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[SOLVED] Resistor divider with multiple simultaneous input voltages

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wileur

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I have been trying to wrap my mind around this one for a while now... I have a resistor voltage divider network as in the attachment.

What happens to the voltage between TA and TB when C changes in voltage?
If it becomes 0V? 200V? etc.

I know Ohm's law and frequently use voltage dividers, but I can't figure out how to calculate how much current will flow where.

Any help is appreciated.
Wileur

(PS: This is not a homework question, I'm really trying to work this out for one of my projects) voltage divider.png
 

Suppose R1+R2 = Ra, R3+R4 = Rc and R5+R6 = Rb
Also suppose Vx is the voltage at node Nx, the point where Ra, Rb and Rc join together.
To solve your problem, consider the currents' balance at Nx: (Va-Vx)/Ra + (Vc-Vx)/Rc = Vx/Rb
Solve for Vx as a function of Vc, then calculate the currents flowing in each branch, and finally replace Ra, Rb and Rc with the original resistor series. The rest should be straightforward.
Have fun! :)

P.S.: you can apply this method even if Vb is not zero. In facts this method is one of the most important analysis method for linear networks, unfortunately I know its name only in Italian...
 
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    wileur

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Thanks, this is very helpful. I spent some time playing around with this and it solved my problems. You pointed me in the right direction and googling for linear networks and network analysis gave some good hits on wikipedia. I just didn't know the what to search for.

Wileur
 

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