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Bifilar Wound Balun Transformer
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rickman
Nov 3, 2012, 5:15:27 PM11/3/12
to
I am learning a bit about antenna design and one of the references I
found talks about coupling the antenna to the feedline with a bifilar
wound balun transformer. I dug a bit and although I found any number
of references talking about bifilar wound baluns, none explained clearly
why it is important to be bifilar wound.
Any pointers?
Rick
found talks about coupling the antenna to the feedline with a bifilar
wound balun transformer. I dug a bit and although I found any number
of references talking about bifilar wound baluns, none explained clearly
why it is important to be bifilar wound.
Any pointers?
Rick
rickman
Nov 3, 2012, 6:18:12 PM11/3/12
to
shows a bifilar balun in the application circuit I would be using it
with and it makes perfect sense now. Well, mostly. The circuit is
single ended to differential coupling.
I get why the thing is wired up the way it is, I suppose it is important
to use a bifilar winding to keep the two windings as identical as possible.
Actually, I've looked at too many pages. I had two pages mixed up. I
see the one that showed a toroidal core matching transformer is not the
same page as the one that said to bifilar wind the balun. Seems the
first one is a transformer like I'm used to seeing, but the bifilar
wound balun is used in a different way that can't match impedance over
the range I believe the toroid is doing.
It's pretty amazing how many web pages there are that cover in such
detail so many highly specialized topics! And most of these are hobby
pages!!!
Rick
Bill Sloman
Nov 3, 2012, 6:25:35 PM11/3/12
to
http://en.wikipedia.org/wiki/Balun
The twisted pair that constitutes the bifilar winding is a
transmission line, with a particular characteristic impedance which
depends on the diameter of the wire involved and the thickness and
natire of its insulation.
IIRR a twisted pair twisted out of enamel-insulated transformer wire
has characteristic impedance in the ball-park of 120R.
Google throws up a few tutorial papers
http://home.earthlink.net/~christrask/TraskTLTTutorial.pdf
http://www.highfrequencyelectronics.com/Archives/Jan06/HFE0106_TraskPart2.pdf
Transmission line transformers keep on working to much higher
frequencies than conventional transformers - the inter-winding
capacitance becomes part of the transmission line rather than a simple
parasitic load - and in fact only start falling over when the
wavelength of the frequency being transmitted approaches the length of
the winding.
And - for John Larkin's benefit - this is electronics.
--
Bill Sloman, Sydney
Phil Allison
Nov 3, 2012, 6:53:24 PM11/3/12
to
"Bill Sloman"
> Any pointers?
A balun is actually a transmission line transformer.
http://en.wikipedia.org/wiki/Balun
The twisted pair that constitutes the bifilar winding is a
transmission line, with a particular characteristic impedance which
depends on the diameter of the wire involved and the thickness and
natire of its insulation.
IIRR a twisted pair twisted out of enamel-insulated transformer wire
has characteristic impedance in the ball-park of 120R.
wires in incidental to their operation as a transmission line. Twisting
merely serves to eliminate radiation and pick up of external EM fields.
A "bifilar wound " transformer may well have no twisting of the wires at
all, but simply has them laid side by side in smooth layers.
... Phil
Tim Williams
Nov 3, 2012, 7:50:54 PM11/3/12
to
"Bill Sloman" <bill....@ieee.org> wrote in message
news:f3d0bcb5-3ca3-4a83...@v9g2000pbi.googlegroups.com...
tapping such that it inverts one side.
> The twisted pair that constitutes the bifilar winding is a
> transmission line, with a particular characteristic impedance which
> depends on the diameter of the wire involved and the thickness and
> natire of its insulation.
>
> IIRR a twisted pair twisted out of enamel-insulated transformer wire
> has characteristic impedance in the ball-park of 120R.
I got closer to 30 ohms last I measured a pair. Enamel is a whole lot
thinner than extruded jacketing. It's going to be even lower in a
piled-up winding due to the crowding.
The low frequency way to think of it: your leakage inductance is almost
exactly the inductance of the windings as a transmission line.
If you take a piece of twisted pair 1m long, it'll have maybe 0.5uH
inductance (measured at one end of the pair, shorting the far end, at a
frequency well below the electrical length of the line). If you wind it
up onto a form with an air core (making a bifilar solenoid, say), the
self-inductance of each winding might be a few uH, while the inductance
between wires remains the same (it's lower, if anything). Note that you
can measure this leakage two ways: terminus shorted (as a transmission
line) or secondary shorted (transformer leakage). The difference is, you
test P1-S1 and short P2-S2, or test P1-P2 and short S1-S2.
Now if you insert a permeable core, inductance goes way up (into the mH,
perhaps), and coupling coefficient likewise goes up (some fraction less
than 1.0). But leakage remains fairly constant.
Leakage depends almost entirely on winding construction. Self-inductance
depends on the windings and core. Coupling coefficient is the factor
relating the two.
(Yes, you can make a transformer that specifically depends on core
geometry, not just winding construction. An example would be two coils at
right angles, with a core snaked through each. Without the core, they
have zero mutual inductance (infinite leakage). With the core, it's
nonzero. I'm more interested in applications where you actually give a
damn about performance in the first place. :) )
The important thing about transmission line transformers is to forget
about using them as transformers. Use them as transmission lines! If you
put a few loops of coax on a core and drive the shield (calling the shield
the primary, P1-P2), you can't expect any useful kind of behavior from
that, because the shield carries all sorts of crazy currents, depending on
how it's looped through, and which turns it's adjacent to, etc. If
instead you drive the transmission line from one end (P1-S1), you'll get
the same signal out (P2-S2), delayed, except the core allows you
common-mode voltage. You could flip the terminal end around (S2-P2), and
get an inverted signal!
http://www.picosecond.com/product/product.asp?prod_id=47
That's more or less what they do here. The shield necessarily does still
carry a signal (the act of flipping the terminals forces the output
voltage onto the shield anyway), but this occurs "after" the signal
propagated through, and what you do with the shield is now an open
variable -- you could loop it through a whole bunch of ferrite beads,
damping out any oscillations.
It follows that you can create any ratio by connecting transmission lines
in parallel, looping them through a core (it doesn't even matter that the
same core is used, it's just a common mode choke now!), and connecting any
desired series-parallel combination on input and output sides to set the
desired impedance and ratio.
The dirty secret of transmission line transformers is, they aren't at all
interested in reducing leakage inductance, or capacitance, or anything
like that. It's just a big common-mode choke that lets you pipe signals
from wherever to wherever else.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
news:f3d0bcb5-3ca3-4a83...@v9g2000pbi.googlegroups.com...
> A balun is actually a transmission line transformer.
Not a necessary construction method; a balun is just a transformer with
tapping such that it inverts one side.
> The twisted pair that constitutes the bifilar winding is a
> transmission line, with a particular characteristic impedance which
> depends on the diameter of the wire involved and the thickness and
> natire of its insulation.
>
> IIRR a twisted pair twisted out of enamel-insulated transformer wire
> has characteristic impedance in the ball-park of 120R.
thinner than extruded jacketing. It's going to be even lower in a
piled-up winding due to the crowding.
The low frequency way to think of it: your leakage inductance is almost
exactly the inductance of the windings as a transmission line.
If you take a piece of twisted pair 1m long, it'll have maybe 0.5uH
inductance (measured at one end of the pair, shorting the far end, at a
frequency well below the electrical length of the line). If you wind it
up onto a form with an air core (making a bifilar solenoid, say), the
self-inductance of each winding might be a few uH, while the inductance
between wires remains the same (it's lower, if anything). Note that you
can measure this leakage two ways: terminus shorted (as a transmission
line) or secondary shorted (transformer leakage). The difference is, you
test P1-S1 and short P2-S2, or test P1-P2 and short S1-S2.
Now if you insert a permeable core, inductance goes way up (into the mH,
perhaps), and coupling coefficient likewise goes up (some fraction less
than 1.0). But leakage remains fairly constant.
Leakage depends almost entirely on winding construction. Self-inductance
depends on the windings and core. Coupling coefficient is the factor
relating the two.
(Yes, you can make a transformer that specifically depends on core
geometry, not just winding construction. An example would be two coils at
right angles, with a core snaked through each. Without the core, they
have zero mutual inductance (infinite leakage). With the core, it's
nonzero. I'm more interested in applications where you actually give a
damn about performance in the first place. :) )
The important thing about transmission line transformers is to forget
about using them as transformers. Use them as transmission lines! If you
put a few loops of coax on a core and drive the shield (calling the shield
the primary, P1-P2), you can't expect any useful kind of behavior from
that, because the shield carries all sorts of crazy currents, depending on
how it's looped through, and which turns it's adjacent to, etc. If
instead you drive the transmission line from one end (P1-S1), you'll get
the same signal out (P2-S2), delayed, except the core allows you
common-mode voltage. You could flip the terminal end around (S2-P2), and
get an inverted signal!
http://www.picosecond.com/product/product.asp?prod_id=47
That's more or less what they do here. The shield necessarily does still
carry a signal (the act of flipping the terminals forces the output
voltage onto the shield anyway), but this occurs "after" the signal
propagated through, and what you do with the shield is now an open
variable -- you could loop it through a whole bunch of ferrite beads,
damping out any oscillations.
It follows that you can create any ratio by connecting transmission lines
in parallel, looping them through a core (it doesn't even matter that the
same core is used, it's just a common mode choke now!), and connecting any
desired series-parallel combination on input and output sides to set the
desired impedance and ratio.
The dirty secret of transmission line transformers is, they aren't at all
interested in reducing leakage inductance, or capacitance, or anything
like that. It's just a big common-mode choke that lets you pipe signals
from wherever to wherever else.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
John Larkin
Nov 3, 2012, 8:23:51 PM11/3/12
to
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.
https://dl.dropbox.com/u/53724080/Circuits/T760_pulses.jpg
If
>instead you drive the transmission line from one end (P1-S1), you'll get
>the same signal out (P2-S2), delayed, except the core allows you
>common-mode voltage. You could flip the terminal end around (S2-P2), and
>get an inverted signal!
>http://www.picosecond.com/product/product.asp?prod_id=47
https://dl.dropbox.com/u/53724080/Circuits/Coax_Inverter/MVC-229X.JPG
https://dl.dropbox.com/u/53724080/Circuits/Coax_Inverter/MVC-235X.JPG
https://dl.dropbox.com/u/53724080/Circuits/Coax_Inverter/MVC-232X.JPG
https://dl.dropbox.com/u/53724080/Circuits/Coax_Inverter/MVC-234X.JPG
Low frequency response sucks because it is, after all, a dead short at
DC. It gets better if you run the coax through a few ferrite cores.
--
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
Bill Sloman
Nov 3, 2012, 8:35:33 PM11/3/12
to
On Nov 4, 10:50 am, "Tim Williams" <tmoran...@charter.net> wrote:
> "Bill Sloman" <bill.slo...@ieee.org> wrote in message
of "balanced to unbalanced transformer".
The wikipea article makes it fairly clear that one should understand
it as a transmission line transformer. As Phil Alison correctly points
out, you don't actually have to twist the wires together to make them
into a transmission line, though twisting them is a mechanism which
does keep the pair close together.
> > The twisted pair that constitutes the bifilar winding is a
> > transmission line, with a particular characteristic impedance which
> > depends on the diameter of the wire involved and the thickness and
> > natire of its insulation.
>
> > IIRR a twisted pair twisted out of enamel-insulated transformer wire
> > has characteristic impedance in the ball-park of 120R.
>
> I got closer to 30 ohms last I measured a pair.
How thick was the wire? The thickness of the enamel is more or less
independent of the copper gauge, and the impedances is going to be
appreciablyb higher for 40# gauge wire than for 10# gauge.
> Enamel is a whole lot thinner than extruded jacketing. It's going to be even lower in a
> piled-up winding due to the crowding.
Most of the field is confined between the two wires of the pair. I
wouldn't think that adjacent wires would make much difference.
<snip>
This is wrong. I've certainly used them as 1:1 isolating transformers
and they worked fine.
> It follows that you can create any ratio by connecting transmission lines
> in parallel, looping them through a core (it doesn't even matter that the
> same core is used, it's just a common mode choke now!), and connecting any
> desired series-parallel combination on input and output sides to set the
> desired impedance and ratio.
There is some interesting literature on creating integer ratio
transmission line transformers, and if you are clever enough I'm
fairly sure that you can create non-integer ratios - I think there's a
famous paper on the subject. There are also a lot of ways of getting
it wrong.
> The dirty secret of transmission line transformers is, they aren't at all
> interested in reducing leakage inductance, or capacitance, or anything
> like that. It's just a big common-mode choke that lets you pipe signals
> from wherever to wherever else.
That's certainly one way of using them.
--
Bill Sloman, Sydney
> "Bill Sloman" <bill.slo...@ieee.org> wrote in message
>
> news:f3d0bcb5-3ca3-4a83...@v9g2000pbi.googlegroups.com...
>
> > A balun is actually a transmission line transformer.
>
> Not a necessary construction method; a balun is just a transformer with
> tapping such that it inverts one side.
In the sense that the original source of the name was as a contraction
> news:f3d0bcb5-3ca3-4a83...@v9g2000pbi.googlegroups.com...
>
> > A balun is actually a transmission line transformer.
>
> Not a necessary construction method; a balun is just a transformer with
> tapping such that it inverts one side.
of "balanced to unbalanced transformer".
The wikipea article makes it fairly clear that one should understand
it as a transmission line transformer. As Phil Alison correctly points
out, you don't actually have to twist the wires together to make them
into a transmission line, though twisting them is a mechanism which
does keep the pair close together.
> > The twisted pair that constitutes the bifilar winding is a
> > transmission line, with a particular characteristic impedance which
> > depends on the diameter of the wire involved and the thickness and
> > natire of its insulation.
>
> > IIRR a twisted pair twisted out of enamel-insulated transformer wire
> > has characteristic impedance in the ball-park of 120R.
>
> I got closer to 30 ohms last I measured a pair.
independent of the copper gauge, and the impedances is going to be
appreciablyb higher for 40# gauge wire than for 10# gauge.
> Enamel is a whole lot thinner than extruded jacketing. It's going to be even lower in a
> piled-up winding due to the crowding.
wouldn't think that adjacent wires would make much difference.
This is wrong. I've certainly used them as 1:1 isolating transformers
and they worked fine.
> It follows that you can create any ratio by connecting transmission lines
> in parallel, looping them through a core (it doesn't even matter that the
> same core is used, it's just a common mode choke now!), and connecting any
> desired series-parallel combination on input and output sides to set the
> desired impedance and ratio.
transmission line transformers, and if you are clever enough I'm
fairly sure that you can create non-integer ratios - I think there's a
famous paper on the subject. There are also a lot of ways of getting
it wrong.
> The dirty secret of transmission line transformers is, they aren't at all
> interested in reducing leakage inductance, or capacitance, or anything
> like that. It's just a big common-mode choke that lets you pipe signals
> from wherever to wherever else.
--
Bill Sloman, Sydney
Jeff Liebermann
Nov 3, 2012, 9:28:08 PM11/3/12
to
On Sat, 03 Nov 2012 17:15:27 -0400, rickman <gnu...@gmail.com> wrote:
>Any pointers?
>Rick
If you're connecting to an antenna, this might be helpful:
A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing
<http://audiosystemsgroup.com/RFI-Ham.pdf>
Quoting:
The primary function of most baluns, at least in our ham
stations, is to minimize the interaction of our antennas
with the transmission lines that connect them to our radios.
There's more to baluns than just impedance matching.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
>Any pointers?
>Rick
If you're connecting to an antenna, this might be helpful:
A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing
<http://audiosystemsgroup.com/RFI-Ham.pdf>
Quoting:
The primary function of most baluns, at least in our ham
stations, is to minimize the interaction of our antennas
with the transmission lines that connect them to our radios.
There's more to baluns than just impedance matching.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Tim Williams
Nov 3, 2012, 9:40:37 PM11/3/12
to
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in
message news:ffcb985qk94e0cf26...@4ax.com...
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.
message news:ffcb985qk94e0cf26...@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
> 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.
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.
John Larkin
Nov 3, 2012, 9:42:22 PM11/3/12
to
rickman
Nov 3, 2012, 9:44:57 PM11/3/12
to
On 11/3/2012 9:28 PM, Jeff Liebermann wrote:
> On Sat, 03 Nov 2012 17:15:27 -0400, rickman<gnu...@gmail.com> wrote:
>
>> Any pointers?
>> Rick
>
> If you're connecting to an antenna, this might be helpful:
>
> A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing
> <http://audiosystemsgroup.com/RFI-Ham.pdf>
> Quoting:
> The primary function of most baluns, at least in our ham
> stations, is to minimize the interaction of our antennas
> with the transmission lines that connect them to our radios.
> There's more to baluns than just impedance matching.
>
Wow, that's a lot of reading. Thanks.
> On Sat, 03 Nov 2012 17:15:27 -0400, rickman<gnu...@gmail.com> wrote:
>
>> Any pointers?
>> Rick
>
> If you're connecting to an antenna, this might be helpful:
>
> A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing
> <http://audiosystemsgroup.com/RFI-Ham.pdf>
> Quoting:
> The primary function of most baluns, at least in our ham
> stations, is to minimize the interaction of our antennas
> with the transmission lines that connect them to our radios.
> There's more to baluns than just impedance matching.
>
Rick
Message has been deleted
Fred Bartoli
Nov 4, 2012, 12:57:27 PM11/4/12
to
Fred Abse a �crit :
> 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,
Fred.
> 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
>
>> The important thing about transmission line transformers is to forget
>> about using them as transformers. Use them as transmission lines!
>
> 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,
Fred.
John Larkin
Nov 4, 2012, 1:41:10 PM11/4/12
to
On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote:
>Fred Abse a écrit :
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.
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.
>Fred Abse a écrit :
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.
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.
Fred Bartoli
Nov 4, 2012, 1:49:14 PM11/4/12
to
John Larkin a écrit :
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.
--
Thanks,
Fred.
> On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote:
>
>> Fred Abse a écrit :
>>> 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
>
>> Fred Abse a écrit :
>>> 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.
>
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.
>
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.
--
Thanks,
Fred.
rickman
Nov 3, 2012, 11:25:46 PM11/3/12
to
On 11/3/2012 9:42 PM, John Larkin wrote:
> On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams"
> <tmor...@charter.net> wrote:
>
>> "John Larkin"<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>> message news:ffcb985qk94e0cf26...@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,
> On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams"
> <tmor...@charter.net> wrote:
>
>> "John Larkin"<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>> message news:ffcb985qk94e0cf26...@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.
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.
Do you not see how your posts make you look?
Rick
John S
Nov 4, 2012, 2:33:59 PM11/4/12
to
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"
>> <tmor...@charter.net> wrote:
>>
>>> "John Larkin"<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>>> message news:ffcb985qk94e0cf26...@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.
> On 11/3/2012 9:42 PM, John Larkin wrote:
>> On Sat, 3 Nov 2012 20:40:37 -0500, "Tim Williams"
>> <tmor...@charter.net> wrote:
>>
>>> "John Larkin"<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>>> message news:ffcb985qk94e0cf26...@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.
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.
> Do you not see how your posts make you look?
>
> Rick
John Larkin
Nov 4, 2012, 3:49:23 PM11/4/12
to
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.
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?
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.
Jamie
Nov 4, 2012, 4:24:35 PM11/4/12
to
The doctor made a mistake when you were born, they disposed the best
part that came out of your mother, the afterbirth.
Jamie
Jamie
Nov 4, 2012, 4:37:19 PM11/4/12
to
would like to make people think otherwise.
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.
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.
Those guilty of this need not to step forward, I already know who
most of you are.
Jamie
rickman
Nov 4, 2012, 4:36:32 PM11/4/12
to
understand this well enough", but the way you say it comes off like an
amateur. I have spent a lot of time in my career fixing systems
designed by people who obviously "only needed to make it work", but then
it stopped working for some unknown reason.
> 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.
>
> In the electronic design business, we seldom really understand what
> we're doing, at the first-principles level.
they were posers. I've never heard any of them brag about it.
> 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]
typically they understand everything about them and how to connect them
that they need to.
>> 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.
someone with no level of understanding.
I shouldn't be posting about this. It is clear that you understand
completely what you are saying and I expect you understand how it makes
you appear. So sorry for bothering you with this.
Rick
Spehro Pefhany
Nov 4, 2012, 5:11:16 PM11/4/12
to
equipment) I got for him was broken-- turns out the brightness control
(or whatever you call it on a digital scope) was turned down. Same guy
claimed an expensive SRS bridge with 0.1% accuracy was giving 10%
error on a reading-- turned out he was using 100Hz to measure a
tens-of-pF cap and it was performing well within spec according to the
manual. He has written peer-reviewed papers on these things.. sad.
>
> Those guilty of this need not to step forward, I already know who
>most of you are.
>
>Jamie
It's a rare person that can get all the theory right and the practice
> Those guilty of this need not to step forward, I already know who
>most of you are.
>
>Jamie
right- they deserve to be well-rewarded.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Michael A. Terrell
Nov 4, 2012, 5:30:25 PM11/4/12
to
Jamie wrote:
>
> Those that don't know shit, should shit elsewhere ! Get it?
Michael A. Terrell
Nov 4, 2012, 5:31:49 PM11/4/12
to
Jamie wrote:
>
> Those guilty of this need not to step forward, I already know who
> most of you are.
John Larkin
Nov 4, 2012, 5:39:37 PM11/4/12
to
Do you do closed-form Maxwell's Equations on every circuit? Or full EM
simulation? I bet you don't.
>
>
>> 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.
>>
>> In the electronic design business, we seldom really understand what
>> we're doing, at the first-principles level.
>
>That is scary. I find a lot of people like that though. I just thought
>they were posers. I've never heard any of them brag about it.
simulate everything we do, down to the physics. Sometimes you do
whatever works.
>
>
> > 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]
>
>Yeah, that's what everyone does, but when they connect those parts,
>typically they understand everything about them and how to connect them
>that they need to.
be great, but we're not privvy to that information.
>
>
>>> 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.
>
>I'm talking about the statements you make that sound like they are from
>someone with no level of understanding.
>
>I shouldn't be posting about this. It is clear that you understand
>completely what you are saying and I expect you understand how it makes
>you appear. So sorry for bothering you with this.
fully understanding a system. But there we are, working with what we
have.
I can't see a lot of risk in designing a transmission-line transformer
by experiment. It should be very reproducible, and it is. A little
math can check for things like breakdown voltage, if that matters.
Tim Williams
Nov 4, 2012, 8:43:52 PM11/4/12
to
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in
message news:u2rd98l8ie7ucnfqk...@4ax.com...
> How deep does your understanding go? Quantum mechanics?
As a physicist, I can affirm that. Others may vary.
> String theory?
Doesn't count -- even the string theorists don't understand the stuff. ;-)
> Do you do closed-form Maxwell's Equations on every circuit? Or full EM
> simulation?
I do on every single board I make. Not closed-form, but open-form
approximation, qualitative accuracy. Implemented in wetware, too. Works
very well.
> I'm not bragging. I wish I had the tools to fully understand or
> simulate everything we do, down to the physics. Sometimes you do
> whatever works.
it -- but I'm guessing that wish isn't as unconditional as it was phrased.
In actuality, you don't care at all, and are more than happy enough
guessing. Which again illustrates your inconsistent self-representation.
<snip>
<quoted from proceeding post>
> 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.
Are you aware that ~20nH is ~86mm of 50 ohm, 0.67c 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.
Assuming the headers pictured are 0.1" centers, the cores are roughly T37
size ferrites, a bit thicker than usual. I get 14mm for the length of a
single turn on a regular T37, so it might be closer to 18mm per turn,
maybe 20mm with coax thickness. That's 60mm total length, or 14nH. The
soldered connections and board traces have almost as much, depending on if
there's a ground plane just out of sight or not. But by then it's not
mutual, which is all the more reason it's not LL you're supposing about.
Actual performance will show helical resonator action starting around
1GHz, which is what the under-hump on your leading edge comes from. And
probably other nasties if you tested it with a ps generator rather than
the "sub-ns" this particular device produces.
rickman
Nov 4, 2012, 9:15:32 PM11/4/12
to
On 11/4/2012 8:43 PM, Tim Williams wrote:
> "John Larkin"<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
> message news:u2rd98l8ie7ucnfqk...@4ax.com...
>> How deep does your understanding go? Quantum mechanics?
>
> As a physicist, I can affirm that. Others may vary.
I learned a little in chemistry classes... very little.
> "John Larkin"<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
> message news:u2rd98l8ie7ucnfqk...@4ax.com...
>> How deep does your understanding go? Quantum mechanics?
>
> As a physicist, I can affirm that. Others may vary.
>> String theory?
>
> Doesn't count -- even the string theorists don't understand the stuff. ;-)
predict anything different from existing quantum theory.
>> Do you do closed-form Maxwell's Equations on every circuit? Or full EM
>> simulation?
>
> And you don't?
>
> I do on every single board I make. Not closed-form, but open-form
> approximation, qualitative accuracy. Implemented in wetware, too. Works
> very well.
Only then will I call you a real engineer ;)
> Are you aware that ~20nH is ~86mm of 50 ohm, 0.67c coax?
>
> Assuming the headers pictured are 0.1" centers, the cores are roughly T37
> size ferrites, a bit thicker than usual. I get 14mm for the length of a
> single turn on a regular T37, so it might be closer to 18mm per turn,
> maybe 20mm with coax thickness. That's 60mm total length, or 14nH. The
> soldered connections and board traces have almost as much, depending on if
> there's a ground plane just out of sight or not. But by then it's not
> mutual, which is all the more reason it's not LL you're supposing about.
>
> Actual performance will show helical resonator action starting around
> 1GHz, which is what the under-hump on your leading edge comes from. And
> probably other nasties if you tested it with a ps generator rather than
> the "sub-ns" this particular device produces.
sounds like it would be right down your alley! I don't know nothing
about birthin' no babies, Ms. Scarlett! But it looks like I'm going to
have to learn...
Rick
John Larkin
Nov 4, 2012, 9:53:23 PM11/4/12
to
On Sun, 4 Nov 2012 19:43:52 -0600, "Tim Williams"
<tmor...@charter.net> wrote:
>"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>message news:u2rd98l8ie7ucnfqk...@4ax.com...
>> How deep does your understanding go? Quantum mechanics?
>
>As a physicist, I can affirm that. Others may vary.
>
>> String theory?
>
>Doesn't count -- even the string theorists don't understand the stuff. ;-)
>
>> Do you do closed-form Maxwell's Equations on every circuit? Or full EM
>> simulation?
>
>And you don't?
Use Maxwell's equations? No, I don't. And I rarely do EM sims; I did
<tmor...@charter.net> wrote:
>"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>message news:u2rd98l8ie7ucnfqk...@4ax.com...
>> How deep does your understanding go? Quantum mechanics?
>
>As a physicist, I can affirm that. Others may vary.
>
>> String theory?
>
>Doesn't count -- even the string theorists don't understand the stuff. ;-)
>
>> Do you do closed-form Maxwell's Equations on every circuit? Or full EM
>> simulation?
>
>And you don't?
post about one such, here a while back, using ATLC2 to design a PCB
stackup for an edge-launch SMA connector. It was tedious, and it
worked. It was sort of cool...
https://dl.dropbox.com/u/53724080/ATLC/Edge_alone_4.jpg
https://dl.dropbox.com/u/53724080/ATLC/E-field.jpg
>
>I do on every single board I make. Not closed-form, but open-form
>approximation, qualitative accuracy. Implemented in wetware, too. Works
>very well.
I use a couple of PC apps to calculate trace impedances, Appcad and
TXLine. But you don't have to understand a lot to drive those.
>
>> I'm not bragging. I wish I had the tools to fully understand or
>> simulate everything we do, down to the physics. Sometimes you do
>> whatever works.
>
>Well, if you really wished, you'd buy the entire Ansoft suite and *do*
>it -- but I'm guessing that wish isn't as unconditional as it was phrased.
that I've mentioned, and a few home-made programs, do what we need.
>In actuality, you don't care at all, and are more than happy enough
>guessing. Which again illustrates your inconsistent self-representation.
there's anything wrong with designing a gate
driver/mosfet/transmission line transformer circuit using instinct and
experiment. The edges I'm getting are about 20x faster than the
numbers on the mosfet data sheet. So much for theory.
If I need a pullup resistor or a bypass cap value, or a trace width
for small DC currents, I usually guess.
>
><snip>
><quoted from proceeding post>
>> 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.
>
>Are you aware that ~20nH is ~86mm of 50 ohm, 0.67c coax?
What I'm really aware of is that it works and we sell lots of them.
>
>Assuming the headers pictured are 0.1" centers, the cores are roughly T37
>size ferrites, a bit thicker than usual. I get 14mm for the length of a
>single turn on a regular T37, so it might be closer to 18mm per turn,
>maybe 20mm with coax thickness. That's 60mm total length, or 14nH. The
>soldered connections and board traces have almost as much, depending on if
>there's a ground plane just out of sight or not. But by then it's not
>mutual, which is all the more reason it's not LL you're supposing about.
>
>Actual performance will show helical resonator action starting around
>1GHz, which is what the under-hump on your leading edge comes from. And
>probably other nasties if you tested it with a ps generator rather than
>the "sub-ns" this particular device produces.
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.
Tim Williams
Nov 4, 2012, 11:52:09 PM11/4/12
to
"rickman" <gnu...@gmail.com> wrote in message
news:k777h0$knd$1...@dont-email.me...
more accurately the problem, as I also understand it.
Sure! My work is done:
http://vk1od.net/antenna/shieldedloop/
Well, maybe not *my* work, but... helpful nonetheless. Lots of excellent
analysis on his website.
Tim
news:k777h0$knd$1...@dont-email.me...
>>> String theory?
>>
>> Doesn't count -- even the string theorists don't understand the stuff.
>> ;-)
>
> My understanding is not that they don't understand it, it just doesn't
> predict anything different from existing quantum theory.
Notwithstanding Feynman's quote, "nobody really understands QM", that's
>>
>> Doesn't count -- even the string theorists don't understand the stuff.
>> ;-)
>
> My understanding is not that they don't understand it, it just doesn't
> predict anything different from existing quantum theory.
more accurately the problem, as I also understand it.
http://vk1od.net/antenna/shieldedloop/
Well, maybe not *my* work, but... helpful nonetheless. Lots of excellent
analysis on his website.
Tim
rickman
Nov 5, 2012, 10:53:20 AM11/5/12
to
designing one... or helping. Still, thanks.
Rick
Bill Sloman
Nov 5, 2012, 5:33:28 PM11/5/12
to
On Nov 5, 8:30 am, Jamie
>
> >>>>"John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
> >>>>messagenews:ffcb985qk94e0cf26...@4ax.com...
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.
>
> At least you actually do something, not like a good many here that
> would like to make people think otherwise.
>
> 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.
>
> I 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.
> Those 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
<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 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"
>
> >>>>"John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
> >>>>messagenews:ffcb985qk94e0cf26...@4ax.com...
> > 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.
>
> At least you actually do something, not like a good many here that
> would like to make people think otherwise.
>
> 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.
>
> I just love those that talk shit and most likely hardly even touch a
> piece of equipment. When they do I am sure
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.
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.
> Those guilty of this need not to step forward, I already know who
> most of you are.
--
Bill Sloman, Sydney
Bill Sloman
Nov 5, 2012, 5:40:55 PM11/5/12
to
On Nov 5, 1:53 pm, John Larkin
<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
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sun, 4 Nov 2012 19:43:52 -0600, "Tim Williams"
> On Sun, 4 Nov 2012 19:43:52 -0600, "Tim Williams"
> <tmoran...@charter.net> wrote:
> >"John Larkin" <jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
> >messagenews:u2rd98l8ie7ucnfqk...@4ax.com...
> >"John Larkin" <jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
<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.
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
John Larkin
Nov 5, 2012, 8:17:22 PM11/5/12
to
On Mon, 5 Nov 2012 14:40:55 -0800 (PST), Bill Sloman
<bill....@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:u2rd98l8ie7ucnfqk...@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.
<bill....@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:u2rd98l8ie7ucnfqk...@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.
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
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
John Larkin
Nov 5, 2012, 8:20:04 PM11/5/12
to
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
Photonics and fiberoptic TTL data links
Bill Sloman
Nov 5, 2012, 9:11:07 PM11/5/12
to
On Nov 6, 12:17 pm, John Larkin <jlar...@highlandtechnology.com>
wrote:
> >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.
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
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:u2rd98l8ie7ucnfqk...@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".
>
>
>
>
>
>
>
>
>
> <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:u2rd98l8ie7ucnfqk...@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.
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.
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
Bill Sloman
Nov 5, 2012, 9:14:09 PM11/5/12
to
On Nov 6, 12:20 pm, John Larkin <jlar...@highlandtechnology.com>
wrote:
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
wrote:
simulations, and pretty much impossible in practice.
> And besides, I like to solder once in a while.
---
Bill Sloman, Sydney
Jamie
Nov 5, 2012, 9:25:35 PM11/5/12
to
Jamie
John Larkin
Nov 5, 2012, 10:25:50 PM11/5/12
to
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.
--
John Larkin Highland Technology Inc
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
John Larkin
Nov 5, 2012, 10:28:25 PM11/5/12
to
breadboarded in an hour.
>
>> And besides, I like to solder once in a while.
>
>There are better reasons.
--
John Larkin Highland Technology Inc
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
Bill Sloman
Nov 6, 2012, 3:36:11 AM11/6/12
to
On Nov 6, 2:25 pm, John Larkin
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
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.
maybe you were just the low bidder.
>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.
Should we trust your claims about your timing modules?
--
Bill Sloman, Sydney
John Larkin
Nov 6, 2012, 10:06:16 AM11/6/12
to
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 S
Nov 6, 2012, 2:20:04 PM11/6/12
to
John S
Nov 6, 2012, 2:24:05 PM11/6/12
to
least they understand the subject whereas you don't even know your job
function.
John S
Nov 6, 2012, 2:41:50 PM11/6/12
to
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.
> At least you actually do something, not like a good many here that
> would like to make people think otherwise.
> 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.
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.
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.
>
Message has been deleted
John Larkin
Nov 6, 2012, 4:23:35 PM11/6/12
to
On Sun, 04 Nov 2012 19:49:14 +0100, Fred Bartoli <" "> wrote:
>John Larkin a écrit :
>> On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote:
>>
>>> Fred Abse a écrit :
>>>> 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
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
>John Larkin a écrit :
>> On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote:
>>
>>> Fred Abse a écrit :
>>>> 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
Photonics and fiberoptic TTL data links
Bill Sloman
Nov 6, 2012, 6:12:50 PM11/6/12
to
<snip>
> > 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.
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
> > 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.
within the rather circumscribed universe of discourse - and the rest
of us know to be quite a way from the truth.
--
Bill Sloman, Sydney
Bill Sloman
Nov 6, 2012, 6:26:09 PM11/6/12
to
On Nov 7, 2:06 am, John Larkin
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
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 6 Nov 2012 00:36:11 -0800 (PST), Bill Sloman
> 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> wrote in
> >> >> >> >messagenews:u2rd98l8ie7ucnfqk...@4ax.com...
<snip>
> >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> wrote in
> >> >> >> >messagenews:u2rd98l8ie7ucnfqk...@4ax.com...
<snip>
> >> 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?
It seems most unlikely, but - accepting that the paper is honest -
>
> >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?
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.
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
Bill Sloman
Nov 6, 2012, 6:29:35 PM11/6/12
to
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 19:49:14 +0100, Fred Bartoli <" "> wrote:
>
>
>
>
>
>
>
>
>
> >> On Sun, 04 Nov 2012 18:57:27 +0100, Fred Bartoli <" "> wrote:
>
> >>> Fred Abse a crit :
>
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
Jamie
Nov 6, 2012, 7:20:23 PM11/6/12
to
you come up with..
Jamie
Jamie
Nov 6, 2012, 7:41:09 PM11/6/12
to
on your solders to think, let alone operate a keyboard and wipe your
ass. You spend all your time searching the web for that black hole of
yours to suck up in hopes that there is some shred of information you
can use to mislead the public with great deception.
Don't be including the general public in your punitive deceitful
appearance. Many here don't know any better, they are simple minded
sheep lost in the propaganda orchestrated by the likes of you.
Jamie
Jamie
Nov 6, 2012, 7:48:18 PM11/6/12
to
Impersonation is more your style.
Jamie
Jamie
Nov 6, 2012, 7:49:35 PM11/6/12
to
Jamie
Jamie
Nov 6, 2012, 7:58:33 PM11/6/12
to
John Larkin
Nov 6, 2012, 8:11:11 PM11/6/12
to
things, and, with luck, be appreciated for it?
>
>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.
their science and help them with the electronics. There's a lot of
scientific gear out there that, as Phil says, needlessly throws away
30 dB of performance. (Remember the insane FTMS preamp I posted about
here? Down 30 dB, but still better than Brand B, who tossed 40 dB.) It
wouldn't be very hard to explore that possibility. It would be fun.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
John Larkin
Nov 6, 2012, 8:17:10 PM11/6/12
to
sample current, and follow that with a 1e6 gain amp with infinite
CMRR.
I like to build analog error computers into my circuits too, so I can
graph error or goodness on the same plot as actual signals.
I do tend to worry about power dissipation and real-world stuff in
sims, where it just doesn't matter. A couple of 1 ohm resistors make a
good divider, but I worry about the current, so I use 1Ks.
Jamie
Nov 6, 2012, 8:31:14 PM11/6/12
to
John Larkin wrote:
> On Tue, 6 Nov 2012 15:29:35 -0800 (PST), Bill Sloman
> <bill....@ieee.org> wrote:
>
>>>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.
>
>
> It's cool to stick a micro-ohm resistor somewhere in a circuit to
> sample current, and follow that with a 1e6 gain amp with infinite
> CMRR.
>
Micro ohms?, we use micro ohms for measuring current but they are kind
> On Tue, 6 Nov 2012 15:29:35 -0800 (PST), Bill Sloman
> <bill....@ieee.org> wrote:
>
>>>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.
>
>
> It's cool to stick a micro-ohm resistor somewhere in a circuit to
> sample current, and follow that with a 1e6 gain amp with infinite
> CMRR.
>
of large in mass. Or are we not talking about copper?
Jamie
Fred Bartoli
Nov 6, 2012, 8:30:01 PM11/6/12
to
conditioning and in this regards a 0V voltage source and a CCVS in lieu
of your 1�ohm and 1E6 gain VCVS is much better.
I have some applications where convergence is sometimes hard to obtain
and I sure wouldn't want to make the situation worse than it needs to be.
--
Thanks,
Fred.
John Larkin
Nov 6, 2012, 8:42:11 PM11/6/12
to
On Wed, 07 Nov 2012 02:30:01 +0100, Fred Bartoli <" "> wrote:
>John Larkin a écrit :
>of your 1ľohm and 1E6 gain VCVS is much better.
sampler is open-loop so won't have convergence problems.
LT Spice sometimes does weird things with time steps, especially if a
circuit has radically different time constants here and there, or
mysterious stuff inside a part model. Real transistors seem to stress
it, too. Somebody should write a book or article about all that.
>John Larkin a écrit :
>I have some applications where convergence is sometimes hard to obtain
>and I sure wouldn't want to make the situation worse than it needs to be.
Spice is all double floats, no? 1e6 isn't a very big number. A current
>and I sure wouldn't want to make the situation worse than it needs to be.
sampler is open-loop so won't have convergence problems.
LT Spice sometimes does weird things with time steps, especially if a
circuit has radically different time constants here and there, or
mysterious stuff inside a part model. Real transistors seem to stress
it, too. Somebody should write a book or article about all that.
John Larkin
Nov 6, 2012, 8:44:26 PM11/6/12
to
We do make our own current shunts, punched or photoetched from rolled
manganin, but generally in the milli-ohms.
Tim Williams
Nov 6, 2012, 9:24:28 PM11/6/12
to
"John Larkin" <jla...@highlandtechnology.com> wrote in message
news:6tej98pr9faetrfr0...@4ax.com...
that save inverting the whole N x N matrix. Matrix operations are O(N^3),
so a modest circuit with 100 nodes takes about 10^6 more operations than a
basic battery and lightbulb circuit. And that's if it guessed the correct
timestep the first time, which very rarely occurs. SPICE throws away a
*lot* of computation.
Obviously, you've never simulated anything of significance, or you'd know
this. The degree of these approximations is controlled by the simulation
parameters, which experienced users understand must be optimized for a
given model to avoid slowing to a crawl (with default settings, LTSpice
likes to wander off into the picoseconds, eating glue) or generating
errors (most often "timestep too small").
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
news:6tej98pr9faetrfr0...@4ax.com...
> Spice is all double floats, no? 1e6 isn't a very big number. A current
> sampler is open-loop so won't have convergence problems.
What the numbers are doesn't matter, the solver uses iterative algorithms
> sampler is open-loop so won't have convergence problems.
that save inverting the whole N x N matrix. Matrix operations are O(N^3),
so a modest circuit with 100 nodes takes about 10^6 more operations than a
basic battery and lightbulb circuit. And that's if it guessed the correct
timestep the first time, which very rarely occurs. SPICE throws away a
*lot* of computation.
Obviously, you've never simulated anything of significance, or you'd know
this. The degree of these approximations is controlled by the simulation
parameters, which experienced users understand must be optimized for a
given model to avoid slowing to a crawl (with default settings, LTSpice
likes to wander off into the picoseconds, eating glue) or generating
errors (most often "timestep too small").
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
John Larkin
Nov 6, 2012, 11:11:41 PM11/6/12
to
On Tue, 6 Nov 2012 20:24:28 -0600, "Tim Williams"
<tmor...@charter.net> wrote:
>"John Larkin" <jla...@highlandtechnology.com> wrote in message
>news:6tej98pr9faetrfr0...@4ax.com...
>> Spice is all double floats, no? 1e6 isn't a very big number. A current
>> sampler is open-loop so won't have convergence problems.
>
>What the numbers are doesn't matter, the solver uses iterative algorithms
>that save inverting the whole N x N matrix. Matrix operations are O(N^3),
>so a modest circuit with 100 nodes takes about 10^6 more operations than a
>basic battery and lightbulb circuit. And that's if it guessed the correct
>timestep the first time, which very rarely occurs. SPICE throws away a
>*lot* of computation.
>
>Obviously, you've never simulated anything of significance,
Only a couple of hundred million dollars worth.
<tmor...@charter.net> wrote:
>"John Larkin" <jla...@highlandtechnology.com> wrote in message
>news:6tej98pr9faetrfr0...@4ax.com...
>> Spice is all double floats, no? 1e6 isn't a very big number. A current
>> sampler is open-loop so won't have convergence problems.
>
>What the numbers are doesn't matter, the solver uses iterative algorithms
>that save inverting the whole N x N matrix. Matrix operations are O(N^3),
>so a modest circuit with 100 nodes takes about 10^6 more operations than a
>basic battery and lightbulb circuit. And that's if it guessed the correct
>timestep the first time, which very rarely occurs. SPICE throws away a
>*lot* of computation.
>
>Obviously, you've never simulated anything of significance,
My first simulation, when I was about 20, was of a 32,000 horsepower
steamship propulsion system, all the way from the my control system to
the hull moving through the water. I didn't use Spice.
It worked just fine.
--
John Larkin Highland Technology Inc
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Photonics and fiberoptic TTL data links
Bill Sloman
Nov 7, 2012, 11:57:30 PM11/7/12
to
On Nov 7, 11:14 am, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
> BillSlomanwrote:
extra credit come up with an idea that makes some kind of sense - you
haven't yet, but while there's life there's hope.
--
Bill Sloman, Sydney
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
> BillSlomanwrote:
> I get the idea that a simulator is the only source for any inclinations
> you come up with..
Congratulations on coming up with an idea. You don't do it often. For
> you come up with..
extra credit come up with an idea that makes some kind of sense - you
haven't yet, but while there's life there's hope.
--
Bill Sloman, Sydney
Bill Sloman
Nov 8, 2012, 12:00:34 AM11/8/12
to
On Nov 7, 12:42 pm, John Larkin <jlar...@highlandtechnology.com>
wrote:
> >of your 1 ohm and 1E6 gain VCVS is much better.
thesis back in 1969.
--
Bill Sloman, Sydney
wrote:
> On Wed, 07 Nov 2012 02:30:01 +0100, Fred Bartoli <" "> wrote:
>
>
>
>
>
>
>
>
>
> >John Larkin a crit :
>
>
>
>
>
>
>
>
>
> >I have some applications where convergence is sometimes hard to obtain
> >and I sure wouldn't want to make the situation worse than it needs to be.
>
> Spice is all double floats, no? 1e6 isn't a very big number. A current
> sampler is open-loop so won't have convergence problems.
>
> LT Spice sometimes does weird things with time steps, especially if a
> circuit has radically different time constants here and there, or
> mysterious stuff inside a part model. Real transistors seem to stress
> it, too. Somebody should write a book or article about all that.
It's been done. I think I referenced a text on the subject in my Ph.D.
> >and I sure wouldn't want to make the situation worse than it needs to be.
>
> Spice is all double floats, no? 1e6 isn't a very big number. A current
> sampler is open-loop so won't have convergence problems.
>
> LT Spice sometimes does weird things with time steps, especially if a
> circuit has radically different time constants here and there, or
> mysterious stuff inside a part model. Real transistors seem to stress
> it, too. Somebody should write a book or article about all that.
thesis back in 1969.
--
Bill Sloman, Sydney
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