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 ?

wbr
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