DC cords and dirty power

I read about a device called an inductor, which acts sort of like a muffler for DC current, getting rid of the ups and downs while letting steady flow through. That sounded like a way to take care of any dirty power on the DC extension cord to my computer, so I made coils at both ends, and it does seem to help.

DC is the way to go, so a way to get on that way is also a way to go.
This sounds like a way to get rid of some turbulance on DC-current.
Of course the inductor will be a source of emf, but probably usually not a very strong one, and can be kept at some distance anyway.
I read the more iron both inside and close to the coil, the higher the capacity of the inductor, besides of course obvious factors like size and number of windings.
Apart from inductors, also rectifiers, capacitors and voltage regulators are used to even out the current.
It's of course more fun to do it yourselves and since it seems to work, congratulations !

Someone told me that the motherboard of a computer can be damaged by a sudden change of voltage.
Probably that's how i destroyed a 12 volt monitor ;(, that was however picked up from the trash anyway.
So we have to be aware here of shortcuts, wires or plugs getting loose ( e.g. on the poles of a battery ), and perhaps even the kickstart of a connected DC fridge or so.
Older fluorescent tube cases, at least where i live, contain two heavy inductors ( blocks of steel with a single large copper coil inside ) that could be used also, just by cutting supply wires and putting one or a few of them in between.
Because these are big inductors, it could both clean up and stabilize the current substantially, but this is a guess and has to be tested or confirmed and preferable further commented upon by someone with the technical knowhow.
I wonder for instance which frequencies would be smoothened out properly, including 50/60 Hz from a AC to DC converter and all sorts of dirty electricity, and wether serious shocks to electronic stuff can be absorbed sufficiently this way.

I've heard that you can kill an audio signal by wrapping the wire into a coil (if it's long enough), so if that's true it should work down to well under 20 kHz (the upper limit of most people's hearing).

Oh, another thing: Is anyone interested if I can get low-EMF cell phone chargers and other small power supplies built? I was thinking of making a custom one with a 5V output (either USB or a barrel plug) to start with. If it works I could probably do other common voltages (9.6, 12, 18).

Nobody using this very simple method as seen in the pictures on?
http://www.milieuziektes.nl/Pagina600.html