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29 May 2004 @ 08:57 pm
today's chocolate ice cream  
So if greg and I sit on the couch with both our laptops plugged in and then touch eachother, the one that touches and moves will feel a (at best guess 60 hz) buzz (the other person, not so much.) The buzz stops if the touch is stationary. If either laptop is unplugged and running on battery this doesn't happen.

Now here's the weird bit

1) both our laptops appear to have plastic bottoms.
2) even when I'm wearing sweat pants, (and theoretically insulated) this happens.

It not unsurprisingly stops when both laptops are plugged into the same outlet.

So best guess is that the two outlets on the opposite side of the room are out of phase, but how are we getting the hum through the plastic case and layer of clothing? Are out laptops really giving off that much RF? and if so, why is it still AC when the power bricks are outputting DC?
 
 
Current Mood: curiousperplexed
 
 
i. m. feyfeylike on May 30th, 2004 02:10 am (UTC)
are the power bricks two-prong or three-prong? if they're both two-prong, the DC output from the power brick will have different "ground" references. also, there is a source of high-voltage RF in most laptops... the inverter for the LCD backlight. it may be of high enough frequency to couple through plastic. also, most power bricks for laptops are switching power supplies, so they're going to put out some RF as well.
bob "the wonder llama"bob_wonderllama on May 30th, 2004 03:03 am (UTC)
your electrical system must be possessed
Binkbinkbink on May 30th, 2004 01:01 pm (UTC)
The only likely way to get the 60Hz past the bricks, is if there is a potential between your two grounds.
I know your wiring. I suspect that one of your neutrals isn't.
That would explain the many amps leakage in the earth ground when the lower kitchen refrigerator was plugged in.
In other words, one of the two outlets involved is wired backwards.
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Because of the two-wire situation, it might be hard to find with your outlet tester, so I would take a wire from the cold pipe in the kitchen, and measure the voltage with an ohmmeter.
Binkbinkbink on May 30th, 2004 01:02 pm (UTC)
Hrrrm. Multimeter. But you knew what I meant.