[EE] impedance of unsecured parallel wires

[Bob Blick]

I was thinking about how wires in DC spot welders jump when you perform a weld, and how it's most likely electromagnetic forces. Then it got me thinking about how it affects power transmission with long spans between the towers. Those wires are far enough apart and other losses are dominant, so I'm sure it's insignificant.

A very long time ago I needed to wire some loudspeakers and used two strands of some salvaged single conductor insulated solid wire, fairly heavy gauge. When I later replaced it with regular speaker cable of similar gauge, the system sounded better. I wonder now if the wires vibrated enough because of the electromagnetic effect that it caused resonances. My ears were pretty good back then.

Perhaps I should do some testing and see if I can measure the effect.

Bob

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[Justin Richards]

I have pondered what would be the best transmission line for speakers and
concluded that two conductors separated by some distance would be optimal.
I assumed skin effect below 20kHz would be negligible but others have
indicated otherwise.
The results of your test would be interesting.
Justin

On 6 Apr 2018 06:58, "Bob Blick" <***@outlook.com> wrote:

> I was thinking about how wires in DC spot welders jump when you perform a
> weld, and how it's most likely electromagnetic forces. Then it got me
> thinking about how it affects power transmission with long spans between
> the towers. Those wires are far enough apart and other losses are dominant,
> so I'm sure it's insignificant.
>
> A very long time ago I needed to wire some loudspeakers and used two
> strands of some salvaged single conductor insulated solid wire, fairly
> heavy gauge. When I later replaced it with regular speaker cable of similar
> gauge, the system sounded better. I wonder now if the wires vibrated enough
> because of the electromagnetic effect that it caused resonances. My ears
> were pretty good back then.
>
> Perhaps I should do some testing and see if I can measure the effect.
>
> Bob
>
> --
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[RussellMc]

On 6 April 2018 at 10:57, Bob Blick <***@outlook.com> wrote:

> I was thinking about how wires in DC spot welders jump when you perform a
> weld, and how it's most likely electromagnetic forces. Then it got me
> thinking about how it affects power transmission with long spans between
> the towers. Those wires are far enough apart and other losses are dominant,
> so I'm sure it's insignificant.
>


Telephone exchange busbars suck [tm].

Removing some of the spacers during maintenance turned out to be a VERY bad
idea in at least one case I read of.
Operating currents can be in the thousands of Amps at 50V. Short cct
current is "higher. Back then, SC protection was fuses.

Accidentally (presumably) shorting a metal vacuum cleaner tube across the
busbars and dropping a wrench thereon was also reported to have been a bad
idea.
Once started an arc would probably have no problem maintaining, and welded
bits of the starter metal would probably help.

I once did not have the nerve to turn off the contactors in a 230V/400V
commercial switchboard in a cafe I was eating at when the switchboard
started throwing impressive arcs from place to place on the FRONT of the
board. I don't know how it managed that and did not wish to become part of
its show.

Friends had phase and neutral to their home swapped by an electrician !!!.
On re-enabling steam came out of the cold taps, the house groaned and
moaned and worms crawled out of the ground. Really.
The electrician had left before the effects became noticed so they had to
summon help. Alas I only heard of it latterly.


Russell
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[Mike]

On 05/04/2018 23:57, Bob Blick wrote:
> A very long time ago I needed to wire some loudspeakers and used two strands of some salvaged single conductor insulated solid wire, fairly heavy gauge. When I later replaced it with regular speaker cable of similar gauge, the system sounded better. I wonder now if the wires vibrated enough because of the electromagnetic effect that it caused resonances. My ears were pretty good back then.
>
> Perhaps I should do some testing and see if I can measure the effect.
>
> Bob
>

The closer the pair of wires, the better the coupling and the lower the
inductance.  If your speaker cable was e.g. 3 meters long (~10ft) then
they could be adding around 1 Ohm inductive reactance at the upper end
of the audio frequency range, if the wires were spaced apart.

Mike
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[John Gardner]

Probably not low-oxygen copper, eh? "8)

On 4/6/18, Mike <***@gmail.com> wrote:
> On 05/04/2018 23:57, Bob Blick wrote:
>> A very long time ago I needed to wire some loudspeakers and used two
>> strands of some salvaged single conductor insulated solid wire, fairly
>> heavy gauge. When I later replaced it with regular speaker cable of
>> similar gauge, the system sounded better. I wonder now if the wires
>> vibrated enough because of the electromagnetic effect that it caused
>> resonances. My ears were pretty good back then.
>>
>> Perhaps I should do some testing and see if I can measure the effect.
>>
>> Bob
>>
>
> The closer the pair of wires, the better the coupling and the lower the
> inductance.  If your speaker cable was e.g. 3 meters long (~10ft) then
> they could be adding around 1 Ohm inductive reactance at the upper end
> of the audio frequency range, if the wires were spaced apart.
>
> Mike
> --
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>

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[Clint Jay]

Needs a dip in liquid nitrogen I reckon

On Fri, 6 Apr 2018 2:24 pm John Gardner, <***@gmail.com> wrote:

> Probably not low-oxygen copper, eh? "8)
>
> On 4/6/18, Mike <***@gmail.com> wrote:
> > On 05/04/2018 23:57, Bob Blick wrote:
> >> A very long time ago I needed to wire some loudspeakers and used two
> >> strands of some salvaged single conductor insulated solid wire, fairly
> >> heavy gauge. When I later replaced it with regular speaker cable of
> >> similar gauge, the system sounded better. I wonder now if the wires
> >> vibrated enough because of the electromagnetic effect that it caused
> >> resonances. My ears were pretty good back then.
> >>
> >> Perhaps I should do some testing and see if I can measure the effect.
> >>
> >> Bob
> >>
> >
> > The closer the pair of wires, the better the coupling and the lower the
> > inductance. If your speaker cable was e.g. 3 meters long (~10ft) then
> > they could be adding around 1 Ohm inductive reactance at the upper end
> > of the audio frequency range, if the wires were spaced apart.
> >
> > Mike
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
>
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[Justin Richards]

Mike,

I assumed the closer the cables the more capacitance which would attenuate
the higher frequencies more.

To clarify, are you saying closer together is better for audio performance
as it gives more coupling which is better as it lowers the inductance.

Whereas cables spread apart gives less coupling and increases the inductive
reactance which would attenuate the upper audio freq range more.


Justin





On 6 April 2018 at 16:09, Mike <***@gmail.com> wrote:

> On 05/04/2018 23:57, Bob Blick wrote:
> > A very long time ago I needed to wire some loudspeakers and used two
> strands of some salvaged single conductor insulated solid wire, fairly
> heavy gauge. When I later replaced it with regular speaker cable of similar
> gauge, the system sounded better. I wonder now if the wires vibrated enough
> because of the electromagnetic effect that it caused resonances. My ears
> were pretty good back then.
> >
> > Perhaps I should do some testing and see if I can measure the effect.
> >
> > Bob
> >
>
> The closer the pair of wires, the better the coupling and the lower the
> inductance. If your speaker cable was e.g. 3 meters long (~10ft) then
> they could be adding around 1 Ohm inductive reactance at the upper end
> of the audio frequency range, if the wires were spaced apart.
>
> Mike
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
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> http://mailman.mit.edu/mailman/listinfo/piclist
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[p***@roadrunner.com]

The capacitive impedance at audio frequencies is quite high.

- - Bob Ammerman
RAm Systems

-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Justin
Richards
Sent: Friday, April 6, 2018 11:10 AM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] impedance of unsecured parallel wires

Mike,

I assumed the closer the cables the more capacitance which would attenuate
the higher frequencies more.

To clarify, are you saying closer together is better for audio performance
as it gives more coupling which is better as it lowers the inductance.

Whereas cables spread apart gives less coupling and increases the inductive
reactance which would attenuate the upper audio freq range more.


Justin





On 6 April 2018 at 16:09, Mike <***@gmail.com> wrote:

> On 05/04/2018 23:57, Bob Blick wrote:
> > A very long time ago I needed to wire some loudspeakers and used two
> strands of some salvaged single conductor insulated solid wire, fairly
> heavy gauge. When I later replaced it with regular speaker cable of
> similar gauge, the system sounded better. I wonder now if the wires
> vibrated enough because of the electromagnetic effect that it caused
> resonances. My ears were pretty good back then.
> >
> > Perhaps I should do some testing and see if I can measure the effect.
> >
> > Bob
> >
>
> The closer the pair of wires, the better the coupling and the lower
> the inductance. If your speaker cable was e.g. 3 meters long (~10ft)
> then they could be adding around 1 Ohm inductive reactance at the
> upper end of the audio frequency range, if the wires were spaced apart.
>
> Mike
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
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[Mike]

Yes, capacitance does increase, but a) It's still very low for audio
frequencies, maybe 20-30pF per foot for conventional cable) and b) a
speaker is (ideally) being driven by a very low impedance source. 
Provided the amplifier can source sufficient current without significant
increases in distortion this will have less effect than series
inductance which an amplifier can not compensate for.

This is taken to extremes by the audiophools (naturaly) who have speaker
cables where each side of the cable is made from dozens of insulated
wires that are braided together to minimise inductance, at the cost of a
significantly higher capacitance.

Mike

On 06/04/2018 16:10, Justin Richards wrote:
> Mike,
>
> I assumed the closer the cables the more capacitance which would attenuate
> the higher frequencies more.
>
> To clarify, are you saying closer together is better for audio performance
> as it gives more coupling which is better as it lowers the inductance.
>
> Whereas cables spread apart gives less coupling and increases the inductive
> reactance which would attenuate the upper audio freq range more.
>
>
> Justin
>
>
>
>
>
> On 6 April 2018 at 16:09, Mike <***@gmail.com> wrote:
>
>> On 05/04/2018 23:57, Bob Blick wrote:
>>> A very long time ago I needed to wire some loudspeakers and used two
>> strands of some salvaged single conductor insulated solid wire, fairly
>> heavy gauge. When I later replaced it with regular speaker cable of similar
>> gauge, the system sounded better. I wonder now if the wires vibrated enough
>> because of the electromagnetic effect that it caused resonances. My ears
>> were pretty good back then.
>>> Perhaps I should do some testing and see if I can measure the effect.
>>>
>>> Bob
>>>
>> The closer the pair of wires, the better the coupling and the lower the
>> inductance. If your speaker cable was e.g. 3 meters long (~10ft) then
>> they could be adding around 1 Ohm inductive reactance at the upper end
>> of the audio frequency range, if the wires were spaced apart.
>>
>> Mike
>> --
>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
>> View/change your membership options at
>> http://mailman.mit.edu/mailman/listinfo/piclist
>>

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ht

[Bob Blick]

Hi Justin,

The capacitance of speaker cables, if considered by itself, doesn't really attenuate the high frequencies. The output impedance of your typical amplifier is quite low due to it basically being a powerful opamp, and it will maintain its output under almost any load. In the amplifier there's a small inductor in series but it's typically only about 1 uH. Since all cable also has inductance, together with the capacitance the cable will have a characteristic impedance. But at audio frequencies it's all pretty much not going to have much effect. With widely spaced conductors the inductance potentially could attenuate the high frequencies. In practice, using speaker cable, the inductance is quite low.

But if one or both of the conductors is vibrating due to electromagnetism, there are going to be (frictional) losses at low and middle frequencies and that is the effect I was curious about.

Friendly regards,

Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Justin Richards
Sent: Friday, April 6, 2018 8:10 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] impedance of unsecured parallel wires

Mike,

I assumed the closer the cables the more capacitance which would attenuate
the higher frequencies more.

To clarify, are you saying closer together is better for audio performance
as it gives more coupling which is better as it lowers the inductance.

Whereas cables spread apart gives less coupling and increases the inductive
reactance which would attenuate the upper audio freq range more.


Justin





On 6 April 2018 at 16:09, Mike wrote:

> On 05/04/2018 23:57, Bob Blick wrote:
> > A very long time ago I needed to wire some loudspeakers and used two
> strands of some salvaged single conductor insulated solid wire, fairly
> heavy gauge. When I later replaced it with regular speaker cable of similar
> gauge, the system sounded better. I wonder now if the wires vibrated enough
> because of the electromagnetic effect that it caused resonances. My ears
> were pretty good back then.
> >
> > Perhaps I should do some testing and see if I can measure the effect.
> >
> > Bob
> >
>
> The closer the pair of wires, the better the coupling and the lower the
> inductance. If your speaker cable was e.g. 3 meters long (~10ft) then
> they could be adding around 1 Ohm inductive reactance at the upper end
> of the audio frequency range, if the wires were spaced apart.
>
> Mike
> --

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[Justin Richards]

This has been interesting. Lots to think about.

Justin


On 7 April 2018 at 01:27, Bob Blick <***@outlook.com> wrote:

> Hi Justin,
>
> The capacitance of speaker cables, if considered by itself, doesn't really
> attenuate the high frequencies. The output impedance of your typical
> amplifier is quite low due to it basically being a powerful opamp, and it
> will maintain its output under almost any load. In the amplifier there's a
> small inductor in series but it's typically only about 1 uH. Since all
> cable also has inductance, together with the capacitance the cable will
> have a characteristic impedance. But at audio frequencies it's all pretty
> much not going to have much effect. With widely spaced conductors the
> inductance potentially could attenuate the high frequencies. In practice,
> using speaker cable, the inductance is quite low.
>
> But if one or both of the conductors is vibrating due to electromagnetism,
> there are going to be (frictional) losses at low and middle frequencies and
> that is the effect I was curious about.
>
> Friendly regards,
>
> Bob
>
> ________________________________________
> From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of
> Justin Richards
> Sent: Friday, April 6, 2018 8:10 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] impedance of unsecured parallel wires
>
> Mike,
>
> I assumed the closer the cables the more capacitance which would attenuate
> the higher frequencies more.
>
> To clarify, are you saying closer together is better for audio performance
> as it gives more coupling which is better as it lowers the inductance.
>
> Whereas cables spread apart gives less coupling and increases the inductive
> reactance which would attenuate the upper audio freq range more.
>
>
> Justin
>
>
>
>
>
> On 6 April 2018 at 16:09, Mike wrote:
>
> > On 05/04/2018 23:57, Bob Blick wrote:
> > > A very long time ago I needed to wire some loudspeakers and used two
> > strands of some salvaged single conductor insulated solid wire, fairly
> > heavy gauge. When I later replaced it with regular speaker cable of
> similar
> > gauge, the system sounded better. I wonder now if the wires vibrated
> enough
> > because of the electromagnetic effect that it caused resonances. My ears
> > were pretty good back then.
> > >
> > > Perhaps I should do some testing and see if I can measure the effect.
> > >
> > > Bob
> > >
> >
> > The closer the pair of wires, the better the coupling and the lower the
> > inductance. If your speaker cable was e.g. 3 meters long (~10ft) then
> > they could be adding around 1 Ohm inductive reactance at the upper end
> > of the audio frequency range, if the wires were spaced apart.
> >
> > Mike
> > --
>
> --
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[Brooke Clarke]

Hi Bob:

Most people think transmission lines have a constant impedance, but that's not always the case.  Below some critical
frequency transmission lines no longer exhibit "real impedance" and are best thought of a lumped elements.  Here's data
showing that the impedance of CAT 5 cable below 18 kHz is no longer  real.  In the case of RG-58/U coax cable the corner
frequency is about 37 kHz.
A 500 dial phone has an impedance of about 1,000 + 500j Ohms at 2 kHz.  Also note the input impedance of a line and a
load depends on a number of factors, but below the corner frequency the line can be thought of as lumped elements, i.e.
it's not a transmission line.
http://prc68.com/I/Zo.shtml

Mechanical vibration of wires may or may not be at the frequency of the audio they are carrying.  But in any case the
sound coming directly from the vibrations probably will cause the sound from the speakers to sound degraded.

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

-------- Original Message --------
> [EE] impedance of unsecured parallel wires

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

-------- Original Message --------
> [EE] impedance of unsecured parallel wires

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[Bob Blick]

Hi Brooke,

Any sound coming from the wires directly is probably negligible. But the vibration is going to result in electrical losses and also distortion. Whether that is what I noticed or is measurable is what I'll try to find out.

First I'll have to find some single strand wire similar to what I'd had before.

Friendly regards,

Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Brooke Clarke
Sent: Sunday, April 8, 2018 1:25 PM
To: ***@mit.edu
Subject: Re: [EE] impedance of unsecured parallel wires

Hi Bob:

Mechanical vibration of wires may or may not be at the frequency of the audio they are carrying. But in any case the
sound coming directly from the vibrations probably will cause the sound from the speakers to sound degraded.

--
Have Fun,

Brooke Clarke

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[Van Horn, David]

I can see it now. Sorbothane wire guides for audiophools.


-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Bob Blick
Sent: Sunday, April 8, 2018 4:28 PM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] impedance of unsecured parallel wires

Hi Brooke,

Any sound coming from the wires directly is probably negligible. But the vibration is going to result in electrical losses and also distortion. Whether that is what I noticed or is measurable is what I'll try to find out.

First I'll have to find some single strand wire similar to what I'd had before.

Friendly regards,

Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Brooke Clarke
Sent: Sunday, April 8, 2018 1:25 PM
To: ***@mit.edu
Subject: Re: [EE] impedance of unsecured parallel wires

Hi Bob:

Mechanical vibration of wires may or may not be at the frequency of the audio they are carrying. But in any case the sound coming directly from the vibrations probably will cause the sound from the speakers to sound degraded.

--
Have Fun,

Brooke Clarke

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[Bob Blick]

Or for paranoids to prevent eavesdropping. Goes well with foil hats.

Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Van Horn, David
Sent: Monday, April 9, 2018 12:34 PM
To: Microcontroller discussion list - Public.
Subject: RE: [EE] impedance of unsecured parallel wires

I can see it now. Sorbothane wire guides for audiophools.


-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Bob Blick
Sent: Sunday, April 8, 2018 4:28 PM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] impedance of unsecured parallel wires

Hi Brooke,

Any sound coming from the wires directly is probably negligible. But the vibration is going to result in electrical losses and also distortion. Whether that is what I noticed or is measurable is what I'll try to find out.

First I'll have to find some single strand wire similar to what I'd had before.

Friendly regards,

Bob

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[Van Horn, David]

I don't need tinfoil hats, I've got faraday cages. 😊


-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Bob Blick
Sent: Monday, April 9, 2018 2:33 PM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] impedance of unsecured parallel wires

Or for paranoids to prevent eavesdropping. Goes well with foil hats.

Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Van Horn, David
Sent: Monday, April 9, 2018 12:34 PM
To: Microcontroller discussion list - Public.
Subject: RE: [EE] impedance of unsecured parallel wires

I can see it now. Sorbothane wire guides for audiophools.


-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Bob Blick
Sent: Sunday, April 8, 2018 4:28 PM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] impedance of unsecured parallel wires

Hi Brooke,

Any sound coming from the wires directly is probably negligible. But the vibration is going to result in electrical losses and also distortion. Whether that is what I noticed or is measurable is what I'll try to find out.

First I'll have to find some single strand wire similar to what I'd had before.

Friendly regards,

Bob

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[Richard Prosser]

"I don't need tinfoil hats, I've got faraday cages. "

What do you feed them? The little buggers keep dying on us!

RP :-)



On 10 April 2018 at 09:28, Van Horn, David <
***@backcountryaccess.com> wrote:

> I don't need tinfoil hats, I've got faraday cages. 😊
>
>
> -----Original Message-----
> From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Bob
> Blick
> Sent: Monday, April 9, 2018 2:33 PM
> To: Microcontroller discussion list - Public. <***@mit.edu>
> Subject: Re: [EE] impedance of unsecured parallel wires
>
> Or for paranoids to prevent eavesdropping. Goes well with foil hats.
>
> Bob
>
> ________________________________________
> From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Van
> Horn, David
> Sent: Monday, April 9, 2018 12:34 PM
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE] impedance of unsecured parallel wires
>
> I can see it now. Sorbothane wire guides for audiophools.
>
>
> -----Original Message-----
> From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Bob
> Blick
> Sent: Sunday, April 8, 2018 4:28 PM
> To: Microcontroller discussion list - Public. <***@mit.edu>
> Subject: Re: [EE] impedance of unsecured parallel wires
>
> Hi Brooke,
>
> Any sound coming from the wires directly is probably negligible. But the
> vibration is going to result in electrical losses and also distortion.
> Whether that is what I noticed or is measurable is what I'll try to find
> out.
>
> First I'll have to find some single strand wire similar to what I'd had
> before.
>
> Friendly regards,
>
> Bob
>
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[RussellMc]

On 9 April 2018 at 08:25, Brooke Clarke <***@pacific.net> wrote:

> Hi Bob:
>
> Most people think transmission lines have a constant impedance, but that's
> not always the case. Below some critical
> frequency transmission lines no longer exhibit "real impedance" and are
> best thought of a lumped elements. Here's data
> showing that the impedance of CAT 5 cable below 18 kHz is no longer
> real.


​Are you claiming that the results are imaginary? [[ :-) ]]

Interest only:

From the days when Copper was king: Telephone cables exhibit frequency
"roll off" which is acceptable for local distribution in most cases but on
very distant customers or on inter exchange ​links where end to end quality
would be affected 'something had to be done'. An often used passive
solution was to add "loading coils" at appropriate intervals to increase
inductance, allowing a reduction in roll off at the expense of increased
losses above the cutoff frequency of the low pass filter so formed. From
long ago memory I think values of 88 mH were common and maybe sometimes 44
mH. Cable characteristics governed the requisite intercoil spacings and
hence number of coils in arun.

In time "high tech" solutions included "NIR"s (Negative impedance repeater)
(Negistors?) made initially by Philips if memory served, which were
adjustable to balance cable impedance appropriately when magically adjusted
correctly, or to make the circuit sound hollow and echoy or even to
oscillate on other occasions.

Agh / Olde:

https://books.google.co.nz/books?id=5Os96O_T16kC&pg=PA143&lpg=PA143&dq=%2B%22negative+impedance+repeater%22+nir+telephone&source=bl&ots=tj0rgD1vtb&sig=IoAsTpiIqp9KKga8xK-7QHgdRQY&hl=en&sa=X&ved=0ahUKEwi684Cd6KvaAhVHVrwKHaGEDlQQ6AEIKzAB#v=onepage&q=%2B%22negative%20impedance%20repeater%22%20nir%20telephone&f=false


Discussion, interesting (maybe :-) ) - search for NIR

http://chiclassiccomp.org/docs/content/telephony/AutomaticElectric/3013-K_AE_CurrentPublications_January1963.pdf


R
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[Brent Brown]

On 9 Apr 2018 at 11:59, RussellMc wrote:

> In time "high tech" solutions included "NIR"s (Negative impedance repeater)
> (Negistors?) made initially by Philips if memory served, which were
> adjustable to balance cable impedance appropriately when magically adjusted
> correctly, or to make the circuit sound hollow and echoy or even to
> oscillate on other occasions.

Yip, Philips negistor. I'm not old enough to know about them, but recently read an
interesting article. Written by a friend & former work colleague, one page, page 9:

http://www.nzart.org.nz/assets/breakin/current/01_BreakIn_JanFeb2016.pdf

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[Richard Prosser]

Hi Brent,
I hadn't realised that "Break-In" was available in pdf on the web!. I can
see may hours of reading ahead of me!

Interesting story regarding the negistors also. I know that in Australia,
bamboo coax degradation on trunk circuits was slowed significantly by
pressurising with N2. Also have memories of paper-Lead (& other) cable
manufacture from when I worked at "the Cable Factory" as it was. (Austral
Std. Cables). I remember looking at the idea someone had regarding using
dry-core (pressurised) cable to go under Auckland Harbour. The pressure
required to prevent water ingress at the deepest part would have caused the
moisture-barrier sheath to blow out at the ends!

Regarding the cable impedance / lumped component models. At low frequencies
the capacitance and resistance dominate while at higher frequencies the
impedance stabilises as the inductive reactance comes into play. Then skin
effect produces a kink in the impedance as that asserts itself. The
frequencies depend on cable construction. PVC insulation also can have an
interesting effect as its dielectric "constant" varies with frequency.

RP


RP

On 9 April 2018 at 12:44, Brent Brown <***@eds.co.nz> wrote:

> On 9 Apr 2018 at 11:59, RussellMc wrote:
>
> > In time "high tech" solutions included "NIR"s (Negative impedance
> repeater)
> > (Negistors?) made initially by Philips if memory served, which were
> > adjustable to balance cable impedance appropriately when magically
> adjusted
> > correctly, or to make the circuit sound hollow and echoy or even to
> > oscillate on other occasions.
>
> Yip, Philips negistor. I'm not old enough to know about them, but recently
> read an
> interesting article. Written by a friend & former work colleague, one
> page, page 9:
>
> http://www.nzart.org.nz/assets/breakin/current/01_BreakIn_JanFeb2016.pdf
>
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[Brent Brown]

On 9 Apr 2018 at 19:00, Richard Prosser wrote:

> Hi Brent,
> I hadn't realised that "Break-In" was available in pdf on the web!. I can
> see may hours of reading ahead of me!

Hi Richard,

Not too much reading... I think there's only that one sample issue on-line. I see
membership is $99/year, but it doesn't specifically say the magazine is published
electronically.

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[Richard Prosser]

Hi Brent,
Yes I see that now. Unfortunate, although $99 a year isn't too bad I guess.

RP (ZL3RHP)

On 9 April 2018 at 21:12, Brent Brown <***@eds.co.nz> wrote:

> On 9 Apr 2018 at 19:00, Richard Prosser wrote:
>
> > Hi Brent,
> > I hadn't realised that "Break-In" was available in pdf on the web!. I can
> > see may hours of reading ahead of me!
>
> Hi Richard,
>
> Not too much reading... I think there's only that one sample issue
> on-line. I see
> membership is $99/year, but it doesn't specifically say the magazine is
> published
> electronically.
>
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[AB, Pearce - UKRI STFC]

> Hi Brent,
> I hadn't realised that "Break-In" was available in pdf on the web!. I
> can see may hours of reading ahead of me!

I see they had part of an article on the AWA Teleradio 1, gee, it is years since I made those, back in my apprenticeship days.



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