Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!ken
From: ken@cs.rochester.edu (Ken Yap)
Newsgroups: sci.electronics
Subject: Re: How to convert weight to volts?
Message-ID: <1989Jul11.202155.8984@cs.rochester.edu>
Date: 11 Jul 89 20:21:55 GMT
References: <7903@etana.tut.fi> <10040010@hprmokg.HP.COM> <5081@umd5.umd.edu>
Reply-To: ken@cs.rochester.edu (Ken Yap)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 14

|	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.

One of the more imaginative solutions I have seen is a project in
Elektor where they used a loudspeaker. The perimeter of the cone was
cut away.  A platform was then glued onto the cone. A photoelectric
sensor was attached.  The circuit was an op-amp which pumped enough
current through the coil to clear the photoelectric sensor (feedback
loop).  The current was then a measure of the weight on the platform.
A DVM chip and display completed the project.  Unfortunately this
balance only did up to 2 kg. Maybe you can get a monster loudspeaker
from a rock group and increase the range. :-)