adding 2 voltages and subtracting 1

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kinarfi said:

I have 3 voltages/signals that I need to combine, I'm using a VCC of 10 and trying to have everything operate around 5, the first input is the controlling signal and has 5 as it's center and the second is the feed back signal and centers on 2.5 by design, I can wire it so feed back is 2.5 + feed back or 2.5 - feed back, then I need to subtract the 2.5 which makes for the 3rd voltage. I've tried to simulate several methods, but just not sure what works most reliably. There are difference amplifiers and inverting and non-inverting summing amplifiers shown in several places, but nothing for adding 2 and subtracting 1.
Any suggestions? I don't have a - voltage that I can add, every thing is above 0. here's what I have, attached

kinarfi,
You need to look at this link. Ratch
https://electronicdesign.com/ideas-...chit@comcast.net&YM_MID=1428104&sfvc4enews=42

Thanks,
Kinarfi
SORRY for double posting, checking to see which works best
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Click to expand...

the first input is the controlling signal and has 5 as it's center and the second is the feed back signal and centers on 2.5 by design

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