Posted by Damir [ 213.202.97.195 ] on July 31, 2006 at 07:08:18:
In Reply to: Re: PS Transformers posted by manualblock on July 30, 2006 at 19:06:36:
Simplest - we have two devices "chained" together, 2nd "sees" output (or source) impedance of the 1st device on its input. For example, if 2nd device is a preamp, and 1st is a pot, then preamp "sees" output resistance of the pot in series on its input. We can describe the pot as a one resistor in series, and one resistor in parallel to the source. Then output resistance of the pot is the parallel combination of those two resistors. If our pot is half-opened 10k device, then its output (or series, or source) resistance (that preamp "sees" in series with its input) is 5k//5k = 2k5.
Power suplies filters are more complicated - they have resistors, but also capacitors and inductors - they have impedance (say, frequency-dependent resistance to AC).
Formulas for output impedances of various filters (Pi-type,CLC, for example) you can find elsevere, RDH comes to my mind...
But, fortunately, large knowledge of network theory isn`t necessary for building a PS... 
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