iPad gives tingly light vibration electrocution when plugged into mains
I thought I'd ask whether this was normal seeing that my friends ipads are doing the same thing;
Using the supplied AC adaptor and supplied USB cable, when I plug my iPad into the mains its gives a kind of tingly vibration feeling on the back, especially when I move my hand around the surface. When not plugged into the mains or when plugged into my PC it does not happen... suggestions? Is this a fault?
Yes, your description fits my experience exactly, and I came to the same conclusions. The case is live, albeit at very low amps. The Macbook charger resolves it 100%. It IS an issue apple should a dress IMHO. The more people who draw attention to the problem, the better, though it will never be an antenna gate unless someone gets really zapped.
"Static doesn't pass a current, as it is static, not moving."
"Static" is short for "electrostatic", and is not the same as the "static means it's not moving".
Your description reminded me of an electrical engineering manager at Xerox who was trying to tell someone why "CMOS" was faster than "NMOS". According to him, "CMOS was faster because electrons are faster than holes". To understand the joke, you need to understand the "hole flow theory" that causes electricity to move (including "static" electricity). His comments caused him to be transferred to another state. You can stay where you are.
Mongy,
"To imply stationary or slow moving electricity?" Right now, I'm thinking of something else besides electricity that is "stationary or slow-moving". Some replies are so off-the-wall, I don't know if they're serious or not. Your reply fits that category. When referring to electricity, "static" is not the opposite of "dynamic". Electricity flows in the opposite direction of holes - you need to understand the "hole flow theory" to make sense of this.
Hey Carl,
You could be right, I don't have a passion for electronics or physics in general it has to be said, but it's just I was not necessarily persuaded by your fairly obvious arrogance, well that and some minor research :
http://en.wikipedia.org/wiki/Electrostatics
Even without the benefit(?) of studying hole flow theory, I can appreciate that stationary electricity is a vast over simplification. All I am suggesting is that a lack of movement at some level is implied by it's name clearly consisting of electro and static. I am fairly confident that the word 'static' predates the human comprehension of anything electrical, and it's therefor likely that whoever first coined the phrase static electricity employed it accordingly.
I am sure a man like you who presumably collects Higgs bosons for a hobby armed with nothing more than a pair of tweezers while sneering at CERN employees for taking so long - could explain to us why static electricity is named as such.
It looks just like it, yes... please remember I am in the UK. That link takes me to a U.S. website. I note also you said 'probably' has a ground pin. The supply that came with the original Ipad had a ground pin adapter which was a dummy, not connected to anything. Just because it's there physically doesn't mean it's an actual ground. With respect, you would need to find this out, not assume. Maybe someone from Apple could respond.
The iPad charger adapter is stamped double insulated so no chance of a short to the secondary so its safe, and therefore it doesnt require an earth (having taken one to pieces I'm not sure how they can claim it is double insulated!!!)
However Apple have put size and form over function and omited a lot of the electrics that normal transformers have, thats why most 5V 1amp transformers are 3 times the size of the apple one
The upshot of this is that the iPad adapter suffers from a floating ground. ie the 0V rail may or may not be at 0V. It has no real earth reference to tie the 0V to. So the 5V rail may not be at 5v either. In the case of one of mine the 5V rail is at 25v RMS and the chasis (0v rail) is at 20V. As long as the Potential difference between the 2 is 5v the iPad acts normally
Now of course, when you insert the cable into the iPad the chasis makes contact with the 0V rail on the cable and the chassis goes to the level of your 0v reference. Hence if you supplys floating ground is well off then your chassis will become charged. How much depends on a lot of things. If you can feel it also depends on many things including how well you are earthed
The Apple PSU from the MBA etc have better circuitry and therefore the reference voltage is nearer true 0V
Is it dangerous, probably not, looking at the circuitry in the adapter I cant see the drift becoming more than 100v and the current will always be pretty low. Still its a design fault
My worry is when you earth the pad (probably via you) you now had a voltage of in my case +25V supplying the pad, this will either charge it much faster or eventually blow something. One person is claiming 90V floating earth, this is not safe for the iPad and probably not good if you have a pacemaker or are an epileptic
I've noticed the same problem on MacBook Pros. If you use one while its plugged in to the mains, if you run your finger across its aluminium body, you feel this tingly light vibration in your finger. The sensation goes away as soon as you stop moving your finger.
Same sensation here too. Even to the point that if you make skin to skin contact with someone touching the iPad the buzzing can be felt on their skin. Also happens with my MacBook pro and the metal bezel on my iPhone 3G.
Correction to your assertion that static electricity does not pass current. This is completely wrong! Just ask anyone who has been hit with lightening. This example can be in the hundreds of millions of amps. Which is why the recipient tends to die.
After having read this thread, I was a little worried. So I took my multi-meter and got a reading. 130 Volt AC ⚠ between the back of the iPad and my hand. Just for reference: The same reading between me and the wooden desk, as well as my PC's casing was 0.6 VAC.
I live in belgium (220 VAC power sockets) and am using the standard wall charger (2 pins, no earth).
FYI, MBP power supply (in the UK) has no earth either. I don't have plain MB so I can not say for sure what that looks like. Regardless of this, if you are plugging in the "figure 8" power cord from a MB into the iPAD "brick" you are still not earthed?
I don't have a Mac Book, but I do have a "figure 8" power cord from some other device (2 lines, no earth). I still have the same readings -> drifting AC voltage on the iPad's metal shell.
My guess is as follows: Any exposed metal of a device should be properly grounded. The iPad's shell is probably connected to the ground connection of the power supply (i.e. exposed metal part of iPad connector). It is also common practice to connect the negative line of a DC circuit, which is otherwise free to float around, to ground. Now, if the power supply does not provide a proper grounding, you end up with the exposed metal being connected to the negative DC line which is free to float around compared to earth. When you touch the iPad's shell, standing barefooted on a stone floor (or being earthed otherwise), you are actually yourself grounding the device, conducting a tiny current from the device to earth.
In short: If using the provided equipment, as you should, the iPad's body is not grounded but connected to internal circuits, as it should not!
This is bad design, not poor, bad. If something goes wrong with the power supply (i.e. internal short circuit between AC and DC circuits) you could end up with an exposed metal body delivering full AC.
If no proper grounding can be guaranteed, the shell should be adequately isolated instead of being connected to internal circuits. Never should a person be able to come in contact with exposed electrics. The goal of the wall socket's earth pin is exactly that: ensure that any exposed metal of connected appliances will not pass on any current.
Again, this is just a (fair) guess. If Apple would have shipped a proper grounded power supply, there would be no problem.
I would appreciate it if anybody could confirm my guesses, as I have no intention of disassembling my iPad nor my power supply.
