What are chokes used for ?

Hi there,

I have here a toroidal inductor/choke, but it instead of having just two ends it has 4 ends. So it has two sets of turns around a toroidal ferrite.

My first question is, where are these used ? And how are they used?

And why are there 4 ends rather than just 2 like a normal inductor ?

Could this be used as a simple transformer to step up or down voltages if the turns ratio are different?

It also says it is Common-mode. What does this mean ?

this is the link to the ebay where I bought them: https://www.ebay.co.uk/itm/10-Pcs-Toroid-Core-Common-Mode-Inductor-Choke-1-2MH-40mOhm-2A-Coil-BT/282240540799?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Thanks folks!

Common-mode choke. They force the currents in the two windings to be equal, but opposite.

If, without the choke, the two currents were not balanced, adding the choke will cause the net current to be zero, so that the wire(s) do not radiate RFI.

If used as a transformer, not much power can be transformed. In normal operation, the flux caused by the current in the two windings cancel; only the unbalance current excites the core.

MikeMl said:

Common-mode choke. They force the currents in the two windings to be equal, but opposite.

If, without the choke, the two currents were not balanced, adding the choke will cause the net current to be zero, so that the wire(s) do not radiate RFI.

If used as a transformer, not much power can be transformed. In normal operation, the flux caused by the current in the two windings cancel; only the unbalance current excites the core.

Click to expand...

You are an angineer and an academic and you can't really answer my question ? I understood nothing of what you said. And it's not like I'm dumb.

They're used like this:

https://i.stack.imgur.com/BA3Ae.png

I'm sorry but AA is nothing but a troll...