ECN Forum Forums General Topics of the Trade General Discussion Area Question for the hive mind

I bought a dvd player today and on the power cord at the plug was a 2-peice magnet clipped onto it with the cord looped thru it.
What is the purpose of this magnet?
If it is so great at what it does, Why dont all eletronics have one?

That would be a ferrite choke on the power cord. It presents a low impedance to the low frequency power line current and a high impedance to high frequency switching transients of the power supply. It doesn't help the performence of the DVD player but helps the mfg comply with FCC interference limits.
Joe

I wonder why they dont place them inside the device?

You might find that these ferrites are only added to different batches depending on the country that they will be shipped to. It goes without saying that the player you bought was not produced in the U.S.A. I wouldn't presume that other nations share the same interference restrictions. The easiest method of achieving "just enough" suppression would be to slap it on at the end. Just my best guess.
Joe

IBM was ferrite happy for a while towards the end of the big water cooled mainframe era. Our power supplies were basically becoming 36kw radio stations.
We used to get ferrites in the 100 piece bag with 200 ferrite "halfs" and 100 plastic clam shells. We were clipping them on everything. We had another round of this with wire printers. I still have a big bag of those smaller ferrites if anyone wants some. (the size on a printer cable)

LOL!!!

Ya, saw many "Field-Filtered" and pre-made cords for IBM Equipment, which attest to that claim.

On the subject of "Ferrites", what is the proper pronunciation of that dang word???!!!

I pronounce it in this Phonetic fashion:

Fair-Rights

Whereas some pronounce it in this Phonetic fashion:

Ferr-Itts (sounds like little Animals, which are in the Rodent Family - a Domestic Polecat)

And others pronounce it as:

Furr-Rhetts (sounds like Fur + "Wet", replace the "W" of "Wet" with an "R")

As this issue is one of major importance + jeopardizes the well-being of many people, it must be debunked ASAP!


My thinking towards the pronunciation as Fair-Rights, comes from a contraction of:

*"Ferrous";
Like Ferrous metals: i.e. Iron, Nickel and Cobalt,

And

*"Ite";
Describing something as a smaller fraction, or stand-alone part of an item or device - such as "Meteorite" from "Meteoroid";
And/or some Elements in their Oxidized, Non-Reduced state - such as "Bauxite", "Pyrite", "Limonite", and "Hematite".

So, anyone know what's the correct way to say it?

Scott35

I had a cousin who had that fur-rhetts syndrome...

man he would shout the darnedest things...