NNTP-Posting-Date: Wed, 15 Jan 2003 22:53:34 -0600
From: "Mike Shonle"
Subject: Re: Need help designing a circuit...
Date: Wed, 15 Jan 2003 23:55:03 -0500
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RE parts, Digikey is good for a lot of things. Also, try www.findchips.com,
enter the part number, and it will search a bunch of vendors. Or if there's
a Fry's nearby, they have some stuff.
But depending on what your time is worth (unless this is for fun anyway), it
may be hard to really do it cheaper yourself.
"ryanm" wrote in message
> "Gary Tait" wrote in message
> > The circuit is rather simple too, or findable, just inteface the
> > analog enviroment sensors to the ADC of the micro (choose a micro that
> > has an ADC, or use and external ADC). You could do it is Assembler,
> > C, or even Basic (if the chip you choose has a Basic compiler)
> I know it's as simple as: probes -> controller IC -> LCD driver ->
> Maybe a clock chip in there somewhere to set how often to check the
> impedance on the probes. I just don't know where to begin to choose
> components. I also don't know what effect adding 5' of wire between the
> probes and the controller micro will have, since a lot of them output an
> impedance relatively equal to the temp or humidity. How do I figure out
> to offset the load difference caused by the wire? What kind of controller
> chips would I use? I've been in software since I got out of high school,
> my EE skills are more than what you would call rusty.
> And a big one, where does everyone go for parts? I've been looking at
> several places on the web, but the last time I needed parts I went to
> shack, and they're no help these days. All they have is phones and