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Old 08-10-2012, 12:04 PM
 
3,495 posts, read 6,443,131 times
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I have a Sony radio boombox in my bedroom. When my fridge automatically goes on or off (because of the termostat), the fridge makes a knock sound, and an instant later, a click comes out of my radio. I know it's linked because it always happens this way.

Is this RF interference being sent through the air or through the power lines?

Also, I have a small room fan at one side of my living area, and an old tube TV at the other side. When I turn the fan on or off, horizontal static lines will briefly flash on the screen. Again, is that RF interference through power lines or the air?

Also, why does turning the fan on or off send a static but when it's just running, there is no static?
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Old 08-10-2012, 12:08 PM
 
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Through the power, most likely.... I don't think it's RFI, just a drop or increase in current. Sounds like you might be pushing your house's electrical capacity.
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Old 08-10-2012, 04:28 PM
 
Location: Central Texas
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I agree it is likely through the power lines unless your radio were tuned to AM radio. AM radios are very sensitive to RFI. Put an AM radio near a computer and you'll see.

When the fan is turned on, a few things happen that could generate "noise" - the arc that occurs when the power switch is turned on, and the tiny arcs that travel on the motor brushes. When the motor reaches speed the frequency of that probably rises high enough that the filtering in the power supply of the TV is not sensitive to it.

A powerline filter might remove the video noise on your TV.
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Old 08-11-2012, 12:23 AM
 
Location: The Ranch in Olam Haba
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The house has old wiring and probably has a grounding issue. The noise you're hearing is the compressor turning on and off. Might want to have it checked for low coolant or a collant leak. But basically its causing an internal power surge in the home. Depending on the age of the fan, its either electronic (newer) or has a wrapped wire transformer (older) and if its the older type then its sending a signal through the wires.
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Old 08-12-2012, 11:12 AM
 
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I'm going to disagree here. If your tv is the old type with tubes, any momentary power glitch is too fast and the power supply and capacitors too solid for it to be an issue. If you saw a shrinking of the picture, then yeah. A scan line interruption is almost always from an air source. The shielding on the pre-amp stages of older tvs can be minimal, and any spark can give enough RFI to show as you describe.

The boombox could be either, but is more likely powerline. The delay is a bit puzzling though. Refer motors commonly have a tiny compressor and a capacitor assisted start, but what you describe sounds more like the effect of a separate starter winding dropping out of the circuit.
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Old 08-12-2012, 07:31 PM
 
Location: New Mexico U.S.A.
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Quote:
Originally Posted by robertpasa View Post
I have a Sony radio boombox in my bedroom. When my fridge automatically goes on or off (because of the termostat), the fridge makes a knock sound, and an instant later, a click comes out of my radio. I know it's linked because it always happens this way.
Probably/possibly the compressor relay being activated to start the motor. They are mechanical relays and can spark.
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Old 11-28-2015, 11:30 PM
 
26,144 posts, read 19,703,385 times
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I tell ya.. I really hate these new appliances..... NO SHIELDING @ ALL!!!!!

My dad put these new lights in the kitchen a few years ago and when they are on,I HEAR NOTHING BUT A LOUD BUZZ ON MY AM RADIO!!!!! (Unless the signal is quite strong -- then I hear the buzz UNDERNEATH it))
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Old 11-29-2015, 08:15 PM
 
Location: Sarasota FL
6,864 posts, read 12,006,456 times
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When my radio is on AM band and I turn on my dining room light that has a slide switch, at a certain point on the slide, I get very noisy static on the radio. This is occurring through the wires? If so, why on a certain road I drive my car that has HV wires do I get loud static on the car radio AM band?
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Old 11-29-2015, 08:31 PM
 
Location: Not far from Fairbanks, AK
20,243 posts, read 36,912,118 times
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Maybe this will help you figure the problem?
See the invisible wireless signals around you with this augmented reality app | The Verge

Probably this app is not very accurate at moment, but sounds interesting.
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Old 11-29-2015, 11:03 PM
 
26,144 posts, read 19,703,385 times
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good RAY!!

Its scary all the signals we are bombarded with daily!!
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