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#1
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Oops, I stand corrected -- thanks, Frank. Once again I read too hastily.
A *mass*/spring combination mimics an inductor/capacitor, of course. A damper adds resistance. So a spring/damper combination would act more like an RC or RL circuit, but with a little stray L or C from the spring's mass. Hope I don't have to give up my new title. Titles really impress folks in some parts of the world. Roy Lewallen, W7EL, ROW, ASI, OFC Frank wrote: Of course, I should have mentioned a mass/spring/damper (equivalent to capacitor/inductor/resistor), not just spring/damper. I think the only physical system that can not be entirely modeled as an electrical analog is a thermal system; which has no inductor equivalent. Frank |
#2
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"Roy Lewallen" wrote in message
... Oops, I stand corrected -- thanks, Frank. Once again I read too hastily. A *mass*/spring combination mimics an inductor/capacitor, of course. A damper adds resistance. So a spring/damper combination would act more like an RC or RL circuit, but with a little stray L or C from the spring's mass. Hope I don't have to give up my new title. Titles really impress folks in some parts of the world. Roy Lewallen, W7EL, ROW, ASI, OFC No problem Roy. To be exact a mass is equivalent to a capacitor. As in Newton's 2nd law: f = m*dv/dt, and its electrical analog i = c*dv/dt, where "v" refers to velocity in the mechanical case, and voltage in the electrical. I think this qualifies me to place the letters "ASI" after my name. Well; I must admit I took a quick look at my physical systems text book, so hope it does not disqualify me. Frank Meredith ASI |
#3
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My EE students, noting that the characteristic equations are the same,
regularly convert mechanical problems (of the mass-spring-damper type) into electrical problems, solve, and then convert back to mechanical answers. Some ME students catch on and some just do not get it. Of course, it helps if one is using SI units all round. I continue to be in awe of MEs who always seem to know whether the "pounds" they are talking of are sort-of-like mass, or sort-of-like force, or money. I have even had it suggested that energy and power are sort-of the same thing. I am keen on Roy being the collector of titles. I have quite enough for a lifetime. 73 Mac N8TT etc. -- J. Mc Laughlin; Michigan U.S.A. Home: "Roy Lewallen" wrote in message ... Oops, I stand corrected -- thanks, Frank. Once again I read too hastily. A *mass*/spring combination mimics an inductor/capacitor, of course. A damper adds resistance. So a spring/damper combination would act more like an RC or RL circuit, but with a little stray L or C from the spring's mass. Hope I don't have to give up my new title. Titles really impress folks in some parts of the world. Roy Lewallen, W7EL, ROW, ASI, OFC |
#4
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Roy Lewallen wrote:
Spike wrote: Can this be the same idiot who thought that a spring/damper combination was the mechanical equivalent of a coil and capacitor, on the grounds that they both exhibited resonance? from Aero Spike I'm that idiot. Actually, one of the very many. The equations for the two systems are identical. Roy Lewallen, W7EL, ROW, ASI (Reg's Old Wife and now Aero Spike's Idiot. The titles just keep accumulating. Of course I'm also a proud member of the OFC.) Posting under the sock-puppet "Airy R. Bean", he said the following quoted below, and to which I was referring. I leave it to you to spot the glaring error. I very much doubt you said anything like this. The original message was posted in sci.physics at 9:53 am on 21st January this year. "Reactance is characterised by the storage of energy. In the case of the capacitor, you might think that your AC source is the only voltage source in your circuit, but after the first 1/4 cycle, the capacitor acts as a voltage source and starts to give back the energy that it has stored. The combined result of the two voltage sources, your AC excitation and the capacitor itself, accounts for the out-of-phase current waveform. (This bothered me for years! How could the current be non-zero if the AC driving voltage was zero?!) The same analogy applies to springs and to shock absorbers; the spring stores energy when stretched; the shock-absorber stores energy when compressed. Both the spring and shock absorber will return energy at some time and this exhibit reactance!" from Aero Spike |
#5
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I have always used the CFA as a mobile antenna!
Get with the program people, you will be hard pressed to find a better antenna for this purpose! As a shack antenna, it sucks! However, what other antenna can you chuck a motor into, slap a steering wheel and horn on and drive? You guys are all wet, as usual... satisfied-smirk John "Polymath" wrote in message ... Actually, just did a quick webbing and found enough to realise that the claims are founded upon feet of clay..... 1. You do not separately excite the E and H fields because if you excite an E field, you get a corresponding H field, and vice-versa, even if it is your intention to excite separately. 2. The differential forms of Maxwell describe the fields at _EVERY_ infinitesimal point and there is no way that the attempt to excite two separate fields from two separate mechanical contrivances will result in registration at every single point. Indeed, it is doubtful that registration will be achieved at all at any infinitesimal point. In any case, as in (1) above, your E field will have its H, and your H field will have its E field already. 3. In the accepted equations describing the generated field, radiation comes only from accelerating charges. Thus the capacitive elements of the CFA will create the near field (decaying as 1/(r^2)) but not any radiated field (decaying as 1/r). I wonder if the measurements resulting in the claims for the CFA were made in the near field? I wonder if the whole thing is intended as an elaborate hoax, and that the authors, in their original paper in Wireless World, relied on the fact that most readers' eyes would glaze over when faced with the maths of vector fields? (Remember, that in this NG we've had someone who boasts of two degrees, one in maths and the other in electronics, stating that e^(-jwt) is a function that decreases with increasing time, thus indicating that the awarding of a degree together with the professing of mathematical equations is no guarantee of competence!) I suggest http://farside.ph.utexas.edu/teachin...es/node53.html etc as a good revising/learning/debunking cookbook. (Don't start from node 53!) "Polymath" wrote in message ... I've just about got enough elec-and-mag theory to be able to understand the claims made for the GM3HAT CFA; any pointers to the patent claims? |
#6
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On Fri, 22 Jul 2005 13:53:42 -0700, "John Smith"
Gave us: You guys are all wet, as usual... satisfied-smirk I suppose then that you consider yourself to be firmly grounded in reality. |
#7
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Firmly grounded?
Actually, when I am finished installing the mercedes turbo-jet engine in the CFA, I plan on flying it!--well, after installing the carbon graphite wings... John "NunYa Bidness" wrote in message ... On Fri, 22 Jul 2005 13:53:42 -0700, "John Smith" Gave us: You guys are all wet, as usual... satisfied-smirk I suppose then that you consider yourself to be firmly grounded in reality. |
#8
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On Sat, 23 Jul 2005 05:24:20 -0700, "John Smith"
Gave us: Firmly grounded? Yes. You made an all wet joke. I made an electrical joke that you should have gotten. Actually, when I am finished installing the mercedes turbo-jet engine in the CFA, I plan on flying it!--well, after installing the carbon graphite wings... Perhaps you did. Top posting is very bad. |
#9
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OK.
It is like this, years ago, in the 1980's, when telnet was still being used on the predecessors of newsgroups, there was no way to logically organize "posts." Still, into the 90's, most all "news clients" lacked any meaningful way to organize threads and/or posts. At the end of the 90's a few news clients managed to "get-it-together" and organize threads and posts with pretty good results. Now it is 2005. Windows xp comes with a completely functional news reader which holds threads and posts in perfect order--no longer do I have to have the text being responded to placed above the text which is being issued in response. Still, many ancient news readers are in use, and the users have not bothered to upgrade them. Also, many are reading these posts from webpages... That is all their responsibility now, if they are unwilling or unable to setup a decent news reader and come up to speed, that is their problem--there is NO longer a real need to bottom post, indeed, it only slows down ones interaction with the group and places an un-necessary burden to be cutting and pruning text... .... the etiquette and use manuals of usenet need upgrading ... I will be top posting... end of story... John "NunYa Bidness" wrote in message ... On Sat, 23 Jul 2005 05:24:20 -0700, "John Smith" Gave us: Firmly grounded? Yes. You made an all wet joke. I made an electrical joke that you should have gotten. Actually, when I am finished installing the mercedes turbo-jet engine in the CFA, I plan on flying it!--well, after installing the carbon graphite wings... Perhaps you did. Top posting is very bad. |
#10
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oh yeah...
It is a half-wave CFA. No ground plane/counterpoise is needed... I live in calif, who worries about lightning here... grin John "NunYa Bidness" wrote in message ... On Sat, 23 Jul 2005 05:24:20 -0700, "John Smith" Gave us: Firmly grounded? Yes. You made an all wet joke. I made an electrical joke that you should have gotten. Actually, when I am finished installing the mercedes turbo-jet engine in the CFA, I plan on flying it!--well, after installing the carbon graphite wings... Perhaps you did. Top posting is very bad. |
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