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Date: Mon, 31 Dec 2001 17:53:58 -0600
Subject: Re: LNC2 Fuel Level Sensors
Message-ID: <20011231.175359.-16455825.2.Earl_Schroeder@juno.com>
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          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
Another idea for 'capacitive probe sensors':

I used the Jim Weir copper tapes to create a 'capacitor' in the wing
tanks and header tank.  Acutally I built three for each wing (with one at
bl50, another in the center and the third on the outboard rib) and placed
a single one in the header on the center baffle.  I use  'surplus'
industrial electronics to convert the capacitance to milli amps which
drives the readout device.  The three probes in the wings are wired in
parallel and provides a near linear indication from full to empty.

The 1/2" wide tapes placed about 1/4" apart (and glassed in that vertical
position) do not provide enough signal change in my case although I have
a useable system with 40 hours of good experience.  I would use 1" wide
tapes placed 1/8" apart the next time.  Mount the tapes on a piece of
1/8" thick foam, glass, and rout out the foam to allow the gas to flow up
an down between the tapes.  I soldered the lead wires onto the copper
foil and then glassed over to seal everything.  The final bit of
'experimenting' was to leave the lowest 1/4" of the tapes bare so if any
water touched them, it would drive the output to the max.  The dielectric
constant of water is 80 and gas around two (if my memory isn't failing
me).

I believe Jim Weir also has a simple capacitance sensing device that
might be useful to read the 'probes' and convert it to a readout.  He
described it at Oshkosh last year or the year before.

Hope y'all have a Good New Year!  Earl

> Pat Redig,  A lot of LNC2 builders have installed capacitive probe 
> sensors in their wings and header tanks, including myself <snip>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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