Talk:Negative resistance/Archive 4

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Note that the article to which this talkpage relates was located at Negative impedance for part of its history.


The rewrite performed by User:Circuit-fantasist has been moved from here to User:Circuit-fantasist/Negative resistance. Zetawoof(ζ) 20:51, 17 January 2009 (UTC)

Moved again to here after it was put back. Consensus is that Wikipedia's policies do not permit such content on article Talk pages. The comments immediately below refer directly to the removed contect but have been left in situ to preserve the history of this Talk page. See Archive 3 for recent discussion re this. Secret Squïrrel 01:16, 20 February 2009 (UTC)

There's something very important that's missing here: Sources. Sources, sources, sources. Can you cite some? Zetawoof(ζ) 00:30, 21 January 2009 (UTC)

You can't quote yourself as a source. — BillC talk 22:59, 21 January 2009 (UTC)

Reconstructing the introductory part

I have replaced the introductory part (Concepts) of the article with the text above. My explanations are so simple, clear and obvious that there is no any need to verify them; all is needed is Ohm's law. Nevertheless, I have wasted mass of time to look for reliable sources (besides my article[1]) that second these speculations. For now, I have found only one expressive picture[2] but I will continue browsing the web. Circuit-fantasist (talk) 16:25, 24 January 2009 (UTC)

Please read WP:OR. Just because your explanations are clear to you doesn't mean they're correct, or acceptable on Wikipedia. Zetawoof(ζ) 20:30, 24 January 2009 (UTC)
Zetawoof, thank you for the remark. I will scrutinize the problem to clarify it. Circuit-fantasist (talk) 20:45, 24 January 2009 (UTC)
I have read the materials about WP:OR. IMO, they do not concern my explanations, the accuracy of which is easily verifiable by any reasonable adult without special knowledge. For example, the figures represent the well-known 19th century Ohm's, Thevenin's and Norton's electric circuits; should I cite these famous scientists? All the assertions are more than obvious; see the examples below:
  • Passive elements absorb energy: resistors dissipate energy while capacitors and inductors accumulate energy... (elementary electricity; what should I cite?)
  • Electrical elements may be connected in series, parallel or mixed (what should I cite?)
  • ...a voltage drop VR = R.I that is proportional to the current appears across the resistor... (Ohm's law; should I cite his "galvanische Kette"?)
  • ...a current IR = VL/R that is proportional to the voltage flows through the resistor... (Ohm's law again)
  • Elements with negative impedance inject energy... (what else can they do?)
  • A negative resistor is a varying (dynamic) voltage source, whose voltage is proportional to the current passing through it...or a varying (dynamic) current source, whose current is proportional to the voltage across it... (Ohm's law again; don't you think it is more than obvious?)
  • ...the first are two-terminal current-controlled voltage sources (see Fig. 3a); so, they act as current-driven negative resistors... (obviously!)
  • ...the second are two-terminal voltage-controlled current sources (see Fig. 3b); so, they act as voltage-driven negative resistors... (obviously!)

Should I continue? Circuit-fantasist (talk) 16:45, 26 January 2009 (UTC)

Moving the content about negative differential resistance to its page

Negative differential resistance and absolute negative resistance are different enough concepts; so, I have moved the main content related to negative differential resistance to the related page. Circuit-fantasist (talk) 16:58, 24 January 2009 (UTC)

Moving the content about Deborah Chung's "apparent negative resistance" to a new page

I have created a new page about Deborah Chung's "apparent negative resistance" and moved the related section from this article to it. I have also copied the related text from the old discussion and from the full version of my suggestions for improving the article about negative resistance. Visit the talk page to see my reasons. Circuit-fantasist (talk) 15:46, 26 January 2009 (UTC)

Reconstructing the top introductory text

I have begun reconstructing the introductory text on the top. I have tried to show there the most typical properties of the negative impedance phenomenon as follows:

  • Negative impedance element is an electronic circuit, not an element (a component). There are not true negative impedance elements; there are only negative differential resistance elements.
  • Negative impedance element is a two terminal (1-port) electronic circuit
  • Negative impedance elements are sources that inject energy into circuits while the according passive elements (resistors, capacitors and inductors) absorb energy from circuits
  • Negative impedance element is not an ordinary, steady source; it is a dynamic source:
    • it may be a dynamic voltage source that produces voltage depending on the current passed through it in the same way as the voltage across the resistors, capacitors or inductors depends on the current passed through them;
    • it may be also a dynamic current source that produces a current depending in the same way on the voltage applied across it as the current passed through the resistors, capacitors or inductors depends on the voltage applied across them.
  • Negative linear resistance is a special but the most popular case of the negative impedance phenomenon
  • There are also non-linear negative resistors (e.g., "negative diodes")
  • Also, we have to mention the most typical applications:
    • Elements with negative impedance are used mainly to compensate the losses in elements having the same "positive" impedance

Please, comment my insertion. Circuit-fantasist (talk) 09:15, 28 January 2009 (UTC)

Renaming the title from "Negative resistance" to "Negative impedance"

I have renamed the title from "Negative resistance" to "Negative impedance" and redirect the first article to the second one. The reason is that the negative resistance phenomenon is a special case of the more common negative impedance phenomenon. Circuit-fantasist (talk) 14:35, 28 January 2009 (UTC)

How to create simple negative impedance elements

I have started the most interesting part of the article where we have to show how to create negative impedance elements. I have exposed in detail my viewpoint at the topic in the full version of my suggestions for improving the article. Here, I will show the truth about these odd, mystic and never explained circuits by using extremely simple and clear explanations that are obvious for every thinking human being. Please, do not put a damper on my enthusiasm; instead, just help me to reveal the truth! Here are the main points:

  • True negative impedance elements do not exist in nature; so, we have to create them
  • The basic idea: to "copy" the voltage drop across the "positive" impedance element (by a voltage follower) and to add an equivalent voltage to the input voltage
  • Putting in practice the idea: making an op-amp produce a "mirror" voltage by using a negative feedback. Revealing the role of the op-amp in all kinds op-amp inverting circuits witn negative feedback. Circuit-fantasist (talk) 11:00, 29 January 2009 (UTC)

How to create true one-port negative impedance elements

I have created the greater part of the most interesting part of the section about negative impedance implementations where we have to show how to create true 2-terminal (one-port) current-driven negative impedance elements... but I'm not contented... I have realized this idea is extremely simple, intuitive and brilliant but yet I have not managed to express it in this, obviously, I have to reword and refine it. Circuit-fantasist (talk) 10:36, 30 January 2009 (UTC)


I nominate this page for deletion

I have started my rewrite of Negative Resistance, as I stated I would do some time ago. The ideas about negative impedance described here are terribly misconstrued. The impedance of capacitors and inductors have opposite signs when circuits are analyzed incrementally. This is why resonant circuits work - the inductive and capacitive impedance cancel each other out at their resonant frequency. An Ohmic device always has a positive impedance. There is no way of creating a resonant circuit with resistive devices. So the ideas put forth in this article are fundamentally wrong. I will continue with my edits to Negative Resistance and if this article is not soon deleted I will rewrite it as well. Negative impedance exists, but is not what is described here.Zen-in (talk) 06:18, 2 February 2009 (UTC)

What negative impedance is

Zen-in, thank you for your reaction to my work. I appreciate your efforts to improve the page about negative impedance and invite more Wikipedians to join this discussion. All we have the same goal - to show the truth about negative impedance (resistance) phenomenon. I will first comment thoroughly your contentions (in bold and italic) and then I will draw general conclusions. I have also saved below your insertion from the article. Circuit-fantasist (talk) 17:36, 7 February 2009 (UTC)

"Negative Impedance is an alternative description of an electronic effect called Negative Resistance. Impedance, however refers to the frequency dependent resistance of a component. Components and materials that display a negative resistance effect may have frequency dependent properties as well. There is no contemporary research in this area and so it might be assumed that the term is a holdover from the 19th Century."

...The impedances of capacitors and inductors have opposite signs when circuits are analyzed incrementally... Maybe, the main problem here is that you think in terms of classical electricity while I think in terms of electronic circuitry. In the area of negative impedance phenomena, it is the custom to say that all natural passive components (resistors, capacitors and inductors) absorbing energy from the input source have "positive" impedance (or just impedance in the wide sense of the word, not only as an opposition to a sinusoidal alternating current); so, from this viewpoint, the impedances of capacitors and inductors have the same positive signs. Conversely, the artificial electronic circuits (negative "resistors", negative "capacitors" and negative "inductors") behaving in an opposite way (adding energy to the input source in the same manner as the according passive components) have a true "negative" impedance.

This classification regards to the way of processing energy - "positive impedance" means consuming while "negative impedance" means producing energy. From this viewpoint, "positive impedance" means "ordinary impedance" while "negative impedance" means something opposite as "inverse impedance", "opposite impedance" or "anti-impedance". Then "capacitor" and "inductor" mean elements that absorb energy from the input source and accumulate it into themselves.

This concept is extremely simple, clear and intuitive if we think in terms of voltages when we apply a constant input voltage to the elementary RC and RL circuit. Then, voltage drops appear across capacitors and inductors; they change in a different (opposite) way through time but both they are voltage drops. Conversely, voltages appear across negative capacitors and inductors; they also change in a different (opposite) way through time but now both they are voltages, not voltage drops.

Well, I would like to ask you what a negative impedance converter does. What does it convert? Does it make a capacitor behave as an inductor and v.v., an inductor as a capacitor? No, it doesn't. A gyrator can do this magic. A negative impedance converter can make capacitors and inductors behave as sources (negative impedance elements) instead as passive elements having positive impedance. I hope all these pages listed by Google will persuade you what negative impedance means in this area.

...This is why resonant circuits work - the inductive and capacitive impedance cancel each other out at their resonant frequency... Zen-in, this is a formal explanation of the unique resonance phenomenon that does not explain anything... But let's leave this discussion or move to the according talk page where Wjbeaty has tried to explain the great phenomenon in such an intuitive manner (...a paired coil/capacitor acts as a passive oscillator which essentially sends out an inverse copy of the incoming signal...) as I try to explain here the no less great negative impedance phenomenon. Although there is some resemblance between them the negative impedance phenomenon is quite different from the resonance phenomenon: negative impedance is a process of injecting additional energy (by an additional outer source) while resonance is a process of using a treasured energy (it is drawn by the input source, not by another source). If you want to say something about resonance here, say that negative impedance is extremely useful for resonant circuits as LC generators are based on the combination resonator + negative resistor.

...An Ohmic device always has a positive impedance... Of course, I second this assertion; who has said the opposite? Only electrical sources can possess true negative impedance (see what negative impedance is).

...There is no way of creating a resonant circuit with resistive devices... Who has said the opposite? There is no such assertion in the article.

...Previously this was extremely overdone,... What do you want to say? Negative impedance (resistance) phenomenon is very, very important. For example, all the op-amp inverting circuits (1,020,000 pages showed by Google) based on the presence of virtual ground (have I to list them?) exploit this powerful idea (of course, if you can see it), the legendary Howland current source (pump) (46,000 pages) and Deboo integrator (4,000 pages) are negative impedance circuits (again, if you are able to discern the great idea), telephony line reperitors are negative "resistors" connected in series...negative impedance converters (120,000 pages), gyrators...have I to continue? The ubiquitous virtual ground phenomenon (448,000 pages!!!) is based on the negative impedance phenomenon; it is a result of "neutralization" between opposite impedances - "positive" and "negative". However, negative impedance (especially true negative impedance) is not explained in a satisfactory way somewhere on the web; there are only particular speculations mainly about differential negative resistance. As a rule, the authors don't distinguish the two kinds of resistances although they are completely different by their nature. See in forums how many people (425,000 pages!!!) want to know what a negative impedance (resistance) is! All they ask, What is a negative resistance?, Does the resistance can be negative?, Have you heard about negative resistance?, etc. So, negative impedance phenomenon deserves to be explained satisfactory.

As a conclusion

Zen-in, as I can see, you have a tendency for extreme actions. I wonder how it is possible to see that someone has gone out of his way to make clear such an unintelligible circuit phenomenon and, at the same time, to remove completely his work?!? Wikipedia is neither yours nor mine. We shouldn't forget its main idea; we have to join our forces in revealing the truth about circuits instead to impede each other. We have to behave as negative impedance elements instead as "positive" impedance ones:)

IMO, a possible solution to eliminate the ambiguity in the meaning of "negative impedance" is to insert some explanation in the lede and to add a link to Electrical impedance; you can do it. Circuit-fantasist (talk) 17:36, 7 February 2009 (UTC)

I disagree. This is not an unintelligible circuit. It is not a complex subject and therefore does need excessive complexity to explain it. Debating semantics is not the answer either. Madhu (talk) 03:55, 13 February 2009 (UTC)

This content is not appropriate for an encyclopedia

This is all fringe thought; what we call pseudo-Science. It doesn't merit being called Engineering. This entire page is simply put a result of your over-active imagination. Can you produce a reference to support any of your ideas? No, because they are all yours. I have a very large library of EE texts by most of the best authors. Nowhere in any of these books is there anything remotely close to what you have written. Negative resistance is well documented. The impedance of negative resistance materials is also well documented. Negative impedance is your idea. Wikipedia is an encyclopedia and is not the place for unsupported research. The purpose of any Engineering pursuit is to become adept at designing useful devices. Those who pursue a career in Electrical Engineering consider themselves fortunate if they eventually learn how to design circuits (among many other options). It is to this goal that EE texts and Wikipedia articles on the subject are directed. I design electronics using mathematical methods. This is something I have been doing for a long time. Your descriptions of circuits don't offer anyone any methods of how to design. Instead they are like a view of electronics. You look at a circuit that someone else has designed and you apply your alternative description of it, complete with crayon drawings of silly stickmen. No one reading your work will be left with an increased ability to design a similar circuit. It is all just confused gibberish. Other concerned Wikipedians hopefully will follow my lead and will remove your grafitti. Zen-in (talk) 19:16, 7 February 2009 (UTC)

I agree entirely with Zen-in (and Zetawoof et al). This article is now worse than when concerns were first raised a year ago. It doesn't matter how important you feel the subject matter is, the treatment is completely excessive for something that should be explained in about half a dozen paragraphs with a couple of accompanying graphs. More importantly, it is original research and the format and style is entirely unsuitable for an encyclopedia. However, you have failed to heed what a number of others have said in this regard. If you feel that you must share with the world your personal insights regarding certain physical phenomena, then your website is the appropriate place for that, not here.
Since you appear to have difficulty comprehending how others feel about this, let me very clear. While you have been making your hundreds of edits to this article, the others who have an interest in writing it properly have looked on without knowing exactly what they should do. It's like at a party, where one person takes over the group's conversation, and goes on and on about some subject about which they feel passionately. Everyone else just stands around in embarrassed silence not knowing quite what to do. After a few unsuccessful attempts at steering the conversation back to normality they make excuses and start drifting away.
You have made your position abundantly clear, both now and back in 2006 when you did something similar. What you should do now is get some perspective. You need to step back and let others have a go at making a proper encyclopedic article (perhaps something like Electrical resistance? - now there's a thought) before they are driven away in exasperation. Secret Squïrrel 02:11, 8 February 2009 (UTC)
I assume you are referring to vast edits made by Circuit-fantasist. I am one of those who had previously given up on this article. I fully support the efforts of Zen-in to bring this article back to reality. My recommendation to Circuit-fantasist is to advance your ideas on your own user page or your own website. I write articles on my user page and on my website, blog etc. You can and should do the same. Madhu (talk) 04:04, 13 February 2009 (UTC)

I won't comment your insulting words, comparisons and hints that you have placed here and on my talk page. Maybe, Wikipedia administrators should take up an appropriate attitude towards your behavior. I will comment here only your general conclusions; in the future, I will scrutinize and discuss only your concrete explanations as I will do below.
I don't think that to show the basic ideas behind circuits in such clear and intuitive manner is pseudo-Science and to veil the truth about circuit ideas by vague definitions and mazy mathematical expressions is Science. Wikipedia is an encyclopedia, not a detailed course on electronic circuit design. The electronics part of Wikipedia is not intended only for "those who pursue a career in Electrical Engineering"; it is intended to all curious people interested in electronic circuits.
IMO, the main goals of every Wikipedia electronics article are first to reveal the general ideas behind the circuit, then to analyze the circuit operation and finally, to give some directions about calculating the component parameters (not in detail). The first part is qualitative; so, it needs specific qualitative methods based on human imagination, intuition and some abilities to generalize and to make associations between apparent different phenomena. Mathematical methods are wonderful but useless for the purposes of the first part; they are useful for the rest. It is a great mistake to "explain" circuits by means of mathematical models. It is also a mistake to play down people having aptitudes to discern the fundamental circuit ideas. Circuit-fantasist (talk) 16:12, 15 February 2009 (UTC)
I didn't state that electronics pages on Wikipedia are just for those who pursue a career in Electrical Engineering. To those who use Wikipedia to further their knowledge of electronics we are obliged to present the subject matter correctly. Electronic circuits can be explained without resorting to mathematics. Any good description of an electronics circuit starts out that way. But you can't take math out of electronics, as you are trying to do. The people who designed OP-Amps (like Bob Pease) didn't design these circuits using methods like yours. They used very precise mathematical models for designing their integrated circuits. And the people who use integrated circuits to design and build useful devices use more simpler mathematical analysis to determine what component values to use. Believe it or not, there are a lot of people in this last category who are not Electrical Engineers. They may want to build a microphone preamplifier, or a power supply for an LED to use on their boat, or they may be high school students working on a robotics project. These people would have to do some simple calculations to get the results the want. There are others who just want to get a general idea of how a circuit work and so need a concise explanation without a lot of mathematics. Your explanations are not concise and in many areas are technically wrong. They are your own ideas and are not supported by any other research. So they are not useful to someone with a casual interest in electronics. They also are not useful to someone who is not an Engineer and is trying to build something. I find it unusual that you have this distaste for mathematics yet you apparently teach at a university. Mathematics is central to any study of Physics. Here's a question for you- Show me something you have designed, and how you used these colorful graphs with the smiling/frowning stickmen on them to create this design. You can do this on your personal webpage, as has been suggested by others.Zen-in (talk) 19:27, 15 February 2009 (UTC)
I say it again: my pursuit is to reveal the basic ideas behind circuits, not to design circuits. I am a circuit thinker, not a doer and this is my vocation. I have a suggestion to you - let's stop making general conclusions and begin considering the concrete circuit phenomena. I have posed a lot of questions to be answered on these pages; please, answer at least one my question. I have already begun considering your rewrite of negative resistance page with revealing the imperfections of the negative resistance definition. Circuit-fantasist (talk) 22:14, 15 February 2009 (UTC)
Please stop plastering talk pages with your theories, graphs, etc. The place for that kind of stuff is your own personal web page. It doesn't belong on talk pages. You have done the same thing to other talk pages Talk:Current_mirror and have been asked by others to desist. I consider that to be graffiti. By the way: The Current_mirror page is very well written. It is a good model for how electronics circuits should be described on Wikipedia. As others have tried to explain to you: Your ideas on "circuit thinking" belong on your own personal blog, not on Wikipedia. We all want to see the pages you have been editing to be opened up so others can contribute their ideas. You have just one viewpoint and it is mostly incorrect. By plastering your graphs, "circuit thinking" ideology, etc on talk pages you are just trying to stake a claim on Wikipedia pages for your own exclusive viewpoint.Zen-in (talk) 22:53, 15 February 2009 (UTC)

Negative impedance

Negative impedance is not a term that is in general use by Electrical Engineers. The only place where this term could possibly be used would be as it applies to the direct measurement of impedance with a Boonton Rx Bridge or similar device. These instruments are used to measure the impedance magnitude and phase of a 2 port device. The imaginary component of the impedance is measured by adjusting the X control until a meter has been nulled. The dial markings on this control are marked in negative and positive mmf (now termed pf). When measuring the impedance of a 2-port component with this instrument, a negative reading indicates a capacitive impedance. This designation of a capacitive impedance having a negative sign is purely arbitrary. Modern network analyzers and Scattering parameters notation use the opposite convention. However, RF Engineers use the term Complex conjugate when considering impedance matching. Zen-in

Edit discussion

Could you take a look at the negative resistance article and its talk page? The article is on the verge of being completely removed (and hopefully rewritten) and we'd appreciate more opinions. Thanks. -Roger (talk) 18:50, 17 February 2009 (UTC)
I have been trying to improve the negative resistance article. This electrical phenomena that this article is about is generally termed "negative resistance" by Electrical Engineers. I have found no case where this effect is called negative impedance. In general negative resistance is a quasi-DC phenomena and the impedance of devices ( ie: scattering parameters ) is a separate matter. Originally this article was titled Negative Resistance. In May 2008 I remarked on it's talk page (now archived somewhere) that the article was a real mess, was technically incorrect and mostly OR. Others agreed and so I asked for a vote to allow me to improve the article. A couple of editors agreed. My attempts to improve this article just get reverted immediately by Circuit-fantasist, who after awhile has spun off parallel articles called Negative_impedance and Negative_differential_resistance. So I restored Negative Resistance and have started working on it. From your discussions it appears you value the contribution of Circuit-fantasist and don't want to see it changed. I am not one to fight an uphill battle so I will leave you to your world of Cargo_cult_science articles and go back to doing what real EEs do.Zen-in (talk) 21:42, 17 February 2009 (UTC)
This isn't really the place to be discussing this stuff. Let's please communicate via my talk page. -Roger (talk) 22:12, 17 February 2009 (UTC)
(ec) (to Zen-in) Please do not be insulting. If you disagree with the name change you should discuss this on the Negative impedance article talk page. If you disagree with the split of the article, you should discuss a re-merger on the talk pages. This is the right way to proceed. Re-creating the article as you like it at Negative resistance is the wrong way to proceed, this is a fork, there should be only one article. SpinningSpark 22:16, 17 February 2009 (UTC)
Sorry if you find my directness to be insulting. I have tried to improve the article and have seen all my changes get deleted. Do you believe that C-F owns the rights to this article? I don't see any effort on your part to convince him to allow others to edit it. Instead you have criticized me on a number of small matters. C-F's writings do not belong in the electronics realm. They are just a product of his over-active (over-helping?) imagination. It all needs to be expunged from Wikipedia and re-written by competent authors. If you are not willing to support this you have no credibility with me. I don't need Wikipedia for anything if it becomes filled with Bizarro Cargo_cult_science articles as written by C-F.Zen-in (talk) 23:09, 17 February 2009 (UTC)
I agree that there is a lot wrong with C-F's writings but this needs tackling head-on, not by producing a fork article. The first thing that needs to happen here is that the fork article is removed and all the discussion and effort is centred around the one remaining article. I am willing to help but I do not support forking the article and it is against Wikipedia guidelines. Are you willing to return the negative resistance article to a redirect and move all edits and discussion to negative impedance?, (which can include discussing changing its name). And please stop accusing me of cargo cult science, I am a trained electrical engineer and fully understand the difference. SpinningSpark 23:23, 17 February 2009 (UTC)
Go ahead and do what you want. I have washed my hands of the matter for the time being. If I see any improvement in the situation my interest in Wikipedia may be restored.Zen-in (talk) 23:47, 17 February 2009 (UTC)
It's not a question of what I want, I had nothing to do with this article until a few hours ago when Roger asked me to look at it. Your help is needed too to get this improved. This is only going to work if everyone collaborates. Washing your hands and leaving it to me is not going anywhere. I am not about to fight one edit war by starting another and undoing your edits to negative resisitance. I need you to indicate that you accept there should be only one article and it would be best if you put it back to one article yourself. That way it is clear to everyone there is no edit warring going on. We can then all move on and start improving the negative impedance article. The alternative is to start an AfD which would be just so horribly messy I don't want to think about it and it would be wasting effort better spent on improving the article. SpinningSpark 00:03, 18 February 2009 (UTC)
You are asking me to do exactly what I have been trying to do for the past few weeks. All my edits have been reverted by Circuit-fantasist. That is not going to change. Until something is done to change that situation I have more productive things to do.Zen-in (talk) 00:30, 18 February 2009 (UTC)
Reverting someones edits without justification is not permitted. If C-f has been doing so, then you simply need to bring it to an admins attention. -Roger (talk) 00:39, 18 February 2009 (UTC)
C-F is unlikely to revert the edit I am asking for here. It is what he wants. SpinningSpark 00:47, 18 February 2009 (UTC)
If it is what C-F wants then why are you asking me to do anything? As I have stated before until C-F is out of the picture entirely I am not wasting any more of my time with this amusing edit war.Zen-in (talk) 00:53, 18 February 2009 (UTC)
I am asking because you created the fork and it is far less confrontational if you remove it. I am asking because a good place to start is something that all sides agree on. You do agree that there should only be one article for one subject don't you? SpinningSpark 00:59, 18 February 2009 (UTC)
I never agreed to having Negative Resistance redirected to Negative Impedance. You removed my edits without my consent. The subject matter is negative resistance and the original article was titled negative resistance. Sorry, I'm not going to be your proxy sock puppet for C-F. Your credibility with me just took another dive.Zen-in (talk) 01:14, 18 February 2009 (UTC)
Oh sorry, Go ahead and do what you want. I have washed my hands of the matter for the time being. seemed quite clear to me that you would not oppose this even if you were not willing to it yourself. SpinningSpark 01:21, 18 February 2009 (UTC)
You can use whatever justification you want. You were going to do it with or without my participation. Your request "I am asking because you created the fork and it is ..." was completely dishonest. Before I replied you went ahead and deleted my edit. I will not work with someone like you. It will amuse me to see more junk science articles added to Wikipedia.Zen-in (talk) 01:36, 18 February 2009 (UTC)

Zen-in (talk) 01:41, 18 February 2009 (UTC)

Ok, I don't want you to think I am steam-rollering you so I will put it back. I need to go to bed now, so I will not respond again tonight (this morning), but if you insist on having both articles around it is going to have to go to AfD. As I say, it is going to be much more straightforward if there is only one article for everyone to work on. SpinningSpark 02:16, 18 February 2009 (UTC)
It was not I who created the forks. The original article was Negative Resistance. C-F created Negative Impedance and Negative Differential resistance. Your statement in Talk:Negative_resistance about xyz impedance, Laplace, complex frequency notation, etc is just nonsense. The correct title for this subject is negative resistance, as it was originally. However I understand why you are so eager to build on what C-F has started. My earlier assertion has proven to be correct.Zen-in (talk) 05:22, 18 February 2009 (UTC)Zen-in (talk) 05:26, 18 February 2009 (UTC)

<outdent> Just in case that has confused anyone, Zen-in has copy-and-pasted the above discussion from my talk page. As I replied there, this article is not forked, it was moved. It is the earlier article as the edit history shows. The article that is currently at negative resistance is a much later creation and is therefore the fork. That is not to say anything about which article is better. My only point here is that creating another article is not the answer to a bad article. The right approach is to improve the original bad article. SpinningSpark 18:29, 18 February 2009 (UTC)

Propose move to Negative resistance

There seems to have been a consensus reached at the negative resistance article (which is currently deleted) that this article should be moved there. Before anyone actually makes the move, can we have a quick straw poll just to make sure? There may be people watching this page who were not watching the other one. SpinningSpark 18:03, 19 February 2009 (UTC)

Oh sorry, if anyone can't find the other discussion it's here. SpinningSpark 18:17, 19 February 2009 (UTC)
  • Move. While there may be an arguable case for a negative impedance article, this article is about negative resistance. Full disclosure; a couple of days ago I deleted the mention of negative capacitance and inductance in the lead on the grounds the article does not discuss these quantities. SpinningSpark 18:03, 19 February 2009 (UTC)
  • Move.Zen-in (talk) 18:05, 19 February 2009 (UTC)
  • Move please. -Roger (talk) 18:11, 19 February 2009 (UTC)
  • Move please. Let's get this process going so that we can clean up the OR stuff.—Tetracube (talk) 18:30, 19 February 2009 (UTC)

Note also that there is a redirect page at Negative Resistance which probably should be cleaned up along with this move as well.—Tetracube (talk) 18:35, 19 February 2009 (UTC)

Ok, we have consensus. I have moved the page. Will tidy up redirects. Will look at renaming the archives so that anyone popping in here will know what's from where. Secret Squïrrel 00:44, 20 February 2009 (UTC)


I think it would be good to have a graph of a theoretical negative resistor near the start of the article, just for illustrative purposes. That graph of a GaAs Tunnel Diode is a bit overused on Wikipedia, but something similar would be good to have as well. I will see what I can produce unless someone beats me to it.Zen-in (talk) 00:59, 20 February 2009 (UTC)

Hey, glad to see you're back. Feel free to work on what you like. I'd like to build up some momentum to tackle the other articles that are in exactly the same state as this one (after we finish here) and think that a couple more bodies will lighten the load for the rest of us. If you don't have your heart set on drawing the pics, User:BillC indicated an interest in contributing in this area, and you might like to explicitly invite him to knock up a graph or circuit-diagram (if a c-d is even needed). I'd start on the text but my first impulse is to completely remove what's there now (and then jump up and down on it in my boots before setting fire to it and hurling it over a cliff) but perhaps there is something worth saving? Up to you. Secret Squïrrel 01:38, 20 February 2009 (UTC)
I think everything from "Negative impedance implementations" to "Generalizing" can go, as well as any OR references. Most of this talk page could be archived as well, some of it is getting old. The remainder all will be useful once it is tied together. Rogerbrent and I both started the lede and I'll merge those later tonight. Thanks for jumping in when you did. I'm happy with how this has progressed and I think almost everyone is in agreement with the outcome.Zen-in (talk) 02:34, 20 February 2009 (UTC)

New images

Some of the current images don't look "encyclopedic" and are a bit cluttered. Several of them also aren't necessary and should be removed.

Circuit-fantasist: I like some of your "Current-driven negative impedance elements" section, but it's currently too long and overly simplified. It would be great if you could make it more concise so we can perhaps salvage some of it. I could also use some help with the definition. -Roger (talk) 04:08, 20 February 2009 (UTC)

I added more to the start of the article; don't know if I am getting into too much detail. There are some better transfer curves for Tunnel Diodes in a manual I have. I'll scan the pages and maybe someone more skilled in gnuplot than I can transform them.Zen-in (talk) 05:55, 20 February 2009 (UTC)

Image numbering is inconsistent at the moment, eg fist image is un-numbered, second figure is labelled as fig 5, text refers to non-existant fig 1a (legacy from a previous article). Obviously this can't be resolved until the article's structure becomes more stable, so I just mention this as a reminder of a copy-edit task we'll have to keep on the to-do-list. -- Timberframe (talk) 11:30, 20 February 2009 (UTC)
Thanks for redrawing the diagrams SpinningSpark. However I think four variations on the same circuit is too much. I suggest we replace them with one that covers all possible cases (i.e. in terms of Z_1, Z_2 and Z_3). -Roger (talk) 17:44, 21 February 2009 (UTC)

"Apparent Negative Resistance"

Deborah Chung's "Apparent Negative Resistance" may be more accurately described as a Meta_material than an example of negative resistance, due to energy considerations. Also the work was done over 10 years ago and may not have been replicated.Zen-in (talk) 06:05, 20 February 2009 (UTC)

Basic active negative resistor

I have been looking at the op-amp implementation of a negative resistor under this title and I think the analysis overlooks a key aspect of how op-amps work. op-amps Any analysis of an op-amp circuit assumes the inputs are high impedance and are always at the same potential. A voltage across the inputs makes the output rail like a comparator, and no current flows between the inputs. Using a current source will not result in a voltage being produced across the inputs. Op-amp gains are always more than 1; usually over 100,000. I found an op-amp circuit that does emulate a negative resistor - I did the math and it checks out.Zen-in (talk) 08:22, 20 February 2009 (UTC)

Zen-in, I am glad to see that we can already discuss concrete circuit ideas and phenomena; this is quite more useful than talk big. Really, how op-amps work is a key point to understanding op-amp circuits. When I was a student in middle 1970s, reading classical explanations (they still exist) I couldn't understand what and how an op-amp really does in op-amp circuits with negative feedback. Later, in middle 1980s, when I began explaining basic op-amp circuits with negative feedback to my students, I realized gradually a paradoxical fact: although an op-amp is really a proportional and, as they consider, an almost "non-inertial" device, in order to understand how op-amp circuits work, we have to think of it as an integrating, inertial device what it actually is (see also op-amp myths, Integrator inside section). Figuratively speaking, we have to think of the op-amp as a "being" that "observes" continuously its input voltage and changes its output voltage until it manages to zero the input voltage. If we think of the op-amp in terms of UOUT = A.VIN (i.e., VIN and UOUT change simultaneously), we fall into a vicious circle traveling the feedback loop and we can never understand circuit operation. We have to assume that the output voltage stays late regarding the input voltage. More philosophically speaking, we have to see the causality in the op-amp operation; to think of the input voltage as a cause and of the output voltage as a result. Quite later I found this concept in The art of electronics, "The golden rules" section (p. 177): What the op-amp does is "look" at its input terminals and swing its output terminal around so that the external feedback network brings the input differential to zero (if possible). As you can see, Horowitz & Hill have also animated the inanimate op-amp with the sole purpose of showing what it actually does in negative feedback circuits. I will use this technique later to consider your circuit emulating a negative resistor. Circuit-fantasist (talk) 18:04, 20 February 2009 (UTC)
Circuit-fantasistYou have already used this circuit and done your kind of analysis on it. It's near the bottom of the section on op-amp circuits. The basic circuit is there but you have added some stuff and created a separate ground for one node. I like to use Kirchoff's Current Law to analyze op-amps. It always gives me a result that agrees with what the circuit is actually doing. And I don't have to add imaginary components. The goal is to figure out the transfer function of the circuit, so that you know what the circuit will do when you drive it with an input. I don't see where you have ever been able to do that. Zen-in (talk) 20:55, 20 February 2009 (UTC)
The section (now named "Op amp negative resistor") is factual as it stands, but lacks notes on practical applications. In contrast to the applications suggested in the "Properties" sections such as compensating for telephony repeaters where accurate reproduction of the input signal is a pre-requisite, this circuit converts any input signal which is not extremely close to zero volts to a signal which chops between the supply rails. Unless we can add some real-world applications for this output function in combination with a need for negative resistance this seems like a trivial and non-notable illustration of negative resistance. (This is close to my objections to C-F's previous version of the article: negative resistance as an incidental consequence of some other function is non-notable, as is a circuit which demonstates negative resistance but has no practical application.) -- Timberframe (talk) 11:17, 20 February 2009 (UTC)
 Done Thanks for adding the more practical implementation. -- Timberframe (talk) 13:50, 20 February 2009 (UTC)
The final paragraph ("Electrical elements with negative impedance are extremely useful... they convert the positive impedance into negative one") seems out of place (it's general introductory stuff, but most of its points have already been made) and unduly laden with peacock phrases. It also introduces negative impedance which, I think we agreed, clouds the issue. I hesitate to edit it without discussion in case someone put it there for a good reason which I haven't appreciated. -- Timberframe (talk) 11:23, 20 February 2009 (UTC)

I've moved the ensuing conversation to Negative impedance, not resistance. -- Timberframe (talk) 21:49, 20 February 2009 (UTC)

History section

I find the stuff about Gabriel Kron highly dubious. As far as I can make out his use of negative resistance arises from a rather weird method of solving the Schrodinger equation by means of analogy with electric circuits. It is entirely a mathematical construct and has nothing whatsover to do with electronics (the article this comes from is titled Early ideas in the history of quantum chemistry). The idea that he actually made a negative resistor seems to have originated here which is a personal website and in my opinion is utterly misrepresenting his work. In any case it cannot be cosidered reliable. I will put in the history according to Belevich who is a reliable source for all things on electrical network history. I will refrain from deleting the Kron stuff for now just in case I am completely wrong even though that may mean there are temporarily some contradictions in the text. Please comment. SpinningSpark 15:22, 20 February 2009 (UTC)

You're probably right. I didn't pay any attention to it myself, so it could all be nonsense. -Roger (talk) 15:35, 20 February 2009 (UTC)
I agree. In fact I was about to re-iterate the comment near the top of this page about "sources, sources, sources." There's a danger that, like C-F, we end up writing a textbook from our first-hand knowledge rather than compiling an encyclopedic survey of documented knowledge. What we're doing at the moment is not encyclopedic and can't be regarded as more than mapping out the structure and general subject matter of a yet-to-be encyclopedic article. That's not a bad way to do it, but we must keep one eye on tracking down reputable sources to back up our knowledge (sounds like you have one for the history) and the other on ensuring the scope is not limited to what we know. -- Timberframe (talk) 15:49, 20 February 2009 (UTC)
Looking back on the original edit by an IP in 2005 [1] I am even more convinced it should go. It seems to be one of those cases where a dubious edit looks better after the copyeditors have been at it. Certainly the phrase referring to "the circuits above" was added later by an editor making too many assumptions. SpinningSpark 19:43, 20 February 2009 (UTC)
Slightly unfair comment on the sources as I have added four so far, but I agree, we still need more, particularly for the specific circuits. SpinningSpark 19:58, 20 February 2009 (UTC)

Are derivations necessary (or even encouraged)?

This is kind of a general question, but it also applies to this article. Is showing circuit analysis steps really encouraged, instead of just stating the final result (perhaps with some minor explanation)? Personally I do sometimes like having the derivations, but they tend to clutter things and don't really seem encyclopedic. -Roger (talk) 20:07, 20 February 2009 (UTC)

Derivations, like paragraphs, aid in understanding. More importantly, they improve transparency (although they are no replacement for citations). Also, don't people turn to an encyclopedia to see how (for example) "lift" keeps a plane in the air? How is that different to asking how an important result is derived? One of the reasons why derivations/proofs are discussed in non-mathematical curriculum is because the derivations themselves add to the result. —TedPavlic (talk) 20:12, 20 February 2009 (UTC)
Roger, the answer to that question is at Wikipedia:What Wikipedia is not#Wikipedia is not a manual, guidebook, or textbook, particularly point 4. SpinningSpark 20:46, 20 February 2009 (UTC)
You and Ted seem to be at a disagreement over this. I'll wait and see what others have to say. -Roger (talk) 21:06, 20 February 2009 (UTC)
I agree with TedPavlic that derivations aid understanding of the stated result. Furthermore, if I'm understanding correctly the distinction made in Spinningspark's citation it would appear to permit derivations: "Other kinds of examples, specifically those intended to inform rather than to instruct, may be appropriate for inclusion in a Wikipedia article". Derivations inform the reader why the result is as stated rather than 'instructing readers on the techniques of circuit analysis so that they can learn how to derive the result for themselves. -- Timberframe (talk) 21:45, 20 February 2009 (UTC)
True, but in many cases the derivations amount to just applying KVL/KCL and some basic algebra. The negative impedance converter article is a good example of how unnecessary this over elaboration can be. -Roger (talk) 17:49, 21 February 2009 (UTC)

Negative impedance, not resistance

Wikipedia's circuit pages have an odd obsession with the term "resistance." Pages should be made more general. This page should be renamed "negative impedance." Likewise, Negative impedance converter should show generic impedances rather than resistances. —TedPavlic (talk) 20:14, 20 February 2009 (UTC)

I like to keep things as general as possible, but in this case I prefer the term "negative resistance". A negative reactance isn't such a big deal, things only get interesting when you have a negative resistance. I guess it's still up for debate, but note that a Google search for "negative resistance" gives an order of magnitude more results than "negative impedance". -Roger (talk) 21:11, 20 February 2009 (UTC)

Earlier conversation moved here from Basic active negative resistor:

Negative impedance certainly has the potential to generate confusion but I think the term has more currency than some people here seem to think as this google search shows. I think perhaps it has a place in negative impedance converter and the material on negative capacitance and negative inductance (with diagrams in more professional svg format) should be moved there. SpinningSpark 15:09, 20 February 2009 (UTC)
I don't disagree with you, but doesn't that beg the question: why have a separate article on negative resistance? We already have a chunk of the neg res article citing the NIC article as the main article; add to that the facts that the definition, history, application and implementation are going to contain a large amount of overlap and the case for a neg res article seems very weak. (To be fair, I've yet to look at the NIC article!)-- Timberframe (talk) 15:30, 20 February 2009 (UTC)
Don't really have a strong view on that. I would be happy if the articles were merged if that's what everyone else wants. However, merging it in here does start to support C-F adding negative capacitance and negative inductance circuits since I believe that these terms also are referencable eg [2]. SpinningSpark 15:40, 20 February 2009 (UTC)
I don't have a problem with that so long as the science is verifiable and we can give references to reputable sources (not just a google index!) -- Timberframe (talk) 16:03, 20 February 2009 (UTC)
The negative impedance converter article could be improved. The circuit analysis is correct but not very readable. A reference to that page from Negative Resistance and the graphic is all I believe is needed on the subject of op-amp circuits. The negative diode, negative capacitor (actually an integrator), etc are all patent nonsense. Putting a component on the feedback of an op-amp produces inverts the normal response and changes the sign. The negative of an impedance is the complex conjugate of it ie: adding an impedance with its complex conjugate results in a pure resistance. So a negative capacitor is an inductor and vica versa.Zen-in (talk) 16:59, 20 February 2009 (UTC)
Zen-in, I have replaced those diagrams with circuits based on the NIC, comments? SpinningSpark 20:03, 20 February 2009 (UTC)
The diagrams look very good. I need to put pencil to paper and do an incremental analysis of them before I can talk in detail, but my belief right now is that just the op-amp circuit I referenced earlier is enough. Even it is mislabeled as an "impedance converter" since there are no reactances in the circuit (not considering internal op-amp compensation). So it really is a negative resistor circuit, like the Lambda_diode. Too much detail for talk pages maybe but Z = R + 2j Z' = R - 2j. Z' is the negative of impedance Z because Z + Z' = 2R, zeroing the reactance. Therefore a negative capacitor is an inductor. and a negative inductor is a capacitor. That's why we use Smith Charts.Zen-in (talk) 20:45, 20 February 2009 (UTC)
You seem to define negative impedance as the complex conjugate, which is fine, but its not what those circuits are doing. If Z=R+iX you would have negative Z as R-iX. The circuit actually produces -R-iX so does not meet your definition. Another point (to Roger) is that a capacitor produces a -iX impedance and an inductor +iX so an inductor is a negative capacitor in that respect, but not in respect of frequency dependance. If the reactance of an inductor is X(ω) and a capacitor -X(1/ω), the negative capacitor is X(1/ω) not the X(ω) of the inductor. SpinningSpark 22:24, 20 February 2009 (UTC)
R+jX + -R-jX = 0 The reactance is zero. The exact negative of an impedance, at a given frequency is the complex conjugate of that impedance. When the sign of the imaginary part (phase) changes, you have gone from capacitive to inductive or vica versa. For example looking at the impedance of an antenna below its resonant frequency, you will see a capacitive reactance, along with the resistive part. When you are at resonance the impedance is purely resistive (hopefully 50 Ohms or 75 in Europe). When you go above, the impedance becomes inductive.Zen-in (talk) 22:45, 20 February 2009 (UTC)
The complex conjugate is the negative of an impedance because when you add it to the impedance the reactance term goes to zero. It doesn't matter what happens to the resistive term, just the phase angle.Zen-in (talk) 22:54, 20 February 2009 (UTC)
The transfer functions are correct of course but I still think the terms negative capacitance and negative inductance are not needed. if you rationalize the transfer function of the second op-amp circuit the denominator becomes -jwC; so the circuit is really a Gyrator, an op-amp implementation of an inductor. There are not 4 reactive components, only 2. I think it is sufficient to just state that because a reactance can store and release energy negative reactances do exist but we know them as capacitors and inductors. Zen-in (talk) 22:31, 20 February 2009 (UTC)
I'd prefer not to go down this path of negative capacitors and negative inductors, at least in this article. They are interesting from a theoretical point of view, but generally not so practical. For a given frequency, impedance of -j is a capacitor and +j is an inductor. Over a range of frequencies you might end up with a frequency dependent capacitor or a frequency dependent inductor. I've looked at this problem, but it's generally not published work, it becomes WP:OR. Negative resistance, as the article states, is published in the literature and has practical applications, e.g. Schmitt triggers, oscillators etc. I don't have a problem mentioning these peculiar elements, maybe even describing them in another article, but this article is big enough as is. Madhu (talk) 22:56, 20 February 2009 (UTC)
First of all, I don't have an issue with this material being moved to negative impedance converter, or deleted altogether. My only motive in putting it in was to replace some poor material in the article with something better. Having said that, I dispute that negative capacitance is merely the opposite of inductance. Madhu said For a given frequency, impedance of -j is a capacitor and +j is an inductor, true but once you move the frequency or apply a signal other than a sinusoid it is no longer valid. Zen-in says the second circuit denominator rationises to -jwC. Well yes, that's right, the negative of a capacitor, as required. Madhu said, generally not published work; really, I had no problem finding references;
  • US Patent 5558477 utilises a negative capacitance circuit very similar to the one in the article (refer to figure 4)
  • US Patent 3578911 has a negative capacitance cicuit built of discrete components for compensating telephone line capacitance.
  • This paper uses negative capacitance circuits to control the mechanical properties of piezoelectric materials.
  • This paper uses negative capacitance in microwave filters. I can only read the abstract but as it says it is NIC based it just has to be a similar circuit.
There is much more out there. I have only stop here because I got bored with this game. SpinningSpark 01:59, 21 February 2009 (UTC)
Interesting patents. I guess if the uspto accepts that terminology its ok. I'm wrong about the negative capacitor = inductor thing. A Negative Capacitor has a reactance of -1/jwC and an inductor has one of jwC. I looked at a low pass filter with a negative capacitor and a normal capacitor. For the negative capacitor LP filter, H(jw) = 1/1-jwRC and for the other H(jw) = 1/1+jwRC Look at bode plots, the section titled a real pole. You will see how it doesn't affect the magnitude, but it does affect the phase. So a negative capacitor behaves the same as a regular capacitor except the poles are moved to the other side of the Re axis. Zeros would be moved to the other side of the Im axis. Whatever the phase angle due to a normal capacitor, a negative capacitor will have the opposite phase angle. The same is probably true for negative inductors. But in terms of frequency response and transfer functions (disregarding phase) they are the same as the normal versions of the component. Zen-in (talk) 04:58, 21 February 2009 (UTC)

Re-structure of article

Circuit-fantasist, thank you for re-organising the article. That is now much more logical, a lot of the recent major changes got things out of order. I just have one suggestion, I notice you have changed some of the titles from negative resistance to negative impedance. A lot of the editors here want a negative resistance article. Can we just discusss negative resistance at the beginning of the article and then move on to negative impedance further down? That has the benefit of making it easier for readers who struggle with complex notation. It will also make it easier if we decide to split out the negative impedance part in to another article. Thanks. SpinningSpark 14:57, 21 February 2009 (UTC)

Spinningspark, I will second fully your suggestion... but only if we discuss your sophisticated negative inductance circuit:) Seriously, I was deeply moved when I saw it yesterday. I had the feeling it was a great challenge to reveal the basic idea behind this eccentric circuit and I began thinking immediately about it. In the beginning, I supposed this is some kind of gyrator circuit converting a capacitance into an inductance but then I realized it is was a true negative impedance converter. I put my mind at rest only today at noon when I began realizing the brilliant ideas on which it is based. It is interesting for me to know more about the origin of the circuit.
Now, about your suggestion... It is obvious there are two concepts - general (negative impedance) and more particular (negative resistance); negative impedance comprises negative resistance. Obviously, there are two possible ways of exposing the topic - deductive (moving from top to down) and inductive (moving from down to top). The first means to present negative impedance as a main (more general) idea and negative resistance as a special case; the second (your suggestion) means to present the specific negative resistance as a main (more used) idea and to generalize it into negative impedance. I chose the first when I moved and redirected the negative resistance to negative impedance page a month ago. But, in the course of time, I have been gradually realizing that the second viewpoint is more acceptable. Really, negative resistance is more widespread concept than negative impedance and the term is in general currency. So, I agree with you and will reword my edits.
Finally, don't you think it's time to consider the main problems - how to distribute the content between the three existing pages about negative resistance phenomena (negative resistance, negative differential resistance and negative impedance converter) and how to structure these articles? Circuit-fantasist (talk) 23:11, 21 February 2009 (UTC)

I removed the first op-amp circuit because it really just has bistable operation. The DC gain of op-amps is very high = > 100,000. There was also a lot of left over stuff that was difficult to read. C-F please don't revert this as soon as you see it. I think everyone should have a look at the article as it now stands and if the consensus is that we should put some of it back we can do that. The properties section needs some work still.Zen-in (talk) 17:29, 21 February 2009 (UTC)

Zen-in, that's not the way to do things, that's just going back to edit warring. I don't think you could even have read C-F's edits to the first circuit, which has made it much more acceptable - it is no longer using an op-amp as you are claiming. SpinningSpark 18:10, 21 February 2009 (UTC)
Maybe it wasn't apparent to you but I saw a real contrast between what you and others have added to the article and the old stuff. The article looks really good now. I read C-F's recent edits and I'm sorry to have to say this but it was just more of the same old stuff. The first op-amp circuit doesn't work in the real world. The input voltage has to be so low you wouldn't know if you were seeing that or the input offset voltage of the op-amp. It is a bistable circuit and I doubt it has any linear regime. Maybe C-F can do some work on the properties section. He wrote most of it originally. There is room for improvement there and maybe he can start writing like a scientist. As to the resistance impedance discussion, the op-amp circuits you added are negative reactances - they have no resistive term. While I was sailing this afternoon I came up with an interesting way of diagramming C, L, -C, and -L. A 2x2 table showing how -C has the phase of L and -L has the phase of C. I added a picture of a tunnel diode amplifier and another reference. Zen-in (talk) 04:06, 22 February 2009 (UTC)
I actually liked having that first circuit. Of course it wasn't practical, but it did serve as a good, simple lead in for improved designs. -Roger (talk) 04:31, 22 February 2009 (UTC)
The criticism of the first circuit I am hearing is just re-inforcing my view that C-Fs edits are being deleted without being read. All those points relate to the section as I originally wrote it. After C-F had edited it, it was a far more practical circuit; the amplifier was no longer an op-amp and the gain was 2, not 106. Another example, C-F grouped the negative resistance circuit with the other cicuits and called the heading negative impedance. That has been reverted to negative resistance without looking at what ciruits are actually under the heading and consequently has now made a nonsense. People just have to come out of this mode that all C-F writes has to be reverted on sight. You have been trying to solve the problems of this article with that attitude for at least two years now and all that has resulted is a bitter edit war and no progress. PLEASE STOP. rare justified use of caps locks SpinningSpark 08:01, 22 February 2009 (UTC)
I told you: I read the edits and the reason I removed the circuit (Basic Initial Circuit below as C-F has so helpfully added it to the talk page again) is because it is a bad example and there is a better example right after it. In fact that circuit is a Transimpedance amplifier TIA. C-F's hand-waving about the gain "(typically, A = 2)" is just pulled out of the air. After more contortions, he summarizes with "The circuit behavior depends on the value of the internal resistance Ri of the input voltage source that constitues a voltage divider with the resistance R. If R/Ri > A, the circuit is stable and operates in linear mode (this is the case when an ordinary amplifier with small but steady gain is used). If R/Ri < A, the circuit is unstable and operates in bi-stable mode" Where is Ri in the schematic? It has to be included as the input impedance, since he is using it elsewhere in the analysis(?). Instead of a negative impedance -R at the input, there is an impedance of Ri-R, possibly not negative at all. This circuit is very speculative as a negative resistor example. Hand-waving and bending op-amp behavior to make the analysis(?) fit the claim doesn't fly in my book
Other parts I removed that never made any sense can be found under "Current-driven negative impedance elements". It begins:
"Real voltage-supplied electrical circuits contain at least two elements with positive impedance (see Fig. 1a again): one useful (the load) and another undesired (for example, line resistance between the source and the load) that has to be eliminated by including an additional current-driven negative impedance element (Fig. 5)."
and ends:
"However, for this purpose, the op-amp needs to "sense" the voltage drop across the positive impedance element; sometimes this is impossible or inconvenient, for example if it is a long telephone line."
Again, with a lot of self-induced contortions betwixed the two and with no realistic conclusion.
I think this article is basically done. In a few days it has gone from a mish-mash of confused thinking about negative resistance; something that probably wouldn't even last on Keelynet very long, to a decent article by Wikipedia standards. Instead of encouraging the backsliding of this article to its earlier state of excessive OR, POV and all the other bad things that give Wikipedians angst we should move on to some of the other articles on our hit list. I see the happy stick men are still inhabiting Negative_differential_resistance. Why is that article still there? I thought all forks must go. So let's move forward and start by deleting that awful mess of POV, OR, etc. That done I think Current-to-voltage_converter needs a re-write like we have done here (collective pat on the back). But the title has to change to Transimpedance Amplifier with TIA redirecting to it. I have worked in the IR field (building FTIR spectrometers, liquid He cooled focal plane arrays, and designing multi-spectral IR cameras) for over 30 years and it would be nice to be able to refer a Wikipedia TIA article that is readable to someone who is just getting started in this field. So let's move forward. Zen-in (talk) 20:42, 22 February 2009 (UTC)
Zen-in, please (again), be reasonable! Please, read carefully the text before to react! I have checked the history and found this section is introduced initially by Madhu in March, 2005. You should at least give a warning to him about your intention before to remove the section! I wonder why it is so difficult for us to discuss step-by-step key points and to make a decision. Well, I will try to do it again here. So what is the purpose of including this section?
First, believe me (I have been explaining circuits to young people for decades), the best way of presenting circuits to people is to show the circuit evolution. The final result is not so important for understanding circuit ideas; the movement from the imperfect initial circuit solution to the final perfect one is the most important. If we want people really understand circuit solutions, we have first to show why the initial (usually passive or transistor) circuit is so "bad" and then to make it perfect by means of electronics according to some clever idea. From this viewpoint, this bare 1-resistor circuit serves as the best initial point of this succession (as Roger has noted above as well). There is no simpler circuit than this one; this is the absolute minimum. Look at it; don't you think this is the initial point of introducing another great phenomenon - positive feedback ? This is the most elementary circuit with parallel positive feedback in the case when the input source has some internal resistance; if it hasn't, we have to connect another input resistor between the source and the amplifier's input. This kind of feedback is named "parallel" because the input source and the output source (the op-amps output) are connected somehow "in parallel" through resistors to the amplifier's input (the same arrangement is used in op-amp inverting circuits with negative feedback). The parallel feedback (no matter positive or negative) does not require an amplifier with differential input; it needs just an ordinary amplifier with a bare single-ended input. But the most amazing feature of this arrangement is that the two sources interact each other; the output voltage influences the input one and exactly this phenomenon is used to create a true negative resistance. The dual series (no matter positive or negative) feedback needs an amplifier with differential input and what is more important for us there is no connection between the op-amp's output and the input source; they are detached by the high input impedance of the op-amp. So we can't make negative resistance (impedance) op-amp circuits based on series positive feedback. Circuit-fantasist (talk) 14:01, 22 February 2009 (UTC)

How do op-amp negative impedance circuits (INIC) work?

What does "to understand circuits" mean?

It is more than obvious that, in order to create this part of the article, we (Wikipedia editors, responsible for it) have to understand all these op-amp circuits. Otherwise, it would be very confusing if we "explain" these circuits to people but the very we do not know what the basic ideas behind them are. But what does "to understand circuits" mean?

Generally speaking, it means to find out all about each of the components constituting the circuit: why it is added to the circuit, what its function is, what it does, how it does it, what its value has to be, etc. Then we have to discern groups of components constituting familiar sub-circuits and to clarify its role. Especially for the present op-amp circuits we have to know the role of the positive impedance element connected between the op-amp output and the non-inverting input, the role of the voltage divider connected between op-amp output and the inverting input and, of course, the role of the very op-amp. Please, answer the concrete questions below and suggest possible circuit explanations. Circuit-fantasist (talk) 15:37, 22 February 2009 (UTC)

Basic initial circuit

Basic initial circuit

What does the resistor R do? What does the op-amp do? How does the circuit behave when connected in parallel to a load load with resistance R driven by a real input voltage source?




Negative resistor

Negative resistor

What does the resistor R do? What do the resistors R1 do? What does the op-amp do? How does the circuit behave when connected in parallel to a load load with resistance R driven by a real input voltage source?




Negative capacitor

Negative capacitor

What does the capacitor C do? What do the resistors R1 do? What does the op-amp do? How does the circuit behave when connected in parallel to a load with capacitance C driven by a real input voltage source?




Generalized circuit

Generalized negative impedance circuit

What do positive impedance element Z do? What do the resistors R1 do? What does the op-amp do? How does the circuit behave when connected in parallel to a load with impedance Z driven by a real input voltage source?




Negative "inductor"

Negative "inductor"

What does the resistor R1 do? What do the resistor R1 do? What do the capacitor C do? What do the combination R1-C do? What does the op-amp do? How has the inductance achieved? How does the circuit behave when connected in parallel to a load with inductance L driven by a real input voltage source?




Defining the main concepts

What does negative resistance mean?




What does differential negative resistance mean?




What does negative impedance mean?




Suggestion for archiving

This page is already 84 kilobytes long. I suggest to archive (at least the first part of) it. Circuit-fantasist (talk) 14:11, 22 February 2009 (UTC)

I have a better idea: Remove your graffiti Zen-in (talk) 20:45, 22 February 2009 (UTC)