Tapping off the power supply for a LCD

[cigardude]

Has anyone ever tapped off the PC power supply to power a LCD? I am making a small bar top and using a mini-itx board with this power solution: http://www.mini-box.com/picoPSU-160-XT-192W-Adapter-Power-Kit. Just wondering if it is possible.

Thanks!

[BadMouth]

linky no worky.

I'm running a little 12v 12" LCD touchscreen off of an old 250w AT power supply that is also powering a megatouch mobo and drive.
Been at least a couple years and haven't had any issues with it.

Just as long as it is putting out enough power for everything.
An online PSU calculator should tell you if it has the power to spare.

[Nephasth]

I've used a PC power supply to run my 7" Panasonic LCDs. Works like a charm.

[Nephasth]

linky no worky.

Had a period at the end of the url. This one works: http://www.mini-box.com/picoPSU-160-XT-192W-Adapter-Power-Kit

To me, it seems expensive for a power supply, but I usually snag my spare power supplies out of free computers listed on CL...

[RyoriNoTetsujin]

To me, it seems expensive for a power supply, but I usually snag my spare power supplies out of free computers listed on CL...

It's expensive because it's really tiny, passively cooled, and designed to work with low-to-moderately powered systems in very small cases.

I don't see any immediate reason why you couldn't tap a picoPSU if you have a spare connector to draw your power from and you're able to provide the proper voltage to the monitor. The fact that others have done so with normal PSUs is proof of that, naturally.

The first question I have regards the power draw. How much does the LCD draw when powered on? (and at what voltage maybe? see below regarding "rails")  How much does the mobo/cpu and whatever else is attached to it (HDD, ROM drives, whatever) draw when at full load?  If all of those numbers add up to less than 160w (I wouldn't push a picoPSU beyond it's rated use,) then yeah, maybe you're in business.

I'm not confident with the whole "rails" concept when it comes to PSU power distribution ("how much power is available on the 12v rail, how much on the 5v rail, etc.") so I can't speak to that. Maybe someone more familiar with the picoPSU can break that down and explain if that might be a factor in this case... ?

An interesting idea, nonetheless! I'm interested in seeing where this goes. 

EDIT: I'm posting this without reading it fully, so it may or may not be interesting/useful: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=207

[cigardude]

Well I am in the concept phase of a somewhat portable bartop and the smaller and lighter it is, the better it will be for travel. I was originally going to use a notebook for the main system and display but I am running into a major issue trying to find some place to solder some wires to extend the power button so that I can turn it on and off. Now I am thinking about using a mini-itx that I was going to use for something else but I do not want a regular sized power supply since it will be too big. I was thinking of tapping off the PSU for the monitor power so I do not have two power cords running into the cab. Perhaps some fancy wiring might be in order first before I start jumping the gun on this. I just checked a power calculator and it seems that I am going to be using more than I will have. The LCD looks like it will be using 30w of power. I am definitely going to have to rethink the whole concept. Your guys responses do help though!!

[RyoriNoTetsujin]

Well, a little Newegg-fu brings this: http://www.newegg.com/Product/Product.aspx?Item=N82E16817104145

So maybe all you need is a non-ATX PSU? The one above measures approximately 6"x3"x1.5" ... That's not a picoPSU, but that's pretty small. Costs about the same... probably not silent... but it's a full 300w PSU!
 
I'm curious to see your design. Any drawings or renderings yet, or is this still in planning?

[ninjasquirrel]

I just finished my build and had a similar issue in regards to space and needing mult devices ran off the same psu. Here is the one that I am using- http://www.newegg.com/Product/Product.aspx?Item=N82E16817256063 the dimensions are only 4.92" x 2.5" x 3.94" so it's much smaller than a reg atx. This thing is a beast too! It has a 36amp 12 volt rail...that is what you're really looking for.  The amount of amps your combined devices will draw. So I have my pc (i3 processor, mini itx mobo, video card, etc), 4 pc fans, a 17" lcd monitor, led marquee, ledwiz running off the that one psu    so far so good! All you need to do...at least all I did, was tap into the 12v line on the molex connector and run that to a barrier strip. From the barrier strip I wired some rca phono quick connects to attach all the misc components.

You do have options though, just need to decide how big of a footprint you have, and how much draw your combined devices will pull and go from there.

[cigardude]

@Ryori - No drawings just yet as I am just thinking things through. But once the project is on it's way I will have some nice AutoCAD files for anyone who wants them.

@Ninja - How loud is that power supply? That might be the solution if it is quiet enough. It's a decent size because if I do go this route that cab will need to be bigger than originally thought since I am not using a notebook now. If you have some pics of your cab with this thing hooked up, I would appreciate seeing them. It would give me a better idea of planning this out further.

Thanks!

[ninjasquirrel]

It's not too loud at all cigardude...I have 4 fans going at the same time and I can't hear it over those puppies 
These are the only pics I have right now of the PSU hooked up in my build.  If you look through the pics of my bartop, you'll see that I physically have no room at all inside the cab once all the components are in!


Here is the barrier strip used to plug everything into the 12v molex line:

[cigardude]

Very cool, I do enjoy that build! Now I have something to think about. Thanks for you help guys.

[cigardude]

So let me ask you about the monitor that you used. Did it take a regular power cable that looks like one that you use for the PC or did it take a power brick? I re-read your build thread and although I cannot find it now, I thought you had an issue with AC DC power for some reason with the monitor. On a side not, man I love those buttons.

[cigardude]

I think I answered my own question here. I took a look at a few monitors that I have and the one with the power brick outputs 12Vdc --- 5A. That is what the power supply is going to be providing isn't it? I see that the positive is on the "inside" and the negative is on the "outside". That would mean that I would need to connect the +12v to the "inside" and the ground to the "outside", correct? If so this is totally doable. I will have to go to a 19" monitor if I don't want to spend money on it since I have one here but it's cool. Kind of excited that I learned this new technique!

[ninjasquirrel]

My monitor was actually part of an all-in-one gateway profile 5 pc so it was powered from the motherboard through an LVDS connection (i didn't know of such a thing until the hours of research I conducted to learn a work around...) I found a distributor from china that makes an lcd inverter board that matches almost any model of screen you have and is powered by a 4 or 5mm (can't remember) dc power connection that provides 12v to the board; it outputs a VGA connection. I had an old car charger that was the same size so i chopped the end off and soldered the leads from the RCA phone cable to this from the barrier strip. Bottom line, I think you're on the right track given the fact that yours has an external power supply so you just trace down your leads and patch into your ATX.  Good luck!

[cigardude]

I just wanted to let you guys know what I ended up doing. I also hate searching and finding threads with no resolutions on them, lol.

I was able to successfully hook up a 19" LCD that uses a power brick to the power supply. It expected 12v DC so I was able to hook it up like NS did in his build. There was a + and a - for the cord, so you just hooked it up accordingly to the power supply. This was just a test as I am planning on building a somewhat smaller project and wanted to used a smaller LCD.

Next step, using a LCD from a notebook. After some searching on google I came across an eBay seller who sells a nice little kit that will let you send a VGA signal to a notebook LCD. I have a bunch of old notebooks that work but are not fast enough for what I was planning on doing. I ended up taking the LCD screen out of the notebook, decased it and disconnected everything from it. Cleaned it up a little bit and waited for the parts to come in. It takes 12v DC so using the same cable that I rigged up earlier, I hooked it up to the power on the kit and the VGA to the kit and viola, I have a nice 15" screen that is thin and very very light for my build.

With the testing done, I can now start designing and getting the project from my mind to reality! I just wanted to thank everyone who responded for their ideas. It really did help a lot!