Full Version: TV interference form light
Ok I just finished wireing everything and turned it on. I got major interference in TV that is upstairs when i turn on light and it gets worse as bulb gets brighter. Anyone got any idea whats causing this?
EMI from the ballast.
This should only be happening on the lower channels (It's gone above channel 13 on my TV) and while it is irritating, it won't damage things.
This should only be happening on the lower channels (It's gone above channel 13 on my TV) and while it is irritating, it won't damage things.
Is there any way to shield it? I have dish network and all tv's are on channel 3.
Put a capacitor across the A/C line, 0.1uF, rated for mains voltage. This should filter out interference on the A/C line itself.
I posted this in your plog and decided post here as well to help anyone else having similar issues:
It is also possible that your bulb or wiring is acting like an antenna and broadcasting the EMI. The easy cure for that would be to cover your projector with foil (inside or outside) and ground it. Also, your coaxial wiring (dish network)should be doing a better job of eliminating external interference. The outer sheath may not be properly grounded.
QUOTE
Putting your ballast inside or outside your enclosure probably won't make any difference. Interference from your ballast can be transmitted through the air or (less likely) through the power wiring. Airborne interference is easy to deal with: simply put your ballast inside a grounded metal box / mesh / foil / container. If your ballast is already in a metal enclosure, adding a ground to the case may solve your problem.
Interference transmitted by your house wiring is a little more difficult to deal with; An isolation transformer is most often used for this type of application.
(EDIT)
SupraGuy's suggestion (in your other thread) for using a capacitor across the input voltage is an excellent idea.
Interference transmitted by your house wiring is a little more difficult to deal with; An isolation transformer is most often used for this type of application.
(EDIT)
SupraGuy's suggestion (in your other thread) for using a capacitor across the input voltage is an excellent idea.
It is also possible that your bulb or wiring is acting like an antenna and broadcasting the EMI. The easy cure for that would be to cover your projector with foil (inside or outside) and ground it. Also, your coaxial wiring (dish network)should be doing a better job of eliminating external interference. The outer sheath may not be properly grounded.
I dont think au foil works as a decent faraday cage.....but hey ive seen crazier work (see: elkin)
Heh. Au is gold. Al is aluminium. 
I don't think that the EMI is broadcast over air. If it were then I'd expect to see more problems with neighbors.
This isn't too far fromt eh same kind of thing that happens when you turn on certain appliances, like vacuum cleaners, or other strong electric motors. While using these will certainly make every TV in your house show interference, it's not likely to cause your neighbors trouble.
The capacitor across the AC terminals will help some. A filter choke (Try one of the torroidal core ones from an old PC power supply) in line with the power will also help. This makes a second order low-pass crossover. There should be virtually no loss on the A/C power line, but it should attenuate RF noise considerably.
I don't think that the EMI is broadcast over air. If it were then I'd expect to see more problems with neighbors.
This isn't too far fromt eh same kind of thing that happens when you turn on certain appliances, like vacuum cleaners, or other strong electric motors. While using these will certainly make every TV in your house show interference, it's not likely to cause your neighbors trouble.
The capacitor across the AC terminals will help some. A filter choke (Try one of the torroidal core ones from an old PC power supply) in line with the power will also help. This makes a second order low-pass crossover. There should be virtually no loss on the A/C power line, but it should attenuate RF noise considerably.
good catch 
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QUOTE (SupraGuy @ Oct 11 2005, 11:14 AM)
I don't think that the EMI is broadcast over air. If it were then I'd expect to see more problems with neighbors.
This isn't too far fromt eh same kind of thing that happens when you turn on certain appliances, like vacuum cleaners, or other strong electric motors. While using these will certainly make every TV in your house show interference, it's not likely to cause your neighbors trouble.
This isn't too far fromt eh same kind of thing that happens when you turn on certain appliances, like vacuum cleaners, or other strong electric motors. While using these will certainly make every TV in your house show interference, it's not likely to cause your neighbors trouble.
Ok, I tested the broadcast EMI theory to be sure I wasn't talking smack. I have two known EMI sources, a computer mushroom fan and an inverter-type microwave oven. I used a battery powered and a plug-in AM radio as EMI detectors. In both cases, the interference was much greater near the source than on the other side of the house, or even the other side of the room. If the house wiring was transmitting the interference, I would have expected the plug-in radio to have the same level of interference in any location.
If the house wiring was transmitting the interference, then turning on your vacuum would indeed disrupt your neighbor's viewing pleasure, because they are on the same electrical circuit as you are. I suspect that anyone on the same stepdown transformer would have the same problem.
The reason all your neighbors can still watch 'Survivor: Sewage Treatment Station' while you hoover is because of the inverse square rule: signal strength at double the distance is one fourth the power. In one case, I had significant interference at 10 feet, but at 40 feet (one sixteenth the power) I could barely hear it.
Wow, I think I beat that one to death.
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