This is the cct I constructed..its output is 4-20mA however using a 250ohm
resistor it provides 1 - 5 VDC which I feed into one channel of a DS2450 A/D.
What you guy's are taking about sounds great ...direct connect from sensor to
1wire input
http://img.photobucket.com/albums/v319/rjconway/4-20.gif
This cct works ok however was never able to get a full range. 1-5VDC I measure
1050mm water gauge with a pressure sensor, and it provides a range of 2.9 - 4.6
VDC. I translate pressure into litres for display of how many litres are
available from a reservoir.
Would really like to know how this project of yours goes...
rob
----- Original Message -----
From: Paul Alfille
To: owfs-developers@lists.sourceforge.net
Sent: Wednesday, December 05, 2007 10:55 PM
Subject: Re: [Owfs-developers] Pressure sensing and One Wire sensors
On Dec 5, 2007 12:17 AM, Gregg C Levine <[EMAIL PROTECTED]> wrote:
Hello!
Of course it would have made more sense to state that fact. These are the
MPX family of sensors first made by Motorola during the beginning of the
MEMS ideas, now made by Freescale, in fact this pair is the MPX12D type.
From the datasheet: http://www.ortodoxism.ro/datasheets/motorola/MPX12DP.pdf
Full scale: 0-70mV with an offset.
Now from my table: http://owfs.org/index.php?page=voltage-measurement
The DS2438 has a Vsens (vis) range +-250mV
The DS2761 has a range +- 64mV
Both also have supply voltage and temperature, both are pretty inexpensive.
The DS2761 allows a software bias setting that might be useful.
The DS2761 also stores a "cumulative current" which could be used for average
pressure. It is also more accurate (higher resolution with the smaller voltage
range).
Paul Alfille
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