[sdiy] Nice push buttons .. & de-bouncing

[Seb Francis]

Been working a bit on my DigiMod today, playing around with the 'Sampler 
Mode' which I think is going to turn out to be a fun little module.

I've bought a selection of different push buttons to try and find one I 
like, but not much luck so far.  The problem with most of them is the 
action is too stiff.  They need to be able to be triggered rapidly and 
with accurate timing - for the sampler recording/playback start/stop and 
for things like tapping in delay tempo in Delay Mode.

My other requirement which is limiting choice is that I need the buttons 
to be panel mount (.. if I found a really nice, PCB mount button then 
maybe I'd could find a way, but panel mount would be much easier)

Suggestions very welcome.... my ideal would be something like the action 
of the Nord Lead/Rack buttons, or like the action of a short-travel 
laptop keyboard - but in panel mount.

One button I've found so far with an acceptable action is this one:
http://www.rapidonline.com/Electronic-Components/Switches/Push-Button-Switches/Miniature-SPST-momentary-push-switches/
It's nice and light to operate.  On the downside though, the button part 
is too small, and it's really cheap and I'm sure would quickly become 
unreliable - even brand new, the switching gets pretty messy on the 
scope when tapping lightly ... which brings me to my next topic:

De-bouncing...

I'm doing the de-bouncing in software so there is a zero latency 
response time to a state change, and then any further state changes 
within the de-bounce time are ignored.  Playing with the above mentioned 
cheap push-button I find I need at least 5ms, and probably significantly 
longer than this once the switch gets a bit old.

This may not sound like a problem in itself, but I also want the same 
Gate input to be triggered from external sources, such as square wave 
oscillator to allow hard-sync effects with sampled sounds.  The 
de-bounce time unfortunately limits the upper frequency of this.

So what's the experience out there?  Are there better push buttons with 
a nice light action that will work reliably with a de-bounce time 
significantly less than 5ms?  Or am I going to have to live with this?

Seb