T
Tauno Voipio
Guest
On 25.4.19 21:17, Clive Arthur wrote:
An oil drill pipe with thin Teflon foil?
--
-TV
An oil drill pipe with thin Teflon foil?
--
-TV
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T
Tim Williams
Guest
"Tauno Voipio" <tauno.voipio@notused.fi.invalid> wrote in message
news:q9sugh$3rc$1@dont-email.me...
Works for me. The cylindrical symmetry isn't very relevant either, at that
aspect ratio; I use it unrolled, where it's more properly called
parallel-plate transmission line, usually made with PCB layers, or copper
foil tape which is flexible and easy to shape (for prototyping purposes, of
course).
The real trouble is that, making connections to it takes a lot of space (at
least the width of the TL, obviously), and hence adds ESL (or more
correctly, some kind of tapered or higher-Z TL section, which exhibits low
frequency equivalent L).
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
news:q9sugh$3rc$1@dont-email.me...
Yes, 5k is impossible. But 500m is easy. You can try it with your
nearest etc.
It's not RG6. It is coaxial.
An oil drill pipe with thin Teflon foil?
Works for me. The cylindrical symmetry isn't very relevant either, at that
aspect ratio; I use it unrolled, where it's more properly called
parallel-plate transmission line, usually made with PCB layers, or copper
foil tape which is flexible and easy to shape (for prototyping purposes, of
course).
The real trouble is that, making connections to it takes a lot of space (at
least the width of the TL, obviously), and hence adds ESL (or more
correctly, some kind of tapered or higher-Z TL section, which exhibits low
frequency equivalent L).
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
G
George Herold
Guest
On Thursday, April 25, 2019 at 3:00:10 PM UTC-4, Tim Williams wrote:
with. So as a model two sheets of aluminized mylar? I guess that will
be hard to solder to without melting the mylar. I don't see your problem
with the ends. Certainly there will be an end effect.. but I assume the
thing is much longer than it is wide, so that should mostly go away.
(Or are you seeing some problem I'm missing? )
George h.
Gee it would have been nice if Clive had told us the impedance to begin"Tauno Voipio" <tauno.voipio@notused.fi.invalid> wrote in message
news:q9sugh$3rc$1@dont-email.me...
Yes, 5k is impossible.Ă But 500m is easy.Ă You can try it with your
nearest etc.
It's not RG6.Ă It is coaxial.
An oil drill pipe with thin Teflon foil?
Works for me. The cylindrical symmetry isn't very relevant either, at that
aspect ratio; I use it unrolled, where it's more properly called
parallel-plate transmission line, usually made with PCB layers, or copper
foil tape which is flexible and easy to shape (for prototyping purposes, of
course).
The real trouble is that, making connections to it takes a lot of space (at
least the width of the TL, obviously), and hence adds ESL (or more
correctly, some kind of tapered or higher-Z TL section, which exhibits low
frequency equivalent L).
with. So as a model two sheets of aluminized mylar? I guess that will
be hard to solder to without melting the mylar. I don't see your problem
with the ends. Certainly there will be an end effect.. but I assume the
thing is much longer than it is wide, so that should mostly go away.
(Or are you seeing some problem I'm missing? )
George h.
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
C
Clive Arthur
Guest
On 25/04/2019 18:26, John Larkin wrote:
Absolutely not, John. There've been some genuinely useful responses
among the rote this-is-the-way-I-was-taught stuff, for which I'm
genuinely grateful. There are large gaps in my knowledge which I try to
fill as needed, and the experience of others is often invaluable.
In an ideal world, we could all reveal everything and contribute
co-operatively. But that's jus' goddam' pinko talk.
Cheers
--
Clive
On Thu, 25 Apr 2019 09:19:56 +0100, Clive Arthur
cliveta@nowaytoday.co.uk> wrote:
On 25/04/2019 07:00, Robert Baer wrote:
snipped
Clive Arthur wrote:
I know the usual method is separate LCR sections, but surely in
reality the L is not discrete sections, neither is the C of course,
but there's nothing I can do about that. In this particular case, the
L and R can be readily made with a long air-cored helix of resistance
wire and there are multiple Cs at taps.
* Why in the heck use resistive wire, that is counter-productive; adds
loss, adds noise, and just plain silly.
I'm emulating something with resistive loss, so I figured using
resistance was the way to go. I did consider using dried Aardvark
pelts, but soon dismissed that as plain silly.
Cheers
Asking for help on a secret and unspecified system is kinda silly too.
Absolutely not, John. There've been some genuinely useful responses
among the rote this-is-the-way-I-was-taught stuff, for which I'm
genuinely grateful. There are large gaps in my knowledge which I try to
fill as needed, and the experience of others is often invaluable.
In an ideal world, we could all reveal everything and contribute
co-operatively. But that's jus' goddam' pinko talk.
Cheers
--
Clive
Guest
On Thursday, 25 April 2019 23:09:03 UTC+1, Clive Arthur wrote:
We can't always reveal a lot, and that's not news. Can be a pain yes, but tis life.
NT
On 25/04/2019 18:26, John Larkin wrote:
Asking for help on a secret and unspecified system is kinda silly too.
Absolutely not, John. There've been some genuinely useful responses
among the rote this-is-the-way-I-was-taught stuff, for which I'm
genuinely grateful. There are large gaps in my knowledge which I try to
fill as needed, and the experience of others is often invaluable.
In an ideal world, we could all reveal everything and contribute
co-operatively. But that's jus' goddam' pinko talk.
Cheers
We can't always reveal a lot, and that's not news. Can be a pain yes, but tis life.
NT
J
John Larkin
Guest
On Thu, 25 Apr 2019 23:08:52 +0100, Clive Arthur
<cliveta@nowaytoday.co.uk> wrote:
You could describe the geometry and maybe the materials and length of
your transmission lines without revealing any great secrets.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
<cliveta@nowaytoday.co.uk> wrote:
On 25/04/2019 18:26, John Larkin wrote:
On Thu, 25 Apr 2019 09:19:56 +0100, Clive Arthur
cliveta@nowaytoday.co.uk> wrote:
On 25/04/2019 07:00, Robert Baer wrote:
snipped
Clive Arthur wrote:
I know the usual method is separate LCR sections, but surely in
reality the L is not discrete sections, neither is the C of course,
but there's nothing I can do about that. In this particular case, the
L and R can be readily made with a long air-cored helix of resistance
wire and there are multiple Cs at taps.
* Why in the heck use resistive wire, that is counter-productive; adds
loss, adds noise, and just plain silly.
I'm emulating something with resistive loss, so I figured using
resistance was the way to go. I did consider using dried Aardvark
pelts, but soon dismissed that as plain silly.
Cheers
Asking for help on a secret and unspecified system is kinda silly too.
Absolutely not, John. There've been some genuinely useful responses
among the rote this-is-the-way-I-was-taught stuff, for which I'm
genuinely grateful. There are large gaps in my knowledge which I try to
fill as needed, and the experience of others is often invaluable.
In an ideal world, we could all reveal everything and contribute
co-operatively. But that's jus' goddam' pinko talk.
Cheers
You could describe the geometry and maybe the materials and length of
your transmission lines without revealing any great secrets.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
G
George Herold
Guest
On Thursday, April 25, 2019 at 6:09:03 PM UTC-4, Clive Arthur wrote:
have with SED. (or elsewhere) and getting back in kind,
I multiply my wisdom by ~N (number of SED who can help)
(lotsa times it only takes one good reply to put my
brain on a better path.)
George H.
who has never seen an NDA.
Hmm I think that's wrong. By sharing what little knowledge IOn 25/04/2019 18:26, John Larkin wrote:
On Thu, 25 Apr 2019 09:19:56 +0100, Clive Arthur
cliveta@nowaytoday.co.uk> wrote:
On 25/04/2019 07:00, Robert Baer wrote:
snipped
Clive Arthur wrote:
I know the usual method is separate LCR sections, but surely in
reality the L is not discrete sections, neither is the C of course,
but there's nothing I can do about that. In this particular case, the
L and R can be readily made with a long air-cored helix of resistance
wire and there are multiple Cs at taps.
* Why in the heck use resistive wire, that is counter-productive; adds
loss, adds noise, and just plain silly.
I'm emulating something with resistive loss, so I figured using
resistance was the way to go. I did consider using dried Aardvark
pelts, but soon dismissed that as plain silly.
Cheers
Asking for help on a secret and unspecified system is kinda silly too.
Absolutely not, John. There've been some genuinely useful responses
among the rote this-is-the-way-I-was-taught stuff, for which I'm
genuinely grateful. There are large gaps in my knowledge which I try to
fill as needed, and the experience of others is often invaluable.
In an ideal world, we could all reveal everything and contribute
co-operatively. But that's jus' goddam' pinko talk.
have with SED. (or elsewhere) and getting back in kind,
I multiply my wisdom by ~N (number of SED who can help)
(lotsa times it only takes one good reply to put my
brain on a better path.)
George H.
who has never seen an NDA.
Cheers
--
Clive
J
John Larkin
Guest
On Thu, 25 Apr 2019 16:45:52 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:
Lots of semiconductor vendors now want a signed NDA before they will
send you a data sheet.
We got some orders from a biggish company that first insisted on a
mutual NDA. Then they decided to design the gear themselves. Too bad!
They had to buy the design concepts from us.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
<gherold@teachspin.com> wrote:
On Thursday, April 25, 2019 at 6:09:03 PM UTC-4, Clive Arthur wrote:
On 25/04/2019 18:26, John Larkin wrote:
On Thu, 25 Apr 2019 09:19:56 +0100, Clive Arthur
cliveta@nowaytoday.co.uk> wrote:
On 25/04/2019 07:00, Robert Baer wrote:
snipped
Clive Arthur wrote:
I know the usual method is separate LCR sections, but surely in
reality the L is not discrete sections, neither is the C of course,
but there's nothing I can do about that. In this particular case, the
L and R can be readily made with a long air-cored helix of resistance
wire and there are multiple Cs at taps.
* Why in the heck use resistive wire, that is counter-productive; adds
loss, adds noise, and just plain silly.
I'm emulating something with resistive loss, so I figured using
resistance was the way to go. I did consider using dried Aardvark
pelts, but soon dismissed that as plain silly.
Cheers
Asking for help on a secret and unspecified system is kinda silly too.
Absolutely not, John. There've been some genuinely useful responses
among the rote this-is-the-way-I-was-taught stuff, for which I'm
genuinely grateful. There are large gaps in my knowledge which I try to
fill as needed, and the experience of others is often invaluable.
In an ideal world, we could all reveal everything and contribute
co-operatively. But that's jus' goddam' pinko talk.
Hmm I think that's wrong. By sharing what little knowledge I
have with SED. (or elsewhere) and getting back in kind,
I multiply my wisdom by ~N (number of SED who can help)
(lotsa times it only takes one good reply to put my
brain on a better path.)
George H.
who has never seen an NDA.
Lots of semiconductor vendors now want a signed NDA before they will
send you a data sheet.
We got some orders from a biggish company that first insisted on a
mutual NDA. Then they decided to design the gear themselves. Too bad!
They had to buy the design concepts from us.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
T
Tim Williams
Guest
"George Herold" <gherold@teachspin.com> wrote in message
news:42071f10-010e-4ede-a564-8aef35026bfb@googlegroups.com...
> Certainly there will be an end effect.. but I assume the
thing is much longer than it is wide, so that should mostly go away.
(Or are you seeing some problem I'm missing? )
>
Well, it is in the things I work with (e.g., switching supplies, where the
TL length is comparable to its width).
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
news:42071f10-010e-4ede-a564-8aef35026bfb@googlegroups.com...
> Certainly there will be an end effect.. but I assume the
thing is much longer than it is wide, so that should mostly go away.
(Or are you seeing some problem I'm missing? )
>
Well, it is in the things I work with (e.g., switching supplies, where the
TL length is comparable to its width).
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
J
Johnny B Good
Guest
On Fri, 19 Apr 2019 17:37:49 -0700, George Herold wrote:
====snip====
Just for the record; None.
--
Johnny B Good
====snip====
The difference between the lumped L and tapped L is that the tapped L
has more linkage/ coupling. Is that right?
So how much coupling is in the real cable?
Just for the record; None.
--
Johnny B Good
J
Johnny B Good
Guest
On Sat, 20 Apr 2019 09:16:27 +0100, Clive Arthur wrote:
Yes, the line is continuously loaded with inductance (it's in the nature
of any current pathway). You could simulate it with a series of hundreds
of very tiny discrete inductances per metre of simulated line to a
reasonable standard of accuracy. The point to remember is that you only
get mutual inductance with parallel current pathways and none of these
discrete inductances run parallel to each other in a real cable, which
means you can't cheat by modelling it with a tapped inductor.
--
Johnny B Good
On 20/04/2019 01:27, whit3rd wrote:
On Friday, April 19, 2019 at 11:45:28 AM UTC-7, Clive Arthur wrote:
would you expect that a resistive inductor tapped with multiple Cs
would make a better model than multiple discrete RLC stages?
NEVER gonna make that work. An inductor with taps is a MUTUAL
inductor, you need decoupled ones. Looks similar on a diagram, but
not at all the same.
Isn't that what a real line is? I mean, continuous, not made of
sections?
Gawd help us!
Yes, the line is continuously loaded with inductance (it's in the nature
of any current pathway). You could simulate it with a series of hundreds
of very tiny discrete inductances per metre of simulated line to a
reasonable standard of accuracy. The point to remember is that you only
get mutual inductance with parallel current pathways and none of these
discrete inductances run parallel to each other in a real cable, which
means you can't cheat by modelling it with a tapped inductor.
--
Johnny B Good
J
John Larkin
Guest
On Fri, 19 Apr 2019 12:53:48 +0100, Clive Arthur
<cliveta@nowaytoday.co.uk> wrote:
This might be useful to someone.
Version 4
SHEET 1 880 680
WIRE 80 128 16 128
WIRE 128 128 80 128
WIRE 272 128 208 128
WIRE 368 128 272 128
WIRE 576 128 464 128
WIRE 656 128 576 128
WIRE 16 160 16 128
WIRE 368 160 320 160
WIRE 512 160 464 160
WIRE 656 176 656 128
WIRE 320 192 320 160
WIRE 512 192 512 160
WIRE 16 272 16 240
WIRE 656 304 656 256
FLAG 320 192 0
FLAG 512 192 0
FLAG 16 272 0
FLAG 656 304 0
FLAG 80 128 GEN
FLAG 272 128 A
FLAG 576 128 B
SYMBOL ltline 416 144 R0
WINDOW 0 2 54 Bottom 2
WINDOW 3 6 60 Top 2
SYMATTR InstName O1
SYMATTR Value PCB1
SYMBOL voltage 16 144 R0
WINDOW 0 -86 50 Left 2
WINDOW 3 -319 88 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 1 1n 5p 5p 500p)
SYMBOL res 112 144 R270
WINDOW 0 -36 59 VTop 2
WINDOW 3 -40 59 VBottom 2
SYMATTR InstName R1
SYMATTR Value 50
SYMBOL res 640 160 R0
WINDOW 0 -53 45 Left 2
WINDOW 3 -50 72 Left 2
SYMATTR InstName R2
SYMATTR Value 50
TEXT 56 400 Left 2 !.model PCB1 LTRA(len=10 R=100m L=7.8n C=3.12p)
TEXT 208 448 Left 2 !.tran 0 5n 0 1p
TEXT 112 296 Left 2 ;Lossy PCB Trace JL May 4, 2019
TEXT 152 344 Left 2 ;50 ohms FR4 microstrip
TEXT -296 328 Left 2 ;w=37 diel= 20 mils
TEXT -296 360 Left 2 ;L = 7.8 nH/in C = 3.12 pF/in
TEXT -296 392 Left 2 ;delay = 156 ps/in
TEXT -296 296 Left 2 ;'len' is inches
TEXT -296 424 Left 2 ;DCR ~~ 15 mR/in
The LTRA series resistance is actually skin effect, so the R=100m is a
wild and inaccurate guess. I might TDR some test cases and refine the
model.
I'll have two edge-launch SMA connectors about 0.7" apart, with a
u-shaped 50 ohm trace between them, and a signal pickoff somewhere,
probably midway. I want to modify the trace or the ground plane or
something to compensate for the lumped capacitance of the pickoff. I
can sort of Spice that.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
<cliveta@nowaytoday.co.uk> wrote:
I wanted to make a physical device to emulate a long transmission line.
This particular line has lots of C, I know the R and can guestimate the
L. So I built a lumped line using T sections, 10 Rs, 10 Ls and 9 Cs to
ground. So far so standard.
It didn't perform very well, and I think part of the reason was the
impedance being too large - dominated by the first R - so limiting the
power into the line.
So I made another, but this time using 38 Cs and a long helix of
resistance wire wound on a plastic pipe to provide the R and L. It
measures quite close to the other in terms of R, L & C, but performs
much better.
I'm guessing that the reasons for this include the impedance issue, but
maybe also because the L is now one long tapped inductor, ie coupled and
no longer discrete. To my mind, that seems closer to a real line. Is
that a valid assumption?
In addition, simulating (different - we use these a lot) lumped models
using LTspice always shows worse performance than the provided LTRA
model with the same RLC. Is this a similar effect?
Cheers
This might be useful to someone.
Version 4
SHEET 1 880 680
WIRE 80 128 16 128
WIRE 128 128 80 128
WIRE 272 128 208 128
WIRE 368 128 272 128
WIRE 576 128 464 128
WIRE 656 128 576 128
WIRE 16 160 16 128
WIRE 368 160 320 160
WIRE 512 160 464 160
WIRE 656 176 656 128
WIRE 320 192 320 160
WIRE 512 192 512 160
WIRE 16 272 16 240
WIRE 656 304 656 256
FLAG 320 192 0
FLAG 512 192 0
FLAG 16 272 0
FLAG 656 304 0
FLAG 80 128 GEN
FLAG 272 128 A
FLAG 576 128 B
SYMBOL ltline 416 144 R0
WINDOW 0 2 54 Bottom 2
WINDOW 3 6 60 Top 2
SYMATTR InstName O1
SYMATTR Value PCB1
SYMBOL voltage 16 144 R0
WINDOW 0 -86 50 Left 2
WINDOW 3 -319 88 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 1 1n 5p 5p 500p)
SYMBOL res 112 144 R270
WINDOW 0 -36 59 VTop 2
WINDOW 3 -40 59 VBottom 2
SYMATTR InstName R1
SYMATTR Value 50
SYMBOL res 640 160 R0
WINDOW 0 -53 45 Left 2
WINDOW 3 -50 72 Left 2
SYMATTR InstName R2
SYMATTR Value 50
TEXT 56 400 Left 2 !.model PCB1 LTRA(len=10 R=100m L=7.8n C=3.12p)
TEXT 208 448 Left 2 !.tran 0 5n 0 1p
TEXT 112 296 Left 2 ;Lossy PCB Trace JL May 4, 2019
TEXT 152 344 Left 2 ;50 ohms FR4 microstrip
TEXT -296 328 Left 2 ;w=37 diel= 20 mils
TEXT -296 360 Left 2 ;L = 7.8 nH/in C = 3.12 pF/in
TEXT -296 392 Left 2 ;delay = 156 ps/in
TEXT -296 296 Left 2 ;'len' is inches
TEXT -296 424 Left 2 ;DCR ~~ 15 mR/in
The LTRA series resistance is actually skin effect, so the R=100m is a
wild and inaccurate guess. I might TDR some test cases and refine the
model.
I'll have two edge-launch SMA connectors about 0.7" apart, with a
u-shaped 50 ohm trace between them, and a signal pickoff somewhere,
probably midway. I want to modify the trace or the ground plane or
something to compensate for the lumped capacitance of the pickoff. I
can sort of Spice that.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics