Quoting dpharris@telus.net: > Quoting ivp : > > > Hi all, > > > > I've got a project which involves selecting from a menu with a long > > slide switch. It will be made of a piece of PCB about 200mm long > > with 20 tracks going off to a PIC ADC. The user control is a slider, > > which moves a finger to complete the circuit. The idea is that the > > position of the circuit completion means a distinct voltage at the ADC, > > like a 1-way 20-pole rotary switch rolled out > > > > 20 positions is a separation of 50 in the ADC. If that turns out to be > > too fine then the 20 can be split into 4 groups of 5, using 4 ADC. The > > PIC has nothing else to do except pass this information on so pins use > > is not a problem > > > > My concern is what material to use for the tracks. As this is a one-off, > > and I haven't found out what expense is involved, I don't know whether > > gold flashing or carbon would be an option. And might not be hard enough. > > Bare copper is probably out, so too perhaps tinned tracks. I can imagine > > poor contact and noise after a time > > > > I've got some thin tin plate, as used for screening boxes, which might > > do. Had it for a while and it still looks bright enough but don't know if > > it would corrode if abraded by a moving contact. Maybe some brass > > shim, but that gets a patina pretty readily > > > > Any suggestions or experiences ? > > Why not a slide potentiometer? If you need indents, then perhaps you could > add > them. Likely to hold up better and easy to obtain, eg > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PP1045SD-ND > > David PS -- oops, these are not long enough for your application --- I like the rotary pot with pulley idea of Bob's. David -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist