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THRobinson
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Powering Laptop Screen and Pi with Laptop PSU

Mon Aug 02, 2021 1:06 am

Hey guys... played with a RaspPi a bit with RetroPie for games, but I don't know anything beyond that in terms of building projects with the Pi, though I would like to (after this) build a guitar pickup winder with some CNC parts.

Anyways... sister's work was getting updated laptops, gave me all the old ones. Few good, few too old to be worth much.

I see on eBay you can buy laptop LCD screen controller boards for some LCD screens. I haven't ripped any laptops apart yet to verify, kinda in the brainstorming phase. One laptop has a bad internal cable so flickers, otherwise good 13" screen. Old CPU and very low ram so, might use this as the donor.

I want to make a 2 foot wide arcade laptop.... so a wedge shaped box, arcade joystick on the left, 6 buttons on the right, few at the top for options/coins, and a 13" screen in the centre. Can fit on the lap, or sit on the table and the wedge shape would angle it towards you a bit.

Would I be able to power both the LCD and the Pi using the PSU that came with the laptop? Probably 19v. I have a few laptop PSU's and all seem to be 19v.

I basically just want the screen, which should run off a laptop PSU since it's from a laptop, the RaspPi which I would think also run off the PSU since the laptop's MoBo ran off it too, probably a pair of 1" speakers or maybe the laptop's speakers, and a small 80mm fan at the back for air.

Can anyone help guide me towards what I would need? Thanks
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aBUGSworstnightmare
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Re: Powering Laptop Screen and Pi with Laptop PSU

Mon Aug 02, 2021 5:25 am

THRobinson wrote:
Mon Aug 02, 2021 1:06 am
..
Would I be able to power both the LCD and the Pi using the PSU that came with the laptop? Probably 19v. I have a few laptop PSU's and all seem to be 19v.

I basically just want the screen, which should run off a laptop PSU since it's from a laptop, the RaspPi which I would think also run off the PSU since the laptop's MoBo ran off it too, probably a pair of 1" speakers or maybe the laptop's speakers, and a small 80mm fan at the back for air.
well .. Depends on your screen and the controller board needed for the display. Some controller boards offer wide voltage supply as they were designed for industrial use, others (most of the cheap ones you can find on ebay) are 12V input only. In such a case you're still able to use the PSU but you will need some additional DC/DC (which might cost more than a cheap 12V PSU).
You will need a 5V PSU anyhow (or another DC/DC) as the Pi requires 5V!

To bet to know what you'll need aou need to know what you have. If there is no controller board for the display nothing else will be needed as your project is not feasible (at least with that particular screen).

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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Tue Aug 03, 2021 8:41 pm

Hmm... is there not such a thing as a voltage converter? maybe something that can be bought or made that would take the 19v in, and split it into 2 outputs, 1 to match the screen and one to match the 5v? Power splitter of some sort?
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aBUGSworstnightmare
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Re: Powering Laptop Screen and Pi with Laptop PSU

Tue Aug 03, 2021 8:43 pm

THRobinson wrote:
Tue Aug 03, 2021 8:41 pm
Hmm... is there not such a thing as a voltage converter? maybe something that can be bought or made that would take the 19v in, and split it into 2 outputs, 1 to match the screen and one to match the 5v? Power splitter of some sort?
voltage converter = DC/DC

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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Tue Aug 03, 2021 10:19 pm

Ha... I just found those before I came here... :D

Was looking at something like a terminal block to split the incoming power... then run a pair of wires to one DC-DC board set to 12v and a pair of wires to the other board set to 5V. Not sure how many amps that would be though... from what I was reading I'd need about 12V 3A for the LCD, and 5V 2.5A for the RaspPi.

https://www.ebay.ca/itm/223524573272?ha ... SwcD5c4ynR
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Imperf3kt
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Re: Powering Laptop Screen and Pi with Laptop PSU

Tue Aug 03, 2021 10:58 pm

Your 19v supply would need to be able to supply around 3A (57W) or more, if you wanted to go that route.
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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Wed Aug 04, 2021 2:37 am

Says 19.5v 4.6A on the one in front of me... I have a few here, but this is the one from the laptop I'm now dismantling.

So.... in theory so far....

- AC adapter (19V / 4.6A)
- Terminal block for splitting
- Two DC-DC step-down boards (set to 12V and 5.1V)
- RaspPi v3 B (Plugged into USB joystick controller and small USB fan)
- LCD controller board (Plugged into LCD screen)

LCD controller and RaspPi both have 3.5mm audio jacks for speakers. Don't want to put too much a load on the RaspPi else get that lightning bolt error.

But... with that list, some wire and solder... doable?
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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Wed Aug 04, 2021 3:18 am

Just took the laptop apart... and yes! I can get an adapter....

https://www.ebay.ca/itm/353424067240?ha ... SwKThgUxlI

LCD Controller Board:

HDMI DVI VGA AUDIO LCD Board Work for LVDS Interface LCD Screen
Input Power Adapter: 12Vdc More than 2A.
Come In Standby Model When Not Input Signal
Standby Model <1W
Video Input: HDMI DVI VGA
Audio Input: HDMI
Audio Output: Speaker Connector
OSD: Brightness Contrast Auto Language And So On
Language: English French German Spanish And So On
Board Size: 125mm x 58mm x 17mm
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fruitoftheloom
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Re: Powering Laptop Screen and Pi with Laptop PSU

Wed Aug 04, 2021 3:52 am

THRobinson wrote:
Wed Aug 04, 2021 3:18 am
Just took the laptop apart... and yes! I can get an adapter....

https://www.ebay.ca/itm/353424067240?ha ... SwKThgUxlI

LCD Controller Board:

HDMI DVI VGA AUDIO LCD Board Work for LVDS Interface LCD Screen
Input Power Adapter: 12Vdc More than 2A.
Come In Standby Model When Not Input Signal
Standby Model <1W
Video Input: HDMI DVI VGA
Audio Input: HDMI
Audio Output: Speaker Connector
OSD: Brightness Contrast Auto Language And So On
Language: English French German Spanish And So On
Board Size: 125mm x 58mm x 17mm
.
Your Laptop has a 19V Charger, though a battery charger and power supply are technically the same, in reality chargers have less need for stable voltage.

In my opinion you should use a 12V 4A PSU for the LVDS Board and the Official Raspberry Pi Power Supply.
Take what I advise as advice not the utopian holy grail, and it is gratis !!

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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Wed Aug 04, 2021 4:19 am

If I have a 12V4A for the LCD, and a 5.1V2.5A for the Pi... then I have 2 adapters hanging out the back.

Other option for a single cord is to use something like the PC power supply cable, then internally have a small 2 outlet extension cord (dollarstore has then, 6" long) and plug the adapters into that... probably easier but... definitely adds to the weight a bit... hmm...

Well, I have options at least. :D
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fruitoftheloom
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Re: Powering Laptop Screen and Pi with Laptop PSU

Wed Aug 04, 2021 4:24 am

THRobinson wrote:
Wed Aug 04, 2021 4:19 am
If I have a 12V4A for the LCD, and a 5.1V2.5A for the Pi... then I have 2 adapters hanging out the back.

Other option for a single cord is to use something like the PC power supply cable, then internally have a small 2 outlet extension cord (dollarstore has then, 6" long) and plug the adapters into that... probably easier but... definitely adds to the weight a bit... hmm...

Well, I have options at least. :D

An ATX PC Power Supply has 5V and 12v, just need a short cable with the correct connector.
XfJWS.jpg
XfJWS.jpg (84.99 KiB) Viewed 685 times
Take what I advise as advice not the utopian holy grail, and it is gratis !!

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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Thu Aug 05, 2021 6:47 am

True, but an ATX is a bit loud and heavy.

Idea is to make something I could feasibly sit in my recliner and have it sit on my lap for playing. Sadly it seems to keep getting slightly bigger and more heavy. :D

Waste of a laptop screen, but laptop was old and slow anyways...

I have a pair of Samsung 204B's... 4:3 (not 5:4) 20" LCD screens. Very good quality, perfect for old games. Also known for have cheap capacitors, so managed to get then for $10 each a few years ago, and for another $10 each I replaced all the caps with Nichicon/Panasonic and now they work amazing. Great for a full size cab, but, cabs take a lot of space and wood prices have gone up a lot so, that's why I'm thinking something a bit more portable and can be put away easily.

20" 4:3 is a fair bit bigger than a 15.3" 16:9... but... no DC-DC board and no AC adapter and no controller board. Just need a 2ft power cable and done. It also has DVI so, a short cable to the Pi and done.

I was looking at the below... 2 outlet and 3 USB... I can get a 2x5w Amp that takes USB power for speakers, and one for a fan, the 3rd to power the USB controller board for the joystick.

Haven't used Sketchup all year so a bit rusty but, I'll post my plans... if anyone is interested that is.

Image

Image
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Imperf3kt
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Re: Powering Laptop Screen and Pi with Laptop PSU

Thu Aug 05, 2021 9:52 am

a 2x5w amplifier can't be powered from the USB on a Pi, the Pi USB is current limited to 1.2A (6W) and a 2x5w amplifier will require 2.4A (10w)
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fruitoftheloom
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Re: Powering Laptop Screen and Pi with Laptop PSU

Thu Aug 05, 2021 10:00 am

THRobinson wrote:
Thu Aug 05, 2021 6:47 am
True, but an ATX is a bit loud and heavy.

Not necessarily, you just have to buy the correct product :?
Take what I advise as advice not the utopian holy grail, and it is gratis !!

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THRobinson
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Re: Powering Laptop Screen and Pi with Laptop PSU

Thu Aug 05, 2021 9:23 pm

@imperf3ct as I said, I was going to plug it and the fans into the powered USB outlet on the extension. I don't want to risk getting that lightning bolt error.

@fruitoftheloom I guess there are smaller ones than standard, like the below, though I still think it would weigh more than a pair of small AC adapters. Unless you're looking at something even smaller?

Image
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Re: Powering Laptop Screen and Pi with Laptop PSU

Fri Aug 06, 2021 11:12 am

regarding dc-dc power conversion...maybe this will interest you....

viewtopic.php?f=29&t=266296&p=1617905#p1617905
(input voltage range test can be seen on 3rd page)

usually I do power my RPi setups using 12v power bricks.... and I've also taken a screen from my old MSI laptop...
as the LVDS are 12v powered, its all too convenient for me... :D

now for your case I'd use 2 buck converters,
one for the laptop screen/LVDS to supply 12v,
and one for the RPi to supply 5.1v
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aBUGSworstnightmare
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Re: Powering Laptop Screen and Pi with Laptop PSU

Fri Aug 06, 2021 2:37 pm

LTolledo wrote:
Fri Aug 06, 2021 11:12 am
regarding dc-dc power conversion...maybe this will interest you....

viewtopic.php?f=29&t=266296&p=1617905#p1617905
(input voltage range test can be seen on 3rd page)

usually I do power my RPi setups using 12v power bricks.... and I've also taken a screen from my old MSI laptop...
as the LVDS are 12v powered, its all too convenient for me... :D

now for your case I'd use 2 buck converters,
one for the laptop screen/LVDS to supply 12v,
and one for the RPi to supply 5.1v
I recommend DIY if you want to have it small and universal.
Image
o.k. ... that's a tablet screen, but as long as it has LVDS interface it doesn't matter. The black board is powered by 12V (coming from the CM4IO Ext PSU connector) with the CM4IO connected to a 12V/5A PSU (right side of the pic). There is a DC/DC on the black board which generates 5V and 3.3V, 3A each to cope with different display requirements.
As LTolledo said, quite a lot of display BL take 12V input voltage (the tablet on is 3.3 to 5V btw), so a 12V setup is most convenient.

The display on the picture below is 12V for the backlight i.e.; same 'LCD controller' to drive it.
Image

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