Electric field through electric blanket?
A little hard to explain but I'll try my luck…
namely, I have under my sheets an electric blanket 230v, due to the winter temperatures is quite pleasant to climb into a preheated bed:-).
Now I have my laptop on the lap which hangs with the cables on the power (Mackbock (Alughäuse)) … If I run my forearm on the laptop, I had noticed small electric shocks, such as slight Nadelpiekser, whereupon I thought of a mass problem of the charging cable… Cable removed, problem disappeared…
Multimeter held on the case but everything 0.0 … Only by accident I noticed that the electric blanket generates an AC field of up to 0.25V which I could measure by pure hang up of the multimeter (40cm distance of the poles) …
my question is now, whether that is dangerous for me or the technology when the AC current flows into the DC laptop?
My question is now, whether that is dangerous for me or the technology when the AC current flows into the DC laptop?
No, this induction is omnipresent.
For example, with an oscilloscope on a human, you can measure a voltage of some 100mV induced by the mains.
However, the inductive coupling is very small, so you can indeed measure this voltage with a multimeter or oscilloscope, however, as soon as the energy is induced in a conductor in your PC, it falls there to a few mV to μv and causes no problems.
Btw in your laptop, there are also AC, such as the processor clock bus signals, etc. Only the power supply is DC here.
I can't imagine that it is harmful for you, because an electric field acts only on charged particles and in the body normally none are present or everything is neutrally charged. In addition, such covers are also strictly tested, as pretty much everything, so if there was a risk, you would certainly not be able to buy the blanket.
Unfortunately, I do not know how it looks with the laptop…
And that I get these small electric shocks is also harmless?
This is strange, usually something like this exists when there's a problem with a protective isolated consumer somewhere.
It may be that your electric blanket is broken. If the charger for your laptop has a grounding, it may also be that the grounding is defective.
By induction itself I can't imagine that you would feel that.
And in the body usually none are present or everything is neutrally charged.
That's not true at all.
The stimulus conduction in nerves is exactly running over such charged particles. For example, sodium and potassium ions are involved.
Likewise, in the blood are extremely many electrolytes, which are then present as individual ions, important are sodium, potassium, calcium, magnesium, carbonate, etc.
Of course, the body as a whole can be electrically charged neutral, but that does not mean that there are no charged particles in the body, only that there are as many positive as negative charges.
Well, of course you're right!
In addition to induction, there's another factor called capacitive coupling.
Whether it is smaller or larger remains a matter of speculation.
Under which protection class does this electric blanket actually fall? I do not have that, can't see.
In any case, I get these surges only in the constellation → ceiling and laptop on the power supply…
cover and laptop on power supply → all IO
ceiling and laptop not on the power supply → all IO
Very difficult to interpret.
I can't really imagine the connection between the electric blanket and the Nadelpieks, although your test (only if both are working) allows opposite conclusions.
Do you sit on the electric blanket while "curling" on the laptop? And does the laptop power supply have a plug with PE contact or just a two-pin, flat Euro plug?
The electric blanket has a long heating wire that generates a measurable field. With a multimeter with high input resistance, so high sensitivity, you already measure with the measuring leads that act as an antenna, a few millivolts "from the air"
Then take me (like realistir) wonder what the meter (set to AC) indicates if you hold the test leads to the laptop's case and to the ground (earth) of a power outlet or grounded component (heater?).
I suspect the following:
Only two-pole power plug
The net filter "pisses" somehow capacitively against the secondary side ground, which is connected to the laptop case. Ev. Do you measure several volts (up to 115V conceivable) between the housing and a grounded component / protective earth contact (set the measuring instrument to AC!).
The electric blanket also has a grounding internally, a grounded sheath around the heating wire. When you sit on it there's a very tight capacitive coupling between the earth and you. So you are grounded "from the point of view of alternating current".
Thus, the capacitive leakage current from the laptop power supply via housing over your body "against earth" flow and cause this current feeling.
It would be safe, but pretty annoying.
Yes I sit / lie on the ceiling and the plug is a so-called Magsafe 1 connector
from the housing to the protective conductor, there are no rashes that indicate the meter…
I've just found that you can hear the flow of electricity flow properly when I run my forearm slowly over the laptop… You also notice how it flows properly…
when I touch the laptop with my second hand, the effect has disappeared → but only if the support surface is big enough… One or two fingers are not enough
is hard to hear
Unfortunately, I'm too ignorant to be able to measure how much there's really flowing… The highest that I could measure on me now are 2.8V AC if I hold the + in my hand and the minus next to me with me on the ceiling ( from the meter). A current could not be determined, but as I said I have no great idea to reliably operate the meter can
…
Incidentally, the heating blanket has no earthing on the plug → is just such a flat plug
Depends on how the electric blanket is actually connected, but it sounds to me as if the electric blanket has a defect and so a current flow from the laptop back into the network takes place.
Turn your multimeter on AC measurement. Lie down in bed and set the laptop aside. Take a measuring tip in your hand and go with the other on the laptop case. Then look what voltage is displayed.
I'd say protection class 2 but I have not even checked myself.
The device shows 1.5-3v even if I do not hold the second tip to the laptop but only lie next to me… If I hold this to the laptop, the values do not really change… I had atoemlein something interesting in the last answer written and linked to a video
Ok: Electric blanket only flat plug. Strange.
Laptop power supply: I meant, which plug is on the net side (not on side of the laptop: is there also only a flat zweipoliger? Or a fat Schuko plug?
But it's almost certainly a capacitive coupling of electricity. And yes, you can feel it on the forearm. This proves that it is gone if you offer another way to the stream (hand, if bearing area is big enough)
Miss the tension between the laptop case and your body when you sit on the electric blanket and do not touch the laptop yet. That would have to be a few tens of volts. And then you can measure even the milliampere, so magnitude 1mA I guess.
Forget the whole thing the best! You've been told by others that your concern is similar to your measurements, erroneously.
We're not ignorant, and you can be sure that if any of us had said anything wrong, written it, and considered it dangerous, one of the experts would have indicated it.
Okay, you have now described the laptop case to the protective conductor, there's no voltage potential to measure, so 0.0 volts. Now how do you want to do something more precise, because firstly you want to measure, and secondly we want to know something else.
Set the meter to 200 ohms or close, then measure the ohmic value of the protective earth contact socket to the housing of the laptop. If there's a direct, galvanic connection from the protective conductor to the housing, this connection should be less than 2 ohms.
If you can't measure anything, leave this wiring and switch the meter to the highest range that this resistance measurement can handle. Is there now a measured value, or is there more than 1 Megaohm displayed.
Show times and report, then we'll see, or try to come to the conclusion of the matter.
Yes it is a Schuko plug… As soon as I touch the laptop with the tip or the hand, the voltage drops to below 0.5v… A current I can't measure… I must also increase to over 6v what I achieve sitting on the ceiling… Unfortunately, I lack the expertise to measure something useful… I'm sorry
I can also measure no resistance from the laptop case to the protective earth… The meter always shows 1 without change on all settings
Still strange.
I had suspected it vice versa (Schuko on Heizkissen, flat plug on Laptopntetzteil).
What material is the electric blanket made of? And is that new? Maybe it really is the source of "capacitive interference," or even has a small leakage current.
