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Old 9th February 2013, 04:37 PM   #34581
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Well, THIS is what I am talking about, when it comes to power line harmonics.
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Old 9th February 2013, 04:44 PM   #34582
DF96 is offline DF96  England
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Quote:
Originally Posted by bcarso
The late (lamentably!) Peter Carroll Dunn has a short table of properties of materials on the front pastedown of his Gateways Into Electronics, which includes the mean free time of electrons in copper, tau sub F, as 2.4 * 10^-14 s, and the average thermal speed of electrons along one axis <|u|> as 5 * 10^6 cm/s [ EDIT: at 290K ]
Thanks. So arithmetic tells me that an electron is likely to be back to normal behaviour about 1.2nm after leaving the BQP. Within perhaps 10nm almost all electrons will have scattered off something so will be 'normal' again.

The mathematical connection between Heisenberg and Fourier is useful, but it does provide scope for the unscrupulous to drag "quantum" into things where it doesn't really belong, such as audio electronic circuits.

If even-order harmonics derive from even-order distortion (they need not, although usually they do) then the even-order distortion will create a DC term too. This disappears completely at the first coupling cap or transformer encountered by the signal. So DC does not necessarily imply even-order distortion; even-order distortion does not necessarily imply DC. Similarly for any asymmetric waveform: DC and asymmetry do not necessarily accompany each other. Having said that, I'm not sure why we are discussing such elementary issues.

Last edited by DF96; 9th February 2013 at 04:53 PM. Reason: add comment on even-order
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Old 9th February 2013, 04:50 PM   #34583
bcarso is offline bcarso  United States
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Quote:
Originally Posted by sofaspud View Post
Just looked it up on Amazon... odd pricing (new hardcover from $10, Kindle edition $136!), but the first review is from none other than Winfield Hill. And it's very positive.
And the second review IIRC is mine. I swear I get no kickback

Lot of those pricing anomalies going on. Sometimes they are errors, sometimes the book is already gone and the listing not updated, but more frequently a bookseller just wants to clear some inventory. Notice closely the ones that show stock on bookfinder dot com (a great site that searches many sites) but then suggest they will ship in a few months! This can mean they will ship if they can find the book! Or, it is not disclosed but it may be a print-on-demand book. Note as well that sellers use multiple listing services and there may be six or seven occurrences of what is actually the same physical copy --- this can be detected from the identical description texts.

I ramble off topic and say this, as I am in the midst (on and off again for >7 years) of cataloging my books, and now getting more meticulous about noting condition and looking for true comparables for valuations. Things fluctuate a lot, with the advent of one-cent books where the seller makes a tiny spread on shipping and handling now common for titles that are plentiful, especially popular fiction and popular science. Other times there is one copy, maybe two, on the net, and the seller with it decides to price it to the sky (one or two thousand US$ is not uncommon). These usually sit there for a while.
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Old 9th February 2013, 05:06 PM   #34584
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And, i would conclude this deep scientific inquiry about BQP on a more serious way, in front of such scientific confusions and ridiculous argues on its site, asking an embarrassing question.
Can somebody provide evidence that Mr Bybee had any degree in physics and had ever worked for the US navy ?
As a secret agent myself, i asked Miss Moneypenny and Mr. Q and they were unable to find any trace of such a man as a provider of the US army neither traces of any BQT in the plans of U.S.submarines we have in our possession.
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Last edited by Esperado; 9th February 2013 at 05:29 PM.
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Old 9th February 2013, 05:11 PM   #34585
marce is offline marce  United Kingdom
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John,
why are these devices only sold to an audio based market, why not other areas of electronics?
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Old 9th February 2013, 05:24 PM   #34586
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Quote:
Originally Posted by DF96 View Post
Having said that, I'm not sure why we are discussing such elementary issues.
I don't either, but twice this week "asymmetrical waveforms have DC" was stated as an obvious fact. In xDSL as in audio large plus or minus crest events are not matched by the opposite polarity but the time average is 0 (especially in xDSL where there is complete galvanic isolation on both ends).
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Old 9th February 2013, 05:54 PM   #34587
DF96 is offline DF96  England
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Quote:
Originally Posted by scott wurcer
twice this week "asymmetrical waveforms have DC" was stated as an obvious fact.
It rather spoils the fun when we have to be continually explaining (and even justifying!) basic physics/maths/EE to people who either ought to know better or can't be bothered to learn the basics. Perhaps the forum should have a pedagogical area for such stuff, so the rest of the site does not have to be clogged up with teaching about elementary circuit theory, Fourier, algebra, calculus, feedback, stability etc. Teaching is not much fun when the pupils are convinced they know better than their teachers.

There is plenty in audio to have genuine arguments about, but we get bogged down in nonsense like "asymmetrical waveforms have DC".
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Old 9th February 2013, 06:42 PM   #34588
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NO, when second harmonic is generated from a primary sine wave, it CREATES A DC OFFSET as well as adding second harmonic. This is WHY we sometimes have DC on the AC power line, and this then makes toroid transformers BUZZ. There are online fixes for this, check it out.
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Old 9th February 2013, 06:45 PM   #34589
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Originally Posted by DF96 View Post
It rather spoils the fun
Have-you noticed that scientific oriented people continuously try to increase and correct their knowledge, while so called audiophiles and other people, living in a world of magic, just continuously try to comfort their believes, even when they hurt the most elementary logic ?

As far as i'm concerned, i have much fun, observing this human comedy. How the majority of people use on a daily basis objects they do not understand, from cars, to refrigerators.
In the between, there are few people that have some kind of basis, and still continue to believe in magic. Means experiment and do not try to understand.
Audio is a marvelous world for this sociological observation. Real science fiction.
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Old 9th February 2013, 06:46 PM   #34590
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Everyone, this is advanced understanding that is brought up in senior year at major universities in electronic engineering. Dr. Don Pederson taught me that, about 40 years ago. Dr. R.G. Meyer taught that to Ron Quan about 35 years ago, and I put up a couple pages of Ron's class notes to verify what I already know. (the added comments are HIS)

Last edited by john curl; 9th February 2013 at 06:52 PM.
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