What is your EM crankosity?
in [Relativity]
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From: Bill Miller on 24 Sep 2009 10:27 "Androcles" <Headmaster(a)Hogwarts.physics_o> wrote in message news:mVzum.166987$4f4.41974(a)newsfe11.ams2... > <snip> > Nobody ever taught me the voltage across a capacitor in an RC > network can *never* exceed the supply voltage, even if some American > idiot taught you that. > Let me see if I understand. You seem to be saying either, 1. Someone taught you that the voltage across a capacitor *can* exceed the supply voltage. In that case, I applaud the perspicacity of your instructor. But my experience in the USA, Canada, UK, Latin America, France Germany, Italy, Australia, HK and Japan (areas where I have interacted professionally with physicists & engineers) has led me to generalize that everyone worldwide is taught the same, erroneous pap that I learned from the "idiots" at UC Berkeley. OR 2. You have never recived instruction in the performance of RC circuits. If the answer is (1) then I would appreciate information as to how you might have learned this. (I am not challenging your education. I am just *very* surprised that you seem to know about this subtle characteristic of "capacitors.") If the answer is (2) then I do not care what your opinion is. All the best, Bill
From: Bill Miller on 24 Sep 2009 10:59 "John Kennaugh" <JKNG(a)notworking.freeserve.co.uk> wrote in message news:zhAKieLq6suKFwmn(a)kennaugh2435hex.freeserve.co.uk... <snip> >>Both of the above can be shown to be false for specific capacitor >>configurations. And they are easy (and kinda fun) to model in SPICE. > > Have you come across a thing called a 'time domain reflectometer'. We > found out a lot using that in the 70s when emitter coupled logic was in > its infancy. It gives an incredibly sharp edge and then displays all the > reflections along the route it is propagating along. It allows you to > check how constant the impedance of a transmission line is, how good a > connector is and what sort of capacitors are best at absorbing high > frequencies as in de-coupling - not necessarily the ones you might think. > At high frequency a supply track is inductive and a good high frequency > capacitor is liable to 'tune' it while a lossey capacitor will absorb the > energy. That was before multi-layer boards. Now you can have a nice > 'supply plain'. > > John Kennaugh Initially, I calculated the performance using Catt's concept. Then an associate that runs SPICE better than I put together a model. Finally confirmed with TDR. And TDR is really useful for figuring out what anomalies exist and where they are located. Kinda neat when you find a small solder blob exactly where the TDR said something bad was happening. Bill
From: Bill Miller on 24 Sep 2009 11:31 "Androcles" <Headmaster(a)Hogwarts.physics_o> wrote in message news:mVzum.166988$4f4.148206(a)newsfe11.ams2... > >> Bill > > I understand the janitor was fired for mopping the toilet bowl with > a burger bun and then ate the evidence with fries, ketchup and a > healthy dose of salt. It wasn't his lunch break so he had to be > dismissed. Fantastic! Maybe there is hope for me. And for Benj. Benj told me that his boss, the janitor, was a goof-off that didn't understand EM. Now that he's gone, maybe Benj will be promoted to janitor and I can get his OLD job!
From: Androcles on 24 Sep 2009 11:22 "Jonah Thomas" <jethomas5(a)gmail.com> wrote in message news:20090924101139.7158f4c9.jethomas5(a)gmail.com... > Benj <bjacoby(a)iwaynet.net> wrote: >> "Androcles" <Headmas...(a)Hogwarts.physics_o> wrote: >> > "Benj" <bjac...(a)iwaynet.net> wrote in message > >> > You think there is a "power factor" of 90 degrees on TEM plane waves >> > in a vacuum? >> > ============================================== >> > Don't be silly, no energy is lost to the vacuum or light wouldn't be >> > able to travel millions of light-years. >> >> So you are saying that TEM waves in space do NOT have E and B 90 >> degrees out of phase? >> >> > The electric and magnetic fields are at right angles to each other >> > AND they are 90 degrees out of phase. >> >> And now you say they ARE 90 degrees out of phase? > > They are 90 degrees out of phase in space, not in time. BULLSHIT!
From: Androcles on 24 Sep 2009 11:46
"Bill Miller" <billmillerkt4ye(a)worldnet.att.net> wrote in message news:7i1dqvF2vn8paU1(a)mid.individual.net... > > "Androcles" <Headmaster(a)Hogwarts.physics_o> wrote in message > news:mVzum.166987$4f4.41974(a)newsfe11.ams2... >> > <snip> >> Nobody ever taught me the voltage across a capacitor in an RC >> network can *never* exceed the supply voltage, even if some American >> idiot taught you that. >> > Let me see if I understand. > > You seem to be saying either, > > 1. Someone taught you that the voltage across a capacitor *can* exceed > the supply voltage. In that case, I applaud the perspicacity of your > instructor. But my experience in the USA, Canada, UK, Latin America, > France Germany, Italy, Australia, HK and Japan (areas where I have > interacted professionally with physicists & engineers) has led me to > generalize that everyone worldwide is taught the same, erroneous pap that > I learned from the "idiots" at UC Berkeley. > > OR > > 2. You have never recived instruction in the performance of RC circuits. > > If the answer is (1) then I would appreciate information as to how you > might have learned this. (I am not challenging your education. I am just > *very* surprised that you seem to know about this subtle characteristic of > "capacitors.") > > If the answer is (2) then I do not care what your opinion is. > > All the best, > > Bill I don't need an instructor to measure the voltage at the mid-point of a resonant series LC circuit. a-----((((()----b-----||------c I *know* bc exceeds ac, 180 degrees out of phase. Theoretically it rises to infinity but in practice there is always some resistance in the circuit or the capacitor pops because its breakdown voltage is exceeded. For an RC circuit, a-----/\/\/\/\/\/----b-----||------c merely allow the voltage across bc to reach the value across ac (charge the capacitor) and then reverse the polarity across ac and measure bc before the cap discharges. It's called voltage doubling and you can block the discharge of the cap with a diode. http://en.wikipedia.org/wiki/Voltage_multiplier If you disagree then I do not care what your opinion is. Actually I don't care what your opinion is even if you agree, it won't prevent voltage multipliers working. |