how can I simply increase the voltage from a 5v sensor indenpendant of the source of reference voltage(ECU).
What I want to do is to change what the ECU reads from the sensor + ~.65v.
I was hoping I could do this just by splicing in a .65v (or whatever addition volt needed) line between sensor output and ECU .
Thanks, Rey
There is a very handy opamp circuit called a subtractor, that outputs the difference of two voltages, but with the result referenced to an arbitrary third voltage. See page 6 of:
You would connect ground to V1, the ECU signal to V2 (so the subtractor would subtract zero from the ECU signal, and connect a .65 volt reference voltage instead of ground to the right side of RF. This adds .65 to the difference of V2 - V1. You will have to come up with a stable .65 volt reference. Perhaps a forward biased diode is stable enough. Or you might use an integrated reference chip, like an LMV431:
I think an LM358 dual opamp would work for this application.
Of course, you have to work out the power supply requirements for these components, in your environment.
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Thank you for the response. I looked at the OP-AMP subtractor / adder. Not having any electronic knowledge, I don't understand RF resistor requirement, or any of the resistors requirements.
I found this searching on terms in your reply:
Seem to be a little closer or same thing with changes you suggested.
But what determinds what resistors go where?
Thanks, Rey
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