> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of jim korman
> Sent: Friday, February 01, 2002 21:55
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: Barometric pressure? (was: 8- vs 12-bit A/D
> advantages)
>
>
> Peter Anderson wrote:
>
> > I have used a Motorola MPX4115 to measure atmospheric
> > pressure.
> >
> > We fussed with a Philips capacitor in a 555
> > arrangement but didn't consider it any too rugged for
> > outdoor temperatures.
> >
> > I have had good luck with the Honeywell HIH-3605 RH to
> > voltage converter.
> >
> > There are BasicX BX24 routines for both the MPX4115
> > and HIH-3605 at http://www.phanderson.com/basicx/.
> >
> > Peter H Anderson, http://www.phanderson.com
> >
> <snip>
>
> I've noticed in your post, and others in a different
> group, the idea of mounting pressure sensors outdoors.
> Bad idea really. Much better to site the pressure
> sensor inside. It won't make any difference for
> the pressure reading as the pressure outside is the same
> as inside AND the temperature inside is much more
> stable!! You will have small pressure spikes from doors
> opening and closing but that is easy to deal with.

        I'm using a Motorolla one mounted indoors and I still recommend you
temperature compensate it, I've seen fluctuations as large as 2kPa from just
a few degrees difference in temperature! :) TTYL

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