www.piclist.com/techref/index.htm?key=formula+unbalanced

I think I got the formula wrong last time...

Treating each side as a potential divider : Vout = Vin(R3/R1+R3) - Vin(R2/Rx+R2)

R1=R2, so this is now :

Vout=Vin(R3/R1+R3) - Vin(R1/Rx+R1)

Vout = Vin((R3/R1+R3) - (R1/Rx+R1))

We want the answer for Rx given the Vout/Vin ratio- call this ratio V,

so this becomes :

V = (R3/R1+R3) - (R1/Rx+R1)

..and this is where my algebraic ability grinds to a halt..!

So the question is how do you juggle this to get either :

Rx = function_of(V)

Or (better, if possible)

Rx/R3 = function_of(V)

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