strange emf loop on laptop

I got the notion that I would set up a 19inch led tv to use as my monitor  
for my laptop. The TV was powered by a 12 volt deep cycle battery and the
laptop  was running off its own battery,  I felt a problem with this in the
form of  stinging in my head as soon as I hooked it up so I checked the setup
with an emf  meter, sure enough it was reading high (the meter is dodgy in
as much as it  resgisters but i dont trust the actual reading nevertheless it
reads out and  detects) basically when I left the meter propped up by the
keyboard it was  reading very low, but when I came within a metre of the
meter it started to go  haywire ? if I put my hand near the meter it would also
go crazy, it was as if  my body was applifying the readings, so all I can
figure is that the ethernet  cable which is connected to a mains supplied
router had some earthing  anomoly relative to the 12volt battery and so my body
was the best earth it  could find and therefore I was pulling in electrons !
 when I powered  the laptop up to the mains the anomoly settled, I suspect
due to the fact  that the power supply has a good earth. I also suspect that
if I use my usb  powered modem then there will be no such problem either.
(will check  later) The moral of the story is be careful mixing ac with dc
and if  you feel symptoms then make sure you check out the scenario with a
meter and or  am radio.
 
puk
 
a better explanation is bound to be given here from some of our resident  
experts so fire away.

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Hi Paul,

> I got the notion that I would set up a 19inch led tv to use as my monitor  
> for my laptop. The TV was powered by a 12 volt deep cycle battery and the
> laptop  was running off its own battery,  I felt a problem with this in the
> form of  stinging in my head as soon as I hooked it up so I checked the setup
> with an emf  meter, sure enough it was reading high
Sounds like a great plan so far!


>  so all I can
> figure is that the ethernet  cable which is connected to a mains supplied
> router had some earthing  anomoly

Yes, that sounds like a problem. The Ground coming by ethernet cable is
not the same ground as the negative side of the 12V battery, and the
imbalance creates a desire for electrons to go from "here to there." But
this is only with the laptop off?

Just to confirm, if the laptop and tv are both powered by battery, and
neither are connected to any charger or ground-providing wire, then do
they get along with each other? Both when on and when off?

And the problem only occurs when the laptop is off?

That is an interesting one for sure. There must be a hidden loop or
return path.
I would take a multimeter and connect the two leads to ground on the
ethernet side, and a screw hole next to one of the laptop cable plugs,
and see what the voltage differential is, in both AC and DC, and if
there are any milliAmps.

It must be a pair of wires in the ethernet cable, if it only happens
when the cable is plugged in.

That's my 5000 mile away analysis :)

Stewart

http://seahorseCorral.org

In a message dated 01/11/2012 02:17:54 GMT Standard Time,  
[hidden email] writes:

 
Hi Paul,

> I got the notion that I would set up a 19inch led tv  to use as my
monitor
> for my laptop. The TV was powered by a 12 volt  deep cycle battery and
the
> laptop was running off its own battery, I  felt a problem with this in
the
> form of stinging in my head as soon  as I hooked it up so I checked the
setup
> with an emf meter, sure  enough it was reading high
Sounds like a great plan so far!

> so  all I can
> figure is that the ethernet cable which is connected to a  mains supplied
> router had some earthing anomoly

Yes, that  sounds like a problem. The Ground coming by ethernet cable is
not the same  ground as the negative side of the 12V battery, and the
imbalance creates  a desire for electrons to go from "here to there." But
this is only with  the laptop off?

Just to confirm, if the laptop and tv are both powered  by battery, and
neither are connected to any charger or ground-providing  wire, then do
they get along with each other? Both when on and when  off?NO PROBLEM WHEN
NO MAINS IN THE SET  UP.




And the problem only occurs when the laptop is  off?NO WHEN ITS ON

That is an interesting one for  sure. There must be a hidden loop or
return path.
I would take a  multimeter and connect the two leads to ground on the
ethernet side, and a  screw hole next to one of the laptop cable plugs,
and see what the voltage  differential is, in both AC and DC, and if
there are any  milliAmps.

It must be a pair of wires in the ethernet cable, if it only  happens
when the cable is plugged in.

That's my 5000 mile away  analysis :)

Stewart

_http://seahorseCorral.org_ (http://seahorsecorral.org/)





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