>From: Mark Dickinson <>
>Does anyone out there know what the operating voltage of the fuel and
>water temp gauges is? My 'voltage stabilizer' is functioning well
>enough to drive the fuel gauge on a full tank to about 3/4+ level on >the
>gauge so I think it may be on the way out. Any advice on an LM317
>voltage regulator substitute? Also what should a warm temperature
>sensor read for impedence? What is the typical range?
I would check the fuel guage / sending unit operation first.
You can simply short the wire at the sending unit to ground.
This should peg the guage. If you still get 3/4 reading _and_
the temp guage is reading low, then the voltage stabilizer might
be suspect. A solid state regulator will work (sort of) but
is not the best choice. This discussion came up recently on
the Brit Car list. Here's what I wrote back then....
--------------------------------------------
It was written:
[...]
> >> Aren't there modern solid state devices that would do the same job but
> >> better and possibility cheaper?
[...]
Because the instruments are bimetalic, they are affected by ambient
temperature. The bimetalic stabilizer compensates for this i.e. takes
longer to heat up if it's cold, therby providing the bimetalic
instrument a little extra (average) voltage to keep the reading
accurate in cold weather. The converse is, of course, true for hot
weather.
Making an electronic version is not trivial, the voltage stability is
simple, but the temperature correction requires look-up-tables, design
data, temperature measurement etc. I expect it could end up costing
(manufacturers) more. My "domestic" vehicles made in the 80s and 90s
still use the bimetallic voltage stabilizers.
-Bob
(digest mode)
--
LBC'ing U,
Bob (& Spitfires)
[digest mode]
http://home.att.net/~stan.part
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