Win Hill: Inverse Marx Generator ??
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From: John Larkin on 11 Jul 2010 11:26 On Sun, 11 Jul 2010 05:27:16 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Sat, 10 Jul 2010 18:13:29 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Sat, 10 Jul 2010 19:13:31 -0500, "Andrew" <anbyvbel(a)yahoo.com> >>wrote: >> >>>"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >>>news:c19h36hekre5kldo38cmdt465f5consr42(a)4ax.com... >>>> On Sat, 10 Jul 2010 11:31:15 -0500, Vladimir Vassilevsky >>>> <nospam(a)nowhere.com> wrote: >>>> >>>>>John Larkin wrote: >>>>> >>>>>> Exactly the point I've been making. Some EEs seem to think that charge >>>>>> is always conserved. Some physicists seem to think that energy is >>>>>> always conserved. They can't both be right. >>>>>> >>>>>> I'll side with the physicists on this one. >>>>> >>>>> >>>>>There is no physical laws of "conservation of ...". >>>>>There are, however, artificially designed parameters such as "energy", >>>>>"charge", "momentum", etc. Those parameters are *defined* in such way >>>>>that their value is preserved through certain transformations of a >>>>>physical system. The only purpose of this is simplification of math; so >>>>>it is possible to balance the states of a system instead of solving >>>>>differential equations. >>>>> >>>> >>>> But it's convenient to balance the books by calculating the total >>>> energy in a system and assuming it's constant. That can short-cut all >>>> sorts of circuit and signal processing problems, avoiding the calculus >>>> you suggest. I know of no cases where the energy balance thing has >>>> been violated. It would make the front page of the New York Times if >>>> it ever were. >>> >>>Every time it found to be violated new item was added to the definiton of >>>"energy" to make it constant. >>> >>>Last time it was mc^2 if I remember correctly. >> >>Well, that was over 100 years ago. And even that addition is >>irrelevant to electronic design. > >--- >Tell that to Tektronix. Do they still make CRTs? John
From: John Larkin on 11 Jul 2010 11:28 On Sun, 11 Jul 2010 09:28:52 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Sun, 11 Jul 2010 07:20:02 -0500, "Tim Williams" ><tmoranwms(a)charter.net> wrote: > >>"John Fields" <jfields(a)austininstruments.com> wrote in message news:3o7j36d5jvgeg5276nkr2t1fuibdmd6fij(a)4ax.com... >>> In your example the current will be one ampere when the resistor is >>> first connected, but will have decayed to about 368 mA after one >>> second has passed, so there's no way you'll get one ampere-second out >>> of it. >> >>Instead of clucking around, you could actually do some math. >> >>Definition: >>q_tot = integral I*dt from 0 to infty >>Equation: >>I(t) = (V/R) * exp(-t/RC) >> >>So: >>q = V/R * integral exp(-t/RC) dt from 0 to infty >>= [-RC * V/R * exp(-t/RC)] from 0 to infty >>= -VC * [exp(-infty/RC) - exp(0/RC)] >>= -VC * [0 - 1] >>= VC >>V = 1V and C = 1F so q = 1C. QED. >> >>This is only highschool calculus, how embarrassing. > >--- >Indeed, since: > >q_tot = integral I*dt from 0 to infty > >should read: > >q_tot = integral I*dt from 0 to t, > >I believe. ;) > > >From: > >http://www.thefreedictionary.com/ampere-second > >"ampere-second - a unit of electrical charge equal to the amount of >charge transferred by a current of 1 ampere in 1 second." > >So, for one coulomb of charge to be transferred through a one ohm >resistor in one second, the voltage would have to remain at one volt >for one second. > >Such is not the case when a one farad capacitor is charged to one volt >and connected across a 1 ohm resistor for one second, since the >voltage will decay from 1V to 0.368V during that time and there'll be: > > Q = CV = 1F * 0.368V = 0.368 coulomb > >still left in the cap when it's disconnected. Priceless! Thanks for the laugh! Isaac Newton had nothing on you. John
From: John Larkin on 11 Jul 2010 11:36 On Sun, 11 Jul 2010 08:14:39 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Sun, 11 Jul 2010 13:47:20 +0100, John Devereux ><john(a)devereux.me.uk> wrote: > >>John Fields <jfields(a)austininstruments.com> writes: >> >>> On Sat, 10 Jul 2010 10:13:27 -0700, John Larkin >>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>> >>>>OK, enlighten me. >>> >>> --- >>> OK. >>> --- >>> >>>>Slap a 1-ohm resistor across the 1F/1v cap and discharge it. You'll >>>>get 1 ampere-second out of it eventually. >>> >>> --- >>> Sorry, Charlie, but no. >>> >>> An ampere-second is the amount of charge transferred by a current of 1 >>> ampere in one second. >> >>That is, 1 coulomb. >> >>> >>> In your example the current will be one ampere when the resistor is >>> first connected, but will have decayed to about 368 mA after one >>> second has passed, so there's no way you'll get one ampere-second out >>> of it. >> >>What on earth are you talking about? This is pretty much the >>*definition* of capacitance. I.e., from Q = CV = "Ampere Seconds". >> >>No wonder John's having trouble convincing you of anything... > >--- >Not of anything, just of some things. > >About the ampere-seconds thing though: > >If you connect a 1VDC supply across a 1 ohm resistor for 1 second then >the amount of charge tranferred will be 1 coulomb. > >Then, since it got transferred in one second, the rate at which it was >tranferred was one coulomb per second, which is one ampere. > > >Now, replace the DC power supply with a capacitor charged to one volt, >connect it to the resistor, and then disconnect it after one second. > >Will one coulomb of charge have been transferred? Quoting myself, "Slap a 1-ohm resistor across the 1F/1v cap and discharge it. You'll get 1 ampere-second out of it eventually." How did you miss the words "discharge" and "eventually"? I worded the situation as carefully as I could, figuring some whiney dork or another would get pretend-lawyer pickey. Sigh. How many ampere-seconds would you get if it was discharged by a 10 ohm resistor? John
From: John Larkin on 11 Jul 2010 11:41 On Sun, 11 Jul 2010 01:54:56 -0400, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > >Vladimir Vassilevsky wrote: >> >> John Larkin wrote: >> >> > I'm an engineer. I design circuits. Philosophy is useless to me unless >> > it allows me to quantify and measure things and predict what the >> > numbers will mean. >> >> Yea, this is what good soldier Schweik used to say: >> >> "When a car runs out of gas, it stops. Even after been faced with this >> obvious fact, they dare to talk about momentum". > > > Really? You come to a dead stop the instant you run out of gas? I >coasted a little over seven miles one night, after the engine died. I >rolled to a stop about 50 feet from a gas pump. Of course, American >vehicles have a marvelous invention called a 'Clutch'. Seven miles? Downhill? John
From: John Larkin on 11 Jul 2010 11:42
On Sun, 11 Jul 2010 00:20:17 -0500, "George Jefferson" <phreon111(a)gmail.com> wrote: >> >> As an EE, I think that a 1F cap charged to 1 volt stores 1 coulomb of >> charge, namely because I can observe 1 ampere-second of integrated >> current if I connect its plates through a resistive conductor. You >> seem to be arguing that, since charge is always conserved, it still >> retains 1 coulomb of charge *after* I extract that 1 ampere-second. > >No, this is your confusion. CHARGE IS THE TOTAL CHARGE!! You are thinking of >electrons which is negative charge. CHARGE IS CONSERVED. Negative or >positive charge alone is not conserved. > >If I transport one electron from point A to point B then negative charge is >not conserved if I think of A or B as an "isolated system". A gained a >charge while B lost one. But the real isolated system contains both A and B >and hence the net charge did not change. > >CONSERVATION OF CHARGE IS NOT TRUE IN A NON-ISOLATED SYSTEM. You are >completely ignoring this fact which is why you look ignorant. > >FORGET CHARGE! Your arugment can equally apply to conservation of energy. >You want to think there is a difference but they are both conserved >quantities. You won't go against conservation of energy because you know it >would make you look like a troll. What you don't realize is that they are >completely analogous arguments and actually abstractly identical(due to >noethers theorem). > >You can surely "Transport" energy from point A to point B. Is energy then >conserved? By your argument no. Why? Because you are not thinking of A and B >as in the same system but separating them. > >Conservation does not deal with non-isolated systems. Why? Because by >definition non-isolated systems are those that do not conserve. > >Suppose you have some system and you find charge is not conserved... guess >what? Your system is not isolated and you need to expand it to find where >charge is. > >Suppose you have a black box. You measure the temperature in it. The >temperature changes. We know temperature is related to heat which is related >to energy. Hence we can see that some energy has changed in the black box. >Where did this energy go? IT HAD TO GO OUTSIDE THE BOX!!! Why? Because >energy is conserved and the only way it could change without going outside >the box is if it were created or destroyed. Hence the box is not an isolated >system. > >In fact, you can't argue against any conservation law because I can just say >your system is not closed. I could argue that every quantity is ultimately >conserved... one just needs to expant their system. (and if everything is >ultimately just energy and energy truely is conserved then everything is >conserved) > >Locally a quantity may change BUT there is an equal and opposite change >elsewhere that cancels it. THIS IS CONSERVATION. If you only look at one >spot then things will seem to violate the conservation law. But we don't say >it's not a conserved quantity because ALL quantities then are not >conserved(Since then they must be globally constant and then are useless). > > >STOP trying to use a local system to say that charge is not conserved. It is >ignorant at best. You don't seem to get that when we say something is >conserved we mean on a global scale(you have to look at it all). > >Even quantum mechanics doesn't necessarily violate this. It does allow for >violates of the conservation law for very short time periods BUT it is >possible that we have to enlarge our system to see that there really is no >violation. > >AGAIN, you can't just take some local part of a system and say "Oh, X is not >conserved". WHY? Because conservation is a property of X and not of the >system. Either X is a conserved quantity or not... independent of the >system. (it may not look conserved but it's beause your making it dependent >on the system when it should not be) > >"Energy is a conserved quanity!" Note that I did not say anything about the >system it uses. It may or may not be "conserved"(in your sense) in a local >system but it is always conserved(if the law is true which it seems to be) >in the largest system(the universe or whatever). For most cases we can >narrow down the system approximate the law for simplification. > >Basically if the system is quasi-isolated with respect to the quanity then >the conservation of the quanity is approximate true and vice versa. > >But to say that the quanity is not conserved in some non-isolated system is >simply wrong because it has nothing to do with non-isolated systems. > >> >> What if I bought it on ebay and, unknown to me, somebody once pushed 2 >> ampere-seconds into it, then discharged it. Does it retain 2 coulombs, >> since charge is always conserved? > > >Again, you can't see the forest because your focused on a single tree. This >is very basic and I'm supprised you can't get it(specially with your vast >intelligence). > >Who every charged it too charge from a some source, say A battery, so he >removed charge from the battery and stuck it a plate of the cap. THE NET >CHARGE IS 0. If you just look at the cap then of course the charge changed. >BUT THIS HAS NOTHING TO DO WITH CHARGE BEING A CONSERVED QUANITY. THE >CHARGED SIMPLY CHANGED! > >To say that it is not conserved because you look at a non-isolated system >and saw it change is just ridiculous. Your just saying the same thing twice. >Your saying because it changed it is not-conserved and because it is >not-conserved it changed. IT'S OBVIOUS IT CHANGED(on the cap)! We can >measure it. We can count the electrons on the plate. BUT WHERE DID THEY COME >FROM? OUT OF THIN AIR? If so then it is not a conserved quanity. > >But if we had an IQ > 50 then we would realize that the ebayer must have >added them and got them from somewhere and didn't create them using magic. > >All conversation means is that in the grand scheme of things the NET change >in something is 0. Charge(not electrons or protons/positrons BUT CHARGE >which is the total). > >Charge != Negative charge(electrons) nor Positive charge BUT THE SUM. > >Feynmen discusses the conservation of energy in his book. (Net)Charge is >analagous. If you think some charge was created or destroyed you simply are >not looking where it went. > >Q = Qe + Qp > >DQ/Dt = 0 > >If DQ/Dt != 0 then your system is not-isolated and you need to enarge it to >satisfy the equation > >if Dq/Dt = q then it means that there are charge(positive if q > 0 else >negative) leaving the system. > >But leaving where? just enarge your system and you'll eventually find that >DQ/Dt = 0. > >You seem to be thinking that charge = negative charge and that is simply not >true. > >"Electric charge is a physical property of matter which causes it to >experience a force when near other electrically charged matter. Electric >charge comes in two types, called positive and negative." > >http://en.wikipedia.org/wiki/Electric_charge > > >> >> I wonder if Jim will agree with you that a charged capacitor and a >> discharged capacitor both retain the same amount of charge. > > >Yes, he would... because he understands that charge = total charge = sum of >positive + negative charge. > >It's very easy to prove you are wrong. Suppose you had 1C of electrons on a >plate on a parallel cap. Do you realize the force that would create? > >Suppose you had two caps, you put 1C of "charge"(electrons) on each plate > > >C1 > | > | > --- +Q = 2C > > --- 0 > | > | > > >C2 > | > | > --- +Q = 2C > > --- 0 > | > | > > >Suppose you brought those caps near each other... lets say 1m > >then > >F = 1/(4*pi*e0)*4C^2/1 > >F != 10^48 N. > >You would not even be able to get them within 1m!!!!!!!!!!! > > >What is really going on? In a cap the net charge is virtually 0(only due to >static electricity could it possibly not be 0). > >Hence F ~= 0. > >Just another point where you are wrong. > >In the real world there is almost no net charge ANYWHERE in any local system >on any practical scale. (static electricity is really the only case I am >aware of) > > >> Do you actually design electronics? >> > >HAHA, Do you? By the looks of it you couldn't design a simple RC filter. Of >course maybe your good at copying other people's work but I'm sure you don't >have a clue how it actually works. > >Do you have anything you have designed yourself? Anything that actually >works and is useful? I doubt it... Even if you did I wouldn't buy it. > >I guess what you are saying is "I don't really know anything about science >but I can design electronics so I'm smarter than you"? > >No, I do not design "electronics" but I do create some electronic circuits. >I have no idea what it means to "design electronics". > > Obviously. John |