The gauge failure posts cursed my car

I built an ICE years ago

RustyRatRod said

Right, which does make me wonder then, why not use 6.5v or 7v? 5v seems a little low in that application. What am I missing?

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I'm gonna say using 5V as a control voltage is kind of an industry standard. Not just automotive.
I built an IVR for my 68 25 yrs ago using a few parts from Radio Shack for less than $5. The chip thing was constant 5V.

I'm a retired Micky though and not a Sparky so I could be wrong.