Plague Boy writes:
Dave Martindale wrote:
snip
In "normal" switches, there is enough current to get a bit of arcing on
open and close, and that keeps the switch contacts clean. This doesn't
work when the current is milliamps. For this purpose, you need a switch
with gold contacts (which don't oxidize), or one where the contacts
mechanically wipe past each other each time the switch is operated.

Fascinating. Would a mercury ("Quiet") switch be a suitable
replacement, then?

That sounds plausible, though I've never heard of one being used in that
application. Probably worth a try.

Dave