How can I avoid my MacBook Pro giving me minor shocks? • Hacker News Board

Re: How can I avoid my MacBook Pro giving me minor shocks?

#141

Post by bitL » Mon, Nov 14, 2016, 2:21 PM UTC

jordwest wrote: post #18

What's fascinating to me about this phenomenon is that you can actually feel the 60Hz AC by running your hand across the lid. It feels as if the surface is slightly bumpy, but the width of the bumps changes as you adjust the speed your finger moves. Unplug from mains, and the surface becomes smooth. As the answer notes, this only happens when using the two-prong adapter without earthing. It also seems to be more noti…

I am sure that's a feature by Apple, they want to give you a nice 9V tDCS running through your brain to make you more productive ;-)

Re: How can I avoid my MacBook Pro giving me minor shocks?

#142

Post by amelius » Mon, Nov 14, 2016, 2:53 PM UTC

bitL wrote: post #141

jordwest wrote: post #18

What's fascinating to me about this phenomenon is that you can actually feel the 60Hz AC by running your hand across the lid. It feels as if the surface is slightly bumpy, but the width of the bumps changes as you adjust the speed your finger moves. Unplug from mains, and the surface becomes smooth. As the answer notes, this only happens when using the two-prong adapter without earthing. It also seems to be more noti…

I am sure that's a feature by Apple, they want to give you a nice 9V tDCS running through your brain to make you more productive ;-)

Or it is a side-effect of Apple's reality distortion field :)

Re: How can I avoid my MacBook Pro giving me minor shocks?

#143

Post by nraynaud » Mon, Nov 14, 2016, 3:09 PM UTC

Hydraulix989 wrote: post #99

nraynaud wrote: post #91

Earlier quoted context omitted.

I would separate the issues, vacuum cleaners are famous for electrically charging dust up to quite high voltages.

I should clarify that the reports indicated that the shock originated from the hand touching the handle.

I guess I should go further: some vacuum cleaners have to have a ground connection in the hose, to try to discharge the dust. If they removed it for unrelated reasons, they probably lowered the overall quality of the product overall.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#144

Post by hatsunearu » Mon, Nov 14, 2016, 3:23 PM UTC

nitrogen wrote: post #94

hatsunearu wrote: post #59

Earlier quoted context omitted.

"clean" mains power has nothing to do with zapping. Where'd you hear this? I've literally never heard this nonsense before.

I suppose a neutral line with a nonzero voltage could be called "dirty", but not in the traditional noise sense.

That still doesn't cause zaps unless you were living in the Edison days or something.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#145

Post by BJBBB » Mon, Nov 14, 2016, 4:31 PM UTC

Geez peoples - so much misinformation. Touch current test methods and limits are well-defined through out the world. Poor power 'quality' may affect this measurement, but is not a significant contributor to the magnitude of potential leakage through the ground wire or through exposed metal surfaces. It is a function of the power conversion equipment connected to, or internal, to the device. Even where wiring does not meet code, the upper limit to this measurement is well defined per the simulated fault conditions required in the test methods.

People that claim to be engineers need to read and understand the basic physics behind the product safety standards scoped by your equipment. For EU, code is defined in BS7671/IEC60364; and NFPA70 (mostly article 250) in the U.S.; and similar stuff in C22.1 for Canada.

ITE power supplies must meet the locally harmonized version of IEC60950-1 (soon to be obsoleted by IEC62368-1). Where there is no ground pin, North American power supplies must meet UL1310/CSA No.223. These standards all have specific limits for voltage, current, and VA levels that can be exposed to the end-user, for both normal and abnormal operating conditions.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#146

Post by gravypod » Mon, Nov 14, 2016, 5:30 PM UTC

If you can get a shock from this, and as someone else is saying that they can feel it when they wave their hand over the lid, then how is this passing any EMI screening?

That's got to be noisier then an old ham radio.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#147

Post by hinkley » Mon, Nov 14, 2016, 5:36 PM UTC

x0x0 wrote: post #69

hinkley wrote: post #12

Earlier quoted context omitted.

Have you seen a tear down of the authentic chargers? There's a lot going on in there.

As mentioned below, a reasonable estimate of the cost is $30. They could also sell replacement user swappable magsafe cords and defang many of the complaints. But then they couldn't effectively charge $90 for a replacement cord.

I have wanted that cord to be replaceable forever. At least it finally is now. Given how many the kids and dog destroy I consider it an improvement.

I have wondered if the degradation of the cord wasn't some sort of safety guarantee rather than planned obsolescence. When the cord wears out you buy a new one instead of using the ancient one from eight years ago.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#148

Post by phee » Mon, Nov 14, 2016, 5:43 PM UTC

BJBBB wrote: post #145

Geez peoples - so much misinformation. Touch current test methods and limits are well-defined through out the world. Poor power 'quality' may affect this measurement, but is not a significant contributor to the magnitude of potential leakage through the ground wire or through exposed metal surfaces. It is a function of the power conversion equipment connected to, or internal, to the device. Even where wiring does not…

> Where there is no ground pin, North American power supplies must meet UL1310/CSA No.223

So, as far as I can tell, with a brief skim of the standard, a class 2 device should have no more than 0.5 mA leakage current, right?

I just measured the leakage from my macbookpro through my body to ground and it's about 50 μA. Well within the limits.

So I guess that's why they never did anything about it. Still amazing that you can clearly feel this current: if you lightly brush your wrist around the sharp edges it actually hurts. I wonder how 500 μA would feel.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#149

Post by creshal » Mon, Nov 14, 2016, 5:59 PM UTC

mavhc wrote: post #124

creshal wrote: post #107

Earlier quoted context omitted.

They didn't "attempt to block Linux", they just shipped hardware without a Linux driver. And later released a workaround to make the hardware work in a slower, more power consuming backwards compatibility mode so Intel can continue not properly supporting the hardware in Linux. But sure, it was totally "Lenovo blocking Linux".

How come Intel is one of the top contributors to linux, but doesn't ship drivers for all their hardware?

Different divisions doing different things. Intel is extremely interested in Linux for their HPC Itanium/Xeon range, moderately interested in Linux for other server and business hardware, as well as mobile; and Intel's consumer PC division doesn't give a fuck at all.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#150

Post by BJBBB » Mon, Nov 14, 2016, 6:11 PM UTC

phee wrote: post #148

BJBBB wrote: post #145

Geez peoples - so much misinformation. Touch current test methods and limits are well-defined through out the world. Poor power 'quality' may affect this measurement, but is not a significant contributor to the magnitude of potential leakage through the ground wire or through exposed metal surfaces. It is a function of the power conversion equipment connected to, or internal, to the device. Even where wiring does not…

> Where there is no ground pin, North American power supplies must meet UL1310/CSA No.223 So, as far as I can tell, with a brief skim of the standard, a class 2 device should have no more than 0.5 mA leakage current, right? I just measured the leakage from my macbookpro through my body to ground and it's about 50 μA. Well within the limits. So I guess that's why they never did anything about it. Still amazing that yo…

Depends on the 'bandwidth' of the signal and the test equipment and the individual. Generally consider many non-medical measurements below 025mA suspect, as few design engineers make an effort to understand the various frequency components of the voltage and current leakage signals, and/or understand the effects to the signal of instrument impedances.

Have had several discussions with Mr.Pete Perkins (he sits on several STCs and has written several IEEE papers) on this subject, and we agree that the human body model referenced by these safety standards being used for the measurement network (IEC60990) have problems because the medical community does not understand physics. As the various standards committees continue to look at the body of work being done by bioengineers, will probably see better measurement methods being codified.

Human response and perception to electricity has significant variance and resultant effects/affects. My wife can detect less than 10uA at 200Hz/42V. My detection threshold is at least an order of magnitude greater, even at 50Hz.