I have had much success with actually using mini speakers. I mounted a rod to the center of the speaker which connected to another = rod that was attached to a pivot. The length of the Pivot rod was 3 times the distance from the center of = the speaker to the pivot, this amplified the movement of the speaker. I = then mounted a front surfaced mirror to the end of the pivot rod. Then = by using two of these mechanisms (Galvanometers), I was able to create = an X & Y axis. Just like on an Oscilloscope, I put a sweep frequency = into the X Galvanometer and an Amplitude frequency into the Y axis and = was able to mimic an Oscilloscope. I also was able to take the X sine wave, by using a filter circuit, I = was able to shift the sine wave by 90 degrees and feed it into the Y = axis. This produced a perfect circle, just like using the Z axis on an = Oscilloscope. Changing the Y axis sine wave by greater or less then 90 = degrees produced Lissajous / Spirographic patterns. Taking things a step further, I experimented using a larger speaker with = a serious magnet, a pivot rod made out of springy sheet metal, extended = the length even further to amplify / exaggerate the movements of the = speakers and attached larger in diameter, but thinner front surfaced = mirrors made from a silicon wafer. I hooked up these speakers to a = power amplifier with music (with bass) and a variable filter to shift = the y-axis by approx 90 degrees for frequencies between 60 and 120 Hz. = In a dark room, these mirrors moved fast enough that you could hardly = see them and the effect was a 3D image of spherical patterns varying in = size and shapes depending on the music. Someday, I would like to try using stepper motors controlled by a PIC, = to see what kind of results I can get for a more controlled image of = patterns or shapes. Tim =20 -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Greg Miller Sent: Friday, June 04, 2004 8:48 PM To: PICLIST@MITVMA.MIT.EDU Subject: [PIC]: Laser scanned display. I thought it'd be fun to use a mirror to scan a laser across a wall for a display. I've had several ideas for how to make the mirror scan the beam across and up and down, but they all seem a bit beyond my mechanical abilities. The latest idea I've come up with is to put four permanent magnets on the back of a mirror, and a coil behind each magnet to push/pull the mirror which is mounted on a pivot in the center. Will that actually work? Is there an easier way? -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.