Getting matching transformer from telephone

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
"Floyd L. Davidson" wrote:
Historically they *all* had such a transformer, and even
today many of them do (it's cheap).

Transformers are not cheap and I haven't ever seen a phone with one in, even
going back 30+ years. There's simply no need.

Graham
Click to expand...
Get a diagram of any given telset you wish that works
without active components (amplifiers), and you *will*
find a transformer.

And trust me, they *are* cheap!

Going back 30+ years, they *all* had transformers.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
 
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Archimedes' Lever wrote:

Paul B <mail@nomail.invalid> wrote:

If I strip down some landline phones I 've got here, then will there
be a matching transformer in each one? Or is their technology
different now?

It isn't a matching transformer. It is for isolation purposes, and
yes, there is one in all phones that attach to Ma Bell.

Backward Americans as usual ! ;~)
Click to expand...
An ignorant statement, to say the least.

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
 
In article <lajhc4nkyef.fsf@pippuri.niksula.hut.fi>,
Tomi Holger Engdahl <then@pippuri.niksula.hut.fi> wrote:

600 ohms 1-to-1 matching transformers are quite rare in telephones.
Modern normal telephones are normally "floating" line powered
devices where electronics connect directly to line. The whole
small device is "floating" isolted from everythign else
so that gives good balance.
Click to expand...
I know of no situation where something specified as say a 150 ohms
1-to-1 matching transformer would perform significantly different than
something specified as a 600 ohms 1-to-1 matching transformer. This
assumes that they both can support the same voltage over the same
(telephone audio) bandwidth. Am I missing something?

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!
 
In article <6rs0iqF32057U1@mid.individual.net>,
"Phil Allison" <philallison@tpg.com.au> wrote:

** Unlike a 600 ohm tranny - fuckhead.
Click to expand...
You really know how to use the language of Shakespeare.

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!
 
"Floyd L. Davidson" wrote:
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Archimedes' Lever wrote:

Paul B <mail@nomail.invalid> wrote:

If I strip down some landline phones I 've got here, then will there
be a matching transformer in each one? Or is their technology
different now?

It isn't a matching transformer. It is for isolation purposes, and
yes, there is one in all phones that attach to Ma Bell.

Backward Americans as usual ! ;~)

An ignorant statement, to say the least.

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.
Click to expand...

Eeyore is a bitter British, anti America idiot who claims to be the
world's top audio equipment designer. Just ask him, and he'll inform you
of his 154 IQ, and the equipment he designed is for sale on Ebay. A
place that would shame Ali-baba & his 40 thieves.


--
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If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
 
On Mon, 29 Dec 2008 08:05:25 -0900, floyd@apaflo.com (Floyd L. Davidson)
wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Archimedes' Lever wrote:

Paul B <mail@nomail.invalid> wrote:

If I strip down some landline phones I 've got here, then will there
be a matching transformer in each one? Or is their technology
different now?

It isn't a matching transformer. It is for isolation purposes, and
yes, there is one in all phones that attach to Ma Bell.

Backward Americans as usual ! ;~)

An ignorant statement, to say the least.

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.
Click to expand...
Which is why I stated its primary purpose as being that of isolation
 
"Floyd L. Davidson"
Eeyore

Historically they *all* had such a transformer, and even
today many of them do (it's cheap).

Transformers are not cheap and I haven't ever seen a phone with one in,
even
going back 30+ years. There's simply no need.


Get a diagram of any given telset you wish that works
without active components (amplifiers), and you *will*
find a transformer.

And trust me, they *are* cheap!

Going back 30+ years, they *all* had transformers.
Click to expand...

** But not the 1:1 matching/ isolating kind the OP asked about - dickhead.

The " hybrid " circuit couples the earphone and mic to the line but is
generally not even isolating.



....... Phil
 
"Salmon Egg"
I know of no situation where something specified as say a 150 ohms
1-to-1 matching transformer would perform significantly different than
something specified as a 600 ohms 1-to-1 matching transformer. This
assumes that they both can support the same voltage over the same
(telephone audio) bandwidth. Am I missing something?
Click to expand...

** Errr - yep.

Impedance ratings matter very much in relation to the drive and load
impedances that are bests for a particular transformer.

Get them wrong like that and the overall frequency response will not be flat
across the audio band.



....... Phil
 
"Floyd L. Davidson" wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Archimedes' Lever wrote:

Paul B <mail@nomail.invalid> wrote:

If I strip down some landline phones I 've got here, then will there
be a matching transformer in each one? Or is their technology
different now?

It isn't a matching transformer. It is for isolation purposes, and
yes, there is one in all phones that attach to Ma Bell.

Backward Americans as usual ! ;~)

An ignorant statement, to say the least.

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.
Click to expand...
So you agree it's NOT a matching transformer you TWAT ?

You won't find pointless transformers (dead weight) in WORLD telecoms.

Graham
 
Archimedes' Lever wrote:

floyd@apaflo.com (Floyd L. Davidson) wrote:

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.

Which is why I stated its primary purpose as being that of isolation
Click to expand...
What exactly needs isolating from what ? Have you noticed they tend to be
made of plastic ?

Graham
 
Salmon Egg wrote:

Tomi Holger Engdahl <then@pippuri.niksula.hut.fi> wrote:

600 ohms 1-to-1 matching transformers are quite rare in telephones.
Modern normal telephones are normally "floating" line powered
devices where electronics connect directly to line. The whole
small device is "floating" isolted from everythign else
so that gives good balance.

I know of no situation where something specified as say a 150 ohms
1-to-1 matching transformer would perform significantly different than
something specified as a 600 ohms 1-to-1 matching transformer. This
assumes that they both can support the same voltage over the same
(telephone audio) bandwidth. Am I missing something?
Click to expand...
Twisted pair cable as used for telecoms has a nominal 100-110 ohm
inpedance. See the ADSL specs.

600 ohms is an irrelevant historical nonsense from the days when they used
telegraph wires for phone circuits.

Graham
 
In article <4959659F.B5338D1E@hotmail.com>,
rabbitsfriendsandrelations@hotmail.com says...
"Michael A. Terrell" wrote:

and the equipment he designed is for sale on Ebay.

IT IS

You forgot; "A place that would shame Ali-baba & his 40 thieves",
Click to expand...
Dumb Donkey.


--
Keith
 
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Salmon Egg wrote:

Tomi Holger Engdahl <then@pippuri.niksula.hut.fi> wrote:

600 ohms 1-to-1 matching transformers are quite rare in telephones.
Modern normal telephones are normally "floating" line powered
devices where electronics connect directly to line. The whole
small device is "floating" isolted from everythign else
so that gives good balance.

I know of no situation where something specified as say a 150 ohms
1-to-1 matching transformer would perform significantly different than
something specified as a 600 ohms 1-to-1 matching transformer. This
assumes that they both can support the same voltage over the same
(telephone audio) bandwidth. Am I missing something?

Twisted pair cable as used for telecoms has a nominal 100-110 ohm
inpedance. See the ADSL specs.
Click to expand...
For some cables. Not for others. It might, for example, be as high
as a couple thousand Ohms too.

600 ohms is an irrelevant historical nonsense from the days when they used
telegraph wires for phone circuits.
Click to expand...
Not at all true. 600 Ohms is somewhat of a compromise,
between the low impedance of an unloaded cable pair and
the higher impedance if loading coils are used.

Telegraph wires were typically a #11 rusty wire, not a
twisted pair.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
 
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Archimedes' Lever wrote:

floyd@apaflo.com (Floyd L. Davidson) wrote:

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.

Which is why I stated its primary purpose as being that of isolation

What exactly needs isolating from what ? Have you noticed they tend to be
made of plastic ?
Click to expand...
The transformers are made of plastic??? (I don't think so...)

A telephone loop has both VF (voice frequency) and DC
signals going in both directions, all of which need to
be "isolated" from each other. The transmit and receive
VF signals also have to be isolated from each other
(which is why the transformer is commonly called a
"Hybrid Network").

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
 
"Phil Allison" <philallison@tpg.com.au> wrote:
"Floyd L. Davidson"
Eeyore

Historically they *all* had such a transformer, and even
today many of them do (it's cheap).

Transformers are not cheap and I haven't ever seen a phone with one in,
even
going back 30+ years. There's simply no need.


Get a diagram of any given telset you wish that works
without active components (amplifiers), and you *will*
find a transformer.

And trust me, they *are* cheap!

Going back 30+ years, they *all* had transformers.

** But not the 1:1 matching/ isolating kind the OP asked about - dickhead.
Click to expand...
I'm sorry, but the nickname your mother uses for you is
not appropriate in reference to other people.

Please not that I have not said it is a matching
transformer, nor have I said that it is necessarily
appropriate for the OP. All I did was properly describe
what it actually is.

The " hybrid " circuit couples the earphone and mic to the line but is
generally not even isolating.
Click to expand...
Wrong again. It provides isolation. As I mentioned in
another post, a POTS loop needs to isolate the VF signal
from the DC signal, and also to isolate the transmit
signal from the receive signal.

It's primary purpose is isolation. It does not provide
impedance matching (in typical telsets, though I assure
you there are special ones that do have exactly that
function built into the hybrid network).

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
 
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
"Floyd L. Davidson" wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Archimedes' Lever wrote:

Paul B <mail@nomail.invalid> wrote:

If I strip down some landline phones I 've got here, then will there
be a matching transformer in each one? Or is their technology
different now?

It isn't a matching transformer. It is for isolation purposes, and
yes, there is one in all phones that attach to Ma Bell.

Backward Americans as usual ! ;~)

An ignorant statement, to say the least.

As far as it being a matching transformer, the line
impedance varies typically from perhaps 100 Ohms all the
way up to perhaps 2000 Ohms... but you will not find
anything in a telset to adjust it to match. That's because
nobody cares if it is even close to matching the line
impedance.

So you agree it's NOT a matching transformer you TWAT ?
Click to expand...
So now you finally agree too, eh? Who does that make
into a "TWAT"?

You won't find pointless transformers (dead weight) in WORLD telecoms.
Click to expand...
An ignorant statement, to say the least.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
 
"Floyd Lunatic Davidson"
Eeysore


Which is why I stated its primary purpose as being that of isolation

What exactly needs isolating from what ? Have you noticed they tend to be
made of plastic ?

The transformers are made of plastic???
Click to expand...

** Don't be such a pompous bloody prick.

Of course he meant the phone itself.


A telephone loop has both VF (voice frequency) and DC
signals going in both directions, all of which need to
be "isolated" from each other.
Click to expand...

** Don't be such a pompous bloody prick !!

Any "isolation " transformer has " galvanic isolation" .

Look it up on Google, if you are still completely clueless.

Wot a Wanker.



..... Phil
 
Eeyore wrote:
Salmon Egg wrote:


Tomi Holger Engdahl <then@pippuri.niksula.hut.fi> wrote:


600 ohms 1-to-1 matching transformers are quite rare in telephones.
Modern normal telephones are normally "floating" line powered
devices where electronics connect directly to line. The whole
small device is "floating" isolted from everythign else
so that gives good balance.

I know of no situation where something specified as say a 150 ohms
1-to-1 matching transformer would perform significantly different than
something specified as a 600 ohms 1-to-1 matching transformer. This
assumes that they both can support the same voltage over the same
(telephone audio) bandwidth. Am I missing something?


Twisted pair cable as used for telecoms has a nominal 100-110 ohm
inpedance. See the ADSL specs.

600 ohms is an irrelevant historical nonsense from the days when they used
telegraph wires for phone circuits.

Graham


Impedance for an un-loaded pair varies with frequency. So at DSL
Click to expand...
frequencies the impedance
is 100 to 110 Ohms. But for telephone use They preferred to use loaded
pairs and they were
designed to be 900 Ohms. And the phone should be a reasonable match to
the line to minimize refections which bother the users as echoes

The transformers in some sets was not an isolation transformer but a
hybrid and matching transformer. The carbon mic. used in the old phones
was powered from the line. And many
of the newer phones derive power from the line. So isolation can't be used.

Bill K7NOM
 
"Floyd Lunatic. Davidson"
"Phil Allison

Going back 30+ years, they *all* had transformers.

** But not the 1:1 matching/ isolating kind the OP asked about -
dickhead.

I'm sorry, but the nickname your mother uses for you is
not appropriate in reference to other people.

Please not that I have not said it is a matching
transformer, nor have I said that it is necessarily
appropriate for the OP. All I did was properly describe
what it actually is.
Click to expand...
** You failed to even do that.


The " hybrid " circuit couples the earphone and mic to the line but is
generally not even isolating.

Wrong again. It provides isolation. As I mentioned in
another post, a POTS loop needs to isolate the VF signal
from the DC signal, and also to isolate the transmit
signal from the receive signal.
Click to expand...

** Listen you fucking dickwad !!

The term " isolation transformer " has a specific meaning in electronics and
electrical work = "galvanic isolation".

You clearly have no bloody clue about the topic.

Piss off.



....... Phil
 
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