Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!gatech!emory!stiatl!john
From: john@stiatl.UUCP (John DeArmond)
Newsgroups: sci.electronics
Subject: Re: How to convert weight to volts?
Message-ID: <5728@stiatl.UUCP>
Date: 13 Jul 89 00:51:48 GMT
References: <7903@etana.tut.fi> <10040010@hprmokg.HP.COM> <5081@umd5.umd.edu>
Reply-To: john@stiatl.UUCP (John DeArmond)
Organization: Sales Technologies Inc., "The Procedure IS the product"
Lines: 28

In article <5081@umd5.umd.edu> jonnyg@umd5.umd.edu (Jon Greenblatt) writes:
>In article <10040010@hprmokg.HP.COM> barry@hprmokg.HP.COM (Barry Fowler) writes:
>>My best guess would be to use a strain gauge.  I don't know if it would
>>fit in your budget constraints, however.
>
>	The least expensive solution that comes to my mind would be a
>transformer with a moving core. The core is connected to a spring of the
>apropriate weight. The rest of the system will consist of a regulated AC power
>supply and an AC meter.
>
>					JonnyG.


I don't remember the original purpose of the load cell but if high precision
is not needed, one of the absolute cheapest cells is a piece of conductive
foam rubber sandwiched between 2 pieces of printed circuit board.  More
weight == more conductivity.  You can thermally compensate the device by
building 2 identical cells and fixing the plates of one against outside
force (epoxy does well here) and then putting them in a wheatstone
bridge arrangement.

John


-- 
John De Armond, WD4OQC                     | Manual? ... What manual ?!? 
Sales Technologies, Inc.    Atlanta, GA    | This is Unix, My son, You 
...!gatech!stiatl!john    **I am the NRA** | just GOTTA Know!!!