Need help with center tap Xformer

[rshayes]

I guess we will have to congratulate you, Chris. You have managed to contribute the bulk of the semantics, smoke screens, and ignorance that have appeared in this thread. I don't know of anyone else that could have supplied these items in such large quantities.<p>Some of the people that participate in this forum are newcomers to the electronics. Some of them are students trying to supplement their course material.<p>Some of them appear to have gone through a full BSEE course and have several decades of work experience. You don't appear to be in that group.<p>From your posts dealing with Physics, it appears that you last physics course was in high school or junior college. I am sure that the professors in my physics courses would have never have heard the last of it if they had described electron motion as "blowing marbles through a hose". It also appears that that you have never had a formal course in circuit analysis, since you are unfamiliar with the concepts and terminology that were well established over fifty years ago.<p>[ March 25, 2005: Message edited by: stephen ]</p>

[rshayes]

Hello Bodgy,<p>I only occaisionally see Wireless World as back issues in a technical library. I assume that it was a predecessor to the magazines that you get now.<p>I have a vague memory of a heated controversy that lasted for several months somewhere in the 1960's. I believe the subject was whether schematic diagrams should be drawn with the positive supply at the top of the sheet or at the bottom. I think that ran for several monthe. Maybe you remember it.

[bodgy]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by stephen:

I only occaisionally see Wireless World as back issues in a technical library. I assume that it was a predecessor to the magazines that you get now.<p>Maybe you remember it.<hr></blockquote><p>Hmm I'm not old enough to have been old enough to have read the 1960's issues (well not at the time), but I am old enough to insist in calling the magazine by its old name instead of its more recent incarnation Electronics World!<p>At the moment a debate is raging over Graham Maynards heretical contention that loud speaker testing setups and the resulting measurements are nonsensical. Letters to the Editor (or is that head hitter?) have been less than flattering since October 2004 edition.<p>Poor old Ivor Catt is having his engineering parentage questioned over his idea of Oxford Logic and some self bemoaning of his various employers nicking his patents and ideas.(This has been ongoing for the last few years in various forms) Douglas Self is quiet at the moment and no-one is attacking him.<p>The only person getting good press is John Linsley Hood, but then he sadly died last year, so people are now reminscing over his various audio and RF designs.

[Chris Smith]

Steven....Actually they named Alternating current just to confuse you? It seems to be working? <p>The current flow theory seems to have evaded your ability to understand it, Steven. <p>I kind of like the circus answer, that alternating current doesn’t really alternate at all, but flows clock wise, depending if your standing above the circuit, or just laying on your back?<p> Other than that, every one of my words on the subject has been accurate and true and the beginner and novice can learn something from it, especially the one about Alternating, because if they were fooled into thinking that it doesn’t do this, they might actually touch the other lead on a transformer and get hurt or worse. <p>But the smoke screen of the electron flow around the atom was a great one, and it should put the current flow in a conductor to rest even though they have nothing in common to share, and serve no purpose to explain anything to any one who is trying to understand a current that is Alternating, and what that means to them.

[Mike6158]

This thread has been interesting. I read it while listening to Niccolo Paganini's Violin Concerto #1 You can't beat reading a good "war story" while listening to a good violin concerto BTW.., it started just as I opened the thread and it ended just as I opened this window If this thread gets any longer it will ruin the symbiosis of the two <p>I wonder where Brad went?<p>[ March 27, 2005: Message edited by: NE5U ]</p>

[jwax]

Brad probably tired of the juvenile "I'm smart, you're stupid" bantering that has been denegrating this forum lately. Insults never had a place on this board, and it will only detract from technological discussion.

[Mike6158]

I reckon that they still don't.<p>On another note, this post comes to via a wireless connection to my Dell Axim X50 PDA. I like my "real" PC better but this is pretty cool.

[rshayes]

Actually, I agree.<p>Brad got the answer he was looking about midway through the first page with Dale's post. By the midpoint of the second page, Chris was accusing everyone of using incorrect terminology.<p>I didn't see anything wrong with the terminology, so I looked it up in some basic books on circuit theory (usually about a Junior level course in most Electrical Engineering curricula). Based on that, I wrote a post defending the terminology being used (closed circuit, loop, mesh, clockwise,etc.). I suspect that the terminology goes back to Steinmetz, but I can't prove that.<p>By the end of the second page, Chris had posted about ten items accusing everyone else of stupidity since no one was talking about alternating current. Finally, he explained that the basic physical difference between alternating current and direct current was that alternating current caused the electrons to reverse direction.<p>I wrote a post showing how it was possible to transfer charge in any direction without changing the direction of a single electron. The reply was that I must be on another planet, since it didn't happen that way on Earth.<p>I looked the subject up in Halliday and Resnick ("Physics for Students of Science and Engineering") and found that what I described was what happens here on Earth.<p>A little digression. When I was in High School, it is entirely possible that I used a Physics text that described electron motion as hopping from atom to atom. I really don't remember. When I went to college, I was required to take their introductory Physics course. This course occupied about one-quarter of the academic curriculum for two years. The text used was "The Feynman Lectures on Physics". Most of us also purchased Halliday and Resnick, since it was more help on homework problems. I still have all four books.<p>Halliday an Resnick directly describes the electron motion in copper, as quoted in my post. Feynman described a derivation of the average energy of this motion from thermodynamic principles. I also consulted two other references, Phillips ("Transistor Engineering"), and Grung (Transistors"). These both gave the same description of a conductor as a material where the conduction band and the valence band overlap, as opposed to a semiconductor, where there is a band gap between them. The electrons in the conduction band of both conductors and semiconductors are described as a cloud, free to move if a field is applied. All four references are consistent with a cloud of electrons in continuous random motion and capable of drifting in an applied field.<p>This type of electron motion also explains several things:
1) Johnson Noise,
2) Positive resistance coefficient in metals,
3) Negative resistance coefficient in semiconductors.<p>Overall, it appears that the electron motion described by Halliday and Resnick is a reasonable description based on modern physics. It certainly appears to be a more advanced view than the one Chris put forward. Since this was taught at the Freshman level, I concluded that the course that Chris took was probably a high school or junior college course.<p>Similarly, his lack of familiarty with the terminology led me to conclude that he had not had a formal circuit theory course.<p>I have to admit that some of his other comments show a great deal of originality if little accuracy. You can wire a variac so that both output leads are hot, but most electricians would use the common lead between the input and output as the neutral.<p>The thought of filling a waveguide with Freon to provide a conductive path is certainly original.<p>If we can convince the audiophiles that the electrons in their speaker cables are moving at relativistic velocities and emitting synchrontron radiation on the corners and X-Rays at the speaker, we should be able to develop a very profitable market in lead-sheathed monster cable.<p>Quite frankly, after Chris spent so much effort insulting everyone in general and specifically, I just got curious to see how far he would go.

[Chris Smith]

Great smoke screen and save Steven? Actually the posts that followed stated several times over, that AC acts like DC, but you were to busy trying to dazzle the crowd with advanced physics. The original post was about AC, NOT DC.

[rshayes]

The original post did not mention alternating current. It simply stated the polarity of the signal applied to the transformer. This could be a pulse, direct current, one half cycle of alternating current, a certain point in a time dependent waveform, or anything else which would result in a positive potential. The polarity of the signal is the only information needed to answer the question. The type of signal that is applying this polarity is irrelevant.<p>[ March 29, 2005: Message edited by: stephen ]</p>

[Chris Smith]

Try again Steven<p>AC, not DC, is the only power a transformer can be used with. <p>“I need help understanding how current flows in a center taped transformer. If the primary side has positive on the top and negative on the bottom then primary current would flow counterclockwise for this cycle” <p> For one half of the cycle it is true, then it is not, as it reverses direction and current flow.

And That’s why its called “Alternating Current”.<p>Such a simple concept eludes so many, just as it did back in class, till they learned to conceptualize what a current really is. <p>And I was happy to help them pass the exam with the basic understanding of what a current is.