Call me daffy!

[John Speth]

I can offer a simple suggestion for a debouncer that I confirmed to work maybe
14 years ago.  This came from Electronic Design News in their Design Ideas
section from March 17, 1982.  It was entitled "One IC debounces six switches".
An ideal debouncer would use a SPDT switch - each "throw" would  register your
open or close state in an SR latch.  The circuit in the Design Ideas section
simply times the closure of SPST switch so that it triggers a state change of a
CD4050 (CMOS!!) bus driver if the switch stays closed for longer than 0.7*RC.
The RC is a resistor and cap used in the circuit too.  I've tried it and it
works really well.  Cheap AND dirty and CMOS to boot.

Here is my attempt at a text only description:

You need a CD4050 gate (or I guess 2 CD4049 gates in series).  You need a cap
(suggested is .1 uF) and a resistor (suggested is 150K) and a SPST switch.
Topology is like this... The cap is wired as a feedback cap with the gate input
to output.  The resistor is wired Vcc to the gate input.  The switch is wired
from the gate input to ground.  The gate input is a node to which the resistor,
cap and switch all connect.  A closure of the switch forces the output low after
0.7*RC time has elapsed if the switch remains closed during that time.  I think
you need a CD4050 because of its' higher current output capabilities than most
CMOS devices will offer but I'll bet a regular CD4049 with an transistor
configured as an emitter follower at the output would work as well.

JJS