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

[Tim Ressel]

Have you considered "touch switches"?

http://www.paia.com/ProdArticles/touchsw.html

There is also a version in the Cmos Cookbook I believe. My copy is hiding again...

--TimR



--- On Mon, 3/16/09, Seb Francis <seb at burnit.co.uk> wrote:

> From: Seb Francis <seb at burnit.co.uk>
> Subject: [sdiy] Nice push buttons .. & de-bouncing
> To: "Synth DIY" <synth-diy at dropmix.xs4all.nl>
> Date: Monday, March 16, 2009, 8:12 AM
> 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
> 
> 
> 
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