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Fortune123

Need a 12V barrel plug adapter to PD (Supplying power to display from mac)

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Posted · Original PosterOP

Im trying to power this controller board for an lcd display I have. 

https://www.ebay.com/itm/VGA-HDMI-DVI-LCD-LED-screen-Controller-Driver-Board-Work-Kit-For-NEW-LTN156AT27/383529326165?hash=item594c211655:g:3JIAAOSwfvlerUsw

Its powered by a 12V barrel plug adapter meant to be plugged into a wall. I want this to work as a second screen for my mac and thus must be portable. Does anyone know of a usbc to barrel plug adapter that will supply the Controller Board power from my mac's battery? 

Something like this I believe:

https://www.amazon.com/USB-C-2-5mm-Emulator-Trigger-Laptop/dp/B07P81526M#customerReviews

But I need it to have a male usbc so I dont have to buy another wire. 

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On 6/4/2020 at 7:09 AM, Fortune123 said:

Why not? Does PD not give DC power?

USB-PD is designed to supply upto 20V/5A(100W). However, the available power is offered at 4 different levels- 7.5W, >15W, >27W, >45W. The available voltages for each level can be checked from this graph-

 

spacer.png

 

Also, in order to select the amount of power you want to draw, USB-PD requires the two connected devices to communicate to each other(a "handshake" has to be made to select the appropriate power/voltage level).

 

Since your display requires 12V(and probably around 2A, as most displays do), you would have to build a logic circuit to communicate with your MacBook via the same USB cable and then hook it to a buck/boost converter to regulate the voltage to 12V.

 

On 6/4/2020 at 6:00 AM, Fortune123 said:

 

On 6/4/2020 at 6:27 AM, bmx6454 said:

 

^Both of these are meant to supply power TO the MacBook and not draw power FROM it, hence these only supply the required power and won't allow you to draw power from the USB port. 

 

If you want to design your own circuit to handshake with your device, I would recommend starting here and here.

 

If not, I too would say to go with a 12V adapter or a battery to power your display, it would add a bit of hassle but is a much simpler solution.

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Posted · Original PosterOP

although according to DIY perks video which I watched, it involved a small controller for converting the DC power on the board. Apparently thats inside the amazon link I sent and according too the reviews, it draws power FROM the mac

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7 hours ago, Fortune123 said:

although according to DIY perks video which I watched, it involved a small controller for converting the DC power on the board. Apparently thats inside the amazon link I sent and according too the reviews, it draws power FROM the mac

Yeah it seems some people have used it to draw power from a charger or power bank as shown in the video, but make sure that the USB port on your MacBook allow you to draw that kind of power (I'm not sure but I think they are limited to about 15W). Do update if you get it working. 

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Posted · Original PosterOP

Alright I definitely will. Probably wont be for another week or so though :\. Ill post something about everything I made

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