'number of turns/diameter of wire used' from Known resistance ?

[vinodquilon]

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 Producing wound components didn't guide me to a final value.

OEP1200 1:1 600 Ohm is not avail in Kerala,India. Single quantity online ordering is also not possible. So I finally decided to make a custom transformer.

 

[mneary]

The DC resistance of the wire is not a direct indicator of the operating impedance. There are a lot of other factors.

If you understood the responses to your two other threads on this same problem, the transformer is not a critical item. It does not need to be 1:1 and it does not need to be exactly 600 ohms. I think you will be pleased with the results from any small audio transformer.

 

[crutschow]

A 600 ohm transformer does not have a DC resistance of 600 ohms, it's likely considerably less than that. For example the OEP1200 1:1 600 Ohm has a resistance of 68Ω per the data sheet. The 600 ohm rating refers to the nominal impedance of the load that is optimum for the transformer operation.

 

[Sceadwian]

The DC resistance of the wire is not a direct indicator of the operating impedance.

The operating impedance of a simple wire can never be lower than it's DC resistance.

 

[mneary]

The operating impedance of a simple wire can never be lower than it's DC resistance.

This is correct, but it would have added little to the OP's understanding. I was answering this:

how can I Calculate the 'number of turns/diameter of wire used' from known resistance of 600Ohm ?

 

[Hero999]

The DC resistance should be as low as you can possibly get.

The turns ratio for an isolation transformer is 1:1 but more turns are often added to the secondary to offset the voltage loss resulting from the copper loses.

The primary needs to have enough turns to prevent core saturation at the minimum operating frequency.