Can a common mode choke be used as a low current mains isolation transformer?

[neazoi]

Can a common mode choke be used as a low current mains isolation transformer, if wired as primary/secondary?
You know these tube projects that require low current (tube preamps, receivers etc.

 

[FvM]

Wire cross section determines the applicable current, number of turns and core cross section the voltage.

Most common mode chokes have an applicable voltage far below 1 V at 50 Hz, not useable for typical tranformer applications.

 

[zenerbjt]

Yes if you mean as a 50Hz transformer then a ferrite CMC is no good for you.

I dare say using one as a high frequency transformer, for very low power output might be possible in some topology.

 

[neazoi]

So the problem is the ferrite core and not so much the number of turns?
Cause I have also seen iron core common mode chokes inside computer PSUs. And some have quite a lot number of turns

 

[FvM]

Vsat = Cross section x number turns x Bsat x freq

Iron core Bsat is about 5 times of ferrite. Number of turns still matter.

For standard transformer core, expect 42 turns per cm^2 and V at 50 Hz.

 

[zenerbjt]

I have also seen iron core common mode chokes inside computer PSUs. And some have quite a lot number of turns

The big thing about a common mode choke is that it doesnt saturate because the fields of diff mode current cancel out....so it would be strange for them to need an iron core.

 

[Easy peasy]

Short answer = no, as there is no safety isolation - I assume you can touch the output circuit ?