On Wed, Aug 1, 2012 at 10:05 AM, Dwayne Reid wrote= : > At 09:30 AM 8/1/2012, Denny Esterline wrote: > > > > >I was going to suggest a DIY solution using either a Magnet/Hall/Reed > >switch combination or, better yet, a photo slot interrupter. > >Pivot a toggle/flag on a plastic axle between some felt washers and you > >should be able to get the noise well below audible. > > I like the way you think. What I might be able to do is to > disassemble a standard mini-toggle switch and solder a metal flag > onto the lower end of the toggle, into the cavity where the switch > mechanism used to be. Add some felt material on either side of the > flag for friction, then use two slotted photo-interrupters to detect > end of travel. The two interrupters would then drive a S-R flip-flop > for clean switching with no problem of position ambiguity. > > This also has the advantage that I can use a standard 4000 series > CMOS part that works at the existing 12V supply rail. > > The existing switch is noisy because the announcer flips the toggle, > which then goes over-center and snaps into the opposite side. Its > that snapping sound that is causing the problem. If I go to a flag > with friction that has to be dragged into its new position, the > snapping noise is eliminated. > > I'll try it out over the next couple of days and let you know how I make > out. > Dragging is not going to be reliable, You have no detent to keep it in position. Jostling from running will likely activate it unintentionally. Bur, if you're gong to disassemble the switch, why not put a couple of to92 hall effects in instead of a flag? Magnetize the shaft and you're dirt and water resistant. Use a tiny rare earth magnet, and the shaft will try to stick to the hall effect or metal backing plate. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .