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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: looking for sensor (Tilt Sensors)
Summary: Electrolytic level sensors
Keywords: tilt sensor, angular displacement, electrolytic sensor
Message-ID: <3816@kitty.UUCP>
Date: 27 Jun 90 00:08:06 GMT
References: <6452.26874295@umiami.miami.edu> <1990Jun26.192024.17036@newkodak.kodak.com>
Organization: Recognition Research Corp., Clarence, NY
Lines: 28

In article <1990Jun26.192024.17036@newkodak.kodak.com>, ornitz@newkodak.kodak.com (Barry Ornitz) writes:
> >I am looking for a very high-precision tilt sensor.  It must be fairly small
> >and operate off of low voltage DC or AC.  The Spectron company makes such a
> >sensor for avionics applications, but $150 is quite expensive.
> ... 
> Another approach that is considerably cheaper but far less accurate is that 
> taken by Universal Photonix, Laguna Hills, CA.  This utilizes an "electronic"
> bubble cell which is essentially an electrolytic sensor.  As cell is tilted
> more of an electrode is immersed on one side of the cell; the electrode on the
> opposite side of the cell is immersed less.  A conductive electrolyte is used.
> Wiring the sensor into a bridge circuit with an op-amp, you should get an
> output voltage propportional to tilt.

	The Spectron sensor is also an electrolytic potentiometer (as above),
with their better models being capable of resolving to seconds of arc (note
that I have not commented about linearity, however).

	An electrolytic potentiometer can be a low-cost means of measuring
inclination.  However, it is important to realize that these devices MUST
be excited by an AC voltage having a waveform with as much symmetry as
possible.  The use of DC may cause internal corrosion of the electrodes
which will have an adverse effect upon performance.  The Spectron data
sheets even go so far as to warn against the use of an ohmmeter for testing
of the device.

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
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