On Tue, 27 Feb 2001, Mike Harrison wrote:
{Quote hidden}> Thanks for the input on this one.
> For your info, after some headscratching and a lot of paper, here's
> the best answer I've got to, and verifed correct with Excel
>
> <use fixed pitch font>
>
> Given a bridge :
> Vin
> +----+
> R1 R2
> +----|--- Vout (differential)
> | +---
> R3 Rx
> +----+
> GND
>
>
> Calculate Rx given V, V=Vout/Vin
>
> R2
> Rx = ------------------
> R1+R3
> ----------- -1
> R3-V(R1+R3)
>
> For my case, where R1=R2, we can also say R2=R2=1 as R3 and Rx can be
> scaled to compensate.
>
> This then simplifies to
>
> R3-V(1+R3)
> Rx = -----------
> 1+(V(1+R3))
On Mon, 26 Feb 2001, Wojciech Zabolotny wrote:
> Rx + R2
> (C3) solve(Vout=V1-V2,Rx);
>
> (R2 R3 + R1 R2) Vout - R2 R3 Vin
> (D3) [Rx = - --------------------------------]
> (R3 + R1) Vout + R1 Vin
Hmm. Looks the same to me.
Now this is Interesting. I didn't realize Excel had an algebraic symbolic solver
like Maxima! Maybe it's about time I revert back to windows.
BTW, I installed Maxima after Dr. Zabolotny's post. I was thoroughly impressed.
You Linux fans oughta go install this
http://www.ma.utexas.edu/maxima.html
You window's fans will be glad to know the author is working on a port. Or you
can cygwin it now.
(mac fans have to wait for OS X)
Scott
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