What is this on a 12VDC power cord?

[bobc]

I am converting a motherboard's power supply to run on a 12VDC battery and am curious about the component on the end of the existing power cord coming from the AC/DC transformer.

I have attached an image - can you tell me what it is? Capacitor maybe?

Will a component like this be necessary if I am using a battery, instead of the AC/DC transformer?

Thanks,

--Bob

 

[daddles]

It's a ferrite choke to help the device meet its RFI specifications.

 

[bobc]

It's a ferrite choke to help the device meet its RFI specifications.

Thanks!

From what I've read on a few websites this filters out the RFI caused by AC - so for a battery powered system I don't need one - right?

--Bob

 

[poor mystic]

...right.

 

[Resqueline]

RFI is caused by RF energy (usually an AC component) but AC in this context does not refer to mains AC. RFI can just as well occur in battery powered systems.
These RFI measures are applied just as much for preventing RF from radiating out into the power supply as to prevent RF from going into the device in question.
It basically prevents the wire & PSU to work as an antenna. The device itself will no doubt work just as well without the ferrite core in >99.99% of the cases.