Forums

Bifilar Wound Balun Transformer

Started by rickman November 3, 2012
On Nov 5, 8:30=A0am, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
> John Larkin wrote: > > On Sat, 03 Nov 2012 23:25:46 -0400, rickman <gnu...@gmail.com> wrote: > > >>On 11/3/2012 9:42 PM, John Larkin wrote: > > >>>On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams" > >>><tmoran...@charter.net> =A0wrote: > > >>>>"John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> =A0wrote in > >>>>messagenews: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. =A0One g=
ets
> >>>>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). =A0Which is often done in po=
wer
> >>>>circuitry. =A0But "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, > >>would turn me off to doing business with you. =A0Geeze, 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. > > > I'm an engineer. I don't need to understand it, I only need to make it > > work. If a deep theoretical understanding of transmission-line > > transformers is helpful, I might use it. But if an hour of > > instinct-driven experimenting works, I'll go with that. My > > mosfet-transmission-line output stage, which we've used thousands of > > times, took about an hour of experimenting to design. > > > Some of the stuff that we do is so complex that closed-form solutions > > are impossible, and serious simulation would cost way too much time > > and money.
And John doesn't like doing that kind of work.
> > In the electronic design business, we seldom really understand what > > we're doing, at the first-principles level. We usually work further up > > the abstraction stack. We usually buy parts, read data sheets, and > > connect them up. It's actually unusual to *make* a part. [1] > > >>Do you not see how your posts make you look? > > > I posted pics of actual isolating transformers made with micro-coax. > > And some nice sub-ns-risetime 100 volt pulses that were pumped through > > similar transformers. Why would a customer be turned off by something > > that works? > > > A sub-ns rise time into a 50 ohm load implies equivalent leakage > > inductance in the 10s of nH. > > > [1] invite interesting tales of actually making components. > > =A0 At least you actually do something, not like a good many here that > would like to make people think otherwise. > > =A0 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. > > =A0 =A0I just love those that talk shit and most likely hardly even touch=
a
> piece of equipment. When they do I am sure
Jamie's confidence is touching. In fact what he is saying is that he is envies people who have better luck when they fight with the PC software, and wants to think that they are less fortunate at the bench. It's a slightly corrosive point of view, and may make him a difficult colleague.
> 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.
It does happen, but not very often. Most people with enough sense to get a PC to do what they want it to have enough sense to also make a soldering iron do what they want it to.
> =A0 =A0Those guilty of this need not to step forward, I already know who > most of you are.
He's made up whatever it is he uses instead of a mind. -- Bill Sloman, Sydney
On Nov 5, 1:53=A0pm, 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. Whatever it is, 2000 of it is going to be a lot of capacitance across a galvanic isolation barrier. -- Bill Sloman, Sydney
On Mon, 5 Nov 2012 14:40:55 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Nov 5, 1:53&#2013266080;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.
> >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. http://arxiv.org/ftp/physics/papers/0111/0111046.pdf (one of my very few published papers) -- 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 Mon, 5 Nov 2012 14:33:28 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Nov 5, 8:30&#2013266080;am, Jamie ><jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: >> John Larkin wrote: >> > On Sat, 03 Nov 2012 23:25:46 -0400, rickman <gnu...@gmail.com> wrote: >> >> >>On 11/3/2012 9:42 PM, John Larkin wrote: >> >> >>>On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams" >> >>><tmoran...@charter.net> &#2013266080;wrote: >> >> >>>>"John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> &#2013266080;wrote in >> >>>>messagenews: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. &#2013266080;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). &#2013266080;Which is often done in power >> >>>>circuitry. &#2013266080;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, >> >>would turn me off to doing business with you. &#2013266080;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. >> >> > I'm an engineer. I don't need to understand it, I only need to make it >> > work. If a deep theoretical understanding of transmission-line >> > transformers is helpful, I might use it. But if an hour of >> > instinct-driven experimenting works, I'll go with that. My >> > mosfet-transmission-line output stage, which we've used thousands of >> > times, took about an hour of experimenting to design. >> >> > Some of the stuff that we do is so complex that closed-form solutions >> > are impossible, and serious simulation would cost way too much time >> > and money. > >And John doesn't like doing that kind of work.
Of course not. It slows things down, even when it's possible. And besides, I like to solder once in a while. -- 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 6, 12:17=A0pm, 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
On Nov 6, 12:20=A0pm, John Larkin <jlar...@highlandtechnology.com>
wrote:
> On Mon, 5 Nov 2012 14:33:28 -0800 (PST), Bill Sloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Nov 5, 8:30 am, Jamie > ><jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: > >> John Larkin wrote: > >> > On Sat, 03 Nov 2012 23:25:46 -0400, rickman <gnu...@gmail.com> wrote=
:
> > >> >>On 11/3/2012 9:42 PM, John Larkin wrote: > > >> >>>On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams" > >> >>><tmoran...@charter.net> wrote: > > >> >>>>"John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> wrote in > >> >>>>messagenews: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 g=
ets
> >> >>>>better performance in that regard from, say, copper foil pairs (wh=
ich,
> >> >>>>ultimately, is still doing the same thing, but with a low impedanc=
e
> >> >>>>symmetrical stripline, not 50 ohm coax). Which is often done in po=
wer
> >> >>>>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, > >> >>would turn me off to doing business with you. 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. > > >> > I'm an engineer. I don't need to understand it, I only need to make =
it
> >> > work. If a deep theoretical understanding of transmission-line > >> > transformers is helpful, I might use it. But if an hour of > >> > instinct-driven experimenting works, I'll go with that. My > >> > mosfet-transmission-line output stage, which we've used thousands of > >> > times, took about an hour of experimenting to design. > > >> > Some of the stuff that we do is so complex that closed-form solution=
s
> >> > are impossible, and serious simulation would cost way too much time > >> > and money. > > >And John doesn't like doing that kind of work. > > Of course not. It slows things down, even when it's possible.
This isn't always true. There is some fiddling that is easy in simulations, and pretty much impossible in practice.
> And besides, I like to solder once in a while.
There are better reasons. --- Bill Sloman, Sydney
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
On Mon, 5 Nov 2012 18:11:07 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Nov 6, 12:17&#2013266080;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. 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. You don't have a job.
> >> 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. -- 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 Mon, 5 Nov 2012 18:14:09 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Nov 6, 12:20&#2013266080;pm, John Larkin <jlar...@highlandtechnology.com> >wrote: >> On Mon, 5 Nov 2012 14:33:28 -0800 (PST), Bill Sloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Nov 5, 8:30 am, Jamie >> ><jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: >> >> John Larkin wrote: >> >> > On Sat, 03 Nov 2012 23:25:46 -0400, rickman <gnu...@gmail.com> wrote: >> >> >> >>On 11/3/2012 9:42 PM, John Larkin wrote: >> >> >> >>>On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams" >> >> >>><tmoran...@charter.net> wrote: >> >> >> >>>>"John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> wrote in >> >> >>>>messagenews: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, >> >> >>would turn me off to doing business with you. 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. >> >> >> > I'm an engineer. I don't need to understand it, I only need to make it >> >> > work. If a deep theoretical understanding of transmission-line >> >> > transformers is helpful, I might use it. But if an hour of >> >> > instinct-driven experimenting works, I'll go with that. My >> >> > mosfet-transmission-line output stage, which we've used thousands of >> >> > times, took about an hour of experimenting to design. >> >> >> > Some of the stuff that we do is so complex that closed-form solutions >> >> > are impossible, and serious simulation would cost way too much time >> >> > and money. >> >> >And John doesn't like doing that kind of work. >> >> Of course not. It slows things down, even when it's possible. > >This isn't always true. There is some fiddling that is easy in >simulations, and pretty much impossible in practice.
And some things that are nearly impossible to simulate can be breadboarded in an hour.
> >> And besides, I like to solder once in a while. > >There are better reasons.
Better than doing what I like? Can't think of any. -- 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 Nov 6, 2:25=A0pm, 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 i=
n
> >> >> >messagenews:u2rd98l8ie7ucnfqk2em03grjthvdmoo1q@4ax.com... > > >> ><snip> > > >> >> That particular transformer in the photo was driven by a gaasfet. I=
t
> >> >> worked fine, made really pretty isolated pulse outputs, about 500 p=
s
> >> >> edges. About 2000 of those transformers trigger most all the variou=
s
> >> >> 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? -- Bill Sloman, Sydney