror is top hinged and has a wire connecting it to the read/write arm of the hard drive. Now when the read/write arm moves the vertical deflection of the laser beam is changed. The first mirror points its laser output to a second mirror is mounted to the center of the hard drive platter. Initially the second mirror was intended to be spun using the hard drive motor however the hard drive motor spins too fast. Instead the platter is moved by hand allowing fine control of the horizontal laser position. We have all seen an oscilloscope hooked up to a speaker output to allow us to “watch” the music. Well now you can see a standard oscilloscope and a Hard Drive Oscilloscope side by side! ref: hackedgadgets.com/2006/04/25/top-5-uses-for-a-dead-hard-drive/2/