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I think any diagram is preferable to no diagram. To this extent, I think the package chosen should be one that is easiest to use as long as the o/p is reasonable and the program is free to use. THis will encourage people to draw a diag, when otherwise they would not bother. The examples of all output shown on project page all look perfectly OK to me.-- Light current 16:59, 22 September 2005 (UTC)
I think its essential to use conn dots on schematics. THose without them are so hard to understand, trying to find out if a wire is just crossing or is actually connected to another wire. So the package must support conn dots-- 88.109.39.70 17:06, 22 September 2005 (UTC)
When drawing resistors on paper I use the squigglies as I find it easier than drawing a rectangle. When using a CAD package I obviously use their symbols. I personally slightly prefer the squigglies but thats only because I was brought up using them. I think most packages now use rectangles for resistors and, to be honest, it does look less fussy. But I dont really mind. Current sources are usually shown as two interlinked circles with an arrow at the side denoting polarity. Voltage sorces are denoted as a single circle with an arrow at the side denoting polarity.(sharp end is positive). But diamonds are OK, its just I think circles are more standard.-- Light current 23:06, 22 September 2005 (UTC)
—
Omegatron
14:05, 23 September 2005 (UTC)
I dont like the German ones!! Lets stick with the US ones (maybe apart from resistors)-- Light current 14:15, 23 September 2005 (UTC)
I would like to revisit the topic of resistor symbols. I believe that the squiggly shape versions (as opposed the the boxes) are more intuitive and more in keeping with the ones we use for inductors. A mere box can represent anything unless you include a reference or value beside it.
Also, I'd like to suggest that we try to simplify our schematics by avoiding unnecessary power or ground connection rails, pin numbers, and adhere to a general left-to-right signal flow where possible. -- Hooperbloob 04:39, 10 October 2005 (UTC)
WikiProject Electronics or WikiProject Electricity?
Basically, how broad do we want it? — Omegatron 06:04, 23 September 2005 (UTC)
I don't think we need to worry about that for now. Remember one of the major criticisms of such a project was that we would spend all our time on bureaucracy and none on editing electronics content. :-) — Omegatron 01:37, 25 September 2005 (UTC)
Added a proposed statement of scope of project-- Light current 14:14, 23 September 2005 (UTC)
I think we can include telecomms biomedical electrical now as we have more members.-- Light current 07:49, 9 October 2005 (UTC)
Could we please change the template names so they start with 'electron' rather than 'electro'. The existing template may imply electr-omagnets, or electro-mechanaical, electro-chemical things etc. Electron is pretty obvoius to anyone.-- Light current 15:25, 23 September 2005 (UTC)
I have the original paper on 'Gaussian magnitude filters' by Milton Dishal and so I would be prepared to contribute a para or 2 on these filters if no one else wants to! Please let me know if you wish me to start on it.-- Light current 21:07, 24 September 2005 (UTC)
I want to get 'O's OK on this as I think he may have wanted to do this one himself! -- Light current 16:59, 25 September 2005 (UTC)
M. Dishal, 'Gaussian Response Filter Design', Elec. Commun., vol36, pp 3-26, 1959.-- Light current 00:43, 17 October 2005 (UTC)
In name of the wikiproject, I sent a private email to the only developer of xcircuit. He has been very nice: he replied to me very quickly and answered all my questions. We are still discussing about e few points, I´ll write what I learnt from the discussion in the xcircuit section of the project. I hope you don´t mind I remove the other two short comments, since the things I know replied to our doubts. I will keep you updated when I get more news. Alessio Damato 21:02, 26 September 2005 (UTC)
What is charge decay? Is it something to do with capacitors?-- Light current 01:02, 27 September 2005 (UTC)
Have a look at the links on this subject (charge decay) on the project page!-- Light current 07:27, 9 October 2005 (UTC)
Maybe this should be in an article an electrostatics if there is one. If not we create one!-- Light current 00:09, 30 September 2005 (UTC)
If I missed off the links when reformatting, apologies-- Light current 16:43, 29 September 2005 (UTC)
Sorry Ive just claimed Electrostatics as one of ours!!!-- Light current 00:44, 30 September 2005 (UTC)
I think Power factor correction could be touched up. I'm not sure if this is better under electricity or electronics, it is somewhat relevant to both. Snafflekid 21:13, 5 October 2005 (UTC)
Its very pleasing to see so much progress being made so quickly here. As the electrican once said "Many hands make light work"!-- Light current 00:07, 30 September 2005 (UTC)
Hi, since I have seen that this thing of the mindstretchers was quite interesting and successful, why don´t you start a "subsection" of the project just about it?? then, all the answers we get may be moved to a proper article. A possible choice might be Wikipedia:WikiProject_Electronics/Mindstretcher or something similar. - Alessio Damato 21:43, 30 September 2005 (UTC)
ok it´s up to you, then you´ll take care of it (just in case). Alessio Damato 20:34, 3 October 2005 (UTC)
Problems to keep you awake at night...(or send you to sleep!)
No1. Bearing in mind the pulse charged transmission line we discussed on Talk:capacitor, what is the difference between ordinary d.c and electromagnetic radiation. Is there any difference? If so what is it? (NB dc is defined here as that steady potential difference that might be observed across a charged transmission line or capacitor.) (This is NOT a trivial question). :-)-- Light current 23:01, 26 September 2005 (UTC)
No2. When is a physiscal inductor not an inductor? (ie what does it really behave like at high frequencies?).(Q. Difficult)
No3a What is an electron made of? (Quite fiendishly difficult)
No3b What happens when an electron gets 'excited'. Does it have anything to do with photons?
No4 Just what is a photon exactly? (not too difficult)
N06 What is the difference between a probability wave predicting the strength of a (standing wave) electric or magnetic field, and the actual magnitude of the same electric/magnetic field standing wave.? For instance, at antinodes the probability of finding some displacement is high. At the nodes, the probability of finding displacement is low.
No5 (Optional question). What is a virtual photon? Extra (virtual) marks for explaning this concept.
Sounds like a 'cop out' to me!! If they cant be detected how do we know they really exist?-- Light current 01:05, 30 September 2005 (UTC)
What causes the magnetic moment? If you say spin, I shall ask you exactly what spinning means!-- Light current 20:52, 30 September 2005 (UTC)
In QED, the electron is the quanta of a spinor valued field. You are probably familiar with a vector valued field, e.g., the vector potential and a scalar field, e.g., the scalar potential. If you rotate a vector around 360 degrees, you get the same vector. However, a spinor must be rotated by 720 degrees to get the same spinor. It is sometimes said that a spinor is the 'square root' of a vector. When Dirac set about to develop a quantum wave equation compatible with special relativity, he essentially took the square root of a quantum operator. The solutions to this equation are Dirac spinors which turn out to describe a spin-1/2 particle and its anti-particle such as the electron and positron. If one includes a magnetic field in the Dirac equation, the solution includes a term that, in the non-relativistic limit, corresponds to a particle with a magnetic moment. Thus it appears that the intrinsic angular momentum and the magnetic moment 'pop out' of the relativistic wave equation naturally. If I can think of some 'deeper' explanation later, I'll let you know. Alfred Centauri 01:25, 2 October 2005 (UTC)
A quantum wave equation results from replacing classical variables such as momentum and energy with quantum operators. Schrodinger's wave equation comes from the Newtonian energy-momentum relation. Dirac's equation and the Klein-Gordon equation come from the relativistic energy-momentum relation. Although the electron has angular momentum, it cannot be said that the electron rotates about an axis as that is a classical concept. The 'spin' of an electron has no classical analog. For example, if you attempt to calculate the magnetic moment from the angular momentum of the electron, you get half the value predicted by the Dirac equation. Further, one can only measure the total angular momentum and one component simultaneously due to the uncertainty principle. Lastly, a spinor should not be confused with spinning. A spinor is a geometric object that is defined by how its components transform under a coordinate transformation. As I said earlier, a spinor changes sign under a 360 degree rotation whereas a vector does not.
I don't know if this will help or not but recall that an electron in an atom has an orbital angular momentum associated with its 'orbit' around the nucleus of the atom. The problem is, the electron doesn't orbit the nucleus like the classical orbit of a planet around a star. The wave function of the electron in an atom is a spherical standing wave unlike a free electron where the wave function is a traveling wave. Take a look at the 'Picture of hydrogen orbitals' in the Hydrogen atom. These don't look like a classical particle revolving around a point of attraction yet there is an angular momentum associated with each orbital. Alfred Centauri 03:24, 2 October 2005 (UTC)
You do understand that the standing and traveling waves I refer to are related to probability density, right? I'm afraid I don't understand how that description lines up with the idea that electrons are made of EM waves. Alfred Centauri 13:27, 2 October 2005 (UTC)
The wave function is a complex valued function that represents the so-called probability amplitude. To get the probability density, one must take the product of the wave function with its complex conjugate. That is, the probability density function is the magnitude squared of the wave function. I don't know if this answers your question or not because I not quite sure what your question was! Alfred Centauri 17:54, 4 October 2005 (UTC)
That's not true, LC. The intrinsic angular momentum of a particle and the spin of a particle are one and the same. BTW, there is another, even more interesting (to me, at least), aspect of spin. Recall that the EM field is a vector field. A vector rotated is unchanged when rotated through 360 degrees. The photon, the quantum of the EM field is a spin 1 particle. A vector is a rank 1 tensor. In general relativity, the gravitiational field equations involve rank 2 tensors. A rank 2 tensor rotates twice as fast as a vector under a coordinate rotation. That is, a rank 2 tensor is unchanged by a rotation through 180 degrees. The graviton, the hypothetical quantum of the quantized gravitational field is thus a spin 2 particle. The Higgs boson is called a scalar particle for the reason that it has spin 0. That is, the Higgs field is a scalar field. Alfred Centauri 17:50, 4 October 2005 (UTC)
Update: Here's a link you might find interesting. But beware: this is crank material! [2]. Alfred Centauri 15:10, 2 October 2005 (UTC)
Answer: d) because it was written by a person displaying crank symptoms such as this little tidbit from Milo:
Just $19.95 in 3 easy payments! Alfred Centauri 18:40, 4 October 2005 (UTC)
Then, either I wasn't clear or you simply misunderstood me. QM and QED do not attempt to answer the question "what is an electron?" and I certainly didn't say that an electron is a standing probability wave. In QM, the possible states of a particle are completely determined by the wave function. When you solve for the wave function of an electron, you are solving for the possible states of the electron. Think of it this way, if you solve for the motion of a classical particle in a force field, you end up with function of time that gives the position of the particle. You would never think of claiming that the particle IS the position function, would you? Alfred Centauri 18:16, 4 October 2005 (UTC)
While I sympathize with your quest for the answer to your question, please consider this: if the electron is not fundamental - if the electron is made of something else - doesn't this lead to the question of 'what is that something else made of?". QED/QM are mathematical models ( Interpretation of quantum mechanics) for how things work at the subatomic and atomic level. A good mathematical model is immensely useful and I can't believe that you, as an engineer, don't understand this so I'll attribute your statements above to frustration. It could be that your question is ultimately unaswerable. It may be that what is fundamental in this universe - the stuff from which everything else follows - may be nothing. After all, 0 = 1 - 1. Alfred Centauri 01:43, 5 October 2005 (UTC)
Your statements above reveal to me that you have no idea how the Standard model was developed. Find yourself a copy of "The Second Creation" to get an idea of the struggle to develop this model. BTW, I'd be proud to be a physicist but I'm just a TV repairman. Alfred Centauri 20:44, 5 October 2005 (UTC)
You are quite correct about my knowledge of the standard model. Thats becuase:
A) It was discovered/developed/published after I finished my formal education
B) I did not study physics, but electronics engineering and did not keep up with physics after graduation.
C) I have forgotten most of what I did learn anyway!
BTW You are far too smart to be a TV repairman.;-)-- Light current 00:15, 6 October 2005 (UTC)
Follow up: I didn't address your last question in my response above. The magnitude squared of the wave function is the position probability density function. Alfred Centauri 22:51, 4 October 2005 (UTC)
Well, it is actually the probability that the something (whatever that is) will be measured or detected somewhere. The funny thing about QM is that it is not at all clear that the something exists at a definite location until it is detected somewhere ( Wavefunction collapse). What is that something? If I knew, I would have told you by now. Alfred Centauri 01:51, 5 October 2005 (UTC)
I'm sorry if I led you to believe that I know what the electron 'is' as I did not intend to, so the 'coming clean' stuff isn't really applicable. Look, I'm having trouble understanding what your issue here is. The electron, as a fundamental entity, exists. It has only a few intrinsic characteristics: mass, electric charge, flavour, spin, magnetic moment and maybe a couple of others that I can't think of at the moment. To the limits of our ability to discern, the electron is point like. By the rules of QM, we can in principle, given some initial information about an electron, determine the wave function for that electron and thereby calculate the probability of finding (detecting) that electron within some volume of space at a later time. When you ask what is it we are detecting, the answer is that 'thing' that has the mass, electric charge, flavour, spin, magnetic moment etc. that we attribute to an electron. That is how we identify an electron. We can measure these properties of a particle. If we detect something that has different values for these properties, it isn't an electron. Thus, I believe your question should not be 'what is an electron?'. Instead, I believe your questions should be 'what is electric charge? what is mass? what is spin? what is flavour?'. If you can unambiguously answer these question, then you will know 'what' an electron is. Alfred Centauri 23:47, 5 October 2005 (UTC)
I suggest we set aside the weak interactions for the moment. What Im interested in is how exactly electrons and photons interact. They seem to consist of essentially the same thing from what I gather (EM energy).-- Light current 10:49, 29 September 2005 (UTC)
OK but we all know that mass is only energy in another form. The origin of 'charge' is something else I would like to find out about-- Light current 00:42, 30 September 2005 (UTC)
So what else is inside an electron? -- Light current 00:42, 30 September 2005 (UTC)
So is an electron pure energy?-- Light current 23:31, 3 October 2005 (UTC)
Can we say that electrons are material particles no matter what while photons are material particles only in motion and are hypothetical at rest? -- Davy Jones 07:48, 26 October 2005 (UTC)
Well no. These questions were posed in order to stimulate discussion on various electronics/physics problems. If you look around her and esp Talk:capacitor you'll see what I mean.
I am finding that there is enough material to warrant both semiconductor and semiconductor device pages. The semiconductor page is very well written and did not need much work. And, it may be too academic for many people who are interested in components. With enough disambiguation and cross linking, the pages are becoming complementary.
I think that the transistor page could use some pruning with stuff being moved to semiconductor device. Snafflekid 01:13, 1 October 2005 (UTC)
I have released semiconductor and semiconductor device into the wild. Edit at will. I will give transistor some attention when I have time. Snafflekid 07:48, 1 October 2005 (UTC)
When I edited the transistor page, I changed the explanation of the BJT operation from a voltage controlled device to a current controlled device. I figured sooner or later it would be questioned, and I think I understand the confusion. In circuitry the transistor is typically "controlled" by applying a voltage to the base-emitter junction, if the base-emitter voltage is above approx. 0.7V the transistor is on. There is even an equation for collector current to base-emitter voltage, Ic=Is(exp(Vbe/Vt))
I agree, I was restating a commonly used concept, albeit wrong. Snafflekid 23:30, 8 October 2005 (UTC) However, the meaning I use is how the physics of the BJT work (maybe the least common way of discussing the BJT control). For an NPN, holes from the base are injected into the base-emitter depletion region, which controls electrons from the emitter getting injected into the depletion region, diffusing across the base and finally collected in the collector. In reality, the BJT is a charge controlled device, but that is confusing.
I suppose if there is a better way of getting my point across on transistor, let me know. Snafflekid 00:32, 8 October 2005 (UTC)
Okay, you asked for it! No mention of voltage-control or current-control, but a gobsmack pile of information. BTW I read the site and I've some comments about Mr. Beatys views...after I've enjoyed my wine. Snafflekid 03:57, 8 October 2005 (UTC)
I suppose I understand the spirit of his complaint, but really I don't see why he thinks every professor and text book doesn't know how a BJT works. (I think he did not do so well in his semiconductor physics course). If his explanation helps someone understand the BJT enough to be useful, well, great. But I don't agree with a lot of it.
"By applying a small voltage between Base and Emitter, we can make the thin layer of insulator become even thinner. If it's thin enough it stops insulating and charges flow across it. (Imagine bringing two wires closer and closer until the electrons start jumping across the microscopic gap.)"
First off, depletion regions are not insulators, at least not in any true sense of the word. Charges can flow through a depletion region, they cannot do that in an insulator. Also, electrons are not jumping across this thin gap. Free electrons in the N are created at room temperature, and they are always flowing randomly around, including into the abuting P where they happen to combine with the acceptor atoms and form fixed negative charges, when enough electrons have flowed into the P, the region develops enough negative charge to repel any more electrons which happen to randomly move towards it and we reach equilibrium.
Very often (very very often) forward voltage is applied to the base-emitter junction, which "lowers the barrier" allowing less energetic electrons (and holes) to move through the depletion region and enter the neutral region of the base (or emitter), where they form the current. So, it would be technically valid to call the BJT a voltage controlled device under these circumstances, but this is not the end of the story. The reason current flows across the junctions is because something upsets the balance of
diffusion and the repelling electric charge in the
depletion region. I explained how voltage can do it. But voltage is not the only thing that can control the bipolar transistor. Photons striking the base-emitter junction generate
electron-hole pairs, carriers which increase the number of carriers on a side of the junction, changing the diffusion constant and causing transistor action. Also, radiation particles can travel through the junction or nearby and create lots of electron-hole pairs, which can cause the B-E junction to conduct. Therefore, IMO it is the action of charge carriers moving across the B-E junction which causes current from Collector to Emitter. So, calling a BJT a voltage-controlled insulator is bunk, also IMO. A fundamental explanation of the BJT action uses charge as what controls the device.
Snafflekid
23:28, 8 October 2005 (UTC)
From this link [3] it seems to me that's what Bill Beaty says. The application of voltage is one way of getting the junction to conduct, but there are other mechanisms to get carriers into the base also which turn on the transistor and have nothing to do with lowering the barrier by using voltage (completely valid and useful mechanisms). Photons and radiation, I've mentioned. Even perhaps a magnetic field using the Hall effect could inject holes into the base. A carrier imbalance somewhere in the base or emitter is going to start the bipolar transistor action. Voltage is not guaranteed to make the transistor work. For instance, voltage could be applied to the B-E junction but if carriers are being robbed by some nearby process (highly contrived situation I know) then the transistor would not turn on. Maybe this discussion seems like splitting hairs, and probably is for a vast majority, but I just wanted to be clear why I think the carriers are the fundamental controller of the transistor. However, I doubt that declaring in the article the BJT as a carrier-controlled device is helpful. So I changed the article to what happens in the BJT and let people draw their own conclusion. Snafflekid 01:37, 9 October 2005 (UTC)
Have either of you 2 seen this [4] It does seem to cast some doubt on whether accelerating charges do in fact radiate!-- Light current 01:02, 6 October 2005 (UTC)-- Light current 01:16, 6 October 2005 (UTC)
It seems fairly clear to me. Have you read thro' it? The textbooks truncate the proper equation and therefore give the wrong answer. The correct answer is that the acceleration has to be cyclic (oscillation like SHM) for radiation to occur. Uniform acceleration does not produce radiation. If it did, then every piece of charged wire in the earths gravitational field would be radiating due to the accelerating charges!.-- Light current 03:22, 6 October 2005 (UTC)
No its not my intention to try to confuse anyone and I certainly dont want to mention GR in the article. Can AC use classical dynamics to solve his problem though - or must he use QED? He has not indicated his line of investigation to us as yet. However, this is really a side issue AFAIC. My main hobby horse at the moment is the importance of EM radiation inside charging and charged capacitors and TLs and whether this tells us anything about the nature of EM radiation, its generation and how EM rad relates (if it does at all) to steady (dc) voltage. The earlier posts on this page will give you a flavour of what AC and I have been discussing at length. When you say accelerating chages radiate, do you still maintain that they do under uniform (constant) acceleration?-- Light current 05:10, 6 October 2005 (UTC)
Probably doesnt have much to do with it at the moment. But how do you explain charged objects in the earths gravitational field. Do they radiate?-- Light current 04:33, 8 October 2005 (UTC)
Charges do not accelerate uniformly in a capacitor, you say? You may be correct. But what happens when the charges reach the edges of the plates? THey should then be accelerated non uniformly and radiate. Yes? :-)-- Light current 17:41, 8 October 2005 (UTC)
OK.Pfalstad. As I said this is not my main hobby horse and I think its a very difficult and controversial question that I'm not realy qualified to answer. So I think I'll leave it there. THanks for the discussion. I have just put the extract below if any other interested parties want to stretch their minds! But I dont think I'll be continuing this one.-- Light current 21:21, 8 October 2005 (UTC)
Heres an extract from mathpages [6] on the subject of radiation from accelerating charges. does it pose a paradox and call into question Larmour's formula?
One of the most familiar propositions of elementary classical electrodynamics is that "an accelerating charge radiates". In fact, the power (energy per time) of electromagnetic radiation emitted by a charged particle is often said to be strictly a function of the acceleration of that particle. However, if we accept the strong Equivalence Principle (i.e., the equivalence between gravity and acceleration), the simple idea that radiation is a function of acceleration becomes problematic, because in this context an object can be both stationary and accelerating. For example, a charged object at rest on the Earth's surface is stationary, and yet it's also subject to a (gravitational) acceleration of about 9.8 m/sec2. It seems safe to say (and it is evidently a matter of fact) that such an object does not radiate electromagnetic energy, at least from the point of view of co-stationary observers. If it did, we would have a perpetual source of free energy. Since the upward force holding the object in place at the Earth's surface does not act through any distance, the work done by this force is zero. Therefore, no energy is being put into the object, so if the object is radiating electromagnetic energy (and assuming the internal energy of the object remains constant) we have a violation of energy conservation.
-- Light current 17:21, 8 October 2005 (UTC)
Does a capacitor have a crystal structure? I've not heard of this one!-- Light current 03:17, 9 October 2005 (UTC)
No neither am I! A capacitor has not been redefined as a semiconductor has it? ;-)-- Light current 04:39, 9 October 2005 (UTC)
Hoe do LEDs work then? ;-)-- Light current 14:24, 9 October 2005 (UTC)
OK Case closed then (for now)!-- Light current 22:56, 9 October 2005 (UTC)
I dont want to break ur heart, but hasn't that got to do with the transition of outermost electron from higher orbital to lower? -- Davy Jones 08:02, 26 October 2005 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | → | Archive 5 |
I think any diagram is preferable to no diagram. To this extent, I think the package chosen should be one that is easiest to use as long as the o/p is reasonable and the program is free to use. THis will encourage people to draw a diag, when otherwise they would not bother. The examples of all output shown on project page all look perfectly OK to me.-- Light current 16:59, 22 September 2005 (UTC)
I think its essential to use conn dots on schematics. THose without them are so hard to understand, trying to find out if a wire is just crossing or is actually connected to another wire. So the package must support conn dots-- 88.109.39.70 17:06, 22 September 2005 (UTC)
When drawing resistors on paper I use the squigglies as I find it easier than drawing a rectangle. When using a CAD package I obviously use their symbols. I personally slightly prefer the squigglies but thats only because I was brought up using them. I think most packages now use rectangles for resistors and, to be honest, it does look less fussy. But I dont really mind. Current sources are usually shown as two interlinked circles with an arrow at the side denoting polarity. Voltage sorces are denoted as a single circle with an arrow at the side denoting polarity.(sharp end is positive). But diamonds are OK, its just I think circles are more standard.-- Light current 23:06, 22 September 2005 (UTC)
—
Omegatron
14:05, 23 September 2005 (UTC)
I dont like the German ones!! Lets stick with the US ones (maybe apart from resistors)-- Light current 14:15, 23 September 2005 (UTC)
I would like to revisit the topic of resistor symbols. I believe that the squiggly shape versions (as opposed the the boxes) are more intuitive and more in keeping with the ones we use for inductors. A mere box can represent anything unless you include a reference or value beside it.
Also, I'd like to suggest that we try to simplify our schematics by avoiding unnecessary power or ground connection rails, pin numbers, and adhere to a general left-to-right signal flow where possible. -- Hooperbloob 04:39, 10 October 2005 (UTC)
WikiProject Electronics or WikiProject Electricity?
Basically, how broad do we want it? — Omegatron 06:04, 23 September 2005 (UTC)
I don't think we need to worry about that for now. Remember one of the major criticisms of such a project was that we would spend all our time on bureaucracy and none on editing electronics content. :-) — Omegatron 01:37, 25 September 2005 (UTC)
Added a proposed statement of scope of project-- Light current 14:14, 23 September 2005 (UTC)
I think we can include telecomms biomedical electrical now as we have more members.-- Light current 07:49, 9 October 2005 (UTC)
Could we please change the template names so they start with 'electron' rather than 'electro'. The existing template may imply electr-omagnets, or electro-mechanaical, electro-chemical things etc. Electron is pretty obvoius to anyone.-- Light current 15:25, 23 September 2005 (UTC)
I have the original paper on 'Gaussian magnitude filters' by Milton Dishal and so I would be prepared to contribute a para or 2 on these filters if no one else wants to! Please let me know if you wish me to start on it.-- Light current 21:07, 24 September 2005 (UTC)
I want to get 'O's OK on this as I think he may have wanted to do this one himself! -- Light current 16:59, 25 September 2005 (UTC)
M. Dishal, 'Gaussian Response Filter Design', Elec. Commun., vol36, pp 3-26, 1959.-- Light current 00:43, 17 October 2005 (UTC)
In name of the wikiproject, I sent a private email to the only developer of xcircuit. He has been very nice: he replied to me very quickly and answered all my questions. We are still discussing about e few points, I´ll write what I learnt from the discussion in the xcircuit section of the project. I hope you don´t mind I remove the other two short comments, since the things I know replied to our doubts. I will keep you updated when I get more news. Alessio Damato 21:02, 26 September 2005 (UTC)
What is charge decay? Is it something to do with capacitors?-- Light current 01:02, 27 September 2005 (UTC)
Have a look at the links on this subject (charge decay) on the project page!-- Light current 07:27, 9 October 2005 (UTC)
Maybe this should be in an article an electrostatics if there is one. If not we create one!-- Light current 00:09, 30 September 2005 (UTC)
If I missed off the links when reformatting, apologies-- Light current 16:43, 29 September 2005 (UTC)
Sorry Ive just claimed Electrostatics as one of ours!!!-- Light current 00:44, 30 September 2005 (UTC)
I think Power factor correction could be touched up. I'm not sure if this is better under electricity or electronics, it is somewhat relevant to both. Snafflekid 21:13, 5 October 2005 (UTC)
Its very pleasing to see so much progress being made so quickly here. As the electrican once said "Many hands make light work"!-- Light current 00:07, 30 September 2005 (UTC)
Hi, since I have seen that this thing of the mindstretchers was quite interesting and successful, why don´t you start a "subsection" of the project just about it?? then, all the answers we get may be moved to a proper article. A possible choice might be Wikipedia:WikiProject_Electronics/Mindstretcher or something similar. - Alessio Damato 21:43, 30 September 2005 (UTC)
ok it´s up to you, then you´ll take care of it (just in case). Alessio Damato 20:34, 3 October 2005 (UTC)
Problems to keep you awake at night...(or send you to sleep!)
No1. Bearing in mind the pulse charged transmission line we discussed on Talk:capacitor, what is the difference between ordinary d.c and electromagnetic radiation. Is there any difference? If so what is it? (NB dc is defined here as that steady potential difference that might be observed across a charged transmission line or capacitor.) (This is NOT a trivial question). :-)-- Light current 23:01, 26 September 2005 (UTC)
No2. When is a physiscal inductor not an inductor? (ie what does it really behave like at high frequencies?).(Q. Difficult)
No3a What is an electron made of? (Quite fiendishly difficult)
No3b What happens when an electron gets 'excited'. Does it have anything to do with photons?
No4 Just what is a photon exactly? (not too difficult)
N06 What is the difference between a probability wave predicting the strength of a (standing wave) electric or magnetic field, and the actual magnitude of the same electric/magnetic field standing wave.? For instance, at antinodes the probability of finding some displacement is high. At the nodes, the probability of finding displacement is low.
No5 (Optional question). What is a virtual photon? Extra (virtual) marks for explaning this concept.
Sounds like a 'cop out' to me!! If they cant be detected how do we know they really exist?-- Light current 01:05, 30 September 2005 (UTC)
What causes the magnetic moment? If you say spin, I shall ask you exactly what spinning means!-- Light current 20:52, 30 September 2005 (UTC)
In QED, the electron is the quanta of a spinor valued field. You are probably familiar with a vector valued field, e.g., the vector potential and a scalar field, e.g., the scalar potential. If you rotate a vector around 360 degrees, you get the same vector. However, a spinor must be rotated by 720 degrees to get the same spinor. It is sometimes said that a spinor is the 'square root' of a vector. When Dirac set about to develop a quantum wave equation compatible with special relativity, he essentially took the square root of a quantum operator. The solutions to this equation are Dirac spinors which turn out to describe a spin-1/2 particle and its anti-particle such as the electron and positron. If one includes a magnetic field in the Dirac equation, the solution includes a term that, in the non-relativistic limit, corresponds to a particle with a magnetic moment. Thus it appears that the intrinsic angular momentum and the magnetic moment 'pop out' of the relativistic wave equation naturally. If I can think of some 'deeper' explanation later, I'll let you know. Alfred Centauri 01:25, 2 October 2005 (UTC)
A quantum wave equation results from replacing classical variables such as momentum and energy with quantum operators. Schrodinger's wave equation comes from the Newtonian energy-momentum relation. Dirac's equation and the Klein-Gordon equation come from the relativistic energy-momentum relation. Although the electron has angular momentum, it cannot be said that the electron rotates about an axis as that is a classical concept. The 'spin' of an electron has no classical analog. For example, if you attempt to calculate the magnetic moment from the angular momentum of the electron, you get half the value predicted by the Dirac equation. Further, one can only measure the total angular momentum and one component simultaneously due to the uncertainty principle. Lastly, a spinor should not be confused with spinning. A spinor is a geometric object that is defined by how its components transform under a coordinate transformation. As I said earlier, a spinor changes sign under a 360 degree rotation whereas a vector does not.
I don't know if this will help or not but recall that an electron in an atom has an orbital angular momentum associated with its 'orbit' around the nucleus of the atom. The problem is, the electron doesn't orbit the nucleus like the classical orbit of a planet around a star. The wave function of the electron in an atom is a spherical standing wave unlike a free electron where the wave function is a traveling wave. Take a look at the 'Picture of hydrogen orbitals' in the Hydrogen atom. These don't look like a classical particle revolving around a point of attraction yet there is an angular momentum associated with each orbital. Alfred Centauri 03:24, 2 October 2005 (UTC)
You do understand that the standing and traveling waves I refer to are related to probability density, right? I'm afraid I don't understand how that description lines up with the idea that electrons are made of EM waves. Alfred Centauri 13:27, 2 October 2005 (UTC)
The wave function is a complex valued function that represents the so-called probability amplitude. To get the probability density, one must take the product of the wave function with its complex conjugate. That is, the probability density function is the magnitude squared of the wave function. I don't know if this answers your question or not because I not quite sure what your question was! Alfred Centauri 17:54, 4 October 2005 (UTC)
That's not true, LC. The intrinsic angular momentum of a particle and the spin of a particle are one and the same. BTW, there is another, even more interesting (to me, at least), aspect of spin. Recall that the EM field is a vector field. A vector rotated is unchanged when rotated through 360 degrees. The photon, the quantum of the EM field is a spin 1 particle. A vector is a rank 1 tensor. In general relativity, the gravitiational field equations involve rank 2 tensors. A rank 2 tensor rotates twice as fast as a vector under a coordinate rotation. That is, a rank 2 tensor is unchanged by a rotation through 180 degrees. The graviton, the hypothetical quantum of the quantized gravitational field is thus a spin 2 particle. The Higgs boson is called a scalar particle for the reason that it has spin 0. That is, the Higgs field is a scalar field. Alfred Centauri 17:50, 4 October 2005 (UTC)
Update: Here's a link you might find interesting. But beware: this is crank material! [2]. Alfred Centauri 15:10, 2 October 2005 (UTC)
Answer: d) because it was written by a person displaying crank symptoms such as this little tidbit from Milo:
Just $19.95 in 3 easy payments! Alfred Centauri 18:40, 4 October 2005 (UTC)
Then, either I wasn't clear or you simply misunderstood me. QM and QED do not attempt to answer the question "what is an electron?" and I certainly didn't say that an electron is a standing probability wave. In QM, the possible states of a particle are completely determined by the wave function. When you solve for the wave function of an electron, you are solving for the possible states of the electron. Think of it this way, if you solve for the motion of a classical particle in a force field, you end up with function of time that gives the position of the particle. You would never think of claiming that the particle IS the position function, would you? Alfred Centauri 18:16, 4 October 2005 (UTC)
While I sympathize with your quest for the answer to your question, please consider this: if the electron is not fundamental - if the electron is made of something else - doesn't this lead to the question of 'what is that something else made of?". QED/QM are mathematical models ( Interpretation of quantum mechanics) for how things work at the subatomic and atomic level. A good mathematical model is immensely useful and I can't believe that you, as an engineer, don't understand this so I'll attribute your statements above to frustration. It could be that your question is ultimately unaswerable. It may be that what is fundamental in this universe - the stuff from which everything else follows - may be nothing. After all, 0 = 1 - 1. Alfred Centauri 01:43, 5 October 2005 (UTC)
Your statements above reveal to me that you have no idea how the Standard model was developed. Find yourself a copy of "The Second Creation" to get an idea of the struggle to develop this model. BTW, I'd be proud to be a physicist but I'm just a TV repairman. Alfred Centauri 20:44, 5 October 2005 (UTC)
You are quite correct about my knowledge of the standard model. Thats becuase:
A) It was discovered/developed/published after I finished my formal education
B) I did not study physics, but electronics engineering and did not keep up with physics after graduation.
C) I have forgotten most of what I did learn anyway!
BTW You are far too smart to be a TV repairman.;-)-- Light current 00:15, 6 October 2005 (UTC)
Follow up: I didn't address your last question in my response above. The magnitude squared of the wave function is the position probability density function. Alfred Centauri 22:51, 4 October 2005 (UTC)
Well, it is actually the probability that the something (whatever that is) will be measured or detected somewhere. The funny thing about QM is that it is not at all clear that the something exists at a definite location until it is detected somewhere ( Wavefunction collapse). What is that something? If I knew, I would have told you by now. Alfred Centauri 01:51, 5 October 2005 (UTC)
I'm sorry if I led you to believe that I know what the electron 'is' as I did not intend to, so the 'coming clean' stuff isn't really applicable. Look, I'm having trouble understanding what your issue here is. The electron, as a fundamental entity, exists. It has only a few intrinsic characteristics: mass, electric charge, flavour, spin, magnetic moment and maybe a couple of others that I can't think of at the moment. To the limits of our ability to discern, the electron is point like. By the rules of QM, we can in principle, given some initial information about an electron, determine the wave function for that electron and thereby calculate the probability of finding (detecting) that electron within some volume of space at a later time. When you ask what is it we are detecting, the answer is that 'thing' that has the mass, electric charge, flavour, spin, magnetic moment etc. that we attribute to an electron. That is how we identify an electron. We can measure these properties of a particle. If we detect something that has different values for these properties, it isn't an electron. Thus, I believe your question should not be 'what is an electron?'. Instead, I believe your questions should be 'what is electric charge? what is mass? what is spin? what is flavour?'. If you can unambiguously answer these question, then you will know 'what' an electron is. Alfred Centauri 23:47, 5 October 2005 (UTC)
I suggest we set aside the weak interactions for the moment. What Im interested in is how exactly electrons and photons interact. They seem to consist of essentially the same thing from what I gather (EM energy).-- Light current 10:49, 29 September 2005 (UTC)
OK but we all know that mass is only energy in another form. The origin of 'charge' is something else I would like to find out about-- Light current 00:42, 30 September 2005 (UTC)
So what else is inside an electron? -- Light current 00:42, 30 September 2005 (UTC)
So is an electron pure energy?-- Light current 23:31, 3 October 2005 (UTC)
Can we say that electrons are material particles no matter what while photons are material particles only in motion and are hypothetical at rest? -- Davy Jones 07:48, 26 October 2005 (UTC)
Well no. These questions were posed in order to stimulate discussion on various electronics/physics problems. If you look around her and esp Talk:capacitor you'll see what I mean.
I am finding that there is enough material to warrant both semiconductor and semiconductor device pages. The semiconductor page is very well written and did not need much work. And, it may be too academic for many people who are interested in components. With enough disambiguation and cross linking, the pages are becoming complementary.
I think that the transistor page could use some pruning with stuff being moved to semiconductor device. Snafflekid 01:13, 1 October 2005 (UTC)
I have released semiconductor and semiconductor device into the wild. Edit at will. I will give transistor some attention when I have time. Snafflekid 07:48, 1 October 2005 (UTC)
When I edited the transistor page, I changed the explanation of the BJT operation from a voltage controlled device to a current controlled device. I figured sooner or later it would be questioned, and I think I understand the confusion. In circuitry the transistor is typically "controlled" by applying a voltage to the base-emitter junction, if the base-emitter voltage is above approx. 0.7V the transistor is on. There is even an equation for collector current to base-emitter voltage, Ic=Is(exp(Vbe/Vt))
I agree, I was restating a commonly used concept, albeit wrong. Snafflekid 23:30, 8 October 2005 (UTC) However, the meaning I use is how the physics of the BJT work (maybe the least common way of discussing the BJT control). For an NPN, holes from the base are injected into the base-emitter depletion region, which controls electrons from the emitter getting injected into the depletion region, diffusing across the base and finally collected in the collector. In reality, the BJT is a charge controlled device, but that is confusing.
I suppose if there is a better way of getting my point across on transistor, let me know. Snafflekid 00:32, 8 October 2005 (UTC)
Okay, you asked for it! No mention of voltage-control or current-control, but a gobsmack pile of information. BTW I read the site and I've some comments about Mr. Beatys views...after I've enjoyed my wine. Snafflekid 03:57, 8 October 2005 (UTC)
I suppose I understand the spirit of his complaint, but really I don't see why he thinks every professor and text book doesn't know how a BJT works. (I think he did not do so well in his semiconductor physics course). If his explanation helps someone understand the BJT enough to be useful, well, great. But I don't agree with a lot of it.
"By applying a small voltage between Base and Emitter, we can make the thin layer of insulator become even thinner. If it's thin enough it stops insulating and charges flow across it. (Imagine bringing two wires closer and closer until the electrons start jumping across the microscopic gap.)"
First off, depletion regions are not insulators, at least not in any true sense of the word. Charges can flow through a depletion region, they cannot do that in an insulator. Also, electrons are not jumping across this thin gap. Free electrons in the N are created at room temperature, and they are always flowing randomly around, including into the abuting P where they happen to combine with the acceptor atoms and form fixed negative charges, when enough electrons have flowed into the P, the region develops enough negative charge to repel any more electrons which happen to randomly move towards it and we reach equilibrium.
Very often (very very often) forward voltage is applied to the base-emitter junction, which "lowers the barrier" allowing less energetic electrons (and holes) to move through the depletion region and enter the neutral region of the base (or emitter), where they form the current. So, it would be technically valid to call the BJT a voltage controlled device under these circumstances, but this is not the end of the story. The reason current flows across the junctions is because something upsets the balance of
diffusion and the repelling electric charge in the
depletion region. I explained how voltage can do it. But voltage is not the only thing that can control the bipolar transistor. Photons striking the base-emitter junction generate
electron-hole pairs, carriers which increase the number of carriers on a side of the junction, changing the diffusion constant and causing transistor action. Also, radiation particles can travel through the junction or nearby and create lots of electron-hole pairs, which can cause the B-E junction to conduct. Therefore, IMO it is the action of charge carriers moving across the B-E junction which causes current from Collector to Emitter. So, calling a BJT a voltage-controlled insulator is bunk, also IMO. A fundamental explanation of the BJT action uses charge as what controls the device.
Snafflekid
23:28, 8 October 2005 (UTC)
From this link [3] it seems to me that's what Bill Beaty says. The application of voltage is one way of getting the junction to conduct, but there are other mechanisms to get carriers into the base also which turn on the transistor and have nothing to do with lowering the barrier by using voltage (completely valid and useful mechanisms). Photons and radiation, I've mentioned. Even perhaps a magnetic field using the Hall effect could inject holes into the base. A carrier imbalance somewhere in the base or emitter is going to start the bipolar transistor action. Voltage is not guaranteed to make the transistor work. For instance, voltage could be applied to the B-E junction but if carriers are being robbed by some nearby process (highly contrived situation I know) then the transistor would not turn on. Maybe this discussion seems like splitting hairs, and probably is for a vast majority, but I just wanted to be clear why I think the carriers are the fundamental controller of the transistor. However, I doubt that declaring in the article the BJT as a carrier-controlled device is helpful. So I changed the article to what happens in the BJT and let people draw their own conclusion. Snafflekid 01:37, 9 October 2005 (UTC)
Have either of you 2 seen this [4] It does seem to cast some doubt on whether accelerating charges do in fact radiate!-- Light current 01:02, 6 October 2005 (UTC)-- Light current 01:16, 6 October 2005 (UTC)
It seems fairly clear to me. Have you read thro' it? The textbooks truncate the proper equation and therefore give the wrong answer. The correct answer is that the acceleration has to be cyclic (oscillation like SHM) for radiation to occur. Uniform acceleration does not produce radiation. If it did, then every piece of charged wire in the earths gravitational field would be radiating due to the accelerating charges!.-- Light current 03:22, 6 October 2005 (UTC)
No its not my intention to try to confuse anyone and I certainly dont want to mention GR in the article. Can AC use classical dynamics to solve his problem though - or must he use QED? He has not indicated his line of investigation to us as yet. However, this is really a side issue AFAIC. My main hobby horse at the moment is the importance of EM radiation inside charging and charged capacitors and TLs and whether this tells us anything about the nature of EM radiation, its generation and how EM rad relates (if it does at all) to steady (dc) voltage. The earlier posts on this page will give you a flavour of what AC and I have been discussing at length. When you say accelerating chages radiate, do you still maintain that they do under uniform (constant) acceleration?-- Light current 05:10, 6 October 2005 (UTC)
Probably doesnt have much to do with it at the moment. But how do you explain charged objects in the earths gravitational field. Do they radiate?-- Light current 04:33, 8 October 2005 (UTC)
Charges do not accelerate uniformly in a capacitor, you say? You may be correct. But what happens when the charges reach the edges of the plates? THey should then be accelerated non uniformly and radiate. Yes? :-)-- Light current 17:41, 8 October 2005 (UTC)
OK.Pfalstad. As I said this is not my main hobby horse and I think its a very difficult and controversial question that I'm not realy qualified to answer. So I think I'll leave it there. THanks for the discussion. I have just put the extract below if any other interested parties want to stretch their minds! But I dont think I'll be continuing this one.-- Light current 21:21, 8 October 2005 (UTC)
Heres an extract from mathpages [6] on the subject of radiation from accelerating charges. does it pose a paradox and call into question Larmour's formula?
One of the most familiar propositions of elementary classical electrodynamics is that "an accelerating charge radiates". In fact, the power (energy per time) of electromagnetic radiation emitted by a charged particle is often said to be strictly a function of the acceleration of that particle. However, if we accept the strong Equivalence Principle (i.e., the equivalence between gravity and acceleration), the simple idea that radiation is a function of acceleration becomes problematic, because in this context an object can be both stationary and accelerating. For example, a charged object at rest on the Earth's surface is stationary, and yet it's also subject to a (gravitational) acceleration of about 9.8 m/sec2. It seems safe to say (and it is evidently a matter of fact) that such an object does not radiate electromagnetic energy, at least from the point of view of co-stationary observers. If it did, we would have a perpetual source of free energy. Since the upward force holding the object in place at the Earth's surface does not act through any distance, the work done by this force is zero. Therefore, no energy is being put into the object, so if the object is radiating electromagnetic energy (and assuming the internal energy of the object remains constant) we have a violation of energy conservation.
-- Light current 17:21, 8 October 2005 (UTC)
Does a capacitor have a crystal structure? I've not heard of this one!-- Light current 03:17, 9 October 2005 (UTC)
No neither am I! A capacitor has not been redefined as a semiconductor has it? ;-)-- Light current 04:39, 9 October 2005 (UTC)
Hoe do LEDs work then? ;-)-- Light current 14:24, 9 October 2005 (UTC)
OK Case closed then (for now)!-- Light current 22:56, 9 October 2005 (UTC)
I dont want to break ur heart, but hasn't that got to do with the transition of outermost electron from higher orbital to lower? -- Davy Jones 08:02, 26 October 2005 (UTC)
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