Re: slightly off-topic: switch de-bouncing

From: Rodger Boots <rlboots_at_cedar-rapids.net>
Date: Mon Sep 03 2001 - 16:21:19 EDT

Probably the simplest way would be to make the capacitors larger. Try 1 uF or
even as much as 10 uF (negative to ground, positive to the switch resistor).
Also, maybe using a 74LS14 instead of the 74LS04 would be a good idea, otherwise
the relatively slow input change due to the capacitors might cause an
oscillation.

By the way, in your schematic the LS04 is the inverters and the LS02 is the
gate. You have them switched.

Anthony Ramos wrote:

> With the goal of using only existing hardware, I've built a TTL multi-game
> switcher. When you hold down both start buttons simultaneously, it cycles to
> the next game.
>
> The switcher works well, but there is a bounce problem. When you press the
> buttons, it sometimes advances one game, sometimes two or three. Apparently
> I need to improve the "de-bouncing" of the start buttons.
>
> I originally posted this question in rgvac. Some EE professionals weighed in
> with lofty analysis and convoluted arguments over the best solution. But
> that "Clash Of The Titans" left me with nothing I could really use.
>
> So, I humbly present the existing circuit to you:
>
> +5v
>
> | |
> \ \
> / / 1K
> \ \
> / / LS02
> | | 220 Ohm (inverters)
> Start 1 []------+-----/\/\/\/--+--------|>o-------|~~~\
> | | |LS04|-- output pulse
> Start 2 []---------+--/\/\/\/------+----|>o-------|___/
> | |
> - - .1µF
> - -
> | |
> === ===
> = =
>
> I don't want to program a PIC or some other ridiculous overkill. Please tell
> me, IN ENGLISH, what I need to do. Thank you!!
>
> -Anthony
>
> --
> Anthony Ramos________
> 600 SE 39th Ave., # 3 \__ aramos@ele-mental.org .. aramos@hyperreal.org
> Portland, OR 97214 \___ information design .. multimedia production
> (503) 236-6303 \____________interactive art .. image synthesis
>
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Received on Mon Sep 3 13:23:31 2001

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