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[–] 87 points 1 year ago (23 children)

What did dude think was coming out of the VGA port? Tiny photographs? It's all electricity through wires, of course it'll send some electricity into a phone

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  • [–] 44 points 1 year ago (7 children)

    Yeah but is the voltage correct? It should be 5V to charge a phone over USB, is that part of the VGA spec?

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  • [–] 18 points 1 year ago (3 children)

    With USB power delivery, you can get 9V, 12V or higher over USB. Usually the device requests higher voltage from a PD charger, but it's not impossible for a modern device to be able to cope with just having 12V shoved into it.

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  • [–] 7 points 1 year ago (2 children)

    The USB device would have been made wrong if it just shoved 12V down the power lines without negotiating it.

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  • [–] 1 point 1 year ago (1 child)

    That's probably only true for USB power supplies - a USB adapter isn't set up to do anything with voltage and probably just passes the positive and negative pins through.

    The VGA adapter feeding power back through USB in the first place, yeah, that's not supposed to happen.

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  • [–] 7 points 1 year ago* (2 children)

    Yeah I don't think there's a 5V pin for VGA.

    I think if we had the scenario where we had a higher voltage than needed, we could have a toasty voltage regulator making something happen, but going the other way would need boost circuitry unlikely to exist in these parts, in my understanding

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  • [–] 19 points 1 year ago (8 children)

    I don't know shit about cables but it's plugged into a monitor. My intuition is that a monitor shouldn't be pushing power out through a video input port.

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  • [–] 27 points 1 year ago (1 child)

    DisplayPort has a +3.3V 500mA pin specifically for pushing power. In theory, great for powering an active adapter. In practice, has killed motherboards because Dell can't design a computer for shit.

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  • [–] 4 points 1 year ago

    Friendly reminder that if you use a Dell charger on a HP, nothing happens but vice versa, you damage the motherboard. It kills a chip used for charging. Dell used the same size barrel jack, but they wired it differently from everyone.

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  • [–] -2 points 1 year ago (3 children)

    Signals aren't magic, they consist of electrical power. You can get at least a little bit of power from anything that isn't an optical port.

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  • [–] 2 points 1 year ago* (last edited 1 year ago)

    Technically, even an optical port can deliver power. Light is just a particular form of electromagnetic wave that just happens to use another method of transmission (and you might need a different mechanism to transform its energy), but it also has an intensity, potential energy and resistance in the medium of propagation.

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  • [–] 7 points 1 year ago (3 children)

    Of course electricity comes out of a VGA port, but it's only a signal, I wouldn't assume that it's anywhere near enough to charge a phone.

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  • [–] 7 points 1 year ago (2 children)

    Pin #9 of the VGA spec is 5v, though it seems unusual that a monitor would provide power on that pin

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  • [–] 1 point 1 year ago

    Maybe somewhere in the chain, the 5V from pin 9 is being converted to 5V shared across power and the video signal. So even if this chain worked in carrying a video signal it could be very weak or distorted.

    Purely a guess though.

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