Forums

Bifilar Wound Balun Transformer

Started by rickman November 3, 2012
On Tue, 6 Nov 2012 00:36:11 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Nov 6, 2:25&#2013266080;pm, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Mon, 5 Nov 2012 18:11:07 -0800 (PST), Bill Sloman >> <bill.slo...@ieee.org> wrote: >> >On Nov 6, 12:17 pm, John Larkin <jlar...@highlandtechnology.com> >> >wrote: >> >> On Mon, 5 Nov 2012 14:40:55 -0800 (PST), Bill Sloman >> >> <bill.slo...@ieee.org> wrote: >> >> >On Nov 5, 1:53 pm, John Larkin >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> On Sun, 4 Nov 2012 19:43:52 -0600, "Tim Williams" >> >> >> <tmoran...@charter.net> wrote: >> >> >> >"John Larkin" <jjlar...@highNOTlandTHIStechnologyPART.com> wrote in >> >> >> >messagenews:u2rd98l8ie7ucnfqk2em03grjthvdmoo1q@4ax.com... >> >> >> ><snip> >> >> >> >> That particular transformer in the photo was driven by a gaasfet. It >> >> >> worked fine, made really pretty isolated pulse outputs, about 500 ps >> >> >> edges. About 2000 of those transformers trigger most all the various >> >> >> gadgets at NIF. >> >> >> >But what's the inter-winding capacitance? I could probably work it >> >> >out, but you presumably know the exact number. >> >> >> It's just a few pF. The winding is just a few inches long. >> >> >That's a "don't know". >> >> >> >Whatever it is, 2000 of it is going to be a lot of capacitance across >> >> >a galvanic isolation barrier. >> >> >> The 2000 outputs are separate triggers, "clients" (things that we >> >> trigger) scattered all over the site. The isolation is only to break >> >> ground loops and keep jitter down. >> >> >Of course. But it's capacitance across a galvanic isolation barrier, >> >and - as such - injects AC current into the isolated ground. >> >> Ground loops are usually low frequencies, like 60 Hz. > >50Hz in some countries, 400Hz in aircraft. However circulating current >at an unusual frequency can create problems too. > >> If your >> >clients aren't keeping track of that, they aren't doing their job >> >right. >> >> My clients do their jobs right, and so do I. > >So you tell us. You presumably convinced them of your competence, or >maybe you were just the low bidder. > >>You don't have a job. > >What's that got to do with their competence? Or yours for that matter? > >> >>http://arxiv.org/ftp/physics/papers/0111/0111046.pdf >> >> >> (one of my very few published papers) >> >> >155.52-MHz seems surprisingly low. I would have thought that there >> >were faster standard frequencies that they might have adopted, with >> >correspondingly lower edge jitter. And it's not "your" paper - you >> >aren't first author, and clearly didn't write it. >> >> >It may be one of the few published papers that list you as an author, >> >which is no small thing, but it's not "your" paper. >> >> My timing modules work; you don't. > >You claim ownership of a paper of which you were a minor author. >Should we trust your claims about your timing modules?
Why would I care what you trust? Do you think the NIF paper was faked? We did two systems for NIF, got some awards, made some money, learned an awful lot. That's what sometimes happens whan you DO stuff. -- 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 11/4/2012 3:24 PM, Jamie wrote:
> John S wrote: >> On 11/3/2012 10:25 PM, rickman wrote: >> >>> On 11/3/2012 9:42 PM, John Larkin wrote: >>> >>>> On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams" >>>> <tmoranwms@charter.net> wrote: >>>> >>>>> "John Larkin"<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>>>> message news:ffcb985qk94e0cf265odu97o95d90sp1bh@4ax.com... >>>>> >>>>>> We do exactly that in a bunch of products, namely use the shield as a >>>>>> primary winding and the inner as the fully isolated secondary of a >>>>>> transformer. We do 1:1 and 1:2 (voltage step up) at levels from 5 >>>>>> volts to over 100. >>>>>> >>>>>> https://dl.dropbox.com/u/53724080/Circuits/Xfmrs.JPG >>>>>> >>>>>> This makes a transformer with very low leakage inductance, so we get >>>>>> sub-ns rise times into a 50 ohm load. >>>>> >>>>> >>>>> Except that, as I said, the leakage is not particularly low. One gets >>>>> better performance in that regard from, say, copper foil pairs (which, >>>>> ultimately, is still doing the same thing, but with a low impedance >>>>> symmetrical stripline, not 50 ohm coax). Which is often done in power >>>>> circuitry. But "very low leakage" is not what you're going for, so >>>>> it's >>>>> best not to claim that's what you're doing. >>>>> >>>>> Tim >>>> >>>> >>>> But it works. >>> >>> >>> See, this is the sort of stuff that, if I were a potential customer, >> >> >> Well, apparently you're not. >> >>> would turn me off to doing business with you. >> >> >> Oops! One potential customer lost! Damn, John, this will put you out >> of business. >> >> >> Geeze, if I am talking to >> >>> someone about what is going on in a system and they say to me, "but it >>> works", I would think they didn't understand it at all. >> >> >> Maybe the foot is on the other shoe. Maybe you didn't understand it at >> all. >> >>> Do you not see how your posts make you look? >>> >>> Rick >> >> >> And you understand how your posts look? That's curious. >> >> > Those that don't know shit, should shit elsewhere ! Get it?
Yeah. Okay. Keep your mouth open.
On 11/5/2012 8:25 PM, Jamie wrote:
> Bill Sloman wrote: >> On Nov 6, 12:17 pm, John Larkin <jlar...@highlandtechnology.com> >> wrote: >> >>> On Mon, 5 Nov 2012 14:40:55 -0800 (PST), Bill Sloman >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> <bill.slo...@ieee.org> wrote: >>> >>>> On Nov 5, 1:53 pm, John Larkin >>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> On Sun, 4 Nov 2012 19:43:52 -0600, "Tim Williams" >>>>> <tmoran...@charter.net> wrote: >>>>> >>>>>> "John Larkin" <jjlar...@highNOTlandTHIStechnologyPART.com> wrote in >>>>>> messagenews:u2rd98l8ie7ucnfqk2em03grjthvdmoo1q@4ax.com... >>> >>>> <snip> >>> >>>>> That particular transformer in the photo was driven by a gaasfet. It >>>>> worked fine, made really pretty isolated pulse outputs, about 500 ps >>>>> edges. About 2000 of those transformers trigger most all the various >>>>> gadgets at NIF. >>> >>>> But what's the inter-winding capacitance? I could probably work it >>>> out, but you presumably know the exact number. >>> >>> It's just a few pF. The winding is just a few inches long. >> >> >> That's a "don't know". >> >> >>>> Whatever it is, 2000 of it is going to be a lot of capacitance across >>>> a galvanic isolation barrier. >>> >>> The 2000 outputs are separate triggers, "clients" (things that we >>> trigger) scattered all over the site. The isolation is only to break >>> ground loops and keep jitter down. >> >> >> Of course. But it's capacitance across a galvanic isolation barrier, >> and - as such - injects AC current into the isolated ground. If your >> clients aren't keeping track of that, they aren't doing their job >> right. >> >> >>> http://arxiv.org/ftp/physics/papers/0111/0111046.pdf >>> >>> (one of my very few published papers) >> >> >> 155.52-MHz seems surprisingly low. I would have thought that there >> were faster standard frequencies that they might have adopted, with >> correspondingly lower edge jitter. And it's not "your" paper - you >> aren't first author, and clearly didn't write it. >> >> It may be one of the few published papers that list you as an author, >> which is no small thing, but it's not "your" paper. >> >> -- >> Bill Sloman, Sydney > You're not racking up many points either. > > Jamie >
And you think you are? Go away and leave these professionals alone. At least they understand the subject whereas you don't even know your job function.
On 11/4/2012 3:37 PM, Jamie wrote:

> At least you actually do something, not like a good many here that > would like to make people think otherwise.
Well, we agree on this.
> I spend more time at actually experimenting with what works the best > instead of fighting with PC software that only gets it close but not > good enough.
So, you spend more time experimenting than designing things yourself. Get a calculator, paper, pencil, and some knowledge, and design something without a computer, imbecile. Nobody said you needed to use a computer. Most professionals here began designing without a computer.
> I just love those that talk shit and most likely hardly even touch a > piece of equipment. When they do I am sure they're all thumbs and > fingers with it and most likely end up getting some one else to do it > for them and take all the credit for it.
Like you, right? People like you tend to join a crowd of similar people. That's why you are only tolerated here. Find your own crowd.
> Those guilty of this need not to step forward, I already know who > most of you are. >
Of course. You are omnipotent.
On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli wrote:

> Fred Abse a &#2013265929;crit : >> On Sat, 03 Nov 2012 18:50:54 -0500, Tim Williams wrote: >> >>> The important thing about transmission line transformers is to forget >>> about using them as transformers. Use them as transmission lines! >> >> Anybody know how to accurately model a transmission line transformer in >> Spice, taking into account core properties? >> >> > For a simple one, just as it is: > use a TLine/RLC tline and between the 2 ""shield/ref plane" connections > you just tie the magnetizing inductance, with maybe your core model > (losses, non linearities, hysteresis,...)
Thanks, I'll try that -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
On Sun, 04 Nov 2012 19:49:14 +0100, Fred Bartoli <" "> wrote:

>John Larkin a &#2013265929;crit : >> On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote: >> >>> Fred Abse a &#2013265929;crit : >>>> On Sat, 03 Nov 2012 18:50:54 -0500, Tim Williams wrote: >>>> >>>>> The important thing about transmission line transformers is to forget >>>>> about using them as transformers. Use them as transmission lines! >>>> Anybody know how to accurately model a transmission line transformer in >>>> Spice, taking into account core properties? >>>> >>> For a simple one, just as it is: >>> use a TLine/RLC tline and between the 2 ""shield/ref plane" connections >>> you just tie the magnetizing inductance, with maybe your core model >>> (losses, non linearities, hysteresis,...) >> >> What's interesting about the LT Spice transmission lines is that they >> have no common-mode DC continuity between ends. They act as if there >> is an ideal 1:1 isolation transformer in the circuit. >> >> That sort of makes sense, since, say, the outer conductor of a coax >> has its own complex impedance against the universe, and Spice elects >> to not model that. Still, it can throw you if you don't know about it, >> and make baluns seem to work much better than they will in real life. >> > >If you want to accurately model a coax cable you need two TLines. One >modeling the center/shield transmission line, and a second one to model >the shield WRT to "space". > >> So a txline can make a handy 1:1 ideal transformer. Unlike a 1:1 VCVS, >> it's bidirectional and the output loads the input. >> > >The "standard" perfect transformer is composed of a vcvs to transport >voltage to the secondary and a CCCS to reflect the secondary current >back to the primary, and a 0 voltage source to probe it. >It is much less computationally demanding than the Tline which has to >maintain history.
I guess there's nothing stopping one from making a couple of gigahenry inductors coupled with K=1. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
On Nov 7, 6:41=A0am, John S <Soph...@invalid.org> wrote:
> On 11/4/2012 3:37 PM, Jamie wrote:
<snip>
> > =A0 =A0I just love those that talk shit and most likely hardly even tou=
ch a
> > piece of equipment. When they do I am sure they're all thumbs and > > fingers with it and most likely end up getting some one else to do it > > for them and take all the credit for it. > > Like you, right? People like you tend to join a crowd of similar people. > That's why you are only tolerated here. Find your own crowd. > > > =A0 =A0Those guilty of this need not to step forward, I already know wh=
o
> > most of you are. > > Of course. You are omnipotent.
I think you meant omniscient. Which Jamie may believe - but only within the rather circumscribed universe of discourse - and the rest of us know to be quite a way from the truth. -- Bill Sloman, Sydney
On Nov 7, 2:06=A0am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 6 Nov 2012 00:36:11 -0800 (PST), Bill Sloman > <bill.slo...@ieee.org> wrote: > >On Nov 6, 2:25 pm, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Mon, 5 Nov 2012 18:11:07 -0800 (PST), Bill Sloman > >> <bill.slo...@ieee.org> wrote: > >> >On Nov 6, 12:17 pm, John Larkin <jlar...@highlandtechnology.com> > >> >wrote: > >> >> On Mon, 5 Nov 2012 14:40:55 -0800 (PST), Bill Sloman > >> >> <bill.slo...@ieee.org> wrote: > >> >> >On Nov 5, 1:53 pm, John Larkin > >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> On Sun, 4 Nov 2012 19:43:52 -0600, "Tim Williams" > >> >> >> <tmoran...@charter.net> wrote: > >> >> >> >"John Larkin" <jjlar...@highNOTlandTHIStechnologyPART.com> wrot=
e in
> >> >> >> >messagenews:u2rd98l8ie7ucnfqk2em03grjthvdmoo1q@4ax.com...
<snip>
> >> My clients do their jobs right, and so do I. > > >So you tell us. =A0You presumably convinced them of your competence, or > >maybe you were just the low bidder. > > >>You don't have a job. > > >What's that got to do with their competence? Or yours for that matter? > > >> >>http://arxiv.org/ftp/physics/papers/0111/0111046.pdf > > >> >> (one of my very few published papers) > > >> >155.52-MHz seems surprisingly low. I would have thought that there > >> >were faster standard frequencies that they might have adopted, with > >> >correspondingly lower edge jitter. And it's not "your" paper - you > >> >aren't first author, and clearly didn't write it. > > >> >It may be one of the few published papers that list you as an author, > >> >which is no small thing, but it's not "your" paper. > > >> My timing modules work; you don't. > > >You claim ownership of a paper of which you were a minor author. > >Should we trust your claims about your timing modules? > > Why would I care what you trust? Do you think the NIF paper was faked?
It seems most unlikely, but - accepting that the paper is honest - which I'm more than happy to do - all it says is that you were the supplier, and your gear worked well enough to be satisfactory in the application. As you have mentioned here, when physicists publish about electronics, they usually have exaggerated ideas about how good their electronics is and how close it is to the state of the art. I've got a couple of comments in Review of Scientific Instruments that criticise particularly flagrant examples of this kind of defect.
> We did two systems for NIF, got some awards, made some money, learned > an awful lot. That's what sometimes happens whan you DO stuff.
I've noticed. That's one of the reasons why I'd like to do some more stuff, and why I'm frustrated by being confined to doing stuff I can afford which solves the kinds of problems that I can dream up without much help from the outside world. I learned a great deal when I was working on the Cambridge Instruments Electron Beam Tester, and I enjoyed the process. -- Bill Sloman, Sydney
On Nov 7, 8:23=A0am, John Larkin <jlar...@highlandtechnology.com> wrote:
> On Sun, 04 Nov 2012 19:49:14 +0100, Fred Bartoli <" "> wrote: > > > > > > > > > > >John Larkin a crit : > >> On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote: > > >>> Fred Abse a crit : > >>>> On Sat, 03 Nov 2012 18:50:54 -0500, Tim Williams wrote: > > >>>>> The important thing about transmission line transformers is to forg=
et
> >>>>> about using them as transformers. =A0Use them as transmission lines=
!
> >>>> Anybody know how to accurately model a transmission line transformer=
in
> >>>> Spice, taking into account core properties? > > >>> For a simple one, just as it is: > >>> use a TLine/RLC tline and between the 2 ""shield/ref plane" connectio=
ns
> >>> you just tie the magnetizing inductance, with maybe your core model > >>> (losses, non linearities, hysteresis,...) > > >> What's interesting about the LT Spice transmission lines is that they > >> have no common-mode DC continuity between ends. They act as if there > >> is an ideal 1:1 isolation transformer in the circuit. > > >> That sort of makes sense, since, say, the outer conductor of a coax > >> has its own complex impedance against the universe, and Spice elects > >> to not model that. Still, it can throw you if you don't know about it, > >> and make baluns seem to work much better than they will in real life. > > >If you want to accurately model a coax cable you need two TLines. One > >modeling the center/shield transmission line, and a second one to model > >the shield WRT to "space". > > >> So a txline can make a handy 1:1 ideal transformer. Unlike a 1:1 VCVS, > >> it's bidirectional and the output loads the input. > > >The "standard" perfect transformer is composed of a vcvs to transport > >voltage to the secondary and a CCCS to reflect the secondary current > >back to the primary, and a 0 voltage source to probe it. > >It is much less computationally demanding than the Tline which has to > >maintain history. > > I guess there's nothing stopping one from making a couple of gigahenry > inductors coupled with K=3D1.
That's the joy of simulation. You can test ideas that would cost a mint in superconducting wire and liquid helium if you wanted to try them out on the bench. The are applications where that kind of expenditure on real parts might be justifiable. -- Bill Sloman, Sydney
Bill Sloman wrote:
> On Nov 7, 8:23 am, John Larkin <jlar...@highlandtechnology.com> wrote: > >>On Sun, 04 Nov 2012 19:49:14 +0100, Fred Bartoli <" "> wrote: >> >> >> >> >> >> >> >> >> >> >>>John Larkin a crit : >>> >>>>On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote: >> >>>>>Fred Abse a crit : >>>>> >>>>>>On Sat, 03 Nov 2012 18:50:54 -0500, Tim Williams wrote: >> >>>>>>>The important thing about transmission line transformers is to forget >>>>>>>about using them as transformers. Use them as transmission lines! >>>>>> >>>>>>Anybody know how to accurately model a transmission line transformer in >>>>>>Spice, taking into account core properties? >> >>>>>For a simple one, just as it is: >>>>>use a TLine/RLC tline and between the 2 ""shield/ref plane" connections >>>>>you just tie the magnetizing inductance, with maybe your core model >>>>>(losses, non linearities, hysteresis,...) >> >>>>What's interesting about the LT Spice transmission lines is that they >>>>have no common-mode DC continuity between ends. They act as if there >>>>is an ideal 1:1 isolation transformer in the circuit. >> >>>>That sort of makes sense, since, say, the outer conductor of a coax >>>>has its own complex impedance against the universe, and Spice elects >>>>to not model that. Still, it can throw you if you don't know about it, >>>>and make baluns seem to work much better than they will in real life. >> >>>If you want to accurately model a coax cable you need two TLines. One >>>modeling the center/shield transmission line, and a second one to model >>>the shield WRT to "space". >> >>>>So a txline can make a handy 1:1 ideal transformer. Unlike a 1:1 VCVS, >>>>it's bidirectional and the output loads the input. >> >>>The "standard" perfect transformer is composed of a vcvs to transport >>>voltage to the secondary and a CCCS to reflect the secondary current >>>back to the primary, and a 0 voltage source to probe it. >>>It is much less computationally demanding than the Tline which has to >>>maintain history. >> >>I guess there's nothing stopping one from making a couple of gigahenry >>inductors coupled with K=1. > > > That's the joy of simulation. You can test ideas that would cost a > mint in superconducting wire and liquid helium if you wanted to try > them out on the bench. > > The are applications where that kind of expenditure on real parts > might be justifiable. > > -- > Bill Sloman, Sydney
I get the idea that a simulator is the only source for any inclinations you come up with.. Jamie