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Eliminating radio interference from Apple charger

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Re: Eliminating radio interference from Apple charger

#121

Post by TylerE »

NovemberWhiskey wrote: post #54
crote wrote: post #53

Earlier quoted context omitted.

Do you have any idea how that power compares to regular FM radio broadcasts, which are somewhat close in frequency? Is this something a regular radio would detect, or is OP just trying to listen to a handheld radio half a continent away using a really sensitive receiver with the volume knob turned all the way up?

To get a very broad idea: if you had perfectly efficient but isotropic antennas (you don't) this would be about the power level you'd get receiving a typical 3W hand-held radio signal at 140MHz from 1,000 kilometers away. This is why you can talk to the International Space Station easily enough with vanilla ham radio equipment. Or, taking a notoriously powerful FM radio station like KRUZ 103.3, it would be like heari…

The ISS also orbits quite low. If you're relatively close to the path it's only a few hundred miles away. Small temporal window due to the speed, but still.

Re: Eliminating radio interference from Apple charger

#122

Post by TylerE »

pnpnp wrote: post #43
stetrain wrote: post #15

Earlier quoted context omitted.

There's a big difference between causing interference in a receiver a few inches away versus an airplane 1000ft above you. It may be that this charger passes the legal requirements while still causing small amounts of interference when placed near a receiver.

There’s also a big difference between one charger emitting some noise, and a couple million in a big city raising the noise floor for the frequency.

Inverse square law dude. We're talking about nanowatts, at most, here.

Re: Eliminating radio interference from Apple charger

#123

Post by TylerE »

pnpnp wrote: post #68
Clamchop wrote: post #60

Earlier quoted context omitted.

It's not Apple's job to determine if there's a problem with that and regulations on this issue are, so far as I'm aware, treated very seriously.

Sorry - I can clarify a little. If it complies with regulations, Apple is definitely not at fault. I was just replying to the above comment which could read “a little noise from a single device isn’t a big deal.” It is definitely up to regulators to decide what is acceptable, and up to Apple to meet those regulations. It’s still a little unclear from the OP whether or not the spurious emissions meet transmission requ…

We're talking "little" as in "need a powerful microscope to see it", not "small".

Re: Eliminating radio interference from Apple charger

#124

Post by BHSPitMonkey »

TheRealPomax wrote: post #101

That's... not a magsafe charger? That's a USB-C NFC charger. By all means show it's shit in every possible way but let's not grace them by acknowledging it has anything to do with magsafe. That's a Applified Qi charger.

How are you determining this?

Re: Eliminating radio interference from Apple charger

#125

Post by bloggie »

The poster's assumption that this is caused by the Apple product could be incorrect. The emissions could be caused by the supply equipment noise propagating down the cable. The load presented by the Apple product could induce the supply equipment to emit noise at that frequency.

Re: Eliminating radio interference from Apple charger

#126

Post by MBCook »

I see something that looks like a MagSafe puck with a black plastic piece snapped on for some reason.

Are we sure it’s a real MagSafe puck? The article didn’t check that.

Sadly copies of Apple stuff are so rampant, especially on Amazon, if you didn’t buy it yourself from a reputable retailer. It’s quite possible it’s a fake. The little white charger bricks were copied rampantly. With Apple’s prices the fakers stand to make a lot.

Given Apple’s normal engineering quality that would be my first guess. Or Bloggie’s guess it’s the PSU that’s the issue.

It’s interesting they found the problem, and that a simple ferrite bead fixed it.

But I have no doubt there are fakes out there for something g like the MagSafe puck. Without ruling that out simply declaring it a “piece of crap” seems unwarranted.

Re: Eliminating radio interference from Apple charger

#127

Post by TheRealPomax »

meatmanek wrote: post #106
TheRealPomax wrote: post #101

That's... not a magsafe charger? That's a USB-C NFC charger. By all means show it's shit in every possible way but let's not grace them by acknowledging it has anything to do with magsafe. That's a Applified Qi charger.

MagSafe® is a registered trademark of Apple Inc., so if they call it a MagSafe® charger, it's a MagSafe® charger. https://en.wikipedia.org/wiki/MagSafe_(wireless_charger)

Gonna hit back with "nope".

If Kleenex gets into toilet paper and tell you that toilet paper is now kleenex, the response is "you clearly don't what what the hell you're talking about, get your head out your ass".

Magsafe is a magnetic power connector that clicks into a socket, whether Apple sticks their head up their ass or not.

Re: Eliminating radio interference from Apple charger

#128

Post by SV_BubbleTime »

Animats wrote: post #110
SV_BubbleTime wrote: post #78

Earlier quoted context omitted.

Oooh. I clicked through your PCB there. I would highly recommend you read a couple books on circuit design. You have a 2 layer PCB with no ground plane and you aren't routing ground, signals passing parallel with each other on adjacent layers, you have mixed analog and digital domain, massively long traces where they could be shortened with a small jumpers. Worst offender is you aren't using a ground plane or routing…

Nothing there is going faster than about 300KHz, so the signal paths are not a big issue. If things had to go faster, there would be a proper ground plane. The tiny area around the switching IC did require careful layout (it just follows the Linear Technology data sheet) but the rest doesn't matter much. There is no one ground. The 120VDC side has an HV ground, and the 5VDC side has a ground. The important point is t…

> nothing faster than 300k

That is exactly one of the misunderstandings I’m trying to warn that you are missing.

I’m certain that your switching transition times are massively faster than the 300k period (each rise and fall time).

You can have split grounds, but you don’t have traces under your grounds so in many cases you aren’t even effectively using them. You are grounding a portion of every signal inside every other signal trace.

“The rest doesn’t matter much”… my man, I can’t explain in this form just how wrong you are.

It’s one thing to be wrong on a design from years ago. My old designs were worse. But it’s another thing to willfully ignore all the ways in which someone who knows better is trying to help you with.

Everything you think about that circuit is wrong in ways you aren’t getting - yet.

Try Phil’s lab videos for EMI.

Re: Eliminating radio interference from Apple charger

#129

Post by bobbylarrybobby »

TheRealPomax wrote: post #101

That's... not a magsafe charger? That's a USB-C NFC charger. By all means show it's shit in every possible way but let's not grace them by acknowledging it has anything to do with magsafe. That's a Applified Qi charger.

MagSafe is simply Apple’s brand name for chargers that “plug in” via a magnet. It used to just be the ones that charged laptops, but now that iPhones have the magnetic ring on the back for specifically this purpose, there are MagSafe iPhone chargers out there too.

Re: Eliminating radio interference from Apple charger

#130

Post by scq »

mschuster91 wrote: post #57
sdflhasjd wrote: post #28

This thread looks like a relevant one to mention an issue with the Mac Studio that causes large inrush currents when you plug it in. The power connector arcs badly enough to trip a domestic 30mA RCD, it's reproducable with several units and on different electrical circuits at both home and office.

The arcs have nothing to do with tripping the RCD part of your breaker. The RCD part only trips on a substantial current (>30 mA, or less for specialty devices, or more for upstream RCDs) between hot and ground, it doesn't care at all about the current flowing between hot and neutral. That inrush current however, given sufficiently large buffer capacitors, can be enough to trip the overcurrent protection that most if…

That is not how an RCD works. It doesn't even look at ground.

An RCD will trip when the difference between the current going down the live and neutral conductors exceeds a certain value -- in normal operation they are opposite and cancel each other out.

If it operated how you describe, it could never detect someone touching a live conductor, because the current would not return through the ground prong.

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