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Why?But you need a stable voltage to generate the output signal offset the TS desires.
I assume the TS has a good reason for not wanting to do that.But my opinion is "just run a second wire".
A given current through a known resistor will produce a specific signal voltage. As long as that stays within the common mode range of a differential amplifier it can be changed to zero referenced or shifted to any required bias offset, for whatever display module is in use.
The differential amp and onward can run on a stabilised supply - but the sensor does not need regulation.
What "stable bias offset"??How do you get a stabile bias offset without a stable voltage?
The offset to give 0V output when the sensor temperature is 0°F (255µA).What "stable bias offset"??
No, it's not part of the vehicle electronics, it's an added display circuit.The only point that needs a stable offset is after the differential amp, which is part of the in-vehicle electronics and can be fully regulated.
I'm actually regulating to 6V (REF voltage) from the battery 6.3V (about 7.2V with the engine running).I do really like your circuit and will certainly give it a shot as it more effectively can regulate the supply at 5 volts without worrying about regulator dropout specifications
Resistor R2 in my schematic serves that function by cancelling out the 255µA current at 0°F.Not sure I'm up on just how to offset the op amp between stages or at the display adjustments for the 255' Kelvin to Zero Degrees Fahrenheit. I guess that is all handled in the "@crutschow" Spice.
"In vehicle", as in being part of the digital display unit, rather than part of the oil pressure switch circuit.No, it's not part of the vehicle electronics, it's an added display circuit.
It's a classic car with a 6V battery and likely little vehicle electronics beyond a possible tube-powered radio.
You may need to have another beer and look at the front.This is a back-of-a-beermat grade version of what I'm getting at;
It's a concept, not an exact circuit.You may need to have another beer and look at the front.