Error on Superposition page

Thread Starter

WBahn

Joined Mar 31, 2012
25,748
Near the bottom on the following page

http://www.allaboutcircuits.com/vol_1/chpt_10/7.html

is the following statement.

It must be noted, though, that the Superposition Theorem works only for circuits that are reducible to series/parallel combinations for each of the power sources at a time (thus, this theorem is useless for analyzing an unbalanced bridge circuit),
This is simply wrong. The only requirement for Superposition to be valid is that the system has to be linear. There is nothing nonlinear about the voltages and currents in an unbalanced bridge circuit. If someone believes otherwise, post a (simple, please) example of an unbalanced bridge circuit having only linear components (use resistors to be consistent with this point in the E-Book) that you believe can't be solved with superposition. I'll work it (and, who knows, may learn that I am wrong) and then, either way, it can be added to this portion of the E-Book, either to show how it can be done, or as an example of how it doesn't work.

A bit later down the page, it this says this:

Another prerequisite for Superposition Theorem is that all components must be “bilateral,” meaning that they behave the same with electrons flowing either direction through them.
But since this is shortly after saying:

... and it only works where the underlying equations are linear
it is in no way "another" prerequisite since components that aren't bilateral aren't linear. Arguably it is redundant and could be removed, but it is probably a useful point to have explicitly made for some readers. This can be patched quite easily by changing it to something like, "Note that the requirement for linearity means that all components must be "bilateral", ...."
 
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