DC Wave Questions

jackbruce9999 · 2005-06-10T21:55:02+00:00

2 questions about a fully DC Sine Wave....let's suppose you have a DCSine wave which varies from +5V to +15V peak-to-peak going into a loadwith R, L, and C components.....Question #1:Is the load's impedance a function of R, L, and C (and wave frequency)or is it simply just R (i.e. Z=R)? In other words does non-resistiveimpedance (L + C) really only matter with an AC signal OR anytimevoltage varies periodically (even if it is all DC)?Question #2:Would a "regular" negative peak detector ciruit, like shown here:work for the DC Wave described? Will it output +5V or do negative peakdetectors only work for AC signals?Thank you.

Jun 10, 2005 365 Replies

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Tom Grayson 20 years ago

Hey JackBruce I got fed up with the crap the other posters wrote about your terminology, and did not really see if anyone actually answered your question, Which, by the way, Was very easy to understand. Ignore the other jackasses here, that nitpick. They have too much time on their hands, i can see.

Question 1 The impedance of inductors and reactors is based on the varying signal frequency, Weather it is offset by the DC component or not. This answer assumes that you are not reaching the current limit of any of the devices, naturally if the DC Current in the "L" Device saturates the Flux medium ( air or iron) then you will get non linearities introduced, Not sure what the limit on a "C" Device would be, probably current again.

Question 2 The link didn't work but most of the modern devices looking for peaks and valleys work fine with a DC Offset.

Tom Grayson

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Danny 20 years ago

I've just noticed this 'long' thread. It is of interest to me as I had a not dissimilar problem. The use of superposition is absolutely correct in a linear system where the system component values do not vary with the signal applies. However, when applying the ac component the skin effect phenomenon will deplete the current carrying carriers from the centre of the conductive component thus reducing the effective cross sectional area......which will also effect the dc resistance....or will it?

Danny

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Reg Edwards 20 years ago

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No, it won't. However, it does appear have affected superposition of your thinking processes. ;o)

Reg.

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<salmonegg 20 years ago

It will not. Each frequency component will work independently of others. The modification of resistance by heating is a nonlinear effect that will couple different frequencies.

Bill

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