[sdiy] Switch debounce

[Paul Maddox]

Alternativly,

 you could get one of the many 'debounce' chips available on the net and
save a lot of messing around :-)

Paul

----- Original Message -----
From: "Scott Gravenhorst" <music.maker at gte.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, January 27, 2005 8:18 PM
Subject: Re: [sdiy] Switch debounce


> Can you show a schematic?
>
> It sounds like you want a differentiator.  You can't just connect a logic
> gate (or switch) output through a cap to a CMOS logic input.  You need to
> put a resistor from the CMOS input to ground to allow the cap to charge
and
> discharge.  Without the resistor, the CMOS input presents a very high
> impedance, millions of ohms.  The size of the resistor will control how
long
> the pulse stays active, smaller making a narrower logic level duration.
>
> xyzzy at sysabend.org wrote:
> >I'm having some troubles with a circuit that has simple switch debounce
> >stuph on it.  The circuit is a 4001 based clock generator going through a
> >.01uf cap, there is also another push button to do a manual pulse.  I get
a
> >nice waveform out of the 4001, but going through the cap turns it into a
> >very momentary pulse which the logic following it doesnt seem to accept.
> >Same for the pushbutton.
> >
> >Quite possible this cold is making me fuzzy enough that I'm not forming
the
> >question correctly, but is .01uf a good value for this? ( given the
limited
> >information I've provided. ).  At two places in the circuit ( which is
> >kitbashed from multiple other circuits ) I've used a .01 cap and in both
> >cases the logic following it doesnt see the momentary pulse as a clean
> >pulse, but I'd assume that the original circuit worked correctly.
> >
> >--
> > -----------------------------------------------------------------
> > - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org
> > - SynthGeek        -
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> >
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