Talk:Virtual ground

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Contents 1 Cleanup Request 2 Do we need the following in the article? 3 Diagrams 4 Language and terminology 5 Virtual ground vs. small signal ground 6 Inconsistent diagram 7 Figures to delete 7.1 Fig 2 7.2 Fig 3 8 Misleading concept 9 Is there an OR in the article? 10 Concise

[edit] Cleanup Request

I'm just a physicist not an EE, but this is too bad to be left alone. Please help, if you have better info Awolf002 22:06, 22 Apr 2004 (UTC)

Your wish is my command! BTW dont feel too bad about being a physicist-- some one has to be! ;-)--Light current 16:56, 25 September 2005 (UTC)

I don't even know where to begin. Maybe redrawing the schematics? This paragraphs need to make sense when people read the first sentence, and then wean them into the complexity of the topic.Bmunden 00:26, 18 February 2007 (UTC)

I've just looked to see if there was an article on Virtual earth (my user name) and found this article. I think it needs some modifications. I will try to make some

[edit] Do we need the following in the article?

Non-electrical domain: The "neutralizing" idea —The preceding unsigned comment was added by VirtualEarth (talk • contribs) 02:19, 21 April 2007 (UTC).

No. Not every example of some kind of equilibrium process is relevant. Take the blue pencil to this article. --Wtshymanski (talk) 17:45, 29 November 2007 (UTC)

[edit] Diagrams

Although the author has taken a lot of time to make these colored diagrams, and whilst they may be ok for a personal note book, I dont think they are of sufficient quality for an encyclopedia. Also they try to show too much information on one diagram and are therefore confusing to the innnocent reader.

VirtualEarth

I second that. The diagrams are confusing and too informal for an encyclopedia. They really should have been computer generated as well. Roger 19:13, 21 April 2007 (UTC)

Yes but we can't ask the author to do that. If he could do it, I presume he would have. It needs someone to redraw, but not before people have decided which diagrams are even worth keeping--VirtualEarth 19:26, 21 April 2007 (UTC)

I think its best if we just leave the article short and to the point, until the current content can be re-written and the diagrams improved. I'm not being vicious. I agree with you that the author put alot of time into this article, but in its current states its just too long-winded and confusing. Roger 22:10, 22 April 2007 (UTC)

I rather think others (and I) may disagree that this is the best way to go about it!--VirtualEarth 23:53, 22 April 2007 (UTC)

Personally I think a concise but sparse article is better than a long and confusing one. Regardless, I'm not getting into an edit war with you unless others care to back me up. In the mean time I just want to point out that the Wikibooks project (http://en.wikibooks.org/wiki/Main_Page) seems like a more fitting place for this article. Roger 00:57, 23 April 2007 (UTC)

So do I actually. But rather than remove stuff wholesale, it need to be deciced carefully which bits to remove, and which to retain. I have already started to look at the figures to see which should be redrawn, which discarded and which kept. i would be interested in your comments.--VirtualEarth 11:13, 23 April 2007 (UTC)

Ideally, yes. But this article needs more than a few minor edits here and there. As Bmunden and yourself have said, the article is awkward and difficult to read. I'm an EE and I find it difficult to understand what the author is talking about. Judging from his website, this is from his own unique teaching method, and frankly, no offense to the author, I think the content here should be pretty straight forward. The previous article was short, but at least understandable. Roger 01:01, 24 April 2007 (UTC)

I totally agree with you, but it is very easy to dismiss a load of work and throw out some gems of insight in the process. That is why I ask you to discuss with me and others what we might safely discard, what we can keep and what must be rewritten. It maybe that we do have to discard most of this stuff, but I would like to give the authors work a fair 'trial' before junking it. Can we start on the diagrams to decide which are useful and which not?--VirtualEarth 01:10, 24 April 2007 (UTC)

I know what you're saying. There's definitely been alot of effort put into this article. The drawings alone look very meticulous drawn. Unfortunately I think they're are a bit too "busy". There's also alot of unnecessary content (such as "Energy considerations", which would be much better suited to a textbook). Anyway, I'd say Figures 2 and 3 are redundant, so are 4 and 5 and also figures 10 and 7a. Roger 01:35, 24 April 2007 (UTC)

I think fig 2 shows something. I think 10 and 7a are useful. Fig 3 is repeat of fig 2. Yes figs 4 & 5 are not really useful. --VirtualEarth 02:22, 24 April 2007 (UTC)

Figures 10 and 7a are the same circuit BTW. Roger 02:53, 24 April 2007 (UTC)

Oh yeah! difficult to tell isnt it? OK we dont need 10., 7a is an acceptable drawing IMO.--VirtualEarth 05:45, 24 April 2007 (UTC)

OK then, I give you first go at deleting the /figs we have agreed are not worth keeping.--VirtualEarth 06:12, 24 April 2007 (UTC)

Drop a note on my talk page if you want any diagrams redrawing in Inkscape. — BillC talk 18:18, 25 April 2007 (UTC)

OK thanks a lot. When we have consensus on any diagrams needing (re)drawing, I will contact you! Thanks. --VirtualEarth 22:39, 25 April 2007 (UTC)

[edit] Language and terminology

It seems that the author may not have english as the first language. I will try to rewrite some of the rather awkward sound phrases. —The preceding unsigned comment was added by VirtualEarth (talk • contribs) 02:30, 21 April 2007 (UTC).

[edit] Virtual ground vs. small signal ground

I think the author is confusing the two or has made his definition too broad. Roger 19:13, 21 April 2007 (UTC)

I concur. Virtual ground is typically the inverting input of an op-amp circuit. The small signal or analog ground is a typically a voltage at about the midpoint of the supply voltages.

We need to split the topics. Much of the material here may be relevant to analog ground. Djhk 02:41, 3 December 2007 (UTC)

[edit] Inconsistent diagram

[edit] Figures to delete

[edit] Fig 2

Do we need Fig2? If not do we need to alter the text to compensate?--VirtualEarth 00:15, 23 April 2007 (UTC)

I think this should stay (redrawn)

[edit] Fig 3

This is the same as Fig 2 and can be removed. The text should then ref fig 2.--VirtualEarth 00:40, 23 April 2007 (UTC)

[edit] Misleading concept

Virtual ground implies ground potential at the node. Adding a component to a ground will have no effect if the other component connection is ground. There is no potential difference, hence no current flows. This may not be true for a virtual ground. In an inverting amplifier adding a capacitor between ground and the virtual ground at the (-) op-amp input can make the amplifier unstable. Stray capacitance from a probe is often sufficient.

A warning should be added.

Djhk 18:26, 23 September 2007 (UTC)

Djhk, you hate virtual ground but this is a phenomenon, fact that exists whether or not we like it. What do we do when we haven't an access to a real ground? Then we use a virtual ground (a typical example is creating of a split supply by one voltage source). Sometimes, we use a "shifted" (e.g. "lifted") ground instead an exact ground.

In a broadest sense, any circuit point having a voltage that is kept artificially (e.g., by means of a negative feedback) can be named virtual ground. In a literal sense, a virtual ground is a result of subtraction of two voltages having opposite polarities. We can say that a virtual ground is actually an active ground. Every active thing in this world is more stable to influence than passive one. Circuit-fantasist (talk) 17:34, 24 November 2007 (UTC)

It is true that I don't like the concept of Virtual Ground when referring to the inverting op-amp input.

You are confusing Virtual ground with analog ground. you need to split the topic into virtual and analog ground. combining the two creates confusion.

Djhk 02:49, 3 December 2007 (UTC)

What do you mean when you say "analog ground"? What is the difference between a virtual and an analog ground? Circuit-fantasist 16:27, 3 December 2007 (UTC)

Analog ground is just "normal" ground, i.e. 0V. Virtual ground behaves like a nullator connected to ground. -Roger 16:34, 3 December 2007 (UTC)

See my reply in Circuit Idea/Virtual Ground talk page. Circuit-fantasist (talk) 14:21, 23 December 2007 (UTC)

The concept of a nullator isn't really a way to understand virtual ground, its just the most concise way to describe and differentiate it from normal ground. No offense, but I think your version of the article is just too long winded and uses too many analogies - it ends up confusing more than helping (especially all the "narrow-minded" readers). Plus its mostly OR and I don't think you'd find this approach anywhere else, essentially the article would only be maintainable by you.

Ultimately I don't think much of your material is suitable for an encyclopedia (without major revision), but it was a very good idea to start a wikibook. -Roger (talk) 16:22, 5 December 2007 (UTC)

[edit] Is there an OR in the article?

I have removed {{Original research}} since the article shows extremely simple, obvious and intuitive truths about the phenomenon that do not need to be proved (see also How do we evade NOR?). Circuit-fantasist (talk) 05:33, 9 December 2007 (UTC)

Looks alot better now, thanks. I do see some mentions of "voltage conflict" a few places in your article. That might still be OR. -Roger (talk) 23:15, 15 December 2007 (UTC)

[edit] Concise

An encyclopedia article should be concise. This now reads like an entry in a Wikibook on circuit theory. It's a one-line definition, really, and should not be adumbrated upon to the extent that is now present in the article. --Wtshymanski (talk) 15:41, 14 December 2007 (UTC)

See the first part of my reply in Circuit Idea/Virtual Ground talk page. Circuit-fantasist (talk) 14:26, 23 December 2007 (UTC)

A month ago, I tried to show, in a human-friendly manner, the truth about the great virtual ground phenomenon (it deserves that) by means of various analogies; you removed them. Then, I tried to say it more concise replacing all the analogies by only one link; you removed the link as a "promotional" one. Finally, I tried to show, in one-line conclusion, the philosophy behind the phenomenon; you removed it. What do I do then?

I suggest a simple procedure. If you (or someone else) can say it more laconically, say it but do not remove it at all! If you know links pointing to better virtual ground resources, insert them into the page; until then do not remove the existing links (even if they look "promotional"). If you have a philosophy about the virtual ground phenomenon, please, expose it on the page. If you have found such a philosophy (or beginnings of thinking about the nature of the phenomenon) somewhere on the web (I have not managed), describe it; until then do not remove the existing philosophy. If you do not accept the assertions about phenomenon, say why. Let's discuss the root of the matter, not only the form of presentation.

Circuit-fantasist (talk) 09:10, 15 December 2007 (UTC)

The recent edits by Circuit-fantasist seem to have improved the readability of the article, but I agree that it should be more concise. Its true that articles should be approachable, but the author seems to be treating the material as being a lot more difficult than it is.

For me, a virtual ground can be created either by buffering (to the degree necessary) a voltage divider to provide dual rail supplies or using negative feedback to make the potential between two points zero. For the first case the explanation is as simple as the voltage divider equation, very little elaboration should be necessary.

The second case is simple too. V_o = A*(V₊-V_-), let A->infinity then (V₊-V_-) must -> 0 if V_o remains finite. Or just use two of the basic negative feedback opamp assumptions: R_in is infinite and V₊ = V_-.

The "tug of war", "fighting", etc. analogies and all the drawings are too much for such a simple concept. -Roger 23:32, 15 December 2007 (UTC)

A wonder. Roger, thank you for the response. I am glad to see that it is still possible to carry on a constructive dialogue on the pages of Wikipedia (it is just a wonder). Obviously, you have the talent to mollify conflicts while I have a bent for strengthening them:) I wanted to modify the page and then to reply to your previous comment but Wtshymanski and you have anticipated me. So, I will try here to reply to all your remarks. I do not suppose this page is the most suitable place for such "philosophical" thoughts but we can finally scatter them among the more appropriate Wikipedia discussion pages (Voltage divider, Voltage source!!, Op-amps, etc.) If you let me, I will copy the most valuable thoughts from this page to the respective discussion pages of Circuit idea wikibook.

A discrepancy. You may wonder but I have agreed on your remarks. I have realized that hardly Wikipedia is the most suitable place for this intuitive approach; that is why I have started Circuit idea wikibook. Only, I can't become reconciled with formal approach that predominates in Wikipedia and try to "humanize" it:) Maybe, the main discrepancy is that Wikipedia is a collective work, a place where to collect established "nameless" facts while I am an individualist who has own philosophy about phenomena. People (especially those that have managed to advance in life and to hold a high position) do not like someone (especially staying below them) to express own ideas even if they are more than obvious. This upsets their mental equilibrium and they react to this "intervention" trying to redress the balance exactly as an op-amp reacts to any intervention to virtual ground:) Contrary, people adopt willingly, use and benefit from nobody's ideas. I have known this truth from my experience since I have been bearing the reactions of people around me through my life. I have reserved a special page (Why Creative Persons are Unhappy) about these phenomenon in Circuit idea (maybe, I will move these "black" thoughts there).

The solution. As far as I can see, there is a simple solution to the problem: you, Wtshymanski, VirtualEarth and other wikipedians can help me to make the page concise; I will move all the excessive pictures and text to the according Circuit idea page. Do you agree? Well, let's now continue the discussion about virtual ground phenomenon (once the wonder has happened, let's do not let it to disappear:) Circuit-fantasist...

The rest of the dialogue is moved to Circuit Idea/Virtual Ground talk page.

This is not the place for a general discussion of operational amplifiers, network theory, etc. etc. - the concept is so general that it tends to drag in too many other elements. Interestingly, none of my circuit theory textbooks have an index entry for "virtual ground" so the concept may not need as much explanation as it is getting here. "Philosophy" (whatever that is meant to mean in this context) belongs in a Wikibook on circuit theory; most of this article is either confusing or obvious. The article should be skinned down to passive techniques such as voltage dividers, and active techniques involving feedback amplifiers. All the metaphors are better expressed in some other venue than an encyclopedia article. --Wtshymanski (talk) 17:55, 17 December 2007 (UTC)