John Fields wrote:
On Sun, 12 Jun 2005 17:15:06 -0700, Don Lancaster
wrote:


Sum a 1 volt peak sinewave with a 0.6 volt dc term and you have a
waveform whose polarity continuously changes but whose average value is
continuous.

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No, you have a waveform with a polarity which changes _periodically_,
making it an AC signal. Do the electrons traversing the circuit
change direction? Yes. Do the electrons in a DC circuit ever change
direction? No.

Ergo, because of the periodic polarity reversals what you're looking
at is AC.
---

Looking at the Fourier terms makes this waveform perfectly clear.
Calling it "AC" or "DC" does not.

---
Why go there? Your description was adequate to indicate that polarity
reversals occur, therefore making the signal voltage alternate between
two different polarities, therefore making the current alternate
between polarities as well. That's why it's called "Alternating
Current".
---

"AC" or "DC" are gross and meaningless oversimplifications.

---
Uh-huh...

It's not unusual to speak of the AC and DC _components_ of a
waveform that does not readily satisfy the simplification.

One also speaks of _DC offset_ of an otherwise AC signal.

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