User talk:Alfred Centauri

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Welcome!

Hello, Alfred Centauri, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

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Contents

[edit] BJT Comment

Alfred , I see that you are removing my edits. My edits are valid. My link was in the external links section, so I was not referring to them as direct support to the claim that the bjt is voltage controlled. I referenced a professor at a recognised university that address this issue. If you have an academic reference that shows that the physics of a bjt is base current controlled, please cite it. The realty is that, “base current control” is simple false. There is no physical mechanism in a bjt that can make that idea work. Kevin aylward 15:22, 8 September 2007 (UTC)

I note your reply to my comments. With all due respect, it is not a matter of debate as to whether the voltage controlled view is the correct view. It is truly basic physics. Anyone that understands the actual physics, can come to no other conclusion. As I have noted, it is F=q(E + vxB). That is, it is forces that make things move. In this case it is electric fields. The charge in the base is due to the applied voltage.

Furthermore, the current controlled model is contradictory to that which is already on the BJT page, to wit, the ebbors-moll equations. These clearly show that the emitter current is a pure function of Vbe. There is no base current term involved, so how can the emitter current be possible caused by base current? Yes, the collector is modified by alpha, but as a first order approximation, it is unity, so equal to the emitter current, therefor base current is not a factor. So, to make the page internally consistent, the notion that the base current controls the collector current should be put to rest once and for all. It cant controll it if, to 1st order, it does not apear in the equations. This is trully obvious. Kevin aylward 16:14, 8 September 2007 (UTC)

[edit] Geodesics comment

Thank you for supporting at least some of my edits. The people who removed them seem to be practically vandals. I mean, for gosh sakes, if you have a mass bobbing up and down on a spring in a freshman lab it's not on a geodesic! My other item, also removed by the vandals or ostrogoths or people's great cultural revolution gave meaning to a spacelike geodesic. Do you see anything wrong with that part? Seems to me if you stretch a practically weightless fiber (maybe silk or catgut) over the shoulder of "The Thinker" and let it remain there, under tension, an instantaneous shot of it is a spacelike geodesic. But to define "instantaneous" you need clock synchronization over a "space section" which is why I threw in the stuff about the Killing vector.

It appears that Linas was thinking worldline when he read geodesic and he has since apologized for the revert. However, I must confess that I don't understand the spacelike geodesic stuff you wrote either as I am still a novice relativist. Let's see, the worldline of a free particle is a timelike geodesic. To 'see' a spacelike geodesic, would not the fiber above also need to be freely falling? Alfred Centauri 22:32, 7 Jun 2005 (UTC)


Not sure what to do - edit back what I had in or report vandalism as well. I don't know how to do a "revert" without mouse-copying and re-editing, do you? Pdn 15:36, 6 Jun 2005 (UTC)

Simply view your last edit, and then select edit, enter a comment that you are reverting and save. Alfred Centauri 22:32, 7 Jun 2005 (UTC)

Thanks, AC. I admit my material on spacelike geodesic was not very clear. I am trying to say, perhaps too mathematically, what "everybody knows" about geodesics in 3-space or even 2-space (like the surface of a spheroid e.g.) but it gets complicated exactly because of that timelike dimension. Maybe you can advise how to put it in simpler terms. Imagine you and a friend are making an old-fashioned toy telephone system across a street, as I did in 1949. You each have a stiff paper cup, and you get some cord that is very light and strong, and put it under tension between the two cups, across the street dividing your apartments. Imagine passing to a limit where the string is virtually massless (actually, the tension in it would interact with gravity, but let the mass ->0 faster than the tension, but the tension -> 0 also! ). That string, which I called a "filament" - confusing Linas - does indeed have a timelike aspect, too. Each particle composing it is moving into the future. So to the relativist it is a sheet and is not a candidate for a geodesic, which has to be a line. But if we synchronize clocks suitably and grab an instantaneous "snapshot" of that string, we have a spacelike geodesic. There are some further problems just below the surface here, however. Due to the rotation of the Earth, one has to synchronize the clocks from a central source, not by exchanging light signals between them, unless the string is oriented exactly North-South. In that case synchronizing to WWV for example, will agree with synchronizing by light signals. (If one goes East-West one runs into the Sagnac effect, and in fact even if North-South there is a small error due to the Earth's motion around the Sun). I am probably being too rigorous. The "problem" I refer to is the "snapshot" issue. If one does not make the assumption I mentioned about a Killing vector (see Killing vector field) one faces the difficulty that the "snapshot" is really a family of short segments, sort of like the fibers one can see in the feathers of a bird - they do not connect because one has not handled the simultaneity issue correctly. One can still construct a spacelike geodesic representing a slice through the sheet that is the string (as explained before), but one has to allow a tiny time variation along it by following those little feathery segments in a continuous way. I was trying to avoid time varying along the spacelike geodesic, but I am probably introducing too many caveats in trying to get a simple static entity (constant time slice). Maybe I can just say that a tightly stretched string taken at one instant is a spacelike geodesic and let the "user" worry about the meaning of "instant." But I have another problem in nomenclature: Linas found the term "filament" confusing. Now I do not want to use "string" because we have string theory nowadays, and ordinary household strings are heavy, and I do not want to use "fiber" because we have "fibre bundle topology" so I tried "filament". I just checked it in Merriam-Webster and it looks OK. And I used to fish with a "nylon filament leader" [[1]] so I am stumped. Seems like a light fibre or cord one could stretch quite a ways and get a good approximation to a space geodesic (remembering to use the snapshot idea rather than to follow the world-lines of each particle making up the filament).

I do hope you get the picture now (you may of course disagree). A tightly stretched filament is a collection of particles each of which has a timelike world-line. Orthogonal to that family of world lines, let's call it a "warp" (not a space-warp and hyperdrive, but a warp) one has a "woof" or weft . If the warp is the set of timelines, the weft lines are the spacelike geodesics (provided the filament or fibre is tightly stretched, and essentially massless). Pdn 01:45, 8 Jun 2005 (UTC)

[edit] Sympathy

My sympathy to you, now you know how I felt trying to explain the dreaded bootstrap cct to 'R'!! I wish I had not bothered. There are none so deaf as those who will not hear. Regards ;-)Light current 04:28, 16 August 2005 (UTC)

[edit] Comments requested

Hi again Alfred, I noticed you've had a lot of input on the operational amplifier talk page and wondered if you could comment on my recent musings on the internals on Talk:Operational amplifer.(funny, cant link to it properly) I am most interested to hear your views. Light current 13:09, 30 August 2005 (UTC)

[edit] Inductance Proposed change of defn

Alfred, I wonder if you could have a look at Talk:Inductance when you have some time. Im not happy with the existing defn. and have proposed an alternative which I think is more scientific/basic and doesnt need to mention inductors as such. The other things like Lenz law maybe could be kept to the other pages where they are mentioned. Also my proposal fits with the analogous defn of capacitance. What do you think? Please post any reply on Talk:Inductance page. THanks! Light current 14:49, 2 September 2005 (UTC)

[edit] Agreement

Alfred, I'm so glad we seem to have reached some sort of agreement on capacitance/inductance. I'm hoping to further integrate (bind together) these ideas and I would really value your help in my attempts. Once again , many thanks for your educated insight into these knotty questions!! Light current 23:57, 3 September 2005 (UTC)

[edit] Inductance Article

Alfred, I have spent some(a lot) time trying to simplify and segregate the topics in inductance, especially by splitting 'induced voltages in inductors' from 'applied voltages to inductors' thereby avoiding the confusion of signs and back emf and all that stuff. I would appreciate your comments on this severely modified page before I tidy into its final(?) form. THanks once more. Light current 07:42, 4 September 2005 (UTC)

[edit] Grounding

Yes ,I agree with you here. 'Ground' seems to be an American term. Over here we use the word 'Earth'. Again not all electronics systems have their reference connected to earth (although for safety reasons many do indirectly). I have always shown the reference on my circuit diagrams (schematics) as 0v. So: Anal 0v, Dig 0v etc. Then, if 0v is connected to chassis, show the connection to the chassis symbol. If the chassis needs to be 'earthed', then this is shown as a wire connected from chassis to the earth pin of the mains plug. I suppose the word 'common' is good too. I could live with that! But the 5v 'return' would normally be connected to 'common' wouldnt it? Light current 21:06, 4 September 2005 (UTC)

[edit] Current status

Thanks for letting me know what youre doing. My current status is reviewing pages for any new material/talk Light current 20:40, 5 September 2005 (UTC)

[edit] Very interesting page

Alfred, wondered if you had seen this [2] before. You may be interested

[edit] Has Electric flux actually been observed?

You say magnetic charge has not been observed, but magnetic flux has. Correct.

Now consider this: Electric charge has been observed. However, I would argue that, whilst we are all familiar with the concept, electric flux( ie flux meaning flow) is an imaginary concept that cannot be observed directly (same as magnetic charges cant). Is this any help in your thinking?? Light current 15:58, 6 September 2005 (UTC)

Well, that's not correct! Magnetic charge may exist but it has not been observed (yet). Further, if it does exist, it will be directly observable with, for example, a particle detector.
Now, contrast this with the question of observability of electric flux or any other field associated with EM. The answer may be suprising to you!
The magnetic flux has, in the absence of magnetic charge, zero divergence. Thus, it can be thought of as the curl of some other vector field we call the A field or vector potential. I once asked my EM professor whether the A field is physical or just a mathematical construct. His answer was "a mathematical construct". In other words, he claimed that the A field was not directly observable. However, I later found out that this isn't true. If you pass a current through a solenoidal inductor, the magnetic flux density B is zero outside the inductor. However, the A field can be non-zero outside the inductor as long as the curl of A outside the inductor is zero. This A field external to an energized solenoidal inductor has been observed by the effect it has on the phase of the wave function of electrons passing near but outside the inductor Aharonov-Bohm effect. Thus, it appears that A is the physical field and B is the mathematical construct!
It is likely the same for the scalar potential. That is, V is the physical (scalar) field and E is the mathematical construct. BTW, if magnetic charge does exist, then there should be an electric vector potential and a magnetic scalar potential too. Alfred Centauri 16:20, 6 September 2005 (UTC)

[edit] Your recent work

Although your recent work is extremely interesting and ,I think, important to the greater understanding of EM field theory, you probably wont be able to publish it on Wikipedia as recent/new work and self citing is not allowed. However, I feel that insights of this type are to useful to be 'hidden under the bed' and I wondered if Bill Beatty (to whose page I referred you) might be interested in your ideas. After all, his pages are full of unconventional ways of teaching people about 'electricity'. Just a thought! BTW Thanks for the tutorials! Light current 02:36, 7 September 2005 (UTC)

Yes, I would definitely encourage you to communicate your ideas to Bill. I think he will be most interested. Maybe he could even incorporate them on his pages!! Light current 17:18, 7 September 2005 (UTC)

[edit] New Discussion

Thought you may be interested in a new discussion just breaking on Talk:Capacitor ;-)--Light current 01:18, 11 September 2005 (UTC)

[edit] Look whose talking

Alfred, I think you have been talking to 'O' the past 30 mins. I havent been addessing you. I have just replied to 'O' on the talk page. Someone has not been signing his posts so it gets a bit dfficult to know whos who.--Light current 15:28, 12 September 2005 (UTC)

Hint: look at earlier posts again....(A friend!)

[edit] WikiProject Electronics

I am wondering if we should start a WikiProject for Electronics. What do you think? — Omegatron 00:21, 15 September 2005 (UTC)

The project was already started by another user, though I think we can consider it a prototype. You should bring up any concerns on the talk page. — Omegatron 13:41, 22 September 2005 (UTC)

[edit] Tom Bearden

Can I just ask you seriously what your view is on Tom Bearden. I had not heard of him till you mentioned him. I dont know if you were joking or not (I suspect you were) in your last post to David on Talk:Displacement current. Do you think he's a crank or what? Serious answer appreciated!--Light current 22:02, 16 September 2005 (UTC)

[edit] Order of replies

If you don't interrupt my replies with your replies, I will stop rearranging your replies. Deal?--Light current 21:47, 17 September 2005 (UTC)

[edit] Time for bed

look Alfred, as much as I enjoy these little chats of ours, I think its time for bed. BTW I dont mean ay offence to you. Lets just say were having a robust agrument and try to remain friends. What do you say?--Light current 01:06, 18 September 2005 (UTC)

[edit] Equivalent series resistance-- can AC look at it please?

Alfred, could you please have a quick look at this page when you have time.Equivalent series resistance. There seems to be some silly statements in it. Can you confirm/deny. THanks--Light current 04:40, 20 September 2005 (UTC)

[edit] Welcome!

Welcome Alfred to the Electronics project. I'm so glad you have decided to join us. I enjoy our little discussions so much! So, I'll probably see you over on WikiProject: electronics quite soon!--Light current 02:15, 24 September 2005 (UTC)

[edit] Is the DC voltage across an inductor zero?

Hi Alfred,

In your User page, under this question you first wrote, "In DC steady state, all circuit voltages and currents are constant." This is also the meaning I understand for the term "DC". That is, not just currents, but also voltages are constant in DC analysis.

You then say, "a constant (DC) voltage across an inductor can exist if the current through the inductor changes at a constant rate." and therefore "the answer [to the titular question] is no." But you've contradicted the definition of DC, which requires that all currents are constant. A current that changes at a constant rate is not constant; it is changing.

To say it another way, for a value (current) to be constant, its derivative must be zero. Therefore the definition of DC requires that all dv/dt and di/dt are zero. Therefore, from the inductor equation v = L(di/dt), we have v=L*0, v=0.

There is probably an analogy here to the question of whether current "flows" or whether current is a flow of charge.

--The Photon 02:31, 14 November 2005 (UTC)

Hi again,

You wrote (on UserTalk:The Photon):

There is not contradiction. You have equated DC steady state and DC which is incorrect. A circuit consisting of an inductor and a DC voltage source has no DC steady state solution yet the voltage across the inductor is constant (DC). Alfred Centauri 11:27, 14 November 2005 (UTC)

I suppose you are right. You have been very subtle about the terminology difference between "DC" and "DC steady state". Your solution is a time-varying solution to a circuit with only DC sources. (But I think it would be confusing to students to call it a DC circuit or DC solution).

Also when you said, "It is commonly said that an inductor is a 'short circuit at DC'", this implies you define "at DC" to mean "in a DC analysis." not "in a circuit with only DC sources." The statement "an inductor is a short at DC" is obviously not correct if "at DC" means "the sources are constant in the time period of interest" in a transient analysis.

I guess I accept that "at DC" means either "in a DC analysis" or "in the limit as t -> infinity in a transient analysis", or "in the limit as f -> 0 in an AC analysis". I haven't heard the term "at DC" used to mean "in a time-varying circuit with only DC sources."

If I took the perfect capacitor and perfect inductor, with nonzero i and v, as described in your page, and put them together to make an ideal lossless oscillator, would you still say the circuit is "at DC"?

--The Photon 17:17, 14 November 2005 (UTC)


[edit] Talk Ivor Catt

Alfred, you may be interested to learn that some idiot on that talk page is again claiming that all capacitors are TLs and that Ivor Catt was in fact totally correct in his 1978 Wireless World article!--Light current 17:21, 21 April 2006 (UTC)

[edit] My beliefs & Merry Xmas

I have changed my wholesale acceptance of Maxwell's equations now. I now believe that displacement current does not in fact exist as a flow of anything at all. Current does appear to be transferred from one plate to the other in a capacitor, but this is purely an effect of the em energy flow down the distributed (TL) structure. NB displacement current I of course admit in dielectrics- but not in vacuum.--Light current 07:23, 1 January 2006 (UTC) As far as em propagation in space is concerned, I believe no current (flow of anything at rt angles to direction of propagation) happens there either, but that the changing electric field creates (by an as yet unknown process) the required magnetic field and vice versa.

My reasonings are outlined on Talk:displacement current

Of course, it may turn out that Maxwell was correct all along, if the theory of vacuum polarisation can be proved. But until then, I think I'll stick with this explanation, which whilst probably not satisfying everyone, satisfies me at the moment. You may not agree with my view, but I would ask you to respect it. Merry Xmas!!--Light current 03:59, 25 December 2005 (UTC)

[edit] A favour

Alfred, I am doing some editing of education and training of electrical and electronics engineers and Im short of syllabus content (mainly final year stuff) for the power engineering/machines/heavy current stuff. Would you be able to oblige us with an up to date syllabus please? --Light current 07:08, 1 January 2006 (UTC)

[edit] Thanks (put other thanks here)

Thanks for the triva on PFM. That'll be a useful term in my major (hint, its your major ; ). Fresheneesz 20:21, 8 February 2006 (UTC)


[edit] Transformer

Alfred, do you know how transformers work - I mean really know how they work?. If so see Talk:Transformer. I think we could do with some insights! 8-)--Light current 01:14, 19 May 2006 (UTC)

[edit] E X H and transformers

Alfred, do transformers depend on Poynting vector for energy transfer? If so, how does it come into play? 8-)--Light current 01:04, 22 May 2006 (UTC)


[edit] Flux in a transformer core

Alfred I am trying to reopen discussion on the important topic of whether or not there is substantial flux (due to increased secondary loading,say) in the core of a transformer aside from the magnetising flux. I am basing my present thoughts on the interesting paper by Edwards and Saha and it seems to me that they are in fact saying something about core flux, but not explicitly stating the magnitude of flux in the actual core. I would value your educated comments if you have time at Talk:transformer. --Light current 13:45, 1 June 2006 (UTC)

[edit] Ground or common?

On your user page, you say:

The so-called 'ground' symbol is ubiquitous in virtually any schematic diagram. Yet, rarely is this node actually connected to 'ground'. Further, in many circuits, there is more than one 'ground', i.e., analog ground, digital ground, rf ground, etc. But technically, the term 'grounded' means connected to the Earth. If this node is not actually connected to ground, a more appropriate name might be 'common' or 'return', i.e., +5V return, analog common, etc.

Another commonly-used (sorry!) term is "reference", so "logic reference", "analog reference", and so on.

Atlant 13:56, 22 May 2006 (UTC)

[edit] Re: Clock synchronization question.

I have posted a response of my talk page. --EMS | Talk 21:15, 23 May 2006 (UTC)


[edit] Opinion needed

Alfred, do you know how magnetic guitar pickups work? I say they work on the variable reluctance principle, but many refs disagree. Even one supposed Univerity paper seems to say that the string must be 'magnetised' to work. Would you be able to spare some time to comment please at Talk:Pickup. THanks 8-)--Light current 18:43, 18 June 2006 (UTC)

[edit] Plato

http://en.wikipedia.org/wiki/Faraday%27s_law_of_induction
discussion
Please, have a look on "Plato".
Martin Segers (Belgium)
Tsi43318 07:03, 9 February 2007 (UTC)

[edit] Horsepower.

First, acceleration is not work and force over distance is not the definition of power (it is the definition of work) and second, while horsepower is important for top speed, it is torque that determines acceleration. Consider the case of an electric powered vehicle at rest. At the moment that the vehicle begins to accelerate, the horsepower generated by the motor (no matter how powerful it is) is exactly zero. Alfred Centauri 02:44, 2 March 2007 (UTC)

You are very incorrect, a running engine (or electric motor) will never have zero horsepower. Because of how hp is measured (hp = tq x rpm / 5252) any rotating object can produce power. If you spin a bowling ball like a top and try to stop it with your hands it will put force on your hands at a certain rate, that is work being performed and to perform work you must have power. So even at idle you can imagine how an engine is making power. The thought that force starts the vehicle off and power keeps it moving is wrong because there is power at the very instant that motor begins to move. So in your electric car example the moment the car would begin to accelerate the motor would have a measurable amount of power. Also the reason power is so important to the performance of a vehicle (and the main thing many people don't understand) is that if you have more power you can create more force at a given rpm. To make a quick example, if you have an engine that makes 400 hp @ 10,500 rpm with 200 lb-ft of torque and an engine that makes 400 hp @ 5,250 rpm with 400 lb-ft of torque they will both be able to provide the same amount of wheel torque at the same rpm thanks to gearing.
200 lb-ft @ 10,500 rpm geared 4:1 = 800 lb-ft at 2625 rpm
400 lb-ft @ 5,250 rpm geared 2:1 = 800 lb-ft at 2625 rpm
The text you removed is not a misconception at all, the statement "horsepower is important for top speed, it is torque that determines acceleration." is very incorrect and a very common misconception. IJB TA 10:25, 11 March 2007 (UTC)

Sorry, but your words demonstrate that you are very confused. You are using words like power *very loosely*. Let me give you an example. You said "because there is power at the very instant that motor begins to move". This is clearly wrong. At the instant the motor begins to turn, it is by definition not turning so the power is exactly zero. This is simply by the definition. But hey, don't take my word for it. **Do the math**. To make it simple, assume the motor produces a constant torque, say 100 lb-ft, from the moment the acceleration starts until the motor reaches 1000 rpm, 10 seconds later. Since the torque is constant, the angular acceleration is constant (assuming losses are minimal). Thus, the rpm is increasing at the rate of 100 rpm per second. So, here is the result:

   Torque = 100 lb-ft from t = 0 to 10 (seconds)
   HP = 100 lb-ft * 100 * t / 5252 = 1.9 * t hp
   t = 0, hp = 0
   t = 1, hp = 1.9
   t = 2, hp = 3.8
   t = 3, hp = 5.7
   ...
   t =10, hp = 19

Don't you see? The horsepower is increasing every second yet the *acceleration* is constant!!! The torque is constant and the acceleration is constant. The horsepower is steadily increasing but the acceleration is constant. Hmmmm... Seems pretty obvious to me which one is responsible for the acceleration. Of course, if losses are *not* minimal but are increasing with rpm, then the acceleration will not be constant but will be reduced as the speed ramps up. However, the result is the same.

Once again, (and this is basic physics - don't take my word for it, go look it up!) it takes (net) torque to change angular speed. This is the definition of torque. Forget any of the other things you have heard - without net torque, angular speed doesn't change. And, if angular speed doesn't change, there is no linear acceleration developed by the tires on the road. To change the angular speed from zero doesn't require any power, only torque. To maintain speed, requires power only if there are losses. For an automobile traveling down the highway at high speed, there are losses from air resistance, tire to road friction as well as mechanical losses in the drivetrain. Thus, to *maintain* this high speed requires power (and therefore torque) from the engine. But, to *increase* that speed rapidly requires far more torque than horsepower.

Consider the following problem that I would think is more applicable to your mind set. Let's say that a car weighing 3000lbs is moving at 60 mph and engine is turning 2000rpm. Let's say the wheels are rotating at half that, 1000rpm (this implies that the radius of the wheel/tire combo is about 10 inches (the diameter would be about 20 inches). The losses (air resistance, tire friction, internal friction, etc.) require that the engine produce 10hp in order to maintain that speed. Using your hp formula above, the torque produced by the engine is 26.26 lb-ft (10hp *5252/2000).

Now, let's say we want to accelerate this vehicle, at the rate of 10mph/per second. This means we need to increase the angular speed of the engine by 334 rpm per second or the wheel/tire rpm by 168rpm per second. Well, at the instant the acceleration starts, the engine is still turning 2000rpm but our torque is way up. In order to *accelerate* the car, we need to change the wheel/tire rpm by 168rpm per second, which requires and additional torque of 1385 lb-ft at the wheels or 692 lb-ft from the engine. That's in *addition* to the torque required to make up the losses at 60mph. So, take a look

To accelerate from 60mph at the rate of 10mph/sec we need:

   Torque = 719 lb-ft which is constant
   Acceleration = 10mph/sec (actually a poor assumption since the air resistance goes up as the square of the speed!) starting at t = 0
   t = -1, hp = 10
   t = 0, hp = 273
   t = 1, hp = 319
   t = 2, hp = 364
   etc...

So, there ya go. To get that acceleration, we're going to need that torque. Note that, once again, the hp is going up as time progresses but the acceleration is remaining constant. Hmmmm... Alfred Centauri 02:15, 12 March 2007 (UTC)

Yes I understand that it is wheel torque that determines the acceleration of a vehicle. The point is that in order to make more wheel torque you must make more power at the flywheel. That is why the statement "horsepower is important for top speed, it is torque that determines acceleration." is so very incorrect. A vehicle with more power will be able to accelerate faster than a vehicle with less power because it can provide a greater amount of force at the wheels. Power to weight ratio, hmmm...wonder why that came about instead of torque to weight ratio. IJB TA 02:36, 12 March 2007 (UTC)

No, to make more wheel torque requires more torque from the engine. You still don't 'get it' You are using the word power when you should actually be using torque. Please consult a physics text to learn the different. Or, try this for a second opinion: http://g-speed.com/pbh/torque-and-hp.html Alfred Centauri

You're forgetting the something VERY important, GEARS! Gears multiply torque. Again:
200 lb-ft @ 10,500 rpm geared 4:1 = 800 lb-ft at 2625 rpm
400 lb-ft @ 5,250 rpm geared 2:1 = 800 lb-ft at 2625 rpm
If you do the math you will notice both of those examples have 400 hp. IJB TA 02:52, 12 March 2007 (UTC)

I understand the principle of gears very well. In fact, a transmission is analogous to an electrical transformer where voltage is analogous to torque and current is analogous to rpm. And, in both cases, the product of the two must equal on each side (assuming ideal lossless components). When gears multiply torque, they simultaneously divide rpm so the power product is the same. Thus, to get maximum power to the wheels, we need maximum power from the engine, period. There can be no other way to see this. The power going in to the transmission is equal to or greater than the power going out. However, if we want maximum acceleration, we want maximum torque delivered to the wheels and the transmission can certainly multiply the torque for us but not the horsepower! Thus, if want the absolute maximum torque delivered to the wheels, we want the engine rpm at it's torque max to be reduced (usually) to the *current* rpm of the wheels. So, if we're going slow, we want a large ratio and if we're already going fast, a not so large ratio. Still, it is the max torque of the engine that determines the max acceleration. No way around that, I'm afraid. The max horsepower determines the max speed because, and again there is no way around this, the **transmission cannot increase the power delivered to the wheels**. Sure, if you want to be cute and stay in first gear then some other parameter will limit the speed.

Look, assume that the losses at some speed due to air resistance etc, exceed the maximum power output of the engine. Can the car go that fast continuously? Obviously, it cannot. What if the losses, exactly equal the maximum power output of the engine. Can the car go that fast continuously? The answer is yes if the gearing is correct. That is, when the engine is turning the rpm required for max power and that is reduced (usually) to the wheel rpm required for the speed at which losses match the max power, then all is good. If you reduce the hp output of the engine, that speed must now decrease. If the gearing isn't right, then the max speed will be lower because the engine power output will be lower at a different rpm. It's that simple. Alfred Centauri 03:28, 12 March 2007 (UTC)

[edit] Is the voltage across a short circuit always zero?

Hi, I stumbled across your user-page, and I couldn't help but comment on this.

Placing a perfect S/C across a perfect voltage source is indeed an indeterminate solution; it's the same idea as connecting two perfect voltage sources together with zero resistance in series, and then trying to analyse it to find the voltage. There is no limit process which would help define it; therefore there is no solution, i.e. the value of the voltage across the S/C does not exist. It wouldn't even help to simply pick a definition (as we can for e.g. 00), as it is a logically impossible scenario (see, for instance Irresistible force paradox).

Given that in all determinate scenarios, the voltage across a S/C is zero, and that in the indeterminate case, its value does not exist, it is safe to say that the voltage across a S/C is always zero.

Also, I'm not sure why you have a problem with the definitions "zero resistance path" and "always having zero volts across it" being equivalent. You say that "a short circuit is not at all like a zero ohm resistor but is instead, an ideal voltage source where the voltage is exactly zero", but this is no different to a voltage source being equivalent to that voltage source in series with a zero-ohm resistor, or a resistor being equivalent to that resistor in series with a zero-voltage source, etc.

Oli Filth 21:20, 23 April 2007 (UTC)

On my talk page, you replied:

"This may seem like hocus pocus but consider a well known derivation of the area under the unit impulse using a pulse of width X and height of 1/X. In the limit as X goes to zero, we have a finite area given by the product of 0 with infinity."

We don't, at least, not in the sense we can somehow derive this fact. We merely define it to be so. And even then, there is no meaningful answer to the question "what is the value of δ(x) at x = 0?". We can only use the definition in things like convolution integrals.

"So, if I for the product of R * I to be V (by putting a V volt voltage source across the resistor) and then let R go to zero, I goes to infinity and the product of R * I remains V!"

What you are saying is equivalent to saying that there is a meaningful solution (or useful definition) to 1 / x at x = 0, which can be derived from a limit process. But there isn't, not least because there are two confliciting limit processes (\lim_{x->0^+} and \lim_{x->0^-}). Sure, we could simply assign a definition to the expression (e.g. by choosing to work on a projective geometry), but what use would it be? e.g. we're told that I = \infty and R = 0, so V = ???.

"I hope you understand that my nitpickery is not intended to be a rant in any way but is instead meant to stimulate a conversation among EEs having a beer or three."

No worries! I don't have a lot to do this evening, so I'm trawling Wikipedia for mental stimulation. Oli Filth 22:55, 23 April 2007 (UTC)

[edit] Objection to deletions

[edit] Distortion measurement

I have added a "{{prod}}" template to the article Distortion measurement, suggesting that it be deleted according to the proposed deletion process. All contributions are appreciated, but I don't believe it satisfies Wikipedia's criteria for inclusion, and I've explained why in the deletion notice (see also "What Wikipedia is not" and Wikipedia's deletion policy). You may contest the proposed deletion by removing the {{dated prod}} notice, but please explain why you disagree with the proposed deletion in your edit summary or on its talk page. Also, please consider improving the article to address the issues raised. Even though removing the deletion notice will prevent deletion through the proposed deletion process, the article may still be deleted if it matches any of the speedy deletion criteria or it can be sent to Articles for Deletion, where it may be deleted if consensus to delete is reached. Alfred Centauri 03:28, 17 April 2007 (UTC)

  • I object to these deletions being made so quickly during a period when I was away from Wikipedia. I now have no way of seeing why this was so. It seems quite wrong to me that there should now be no page on 'colouration' where I had created one - it's a perfectly valid word with a well understood meaning.

Is there a way that I can see the two pages now as they existed? --Lindosland 13:45, 8 May 2007 (UTC)

[edit] Suggested changes to Electrical impedance

Hi there Alfred Centauri, I am interested in making some changes to the article on impedance and noticed that you have been an active editor for a long time. I have explained my thoughts on the talk page, including a link to my user subpage where i'm trying out ideas.

The reason why i'm not immediately editing the article is that i'd like to make some wholesale changes, so I feel it's worth getting input from others before going ahead. Feel free to reply here, on the article talk page or on my talk page.

Thanks,

--DJIndica 00:18, 27 May 2007 (UTC)

[edit] magnetic field comment

Starwed, please reconsider posting comments in the middle of another comment. Thanks. Alfred Centauri 14:00, 11 July 2007 (UTC)

Not something I normally like to do, but quoting specific points in order to directly respond to them would have bloated the talk page length even further. :( Looking back, I guess it makes it hard to read anon's comments as a whole, though, so I'll avoid this in the future..--Starwed 17:41, 11 July 2007 (UTC)

[edit] Archiving Magnetic Field talk page

Get ready for a lengthy rant about an Orwellian cabal of fanatics dropping any traces of dissent down the memory hole.  ;-) Pfalstad 15:40, 18 July 2007 (UTC)

[edit] Objectivism RFC

Hi,

To let you know, I'm moving your comment in the above section of the talk page to where mine and the other guy's are - the comment section is for the person answering the request for comments, not us. WLU 16:42, 14 August 2007 (UTC)

To qualify, I'm 99% sure that the comment section is for the third party, based on the RFC instruction page. If you find on that page that I'm incorrect, feel free to move it back, but please drop me a line on my talk page so I won't repeat my mistake in the future. Thanks! WLU 16:44, 14 August 2007 (UTC)
My feeling is the RFC should come from someone completely removed from the article and all previous discussions. I don't know if the RFC page backs me up, but we'll see what the commentor says. WLU 17:22, 14 August 2007 (UTC)
That's cool, thanks for the line. WLU 21:05, 14 August 2007 (UTC)


[edit] Wikiswarm

A tag has been placed on Wikiswarm, requesting that it be speedily deleted from Wikipedia. This has been done for the following reason:

Non-verified neologism

Under the criteria for speedy deletion, articles that do not meet very basic Wikipedia criteria may be deleted at any time. Please see the guidelines for what is generally accepted as an appropriate article, and if you can indicate why the subject of this article is appropriate, you may contest the tagging. To do this, add {{hangon}} on the top of the page and leave a note on the article's talk page explaining your position. Please do not remove the speedy deletion tag yourself, but don't hesitate to add information to the article that would confirm its subject's notability under the guidelines.

For guidelines on specific types of articles, you may want to check out our criteria for biographies, for web sites, for bands, or for companies. Feel free to leave a note on my talk page if you have any questions about this. WebHamster 23:09, 21 August 2007 (UTC)


[edit] Image copyright problem with Image:7points-in-plane.JPG

Image Copyright problem

Thank you for uploading Image:7points-in-plane.JPG. However, it currently is missing information on its copyright status. Wikipedia takes copyright very seriously. It may be deleted soon, unless we can determine the license and the source of the image. If you know this information, then you can add a copyright tag to the image description page.

If you have any questions, please feel free to ask them at the media copyright questions page. Thanks again for your cooperation. NOTE: once you correct this, please remove the tag from the image's page. STBotI 00:12, 24 August 2007 (UTC)

[edit] Plagarism at How a transistor works

Thank's for the heads up. If someone likes my writing, they should link to it rather than copying its content to WP! BTW, I've given up on WP myself. The presence of huge numbers of anonymous trolls isn't worth the aggravation. A wikipedia with real people and no anonymous authors? Where good or bad behavior remains forever connected to the perpetrator? Now THAT would be something amazing and wonderful. --Wjbeaty 18:59, 9 September 2007 (UTC)

[edit] WikiProject Relativity

I've decided to introduce Wikipedia:WikiProject Relativity as a subproject of Wikipedia:WikiProject Physics. In particular, I'd like to bring your attention to the 'Missing articles' section which people can get their teeth into. Hope all's well. MP (talk•contribs) 13:57, 24 October 2007 (UTC)

[edit] Rand Anon IP RfC

Looking at the dispute resolution protocol, I've made an RfC regarding one of the anon IPs who's trolling this article. Since you've been involved in a dispute with this person please certify it and post your observations here [3]. Idag (talk) 06:09, 6 May 2008 (UTC)


[edit] An invitation to Circuit idea wikibook

Dear Alfred, a year ago you suggested me to begin exposing my ideas in a form of a wikibook. Then I followed your advice; as a result, Circuit idea wikibook has appeared. I have started it with the purpose to reveal once and for all the true, pure and real fundamental ideas behind circuits. Now (in acknowledgement of your wise advice:), I would like to suggest you to join Circuit idea.

Of course, everyone can contribute this wikibook; only, I would like the contributors to be creative people that can say something new and original. For example, you can join the "physical" stories about time-dependent circuits: capacitors, inductors (I have noted your original thoughts about these components) and circuits containing both of them - e.g., LC tank. Also, what is even more interesting, you might contribute the introductory methodological pages. Finally, what is maybe the most interesting for you as a university teacher, you might join my last "open student wiki project".

I decided to join my students to Circuit idea a half month ago somehow "in sport"; but it turned out so successful and exciting that now I am entirely absorbed in this new web undertaking. I have told how it has begun in the discussion of the first completely finished page that my students and I have dedicated to the famous Ohm's experiment. After I saw the rapturous reactions of my students I realized the potentialities of this approach and began enlarging this educational experiment. For this purpose, I have created separate pages of all the ten student groups (64a, 65a, 66a, 67a, 68a, 64b, 65b, 66b, 67b and 68b). In these group pages, my students and I, all together, have been placing what we have done in the laboratory and the lecture hall - photos, drawings, texts, etc. During labs and lectures I record our conversations and discussions by a small solid-state recorder and make snaps by a digital camera; some students do the same. The photos show drafts on the whiteboard, screen shots, laboratory setups, the very students (and sometimes, their teacher:), etc. On returning at home I download the records and pictures to my computer and begin processing them. In order to help students, I outline briefly the structure of the future modules in the student and talk pages; then I place all the raw materials (pictures) in the pages. I add also links to useful resources and some provoking questions. Then I leave students to go on developing the stories; I only intervene in their works from time to time to edit and refine them. Finally, I expand student works by adding more explanations and use these materials to create the according modules. You can see how I have placed (on the right) links in the list of started circuit stories pointing to the corresponding student pages.

Alfred, you can imagine how powerful this approach is where students and their teacher, all together, work on the same common project! They add, edit and continuously refine it; they learn how to present what they have done to other, how to contribute a wiki project, how to communicate with people, etc. Furthermore, any web visitors (including other students and their teachers) through the world can join and enrich this open project! It is just wonderful! I have started a concrete page where to tell how I have joined students from Technical University of Sofia to wikibooks. Also, I have prepared a link to a more general story about joining students; we might discuss this idea in the talk page. Regards, Circuit-fantasist (talk) 07:38, 6 May 2008 (UTC)

[edit] Invitation

WikiProject Objectivism
Salutations, Alfred Centauri. I notice you were once a participant in the inactive WikiProject Objectivism and I am excited to inform you that I have resuscitated the project. I was not active in the original project, so your experience and ideas would be most valuable. If you're interested in taking part, please consider changing your inactive status in the list of participants and joining the discussion on the talkpage.

Yours in enlightened self-interest, Skomorokh 00:52, 15 June 2008 (UTC)
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