I am planning to tap a telephone line through an isolation transformer 600O/600O of 1:1 type. In our local market it is not readily avail. After a lot of search I have found one Dax 56K DX-56PU modem from one electronic shop and they put forward $45 for modem. Actually I only want one small transformer inside it.

Find the attachment. Non-SMD Type transformer with white colored core. T1 AASUPREME.
I have heard there also exists modem line transformers with 600O primary and different secondary (600,330,560,etc) resistances. How can I fix this should be 600O/600O Type.

Does it is mandatory to use 600O/600O in Telephone tap......

Can I possible to take outs from transformer leads on underside of the PCB without desoldering the costly PCB board.

 

I can't speak for what would happen to the rest of the components on the board if you were to tap the underside, tho your derived signal would likely be indecipherable.

As to other appropriate isolation / audio transformers, based on size parameters.......... How many would you like I gotz lotz some new, some like new............. all good as gold.

It pays to be a packrat sometimes......

 

for what it's worth they're 17.95 AUD from my closest electronics shop...
http://www.jaycar.com.au/productView.asp?ID=MA1510&CATID=19&form=CAT&SUBCATID=411

 

Oh and another thing. The only reason they're not like $5 is that they have to be tested and approved by the relevant telecommunications standards board.

 

You could make your own.

 

I like that idea!! make your own....Faraday's Law is a start.....

 

How about $1.25?

 

You could make your own.

How can I design and set-up 600 ohm to 600 ohm modem transformer ? Pls give me details about no.of turns, core type, coil type, etc... Is concentric type winding is enough. The aim of the transformer is to tap telephone line.
After reading all the transformer design procedures through internet, I am sure I wouldn't be possible to design myself. On approaching a local winding store they told only after getting exact number of primary and secondary turns, they could make it. How can I design myself ?

 

These transformers can be found on anything that has a modem. Find some old junk computers or fax machines. Look for the modem PCB.

 

Almost any transformer from an old computer modem will do the trick. You should be able to find that for near nothing.

Here is an adaptor that I made:

http://www.electro-tech-online.com/general-electronics-chat/88269-phone-line-sound-card-adaptor.html

Alain

 

Can you order from Digikey? They have several available, example:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=237-1127-ND

Most large suppliers like Farnell should also have various types.

 

This link has all the information you will need to make your own inductors, transformers, and coils of all kinds. The parts to make it will cost more than buying one, but, for that start up price, you can make many different coils.

This is one of those links EVERYONE should have bookmarked. (Well everyone who cares about wound components.)

http://info.ee.surrey.ac.uk/Workshop/advice/coils/index.html

 

This link has all the information you will need to make your own inductors, transformers, and coils of all kinds. The parts to make it will cost more than buying one, but, for that start up price, you can make many different coils.

This is one of those links EVERYONE should have bookmarked. (Well everyone who cares about wound components.)

http://info.ee.surrey.ac.uk/Workshop/advice/coils/index.html

For a telephone line audio isolation transformer 600Ohm/600Ohm of 1:1 type, how can I Calculate the 'number of turns/diameter of wire used' from known resistance of 600Ohm ?

Pls give me a final accurate value.The link http://info.ee.surrey.ac.uk/Workshop/advice/coils/index.html didn't guide me to a final value.

Someone suggested me to use OEP1200 1:1 600 Ohm. But it is not avail in Kerala,India. Single quantity online ordering is also not possible. So I finally decided to make a custom transformer.Pls help me to make it.
Pls find the attachment to see its correct use.