>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?
Mark, from what I gathered from trial-and-error, the Spitfire regulator
system seems to be a sort of electro-mechanical "chopper" device that
regulates voltage by using thermal bi-metal contacts that open and close to
keep the voltage at a constant level. The higher the voltage, the more
current/heat is generated and the faster the contacts open and close. The
gauges, being very slow to respond, do not see the switch actions, but do
see an overall constant voltage. At least this is how I figured it when I
was checking my system. As was stated on another response, you could use a
10V regulator IC, but I don't know if 10V would give you the right voltage
for an accurate reading. Sounds like it would be worth a try if you
suspect the regulator is shot, since the IC is pretty cheap. If you buy
the IC from Radio Shack, they usually have the pin-out configuration on the
package. Also you will probably want to put a 1mfd by-pass cap on the
input and one on the output to prevent the IC from breaking into
oscillation and going into thermal runaway and overheating. Additionally,
there are lower voltage versions (8V, 5V) if 10V is too high.
Let us know if that IC works for future reference.
Regards,
Richard
|