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Eliminating radio interference from Apple charger

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Re: Eliminating radio interference from Apple charger

#111

Post by FireBeyond »

amatecha wrote: post #61
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?

Due to proximity, the interference from the charger is comparable to what the receiver was expecting from a normal signal (like an amateur radio repeater or fellow operator's station), which is why his radio broke squelch while scanning. Because the radio is relatively close to the charger, the RFI is picked up quite well. Comparing to a broadcast FM station, the strength of the RFI as observed by any nearby radio wi…

> Broadcast stations are some of the highest-power radio transmissions around us, typically thousands of kilowatts (for example the rock station near me transmits at an ERP of 51,000 watts[0]).

I don't think so.

Not "thousands of killowatts" transmitted. Your example is as you say, an ERP of 51kW.

But even ERP doesn't refer to the transmitter. An ERP of 51,000W is most likely a 5-10kW transmitter, with a gain factor of 5-10.

Re: Eliminating radio interference from Apple charger

#112

Post by thenickdude »

skykooler wrote: post #91
jrockway wrote: post #77

Earlier quoted context omitted.

> Since on a narrow-body aircraft passengers can easily be within 2 meters of some of the VHF antennae. But, separated by a very large piece of conductive metal. (I think even carbon fiber planes have a conductive layer in there, to prevent damage from lightning strikes.)

Isn’t carbon fiber conductive itself?

Yes, and blocks radio transmissions very nicely. When making a model airplane with a carbon fibre hull, we have to add a plain fibreglass or plastic window for the antenna to receive through.

Re: Eliminating radio interference from Apple charger

#113

Post by Mistletoe »

js2 wrote: post #17
Animats wrote: post #10

> This radio interference was also present on the aviation frequencies (around 124 MHz) How did this thing get FCC approval? What's it's FCC approval number? Who tested this thing? Want to look that up. If RF got outside the charger and into the USB cable, it's very badly designed. The power in the USB cable is DC. There shouldn't be any significant RF component. There should be ferrite beads and capacitors in the po…

I can't be sure this is the exact model as OP, but the FCC testing doesn't seem to indicate any issues from my brief skim: https://fccid.io/BCGA2548 (I have not read the entire report and I have no expertise in RF.)

Is the original author certain he has an authentic Apple charger? I’ve seen teardowns many times of bogus Apple chargers that use worse designs and components.

http://www.righto.com/2016/03/counterfeit-macbook-charger-te...

Re: Eliminating radio interference from Apple charger

#114

Post by kazinator »

Once upon a time, when I was working at Broadcom, I put on a nice demo for some colleagues.

I had a long serial line strung across my desk from a USB-Serial dongle to an embedded board. It ran under the LCD monitor. Weird banding and noise was showing on the monitor.

The demo was: "watch the artifacts on the monitor go away, as I clamp this ferrite bead around the serial cable".

Re: Eliminating radio interference from Apple charger

#116

Post by ayx »

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.

Yep, it looks like a knockoff.

Re: Eliminating radio interference from Apple charger

#117

Post by TylerE »

FireBeyond wrote: post #111
amatecha wrote: post #61

Earlier quoted context omitted.

Due to proximity, the interference from the charger is comparable to what the receiver was expecting from a normal signal (like an amateur radio repeater or fellow operator's station), which is why his radio broke squelch while scanning. Because the radio is relatively close to the charger, the RFI is picked up quite well. Comparing to a broadcast FM station, the strength of the RFI as observed by any nearby radio wi…

> Broadcast stations are some of the highest-power radio transmissions around us, typically thousands of kilowatts (for example the rock station near me transmits at an ERP of 51,000 watts[0]). I don't think so. Not "thousands of killowatts" transmitted. Your example is as you say, an ERP of 51kW. But even ERP doesn't refer to the transmitter. An ERP of 51,000W is most likely a 5-10kW transmitter, with a gain factor…

Back in the pirate radio days 100 and 250kw transmitters were common.

Back in the '30s a few AM stations ran at 500kw, and could be picked up on other continents.

Re: Eliminating radio interference from Apple charger

#118

Post by fsckboy »

stainablesteel wrote: post #115

so does this make charging more efficient? does it help preserve hardware in the long-run? is there a guarantee that these frequencies weren't added in for some engineered purpose?

I have a feeling this makes charging less... not efficient, but slower charging.

The end of this thing is a bunch of wire in a loop, the inductor that transfers the energy to the phone. So it was odd to me that he chose the cord as the antenna that was broadcasting the noise, when I'd think it would be the business end. These frequencies being broadcast might be overlooked harmonics, ok to filter out, but they might be a designed part of the energy transfer that the charger is attempting. It's possible that he's damped the noise and the charging, but under normal use he doesn't need the maximum charge so it's still a win.

not my specialty, just speculating based on basic EE knowledge.

Re: Eliminating radio interference from Apple charger

#119

Post by ayx »

NtG_UK wrote: post #4

From a marketing standpoint, Apple managed to turn "The Notch" into a feature. Whether they could do the same with "The Lump" is asking a lot IMHO. Perhaps (as the author says), the engineers could come up with something more elegant.

Hahaha, I can imagine a buttoned up exec channeling jobs brandishing "the lump" on stage at one of their events. And he is saying: This is the best "lump" we've ever made. 20% Lumpier than the previous generation, 30% lighter, with a brand new crazonium body with a ferrite core!

Re: Eliminating radio interference from Apple charger

#120

Post by JoeAltmaier »

yreg wrote: post #97
JoeAltmaier wrote: post #89

I heard years ago, Steve Jobs wouldn't allow a choke on a cable because they looked bad. A chronic problem as long as Apple has existed?

Can you ELI5 how does this negatively affect the consumer and why should the consumer prefer the 'bad looking' choke option?

Not only does the device feed high-frequency signals into your power wiring, it can get noise from it like motors turning on or off and spiking the voltage.

It's only a problem if it's a problem. If they'd done proper filtering inside the device maybe it's ok.

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