On Tue, 29 Dec 2009 12:56:01 -0600, Tim Wescott <tim@seemywebsite.com> wrote:>On Tue, 29 Dec 2009 11:52:40 -0500, Jerry Avins wrote: > >> Rick Armstrong wrote: >>>> If arguments about capacitor nonlinearities are too subtle, try doing >>>> this with a 1000 ohm resistor, a 1 microfarad, 50V cap, then plug the >>>> assembly into a 120V, 60Hz wall socket. >>>> >>>> As a thought experiment, of course. >>> >>> I've done that one, inadvertently. It's a real...blast! >> >> "Blast" reminds me of the time I wired up a 2000-microfarad 60-volt >> 'lytic backwards. It worked for a while, then it exploded about a foot >> from my head. It was overnight before I could hear normally again. >> (Normal includes tinnitus anyway.) The innards, mostly unrolled foil, >> overflowed a large office wastebasket. Perfect? Who, me? > >The one time I blew up a 'lytic I never found the pieces.I am really curious how one of these babies (http://tinyurl.com/ylatbs6) will react to over-voltage when fully charged. Hopefully we'll see in a couple of months. As a comparison a 2000uF cap at 60V stores 3.6J whereas a 650F cap at 2.7V stores ~2400J (when fully charged). -- Muzaffer Kal DSPIA INC. ASIC/FPGA Design Services http://www.dspia.com
Convolution Tutorial
Started by ●December 26, 2009
Reply by ●December 29, 20092009-12-29
Reply by ●December 29, 20092009-12-29
Eric Jacobsen <eric.jacobsen@ieee.org> wrote: (snip, someone wrote)>>> I was talking to a power electronics lecturer from a reasonably >>> good university in the UK recently. He told me only two courses >>> in their entire electronics degree program now have any practical >>> content. For everything else, the only lab is Matlab.(snip)> I can't imagine an EE degree without the hands-on lab stuff. How do you > make people responsible for building stuff safely if they're never > allowed to see for themselves what the issues may be?I am not so sure how it works in EE, but in physics there are theoretical and experimental physicists. Many good theoretical physicists aren't very good at lab work. There is the well known "Pauli effect" http://en.wikipedia.org/wiki/Pauli_effect which causes experiments to fail when Pauli is anywhere close. It seems to me that as EE (with subfields such as DSP) gets more theoretical it may go the same way. As I understand it, digital logic is being taught with computer simulation and no actual TTL circuits.> It reminds me of the infantry trained without the benefit of actually > using guns...pointing sticks at each other and yelling "bang". I > understand the motivation, but the effectiveness is pretty questionable.-- glen
Reply by ●December 29, 20092009-12-29
Randy Yates wrote:> Jerry Avins <jya@ieee.org> writes: > >> Randy Yates wrote: >>> Rune Allnor <allnor@tele.ntnu.no> writes: >>>> [...] "He who thinks his education has finished is not educated. He >>>> is finished." >>> I have found that education exposes one's own ignorance. >> Isn't that its most important purpose? > > Good question. I think most people hope it prepares them for a > career. What I was trying to say is that you don't know how ignorant you > are until you get illuminated.Exactly. What we wrongly believe we know hurts a lot. When we perceive our ignorance, we can be careful or use the library.> I know I still want to continue to study (e.g., some more math) but it > comes down to time and money. If I won the lottery I'd probably become > a permanent student!If you don't study your surroundings as you walk, you are in danger of stepping into an open manhole. (I repeat: why are manhole covers round?) Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●December 29, 20092009-12-29
On Dec 29, 8:26�pm, Rune Allnor <all...@tele.ntnu.no> wrote:> > Again, *first* earn the privilege; *then* recieve ranks > and titles. Ceremonies are nothing but voodoo and mysticism > that have nothing to do with engineering. > > RuneYou are missing the point. A Ph.D means you have particular training in an area of research and that you have contributed to knowledge in that area. It doesn't make you a good engineer and never has done. Should it? no. A Ph.D is scientific training not engineering. There are places that have D.Eng which may be more in line with what industry wants. A D.eng would be like a Ph.D but their is more application to a real engineering problem.Applying advanced knowledge to an engineering problem and making it work. You see engineers are compared with other depts within a Uni and cannot afford to have different rules. A Ph.D is common currency throughout the world. yes they do kick people out. Doesn't happen too often but it does happen. Now I am a bit like you - a reluctant Ph.D. I often wonder if it did me any good at all. Before I was with a company and they told me - sure - go off and do your Ph,D but when you come back don't expect any more pay and you start as a graduate again! That was a long time ago of course. work for the US airforce (maybe army too) and you start with a rank of Major if you have a Ph.D. Hardy
Reply by ●December 29, 20092009-12-29
On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins wrote:> Randy Yates wrote: >> Jerry Avins <jya@ieee.org> writes: >> >>> Randy Yates wrote: >>>> Rune Allnor <allnor@tele.ntnu.no> writes: >>>>> [...] "He who thinks his education has finished is not educated. >>>>> He is finished." >>>> I have found that education exposes one's own ignorance. >>> Isn't that its most important purpose? >> >> Good question. I think most people hope it prepares them for a career. >> What I was trying to say is that you don't know how ignorant you are >> until you get illuminated. > > Exactly. What we wrongly believe we know hurts a lot. When we perceive > our ignorance, we can be careful or use the library. > >> I know I still want to continue to study (e.g., some more math) but it >> comes down to time and money. If I won the lottery I'd probably become >> a permanent student! > > If you don't study your surroundings as you walk, you are in danger of > stepping into an open manhole. (I repeat: why are manhole covers round?)Because they're easier to turn out on a lathe, of course! (except for those square dimples -- those are hard). :-) -- www.wescottdesign.com
Reply by ●December 29, 20092009-12-29
Eric Jacobsen wrote: ...> When I was at school the math building had once housed the EE dept. with > the labs in the basement. It was a small school and we spent a lot of > time with the Professors, a fair amount of it just socially. During our > power lab introduction we were being warned about the dangers of DC > motors, and told to go look at the walls in one of the basement rooms of > the math building, where the motor lab was once installed. > > It was a concrete basement, the walls were (still) unfinished, and there > was a nice, well-defined line of divots in the concrete walls, floor, > and ceiling where a DC motor had overrun and essentially detonated. > There may have still been pieces of armature embedded deep in the holes, > I don't know. > > Naturally we had to ask about the story behind that, and it turned out > my advisor, a well-respected faculty member (and to this day still a > friend I keep in touch with) had done that when he was an undergrad > there. I still chuckle about that. > > I can't imagine an EE degree without the hands-on lab stuff. How do you > make people responsible for building stuff safely if they're never > allowed to see for themselves what the issues may be? > > It reminds me of the infantry trained without the benefit of actually > using guns...pointing sticks at each other and yelling "bang". I > understand the motivation, but the effectiveness is pretty questionable.My father worked in building construction. One school holiday, he took me to a job site where they were rebuilding the freight elevator. The motor room was all concrete, as you described. The walls, ceiling, and as much of the floor as I could see were studded with embedded bits of copper and armature iron, as you described. The room had a steel door and the motor shaft passed through a small aperture in a wall to the machinery room on its other side. The motor that had succumbed to centrifugal force (all right, purists: exhibited insufficient centripetal strength) had been a rather disk-shaped series interpole motor. A broken shaft coupling had unloaded it. (Commutator arcing often limits the speed of runaway series motors, but the interpoles are there precisely to avoid arcing. Poof!) The "modern" motor replacement was a Ward Leonard system. I loved the old ones. Does anybody else remember an elevator with a brief delay while the generator came up to speed? Anyhow, the memory of that room probably contributed to my having frozen while the over-compounded motor was revving up. All I would have had to do was close the knife switch I had just opened. It was still in my hand. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●December 29, 20092009-12-29
On 29 Des, 20:44, HardySpicer <gyansor...@gmail.com> wrote:> On Dec 29, 8:26�pm, Rune Allnor <all...@tele.ntnu.no> wrote: > > > > > Again, *first* earn the privilege; *then* recieve ranks > > and titles. Ceremonies are nothing but voodoo and mysticism > > that have nothing to do with engineering. > > > Rune > > You are missing the point. A Ph.D means you have particular training > in an area of research and that you have contributed to knowledge in > that area.No, it doesn't. That's what everybody *think* it means, and it might even have been true some time in ancient history, but it is not true now. My own thesis fails your proposition simply because everything I did had been done before. I assembled a number of DSP methods and applied them to 'weird' data. And that's what engineering is all about. I did nothing in that project I wouldn't expect any engineer worth his salary would be able to do, at any time.> It doesn't make you a good engineer and never has done. Should it? no. > A Ph.D is scientific training not engineering.No, it's not. It has nothing to do with 'training' in any sense of the word. If somebody were to 'train' somebody else, it would mean teaching work habits, best practices, how to spot poor projects and ideas - tutoring and follow-up. None of that happens in any university - and even in few companies - today. People are so desperate for income that they accept any projet proposal anyone are willing to pay for. After I left University my only contacts with academics have been to expose them as frauds. You would be surprised what levels of knowledge one needs to deflate a project. I don't think I have ever used arguments a 15-year-old high-school kid wouldn't understand.> There are places that > have D.Eng which may be more in line with what industry wants. A D.eng > would be like a Ph.D but their is more application to a real > engineering problem.Applying advanced knowledge to an engineering > problem and making it work. You see engineers are compared with other > depts within a Uni and cannot afford to have different rules. A Ph.D > is common currency throughout the world. yes they do kick people out. > Doesn't happen too often but it does happen.Nope. Kicking people out would mean that the prof in charge made some mistake. No prof in charge will ever admit to such a fact, because it would undermine his position for future funds. And of course, it is the prof in charge who selects the evaluation comittee, so he naturally selects people who would not challenge the candidate too hard. Again, I have debunked a couple of theses in my time. Not such that the candidate flunked, but such that the candidates knew why they ought to have flunked. Again, the high-school curriculum has been more than enough to do that. Rune
Reply by ●December 29, 20092009-12-29
Tim Wescott wrote:> On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins wrote: > >> Randy Yates wrote: >>> Jerry Avins <jya@ieee.org> writes: >>> >>>> Randy Yates wrote: >>>>> Rune Allnor <allnor@tele.ntnu.no> writes: >>>>>> [...] "He who thinks his education has finished is not educated. >>>>>> He is finished." >>>>> I have found that education exposes one's own ignorance. >>>> Isn't that its most important purpose? >>> Good question. I think most people hope it prepares them for a career. >>> What I was trying to say is that you don't know how ignorant you are >>> until you get illuminated. >> Exactly. What we wrongly believe we know hurts a lot. When we perceive >> our ignorance, we can be careful or use the library. >> >>> I know I still want to continue to study (e.g., some more math) but it >>> comes down to time and money. If I won the lottery I'd probably become >>> a permanent student! >> If you don't study your surroundings as you walk, you are in danger of >> stepping into an open manhole. (I repeat: why are manhole covers round?) > > Because they're easier to turn out on a lathe, of course!An important secondary reason.> (except for those square dimples -- those are hard). > > :-):-) Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by ●December 29, 20092009-12-29
Tim Wescott <tim@seemywebsite.com> wrote: (snip)> Because they're easier to turn out on a lathe, of course!That was the reason we were told we needed to learn about Bessel functions. Objects made on a lathe have cylindrical symmetry. -- glen
Reply by ●December 29, 20092009-12-29
Jerry Avins <jya@ieee.org> writes:> Tim Wescott wrote: >> On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins wrote: >> >>> Randy Yates wrote: >>>> Jerry Avins <jya@ieee.org> writes: >>>> >>>>> Randy Yates wrote: >>>>>> Rune Allnor <allnor@tele.ntnu.no> writes: >>>>>>> [...] "He who thinks his education has finished is not >>>>>>> educated. He is finished." >>>>>> I have found that education exposes one's own ignorance. >>>>> Isn't that its most important purpose? >>>> Good question. I think most people hope it prepares them for a career. >>>> What I was trying to say is that you don't know how ignorant you are >>>> until you get illuminated. >>> Exactly. What we wrongly believe we know hurts a lot. When we perceive >>> our ignorance, we can be careful or use the library. >>> >>>> I know I still want to continue to study (e.g., some more math) but it >>>> comes down to time and money. If I won the lottery I'd probably become >>>> a permanent student! >>> If you don't study your surroundings as you walk, you are in danger of >>> stepping into an open manhole. (I repeat: why are manhole covers round?) >> >> Because they're easier to turn out on a lathe, of course! > > An important secondary reason.To save material? A round cover is the least amount of material for a given minimum radius. -- Randy Yates % "Rollin' and riding and slippin' and Digital Signal Labs % sliding, it's magic." mailto://yates@ieee.org % http://www.digitalsignallabs.com % 'Living' Thing', *A New World Record*, ELO
