this post was submitted on 06 May 2025
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I found an interesting barrel plug cable. Thought I'd share in case anyone else is looking for a 5.5mm barrel power plug. No clue if it's any good.

Looks like it's available in 5v 5A to 28v 5A and the cable will only supply the rated voltage or 5v if the power supply can't supply the required voltage.

It does have a datasheet, which unfortunately is written in a language I can't read. Doesn't look like it comes with a power supply.

I see two issues with it. First, I don't have a boat load of spare USB-C PD power supplies so this solution winds up costing me more. Second, while the voltage is printed on the cable, it's printed grey on black so it probably going to be hard to read and once that wears off your back to playing "what's this cable".

This cable includes an EMARK chip

This cable is 1.2 meters long

Tip is 5.5mm outer diameter, 2.5mm inner diameter with center positive voltage, but it's springy so it works just fine for 2.1mm as well.

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[–] hperrin@lemmy.ca 10 points 23 hours ago

This is called a PD Trigger or a PD Emulator. They come in adapters too with a female USB C port and are only a few inches long.

Like this:

I’ve used several of them before. They’re super useful.

[–] cmnybo@discuss.tchncs.de 17 points 1 day ago (3 children)

It would be much more useful with USB PPS support for adjustable voltage and barrel plugs that can be swapped.

[–] Semi_Hemi_Demigod@lemmy.world 17 points 1 day ago (1 children)

My dad has had a wall wart that does this since the 80s. Goes from 1.5 to 9 volts and even lets you adjust barrel polarity.

I broke so many electronics with that thing…

[–] cmnybo@discuss.tchncs.de 8 points 1 day ago

Yes, you definitely have to be careful with them. They do come in handy when I can't find the correct power supply or even one that will work despite having a 50 pound bin full of them.

[–] Onomatopoeia@lemmy.cafe 3 points 1 day ago* (last edited 1 day ago)

Yea, I do have a box of wall warts of different voltages, max current, and a box of coax adapters. Not hard for me to grab what I need and modify as required.

I also have a box of USB C chargers, many of them PD. This cable is a neat concept, but like you said it needs coax adapters, and adjustability on the cable for voltage.

[–] aquafunk 1 points 22 hours ago

FYI they sell one that can be reprogrammed. It's still USB PD, but that covers most use cases.

They also sell a kit of compatable barrel jack plug adapters of many shapes and sizes.

[–] nickwitha_k 1 points 22 hours ago (1 children)

I basically just use USB-C trigger boards for my projects these days. Super convenient.

[–] StrawberryPigtails 1 points 21 hours ago (1 children)

I think that is basically what this is. I was actually looking for a replacement power supply for a cat feeder when I found this. Considered it for a minute then discarded the idea as cool, but overly expensive in my case. If I had had a spare 30w USB-C power supply, might have gone another way, but the older wall wart style power supply only cost me $15.

[–] nickwitha_k 1 points 10 hours ago

These cables are indeed basically just that. They're a good solution for reducing wall warts when powering older projects that use barrel jacks or don't have room for a trigger board.

[–] possiblylinux127@lemmy.zip 1 points 22 hours ago