[sdiy] Minimum parts count switch de-bouncer.

[Dave Kendall]

Hi guys.

Very grateful for all the help - going to have to decide now...... :-)

Looks like the simplest, lowest parts count circuit, using stuff I've
already got, is this circuit;

                I-------------------------I>o------------o out
                I                     schmitt trigger
+15V            I  
    I     sw    I   I------I Rx I-------I
    I    ____   I   I                   I
    I----o  o-------I                   I
                    I      +            I
                    I------II Cx II-----I----GND


There's a variant using 4069 NOT gates, which I've got more of, but which
uses 2 stages, and 2 extra resistors ;


                                I---I IM I------I
                                I               I
                                I               I
                I------I 100K I---- I>o--I>o------------o out
                I                4069 - 2 stages
+15V            I
                I  
    I     sw    I   I------I Rx I-------I
    I    ____   I   I                   I
    I----o  o-------I                   I
                    I      +            I
                    I------II Cx II-----I----GND


where Rx = 10k, and Cx = typically 1uF. I'm not sure, but from what I
understand, the pulse duration in ms is R in Kohms, x C in uF = 10ms.
Am not sure if the output pulse will be negative or positive going.

I guess the +15V and GND connections could be reversed (making sure the
electro is reversed too) to change this?

I'm soldering away right now, so we'll see soon...

cheers,

Dave

on 13/4/06 5:50, Tim Daugard at daugard at sprintmail.com wrote:

> Here's my entry into the fray.
> 
> http://home.earthlink.net/~synthfred/h_ssssg1.htm
> 
> With a Schmitt trigger, it would be 4 parts - C1, R3, S1 and the Schmitt
> trigger.
> 
> Tim Daugard
> AG4GZ 30.4078N 86.6227W Alt: 12 feet above MSL
> http://home.sprintmail.com/~daugard/synth.htm
> 
> 
> From: "Dave Kendall" <davekendall at ntlworld.com>
> 
>> Many thanks for all the replies - have now got plenty of options to try!
> 
>