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> Any thougts about MC14490 (Contact Bounce Eliminator)? It's around
> 3.5 USD a piece (on their web site): 

If you were thinking of a chip solution, a cheaper option might
be a monostable made from NOR (eg 4001, 7402) gates. Using
a 4001 with 1M for R and 100nF for C you might expect a
period of around 50ms. The first L-H transition sets the o/p high
and any further triggers (ie noise) are ignored until the timing
period is over. Unfortunately, switches also make noise when
they release too, so an RC filter on the i/p would help avoid
re-triggering on release. You could filter the signal ad nauseum
with both s/w and h/w (even a couple of transistors arranged as
a Schmitt Trigger) but could still be caught out by a rubbish
switch

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