How to power devices that expect to be powered through hdmi

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oldgamer
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Joined: Tue Dec 03, 2019 3:08 am

How to power devices that expect to be powered through hdmi

Post by oldgamer »

How can you power devices that expect to be powered through hdmi if the hdmi source does not provide enough power?


I mean devices that want to be powered through the hdmi connector and don't have a connector dedicated to power.

My tendak hdmi to vga is such a device and if the hdmi cable is too long it simply will not work, but I like it otherwise, just would like to use longer hdmi cables.

I wonder if something like this would actually work.
Image

EDIT:
Updating thread to say the adapter in the picture DOES indeed work.

I got a cheap one from aliexpress exactly like the one in the pic and it works to power an HDMI dongle.
Last edited by oldgamer on Mon Nov 08, 2021 9:19 pm, edited 1 time in total.
gray117
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Re: How to power devices that expect to be powered through h

Post by gray117 »

Entirely possible ... usb power supply is several times that of hdmi ...

My incliniation would be use something like a (powered) hdmi splitter that you can feed multiple devices to a single vga adapter.... but whether or not it'll work is as much as a crapshoot as whatever that little device is... just never tried it.

Out of interest what's the distance involved and devices used?
oldgamer
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Re: How to power devices that expect to be powered through h

Post by oldgamer »

gray117 wrote:
Out of interest what's the distance involved and devices used?
The distance is nothing special, just an hdmi cable that is about 2m long.

But this would be useful even if the cable length isn't the issue, but rather something like a DP to hdmi adapter that does not provide power to the hdmi port, so a device like the tendak would not work in this situation but could be fixed via getting power from something else.
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matt
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Re: How to power devices that expect to be powered through h

Post by matt »

Why not use a short hdmi cable and a long VGA cable?
oldgamer
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Re: How to power devices that expect to be powered through h

Post by oldgamer »

matt wrote:Why not use a short hdmi cable and a long VGA cable?
That would work really, but it's mostly for the sake of finding the "correct" solution to the problem. These dongles should really have a power connector.
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matt
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Re: How to power devices that expect to be powered through h

Post by matt »

I'm sure the adapter in your photo would work - if your problem is indeed that the device isn't getting enough power. It would definitely help for applications like the Carby that wouldnt otherwise be able to power a DAC. Searching for "HDMI power injector" brings up plenty of results so it seems to be a common issue.
Edwards94
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Re: How to power devices that expect to be powered through h

Post by Edwards94 »

gray117 wrote:Entirely possible ... usb power supply is several times that of hdmi ...

My incliniation would be use something like a (powered) hdmi splitter that you can feed multiple devices to a single vga adapter.... but whether or not it'll work is as much as a crapshoot as whatever that little device is... just never tried it.

Out of interest what's the distance involved and devices used?
Hello,

HDMI can't carry power, any monitor with an HDMI connection is going to need a separate power connector. This means if you want to have the monitor powered over USB-C, you would need two pathways for power. You would also need to make sure the computer's power supply was robust enough to supply the monitor.
oldgamer
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Re: How to power devices that expect to be powered through h

Post by oldgamer »

Updating thread to say the adapter in OP picture DOES indeed work.

I got a cheap one from aliexpress exactly like the one in the pic and it works to power an HDMI dongle.
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