This sounds like an automotive question, but its really not.
I have a engine temperature sensor (presumably a thermistor, as it reduces resistance with increasing temperature). I need to mate this to a temperature gauge, but the gauge is calibrated for a different sensor with a different temp. response curve.
temp/ohm curves are known for both sensors (see graph)
For various reasons I can't replace the engine sensor. Also the gauge is a sealed unit, so lets assume I can't modify the gauge internals.
Is there anyway I can insert a circuit between the sensor and gauge, so the gauge 'thinks' its connected to the 'correct' sensor? Preferably a circuit of passive components as I don't have too much electronics experience.
Initially I assumed I might be able to do this by putting a suitable resistor in parallel with the sensor, but any resistor like that will only 'flatten' the response curve and as you see, response curve needs to be 'stretched'.
A couple of other factors to consider.
- I don't need super accuracy; +/- 3 deg C is fine
- I only this to work well in the range 85-105 deg C
Is this possible in principle and what is the general approach?
EDIT: More info
The red curve is given by: resistance(ohms)=114+6014*e^(T*-0.0396), where T=temp in deg C
Measured resistances from the existing engine sensor (blue line) is below. I would hope there is enough data there to predict the remaining values up to 105degC (do themistors follow a standard curve?)