Magdrive pump video & audio interference

[Colin]

OK, so I now have an h2o rig. There is only one problem, the magdrive pump is causing a slight flicker in my video and a bit of hash in my CD audio. Not that I expect my computer to meet my tweak audiophile standards but it ought to have clean video and decent audio through my HeadRoom Supreme headphone amp (http://www.headphone.com/Home.asp) . I have cut some of the interference by shielding the pump with aluminum foil. There is a possibility that the pump is feeding back into the AC and causing the audio problems. Does anyone have any ideas?

Colin

[stool]

If you can lay your hands on ferrites they may solve your problem. It's probably overkill, but I have them on all my fan wires, and power cables.

[dimmreaper]

Hey Colin-

Sometimes when you hear a "ticking" on a car stereo system, the distributor is emitting a small electro magnetic impulse. This can be solved by wrapping the distributor in aluminum foil.

It's a long shot, but maybe the same principal can be applied to your water pump.

Hope this helps :-)

[Mr_Goat]

Dunno if this will work but try running the pump off a different circuit

[Colin]

I must be feeling my age. I totally forgot what I learned in school. Brain flatulence! What’s needed is Mu metal. It has a 80% nickel-iron-molybdenum content and is used for shielding components with strong magnetic fields. There is some in your computer right now. It’s the case for your PSU. For shielding a magdrive pump, the most convenient product is Mu metal foil. You can buy foil here http://www.lessemf.com/mag-shld.html .

This weekend I replaced the Rio 800 (133 gph) pump with a 650 gph Nursery Pro. Although the magnetic field is stronger, I have relocated the pump for less interference. It still needs to be shielded. I am a little nervous about it being under my hard drive cage. My TriField meter indicates 100 milligauss at a one foot distance from the pump inside a closed computer case. For comparison, my monitor reads 5 milligauss at the same distance.

[Shadow ÒÓ]

Jeff Evans (Feb 03, 2001 03:46 a.m.):
Hey Colin-

Sometimes when you hear a "ticking" on a car stereo system, the distributor is emitting a small electro magnetic impulse. This can be solved by wrapping the distributor in aluminum foil.

It's a long shot, but maybe the same principal can be applied to your water pump.

Hope this helps :-)

Jeff's right.....but you have to ground the alum foil. Otherwise the foil becomes an antenna. =)

Just rap that sucker up and place a ground wire on it.....should solve it.

[Colin]

Do some research. Just aluminum foil and a ground won't do it. There is a reason why the electronics industry uses Mu metal.

Colin

[Eriksson]

What kind of pump are you using 12Vdc or 110/220V Ac ??

[Colin]

110 volts. Given the strong EMF from the pump, I will start there. If necessary, I will shield the incomming AC line with a double braid but I doub't this will be necessary.

Colin

[Eriksson]

I think it might be possible to filter some of this **** out with capacitors. You could try to put small one (1uf / high voltage) between the pump wires close to the pump, or between wire to ground (make sure your case is properly grounded to the wall socket).

I suggest you do some research first, if you want to try this. Do not put any big electrolyte capacitors between power wires (they might blow). And I guess you know already about the danger playing with 110V AC :)

[Colin]

Another note. Since installing the more powerful pump, my Intuos graphics tablet is behaving strange. When using the pen, the curser flutters about. On screen it looks like I have Parkinson’s! The magnetic field is about 12 milliguass next to the tablet. The tablet alone produces a field strength of 6 milligauss. Time to get serious about this shielding stuff.

[dimmreaper]

Colin (Feb 05, 2001 12:44 a.m.):
Do some research. Just aluminum foil and a ground won't do it. There is a reason why the electronics industry uses Mu metal.

ColinThe water in the lines was conducting the EMF, that's why it didn't work, try wrapping the lines in foil too. Good luck :-)

[Colin]

Today I spent some time on the phone with an engineer that specializes in magnetic shielding. Given the strength of my pumps magnetic shield, his suggestion was a 16 gage cold rolled steel enclosure with ¼ inch of space between the pump and the enclosure. If this does not cut the interference enough, a second shield of Mu metal can be applied to the steel with a double stick foam tape to provide the necessary gap.

I found some ferrite chokes in my electronic parts junk box today. I’ll try those on the power lead where it exits the pump

Developing………..

[Tomsawyer]

Your post reminds me of something that happend out at the university last week. Some friends where messing around witha supercooled electromagnet in one of the labs. A tech came in with his lap top, set the damn thing right near the magnet. Welll no one noticed it was there and they fired up the beast. Result: one laptap on its way to the repair shop. Amazing what a megaguass field can do to electronics heheheh

[Colin]

Classic! ROTFLMAO.

BTW, the steel shield is for cost effectiveness. Mu metal would handle the job best but it’s danged expensive and needs to be annealed at 1900 degrees in a vacuum furnace after being formed. The Mu foil alone is not enough, hence the proposed combination.