this post was submitted on 26 Dec 2024
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I never knew that USB-C extensions are not allowed for a reason (www.youtube.com)
submitted 7 months ago by quiescentcurrent@discuss.tchncs.de to c/technology@lemmy.world
11 comments fedilink hide all child comments
 

There is a reason for USB-C extensions not to be part of the standard. They can be bothersome in the best case and dangerous in the worst.

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[–] MargotRobbie@lemmy.world 2 points 7 months ago (1 children)

If you want a more detailed explanation, USB-C is a small connector that was designed primarily for data transfer, extended power range delivery (240w) was essentially hacked on to the standard. Electricity arcing between the contacts on the connector is the biggest challenge with this hack, since the contacts are small and very close together, which could burn out the circuit board and start fires. For EPR to work safely, there needs to be a lot of extra components on the circuit board/female connector side, which there simply isn't enough space for on an f2m extension cable.

As for why USB-C cables are so short, it's simply a matter of physics, carrying high speed data over larger distances would result in higher losses and requires thicker conductors and more shielding, which is why you don't see USB4 Gen3 cables over 1 meter unless they are optical, and longer "charging cables" are only rated at USB 2.0 speeds, because more often than not they don't even have the USB 3.x data pins on their connector.

[–] Agent641@lemmy.world 1 points 7 months ago (1 children)

You are a brilliant woman of many talents, Margot Robbie!

[–] MargotRobbie@lemmy.world 1 points 7 months ago

That's esteemed Academy Award nominated character actress Margot Robbie to you!

Also, thank you.

[–] BombOmOm@lemmy.world 1 points 7 months ago

Seems negligent to not include extension cables in the spec. Lots of hubs have too short of cables, or one needs to expose a plug somewhere other than where the PC is.

[–] AnUnusualRelic@lemmy.world 1 points 7 months ago

I'll have you know that I've been using a 2m extension on my deck power supply for a while and haven't had any fires to speak of. Almost none actually.

[–] NobodyElse@sh.itjust.works 1 points 7 months ago (1 children)

Anybody care to sum this up for people who can’t watch videos?

[–] WraithGear@lemmy.world 1 points 7 months ago* (last edited 7 months ago)

So a standard cable needs to be chipped to show its rating to the device, its not that the device can pull what it wants or can get, but the cable itself tells it what it can supply. Extension cables can’t do that, because it doesn’t know what it’s plugged into, and that would be if they even bothered to put a chip in. They instead piggy back off the chip for the main cable. The problem comes when you you have a 240 watt cable hooked up to a cheap 120 watt cable, with the device being told it can push 240, and starts to super heat the extension cable

[–] VerticaGG@lemmy.blahaj.zone 0 points 7 months ago (1 children)

How does this apply to a usb-c-to-headphone-port adapter, if at all? If someone's using one to regain access to a 3.5mm audio jack, are any risks posed?

[–] AmbitiousProcess@piefed.social 1 points 4 hours ago

That's not an extension cable, but an adapter, thus it's not a problem in this case. It's a cable that can convert the data from an audio jack to something that can go through USB-C, not a cable that simply extends a USB-C cable. The cable can almost certainly handle any amount of power and data that an audio jack would pass through it, no problem, even if it were a USB-C to USB-C extension cable, and not an adapter.

The problem arises when someone tries using a higher-spec USB-C cable with a lower-spec USB-C extension cable, such as using a 240W charger with the lower-spec USB-C extension cable in the middle that can only do 120W. In that case, it would pass more electricity through than the lower-spec cable could handle, and it would overheat.

The amount of data and power from an audio jack is simply too small to overwhelm practically any USB-C cable or adapter that exists, thus it's not an issue.

[–] Magister@lemmy.world 0 points 7 months ago (1 children)

I have a 240W extension from AliExpress, used with a 120W power for my laptop, it never gets hot even when using 100+W

[–] jayandp@sh.itjust.works 1 points 7 months ago

Because you made sure the cable is rated for more than what you're using it for. The problem is when somebody doesn't do that. A 60W cable hooked up to a 120W power supply, for example.