LM2903N differential op-amp

[davenn]

Also, wanted to confirm that a "regulated" supply isn't really needed for the op-amp power as is shown the circuit - vs typical vehicle battery-alternator power, since spec sheet shows Vcc OK for a wide input range.

And would a 7805 be my best bet for the +5V to the new senders, since I won't need to handle much current?

For the first application (resistive sender) I am now realizing I should dig into the gauge a little to see what the basic movement is; if it's a voltmeter movement, then I can treat both of these as essentially the same design. I'll look at that this weekend if weather permits...

relative to this part tho.
just because it can operate over a wide range doesn't mean you can feed it a voltage that is continuously varying. that's a bad idea. as it will cause a uncontrolled and unpredictable output

for stability you must use a stable regulated supply

cheers
Dave