This is funny.... note sure of the original date, but my old
email address was from 1993 or so. :)
I think we discovered that the best way to calibrate was for the
TEMPERATURE READING on hot.... which varied from 7 to 8 volts
depending on the car and meter. To calibrate the temp sender
I had connected it to a ohmeter, and dropped it into boiling
water. Then used an old adjustable resistor (big one!) to set
to the same temp reading. Sorry, don't remember the resistance
I had measured.
Todd made up a little circuit board to fit into the original
regulator can that was up under the dash. Fun project for those
of you who like electronics. :)
Cheers,
Tom Walter
Cedar Park, TX
From some obscure hard drive:
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The voltage regulator, is a bimetallic strip as you surmised.
The do fail, but I'd first double check the little screw
that grounds the case to the body. A little corrosion will
play havoc with the gauge readings. Clean the terminals.
The average voltage output is around 8 volts. With the "on-off"
action switching between full voltage (battery) and off, it is
the average value that is of interest. The meters are "dampened"
so this "on-off" fluctuation is not noticed.
Seems like the "ideal" voltage would lay around 8 volts. Seems like
an LM317 could be used for the task to make an adjustable voltage
regulator. Calibration is done by filling the tank full of gas, and
adjusting the output voltage to give a "full" reading.
For those "non-electronic" people; a LM317 is a part number of a
common voltage regulator, but you need additional components to make
everything work. I'll add this on my "things to do list" and post
a follow up if I ever get around to making something up (which usually
occurs after MY regulator fails). Hmm, I have a feeling the current
needed is about ONE AMP! Seems high, but the senders had low resistance,
so I'd have to check that first.
Cheers,
Tom Walter twalter@agora.rain.com
Beaverton, OR.
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