On Mon, 4 Jun 2012 00:34:20 -0700 (PDT), Bill Sloman <bill.sloman@ieee.org> wrote:>On Jun 4, 6:00�am, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Jun 3, 10:09�pm, Phil Hobbs >> ><pcdhSpamMeSensel...@electrooptical.net> wrote: >> >>BillSlomanwrote: >> >> >> > On Jun 3, 9:02 pm, Fred Abse <excretatau...@invalid.invalid> wrote: >> >> > > On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >> >> > > > We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >> >> > > > gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >> >> > > > root turn by grinding back the centre pillar by 0.4mm, >> >> >> > > I think that should be "per turn squared". >> >> >> > Wrong. Inductance is proportional to the square of the number of >> >> > turns, as long as they are closely coupled. >> >> >> >http://en.wikipedia.org/wiki/Inductor >> >> >> If L = alpha * N**2, then alpha has units of henries per turn squared. >> >> (Of course a turn isn't really a unit, just as a radian and a steradian >> >> aren't, but it sure isn't per square root turn.) >> >> >Applying dimensional analysis to a manufacturer's design fudge factor >> >is the sort of thing that physicists do. >> >> Engineers, too. My first engineering course at Tulane, first semister >> freshman year, was an introduction to units and dimensional analysis. >> It was taught by Dr Johnson, the Dean of the Engineering School, who >> thought it was important. >> >> Random noise increases as the square root of bandwidth, so we specify >> it as volts per root Hz. >> >> Inductance increases with turns squared, so we spec a core Al as >> henries per turn squared. >> >> See the difference? > >It's 9:30am and my brain is working again, so yes - I do.Did you PWBC, post without benefit of coffee? I'm doing that now, and it's a great hazard.> >> >It's not a particularly useful activity. Reminding junior engineers at >> >every possible opportunity that inductance is proportional to the >> >square of the number of turns in a winding is an extremely useful >> >activity, and saves loads of time at design reviews. >> >> They were probably polite enough to laugh at you after you left the >> room. > >Perhaps. But they'd got the point - attention-getting devices don't >have to be pedantically correct to work. Look at Howard Johnson on >high speed signal propagation.He's as dangerous as Professor Moriarty. (Incidentally, the latest "Sherlock" was stunning.) -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
LTC Switcher CAD3 ?
Started by ●June 2, 2012
Reply by ●June 4, 20122012-06-04
Reply by ●June 4, 20122012-06-04
On Jun 4, 4:09=A0pm, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Jun 4, 6:00=A0am, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman > > >> <bill.slo...@ieee.org> wrote: > >> >On Jun 3, 10:09=A0pm, Phil Hobbs > >> ><pcdhSpamMeSensel...@electrooptical.net> wrote: > >> >>BillSlomanwrote: > > >> >> > On Jun 3, 9:02 pm, Fred Abse <excretatau...@invalid.invalid> wrot=e:> >> >> > > On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: > >> >> > > > We've just measured a coupling of 0.98 in a gapped RM14 core =- EPCOS> >> >> > > > gapped it down from 6000uH/root turn for an ungapped pair to =630nH per> >> >> > > > root turn by grinding back the centre pillar by 0.4mm, > > >> >> > > I think that should be "per turn squared". > > >> >> > Wrong. Inductance is proportional to the square of the number of > >> >> > turns, as long as they are closely coupled. > > >> >> >http://en.wikipedia.org/wiki/Inductor > > >> >> If L =3D alpha * N**2, then alpha has units of henries per turn squ=ared.> >> >> (Of course a turn isn't really a unit, just as a radian and a stera=dian> >> >> aren't, but it sure isn't per square root turn.) > > >> >Applying dimensional analysis to a manufacturer's design fudge factor > >> >is the sort of thing that physicists do. > > >> Engineers, too. My first engineering course at Tulane, first semister > >> freshman year, was an introduction to units and dimensional analysis. > >> It was taught by Dr Johnson, the Dean of the Engineering School, who > >> thought it was important. > > >> Random noise increases as the square root of bandwidth, so we specify > >> it as volts per root Hz. > > >> Inductance increases with turns squared, so we spec a core Al as > >> henries per turn squared. > > >> See the difference? > > >It's 9:30am and my brain is working again, so yes - I do. > > Did you PWBC, post without benefit of coffee? I'm doing that now, and > it's a great hazard. > > > > >> >It's not a particularly useful activity. Reminding junior engineers a=t> >> >every possible opportunity that inductance is proportional to the > >> >square of the number of turns in a winding is an extremely useful > >> >activity, and saves loads of time at design reviews. > > >> They were probably polite enough to laugh at you after you left the > >> room. > > >Perhaps. But they'd got the point - attention-getting devices don't > >have to be pedantically correct to work. Look at Howard Johnson on > >high speed signal propagation. > > He's as dangerous as Professor Moriarty.I don't know about dangerous, but pedagogically horrible. If you compare the lucid exposition of practical physics you get in Ralph Morrison's "Grounding and Shielding Techniques in Instrumentation" http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/dp/0471= 245186 with the incoherent messes that Howard Johnson peddles,you go from the sublime to the despicable.> (Incidentally, the latest "Sherlock" was stunning.)You mean the BBC televison series? We've been watching it here - we get BBC 1 and 2 on the local cable - and liked it a lot. -- Bill Sloman, Nijmegen
Reply by ●June 4, 20122012-06-04
On Mon, 04 Jun 2012 00:28:55 -0700, Bill Sloman wrote:> You are right, and the units ought to Henry per turn^-2Contradicts what Phil, Tim, John, and I all seem to agree on. Henry per turn^2. Lose the minus. Being of a charitable disposition, I'll put it down to the lateness of the hour ;-) -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
Reply by ●June 4, 20122012-06-04
On Mon, 04 Jun 2012 05:06:36 -0700, Bill Sloman wrote:> Thanks for the correction, and my apologies for responding without > thinking hard enough.Graciousness/gratitude duly noted :-) -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
Reply by ●June 4, 20122012-06-04
On Mon, 4 Jun 2012 08:51:29 -0700 (PDT), Bill Sloman <bill.sloman@ieee.org> wrote:>On Jun 4, 4:09�pm, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Jun 4, 6:00�am, John Larkin >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >> >> >> <bill.slo...@ieee.org> wrote: >> >> >On Jun 3, 10:09�pm, Phil Hobbs >> >> ><pcdhSpamMeSensel...@electrooptical.net> wrote: >> >> >>BillSlomanwrote: >> >> >> >> > On Jun 3, 9:02 pm, Fred Abse <excretatau...@invalid.invalid> wrote: >> >> >> > > On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >> >> >> > > > We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >> >> >> > > > gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >> >> >> > > > root turn by grinding back the centre pillar by 0.4mm, >> >> >> >> > > I think that should be "per turn squared". >> >> >> >> > Wrong. Inductance is proportional to the square of the number of >> >> >> > turns, as long as they are closely coupled. >> >> >> >> >http://en.wikipedia.org/wiki/Inductor >> >> >> >> If L = alpha * N**2, then alpha has units of henries per turn squared. >> >> >> (Of course a turn isn't really a unit, just as a radian and a steradian >> >> >> aren't, but it sure isn't per square root turn.) >> >> >> >Applying dimensional analysis to a manufacturer's design fudge factor >> >> >is the sort of thing that physicists do. >> >> >> Engineers, too. My first engineering course at Tulane, first semister >> >> freshman year, was an introduction to units and dimensional analysis. >> >> It was taught by Dr Johnson, the Dean of the Engineering School, who >> >> thought it was important. >> >> >> Random noise increases as the square root of bandwidth, so we specify >> >> it as volts per root Hz. >> >> >> Inductance increases with turns squared, so we spec a core Al as >> >> henries per turn squared. >> >> >> See the difference? >> >> >It's 9:30am and my brain is working again, so yes - I do. >> >> Did you PWBC, post without benefit of coffee? I'm doing that now, and >> it's a great hazard. >> >> >> >> >> >It's not a particularly useful activity. Reminding junior engineers at >> >> >every possible opportunity that inductance is proportional to the >> >> >square of the number of turns in a winding is an extremely useful >> >> >activity, and saves loads of time at design reviews. >> >> >> They were probably polite enough to laugh at you after you left the >> >> room. >> >> >Perhaps. But they'd got the point - attention-getting devices don't >> >have to be pedantically correct to work. Look at Howard Johnson on >> >high speed signal propagation. >> >> He's as dangerous as Professor Moriarty. > >I don't know about dangerous, but pedagogically horrible. If you >compare the lucid exposition of practical physics you get in Ralph >Morrison's "Grounding and Shielding Techniques in Instrumentation" > >http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/dp/0471245186 > >with the incoherent messes that Howard Johnson peddles,you go from the >sublime to the despicable.Yup. It's painful to read, even in the parts where he's technically correct.> >> (Incidentally, the latest "Sherlock" was stunning.) > >You mean the BBC televison series? We've been watching it here - we >get BBC 1 and 2 on the local cable - and liked it a lot.There are two running here now. The "classic" with Jeremy Brett, pretty good, and the modern-day one. It's the new one that I was referring to. I read all the Sherlocks several times when I was a kid, and revisit them now and then for a quick read. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●June 4, 20122012-06-04
Fred Abse wrote:> On Mon, 04 Jun 2012 00:28:55 -0700, Bill Sloman wrote: > > >>You are right, and the units ought to Henry per turn^-2 > > > Contradicts what Phil, Tim, John, and I all seem to agree on. > > Henry per turn^2. Lose the minus. > > Being of a charitable disposition, I'll put it down to the lateness of the > hour ;-) >He lives in a negative world! It's natural for him. Jamie
Reply by ●June 4, 20122012-06-04
On Jun 4, 6:17=A0pm, Fred Abse <excretatau...@invalid.invalid> wrote:> On Mon, 04 Jun 2012 00:28:55 -0700,BillSlomanwrote: > > You are right, and the units ought to Henry per turn^-2 > > Contradicts what Phil, Tim, John, and I all seem to agree on. > > Henry per turn^2. Lose the minus. > > Being of a charitable disposition, I'll put it down to the lateness of th=e> hour ;-)Inductance =3D Al x turns^2 Henries so the dimensions of Al are Henries. turns^-2. If you three agreed on anything else, you got it wrong. -- Bill Sloman, Nijmegen
Reply by ●June 4, 20122012-06-04
On Jun 4, 8:44=A0pm, Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:> Fred Abse wrote: > > On Mon, 04 Jun 2012 00:28:55 -0700,BillSlomanwrote: > > >>You are right, and the units ought to Henry per turn^-2 > > > Contradicts what Phil, Tim, John, and I all seem to agree on. > > > Henry per turn^2. Lose the minus. > > > Being of a charitable disposition, I'll put it down to the lateness of =the> > hour ;-) > > He lives in a negative world! It's natural for him.Jamie gets it wrong - as usual. -- Bill Sloman, Nijmegen
Reply by ●June 4, 20122012-06-04
Bill Sloman wrote:> On Jun 4, 8:44 pm, Jamie > <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: > >>Fred Abse wrote: >> >>>On Mon, 04 Jun 2012 00:28:55 -0700,BillSlomanwrote: >> >>>>You are right, and the units ought to Henry per turn^-2 >> >>>Contradicts what Phil, Tim, John, and I all seem to agree on. >> >>>Henry per turn^2. Lose the minus. >> >>>Being of a charitable disposition, I'll put it down to the lateness of the >>>hour ;-) >> >>He lives in a negative world! It's natural for him. > > > Jamie gets it wrong - as usual. > > -- > Bill Sloman, NijmegenThe only thing I did wrong was acknowledging your existence here. Jamie
Reply by ●June 4, 20122012-06-04
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:798e6541-19e0-4e08-a11d-c774ce0777ee@fr28g2000vbb.googlegroups.com...>On Jun 4, 6:17 pm, Fred Abse <excretatau...@invalid.invalid> wrote: >> On Mon, 04 Jun 2012 00:28:55 -0700,BillSlomanwrote: >> > You are right, and the units ought to Henry per turn^-2...>so the dimensions of Al are Henries. turns^-2.Bill: "per" means "divided by". Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
