I know that there a bunch of EE's on this list and hereby
enlist their skills.
The temp gauge on my daughter's SV always pegs out in city
traffic, but the radiator doesn't boil over. The car has a
2.3 L Ford transplant and a 4 core radiator. I always
assumed that the temp sensor was a thiristor (sp?) and that
I could calibrate the gauge by adding a resistor in series
with the sensor. I planned to bring home a stirred hot oil
bath and a lab grade thermometer, emerse the sensor in the
bath and put a pot in the circuit and adjust it until I had
accurate readings. I would then substitute resistors of
suitable value.
Before I got to this undertaking I decided to open up a
rather doggie gauge from one of my parts cars and see if
there was some internal adjustment available. Much to my
suprise what I found was a crude bimetalic arm wrapped with
resistance wire.
I assume that what happens is that with a good instrument
voltage regulator in place the heat generated in the
resistance wire will be proportional to the resistance of
the sensor. Now the deflection of the bimetalic arm is
dependent on its temperature, not the heat generated by the
wire. Given two identical engine temperatures in two cars,
will the one in North Overshoe in the middle of a blizzard
read the same as the car in New Orleans on a hot summer
day? Isn't there a better way to do this, and where do I
find one?
Paul Gilbert in New Orleans
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 08:44:54 CDT