Talk:Virtual ground

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

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)

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)

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).

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)

Inconsistent diagram

Fig. 1. A virtual ground point on the voltage diagram of a linear potentiometer

Figures to delete

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)

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)

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)

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)

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)

I think this is the only article on WikiPedia about a circuits / electronic fundamentals concept that I could understand when I was new to the concept. Every other article jumps straight to equations without adequate explanation for those that do not know the concept yet. It defeats the purpose of wikipedia if explanations of the concept and the reason for the concept's existance and use (the philosophy) are not permitted on it. Please stop making wikipedia suck, Wtshymanski. --24.98.65.137 (talk) 06:51, 9 October 2008 (UTC)

This is still pretty bad and out of place on an encyclopedia. Wikipedia is not a textbook and this essay should be thrown out or severly truncated. --Wtshymanski (talk) 16:30, 22 December 2008 (UTC)

Hopeful prospects

Oli Filth, thank you for the assistance; this page needed improvement. I admire your edits although you have gone too far somewhere. Maybe, I will make some cosmetic edits here. Circuit dreamer (talk) 14:41, 1 April 2010 (UTC)

Yes, this page is long overdue for a make-over. The colorful diagrams need to be converted to an editable format. I pruned some of the wordiness from a couple of paragraphs. BTW no circuit is "perfect". The correct terminology is "passive" (just uses resistors) and "active" (includes an amplifying device). Zen-in (talk) 16:15, 1 April 2010 (UTC)

Virtual ground serving as a voltage reference

I would like to discuss this virtual ground application (as an artificial middle point). Please, visit these pages and discuss.

---

...A simple method for creating a "pseudo ground" is to use a resistive divider...

http://www.analog.com/library/analogDialogue/archives/29-3/consider.html

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...The virtual ground is simply a voltage reference that is typically half way between Vcc and ground. One way of generating a virtual ground is shown below...

http://www.swarthmore.edu/NatSci/echeeve1/Ref/SingleSupply/SingleSupply.html

---

I believe that the original definition of "virtual ground" was only the zero volts which appears at the negative input pin of an op amp whose noninverting input is connected (perhaps through a resistor) to GND, and has DC feedback to the inverting input.

The term has been used more recently to denote the voltage divider which is used in single-supply op amp circuits, and serves as the bias voltage for the noninverting pin(s) on those op amps. This is not really, IMHO, "virtual ground". It's a bias voltage. The summing vodes of the op amps could be called, I suppose, "virtual bias voltage", or "virtual AC ground".

http://www.electro-tech-online.com/general-electronics-chat/32096-explanation-required-virtual-ground.html

---

...If we only need one imprecise bias point, two 5% resistors will do...

http://www.maxim-ic.com/app-notes/index.mvp/id/4344

Circuit dreamer (talk) 17:14, 2 April 2010 (UTC)

Ummm, what would you like to discuss about it with respect to the article? Oli Filth^{(talk|contribs)} 17:20, 2 April 2010 (UTC)

I would like to discuss this application as it is closely related to the clever "bad pseudo ground" trick used in the single supply inverting Schmitt trigger. It may be also used to build single supply non-inverting amplifiers by using only four resistors (I have not still found links about it). Circuit dreamer (talk) 17:41, 2 April 2010 (UTC)

I have found these thoughts (related to the topic) that I moved to Circuit idea wikibook three years ago. Circuit dreamer (talk) 17:58, 2 April 2010 (UTC)

A tale about virtual ground evolution

...Voltage is a differential quantity; so, to process "true" voltage signals we need differential-input (-output) devices. If we want to deal with single-ended voltages (potentials) that is usually more conveniently, we need a voltage "mainstay" (a ground) where to connect one of the device terminals and regarding to which to measure the voltages (potentials). For this purpose, we usually use one of the power source terminals as a natural, true, genuine ground; thus, we can deal with only positive or only negative voltages. If we want to have both positive and negative voltages, we use an internal power source point as a ground (for this purpose, we usually connect two or more voltage sources in series and in the same direction. If there is no such a compound power source, we create an artificial but still real ground, for example, by using the bare voltage divider. This ground is a real one simply because there isn't any other ground (more precisely speaking, there is such a point somewhere inside the source but we have no access to it). Finally, we "clone" the ground (no matter it is true or artificial) by making another circuit point (virtual ground) follow the ground; for this purpose, we usually make an op-amp with negative feedback do this donkeywork:)... Circuit-fantasist 18:47, 18 December 2007 (UTC)...

I'm still not sure what your suggestion for the article is! Oli Filth^{(talk|contribs)} 15:46, 3 April 2010 (UTC)

Artificial middle point

IMO, this is a very typical virtual ground application - as an artificial ground (artificial middle point of a power supply). Here, we have first to show that, in order to obtain such steady ("stiff", "hard", "immovable") ground in these single-supply op-amp applications, we have to use as much as possible low resistances. Then, we may show that in some single-supply op-amp applications (inverting Schmitt trigger and non-inverting amplifier), we may do the opposite - to "soft" the artificial ground, to make the op-amp output influence it. As a result we may simplify these circuits.

Well, let's consider an imaginary situation where two people ("standard" and "non-standard" thinking) design a single-supply inverting Schmitt trigger. The standard thinking designer will choose extremely low resistances for the two resistors of the voltage divider (to "harden" the ground). Then, he/she will connect another voltage divider (further two resistors) in the positive feedback loop. Thus, the overall circuit is a 4-resistor one.

The non-standard (clever, inventive) thinking designer will guess that he/she may do the opposite instead and will choose relatively high (not so low) resistances for the first voltage divider (to "soften" the ground). Then, he/she will connect only one resistor between the op-amp output and the "soft" ground to influence it. Thus, the overall circuit will be a 3-resistor one (the circuit from hyperphysics). Circuit dreamer (talk) 17:27, 3 April 2010 (UTC)

Some points:

1. The article already discusses the use of a virtual ground as a voltage reference
2. I don't think anyone considers the V+ input of an inverting op-amp Schmitt trigger as a virtual ground
3. Similarly, no-one considers the V- input of a non-inverting amplifier as a virtual ground.

Oli Filth^{(talk|contribs)} 17:12, 3 April 2010 (UTC)

This is the very clever trick - to connect the op-amp inputs to "bad" ground instead to "good" one. BTW, can you help Zen-in to realize why the simulated inductor does not store energy as the real one? Circuit dreamer (talk) 17:31, 3 April 2010 (UTC)

This is a very obscure way of viewing what's occurring. Can you find a source that describes it this way? Oli Filth^{(talk|contribs)} 17:35, 3 April 2010 (UTC)

I'll try to find something similar. Circuit dreamer (talk) 17:52, 3 April 2010 (UTC)

As for inductors, start a thread at Talk:Gyrator and I'll respond. Oli Filth^{(talk|contribs)} 17:39, 3 April 2010 (UTC)

Well, I will move now there. Circuit dreamer (talk) 17:52, 3 April 2010 (UTC)

A few editors in the past few years have commented that this article is already over-worked and could be reduced to just a couple of lines. The concept of a virtual ground is quite simple. So instead of a discussion about adding things I suggest we discuss what should be removed. First items on my list would be OR and the the non-standard diagrams. Zen-in (talk) 19:14, 3 April 2010 (UTC)

Returning at the beginning

Oli Filth, I am a little surprised by you as I have been expecting you to join the discussion about storage properties of gyrators. But you have preferred to leave me along on the field of battle:) I have been thinking about the clever ideas behind these so odd gyrator circuits but you have ceased my chain of thoughts... As I can see, you have almost blanked the page about virtual ground and returned it nearly to its initial stage.

Honestly, I was a little stressed by your "edits" this morning and I decided to examine thoroughly your contributions to see the reason for your high spirits. Looking at your edits (more of them in complex and abstract areas), I have the feeling that you are (too) able, clever and intelligent. But, at the same time, you are formal and sterile thinking specialist who does not like powerful, clear and simple intuitive explanations based on common reason. I am absolutely sure you understand perfectly great circuit ideas but the entire problem is that you do not see any need of showing them to people, to Wikipedia visitors. You looks like a famous professor or (worse) a researcher, that has decided, for some reasons, to teach pupils in a primary school but he/she is nervous as he/she wastes his/her so valuable time on explaining trivial things. But you please, do not forget that Wikipedia visitors are not mainly engineers, designers, scientists; they are mostly ordinary people that would like to know the basic circuit ideas, the clever tricks on which circuits are based, the simple truth about circuits.

Let's see only one example that is closely related to virtual ground and to simulated inductor - the page about the simple RC circuit (in particular, the sections about the passive integrator and differentiator). Will the reader understand what the main problem of these humble circuits is? Will the visitor come to know what the general solution is? No, the reader will learn that "...more accurate integration and differentiation can be achieved by placing resistors and capacitors as appropriate on the input and feedback loop of operational amplifiers..." The information in this sentence is almost zero... But if we show here the problem (the voltage drop across the grounded element), and if we suggest, right here, the general solution (compensating the voltage drop by adding an equivalent voltage), the reader will understand momentarily how the op-amp integrator and differentiator work, what the op-amp does in these circuits. What is more, the reader will understand what the op-amp does in all the op-amp inverting circuits there...

Wikipedia is intended to human beings, not to computers. If we continue creating so formal, sterile, dull and synthetic pages, people will not read them! These pages will be read only by bots! Circuit dreamer (talk) 15:06, 5 April 2010 (UTC)

I generally edit to remove "clutter" and tangential material that won't improve the reader's understanding of the core topic of the article. If this makes for "formal" articles, then so be it! I made my edits today in response to Zen-in's point that this article is far more complicated than it needs to be for such a simple concept. I'm quite happy to discuss or revise any of my edits that I made. In summary:

• I removed the "Problems" section because they're true of any voltage reference, and therefore if this information lives anywhere, it should probably live at the Voltage reference or Voltage regulator article.
• I removed the "Circuit input" section, because really that's just a description of applications for circuits with low input impedance, and what's more, a virtual ground isn't necessarily low impedance.
• I removed the "Circuit output" section, because this isn't really an application of a virtual ground.

(P.S. As far as Talk:Gyrator is concerned, I don't think there's much I can add to what has already been said there!) Oli Filth^{(talk|contribs)} 15:56, 5 April 2010 (UTC)

opamp virtual ground

I think that we should add that virtual ground at the inverting terminal of ann opamp is present only if the opamp is connected in (-ve)feed back configuration AND its output has NOT saturated (opamp is inlinear region). (Applications and design with analog integrated circuits by jacob michael. chapter 6) — Preceding unsigned comment added by Cplusplusboy (talk • contribs) 15:32, 12 February 2013 (UTC) also, [[1]], [[2]]#an Inverting Amplifier 02:45, 13 February 2013 (UTC)

virtual ground states

when elements from the carbon group interact with a plasma field ,three virtual ground states can occur . one is the ground interaction with earth, two is the ground state when the observer interacts with the circuit, and the third is the same interactory metal outside the plasma field.all three conditions creating different node potientials or stops.50.93.20.150 (talk) 17:26, 27 July 2013 (UTC)

That looks like it's copied from a textbook. It's not relevant to this article, but possibly to ground state. Anyway, have a look at WP:TPG and try to make more useful comments in future. --Nigelj (talk) 17:25, 29 July 2013 (UTC)

Op-Amp

How does current flows through an Op-Amp as input impedance is infinite in an ideal Op-Amp, since no current is entering in it? Vaibhav Singh (talk) 18:29, 26 August 2016 (UTC)

I would suggest to pay more attention to the context sensitivity of the expression "virtual ground"

As far as I can see, the expression "virtual ground" is highly context senitive, compared with expressions like "Impedance" which have a clear context free definition.

The only common thing about the virtual gound idea, is that, for some reason, we can refer to a specific node as being "Ground Potential", in other words, a steady voltage compared to what we call ground potential (0V) in our schematics, which does not have to be earth potential.

And we can use the fact, that we know that value, in our mathematics. Not more and not less.

But which nodes my be seen as a virtual ground and which implications will follow for the analysis of our schematics, depends highly on the question, what we are analyising.

It is also not related to the question, if the node behaves like a source reference point with low impedance or not. But this has a strong impact on the behaviour of schematics, not just practically, also theoretically.

So if we can see a point as a virtual gound, that does not tell us anything about the role, that this node plays for the reviewed schematics.

I saw this expression used in different meanings, sometimes as a node, that will calcualte out to a stable voltage, sometimes a virtual reference for signals, which are not related to ground.

In all scientific literature that I know, where this expression is used, it was also explained, what is ment with the term virtual ground in their specific case.

I would be much happier with this article, if these aspects would be mentioned more clearly.

Best Regards Felix Seib — Preceding unsigned comment added by 2A02:908:DF51:A040:4834:221D:BBF0:60A2 (talk) 17:14, 23 November 2020 (UTC)