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LTC Switcher CAD3 ?

Started by Robert Baer June 2, 2012
On Mon, 4 Jun 2012 00:34:20 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Jun 4, 6:00&#2013266080;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&#2013266080;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
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
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 ;-) -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
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)
On Mon, 4 Jun 2012 08:51:29 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Jun 4, 4:09&#2013266080;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&#2013266080;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&#2013266080;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
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
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
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
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, Nijmegen
The only thing I did wrong was acknowledging your existence here. Jamie
"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