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Something like this (Attachment)? Is this a better solution than optoisolator?


On Wed, 23 Feb 2005 11:09:32 +1300, Jinx <joecolquitt@clear.net.nz> wrote:
> > I need to connect a simple push-on switch with a PIC, but the
> > cable connecting it can be up to 30 meters. What are the potential
> > problems here? Interference and such?
> 
> I'd suggest sending Vcc or high output out through a series resistor,
> eg 470 ohms, and the input pin (IP) pulled low with a resistor of
> around 10x this, or a value that ensures the signal comfortably falls
> outside the transition thresholds of the input. If the environment is
> or could be noisy, add a small cap (100n) from IP to Vss, 5V1 zener
> (k to IP, a to Vss) to clamp positive excursions and a Schottky diode
> (k to IP, a to Vss) to clamp negative excursions
> 
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>

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