Getting matching transformer from telephone

BS. It is *very* simple. Every simple (or complex) telephone for a hundred years or so has been doing the exact same thing!

And *you* don't know how to set levels properly to handle that?

Most people do know...

Why not use a properly designed pad, with the correct impedance? "Pulling the line low"???? Giggle snort, cough and laugh...

You falsely claimed it was otherwise. Seems *you* are the one with a lack of "know" about this topic.

That is true, but doesn't mean what you apparently think it does.

A mismatch at the distant end will result in echo, and if the distance (no matter whether it is traversed via metallic cable, fiber, microwave or satellite) is far enough to delay the echo long enough, it will be heard as an echo by the near end user.

Typical local calls usually have a low echo return delay, while long distance will be higher. However, that is not always the case and I can demonstrate examples of local calls that are routed over satellite systems (meaning the echo delay is necessarily very close to 400-500 milliseconds). Those calls require echo cancellation, because even if the echo is 30 dB down, it is still very annoying when there is that much delay.

In civilised parts of the world with proper infrastructure it can.

Graham

Such as ?

Graham

It isn't. Not for about 45 years.

Graham

Damn right ! Not ONE of these 'phone experts' has mentioned that.

Graham

A: OFF HOOK you twit.

B: the DC resistance of the transformer primary may cause the phone to stop working by lowering the line voltage too much.

Graham

What ?

Look, I've designed line interfaces FFS. For Xerox. I've already mentioned it once.

Graham

Rather different to 2k I think you'll agree.

Ribbons are FAR lower. Maybe 50 ohms AFTER the transformer !

And Pin 1 on an XLR is ALWAYS the cable shield. It may also be GROUND - but that's another story. It certainly isn't used to provide phantom power under ANY circumstances. And the last time I came across a centre tapped transformer in pro-audio was 35 years ago. It caused a bloody nuisance too. Modern balanced audio circuits are 'floating'. The centre tap provides ZERO advantage.

I now expect you to make an idiot of yourself trying to refute that one.

Graham

How would you know that?

Off hook is a loop *current* condition.

Typically a split winding is used, with a mid-point capacitor to block DC current.

Even you should have known that.

Jesus Wept !

Graham

You can say anything you like, but when you make up all the ridiculous garbage you are posting to this thread there is little doubt that you haven't got even the faintest clue how telecommuncations equipment works.

BS. I had previously discussed it in detail.

"Archimedes'= SCHIZOPHRENIC LUNATIC TROLL"

you VILE TROLLING PIECE OF AUTISTIC SHIT

In article , Eeyore scribeth thus

More fibre these days, BT seems to be taking their large scale microwave equipment's out of service very quickly.

They do however in common with other carriers seem to be using microwave more for last mile applications but for "trunk" applications fibre is the main or only means of transmission...

In article , Eeyore scribeth thus

Apart from providing the -return path- for the current sent over the balanced pair;)...

And the last time I came across a centre tapped transformer