View Full Version : Closed Power board request for 12V and 5V

21st July 2012, 20:50
I aim to make my Raspberry Pi more portable.

To do so, I have a small LCD TV that requires a 12VDC 1A input and the Raspberry Pi requires a 5VDC usb input which I believe is around 700mA. I want to use a single switching plug as I currently have, which is a 3 prong wall plug that switches down from 240VAC to 12VDC 1.25A. I'd like to be able to use a single plug such as this to power both devices. Oh and a nice to have would be an on/off switch option so I don't have to unplug it or switch it off at the wall either.

Are there any electronic gurus here that would be able to do such a thing for me or recommend something? I know nothing about doing this myself as I have no background or much experience in this field.


21st July 2012, 21:56
I copuld probably do the actual work to make a plug that out puted both to seperate wires from 1 single plug..
But unless you want something made of wood and 6 inch nails as a casing i would find some 1 els lol..
I am definatly not the best when it comes to making casings. :lol:

i just had a thought..

I think i may actualy have something like that already..

what kind of power connections would you need??

21st July 2012, 22:57
This is effectively what I have that currently plugs into the tiny lcd tv screen.


I'd like to continue using this plug but to plug it into a breadboard instead, or something that will then split the power which I can then wire up to a USB cable for the Pi and same size plug to the LCD TV. In fact, I have two of these switching plugs, and I'm willing to sacrifice one to use from the breadboard into the LCD TV for the connector.

Come to think of it, I didn't think through that I will need a modded mini USB cable to plug into the Pi but that will need wiring in/soldered into the breadboard!
Hope that makes sense?

PS. As long as the breadboard is less than 4inches square the shape and size doesn't matter. I'll be enclosing the entire setup in a custom case I'm putting together.

21st July 2012, 23:07
what i have looks more like a power brick for a laptop.
it has a 5 pin din out. they supply 12v and 5v. i could easily desolder the din cable, and solder in the connections needed..

this would give you 1 source with 2 outs

id have to rumage through some boxes to find it but shouldnt take to much effort..

I think its an easier solution but if its not what you want then thats no problem.

21st July 2012, 23:20
No that actually sounds like quite a good idea. I wasn't aware laptop bricks do that. I'm just worried that might pump too much amperage into the Pi for example. I'm not sure what the limit is but I vaguelly recall something along the lines of 2A. Also, the LCD TV can probably only handle 1-2A max.

It's not a clean solution using a laptop brick though. I wanted to basically have a plug hole at the back of the case I'm building, where you plug the switching plug into and the rest of the power distribution happens in the case out of sight, keeping the look tidy and making it easy to unplug the power plug from the case IYSWIM?

As in this pic http://www.koenigs.dk/mame/eng/nanocade60.jpg

21st July 2012, 23:30
its not for a laptop its from an old external hard disk enclosure..
thats why it does 12v and 5v.
il dig it out in the morning and chek its out put visialy and with a multi meeter.

Il also send a pic. its actually prety darn light. and not that big.
it takes 240v in though. not sure if its a figure of 8 cable or a 3 pin clover or what, i had forgotten about it andf then i just rememberd i had it.

22nd July 2012, 00:15
Thanks a lot Shambles. That's great. Again, that's a rather good idea. Using a USB HD power board could well solve that problem. I have a 3.5 HD in a USB enclosure and it has a power brick too, so that's definitely a way to approach it.


22nd July 2012, 09:40
This is the kind of thing he is talking about...


22nd July 2012, 12:20
found it..
Input 100-240Vac 50/60Hz
12v 2000mA
5v 2000mA

il give you some dimentions in a min,

4.5 inche long
about 1 3/4 inches wide (less than 2 inches at any rate)
les than 1 and 1/4 inches tall..

and the power input is a 3 pin jopbby like you use on pc's/monitors.
if you want me to change the conectors for the correct out upt i will definatly need to know what connections you need..

mini usb male/female some freaky phone connection. what sized plug in cable. (i see that the plug you use now has a standard + and - config but thats just a pic so id need to know that too..

i can probably do the mod and sell you the thing for something like 5 + postage.
which should be considerably cheaper than the feebay link.

22nd July 2012, 12:53
Hi Shambles1980

I thought it would be best to take pics of what I have to make it clear :)

As you can see, the Pi requires a microusb connector. Currently I am using a stock USB to MicroUSB cable. Maybe you can wire that up to the 5V connection?

Since the Amperage into the Pi doesn't seem to matter much, having 2A is awesome, as I was hoping to connect mini USB speakers to the Pi as well so it would need to power that and possibly another small USB device like mouse/keyboard.

The dimensions of the one you have is fine. I'll lay it at the bottom horizontally inside the case so that you can plug the kettle lead in at the back. However, could you integrate an on/off wiring that I can wire up to an on/off switch so I won't have to pull the kettle lead out to power it all off?

Let me know if you need a picture of the switching plug connector?

22nd July 2012, 13:04
it looks a bit like one of the samsung phone inputs rather than a standard mini usb.
think i have one of those.

il get to work on it as soon as i get back. :thumbsup:
should be taking abigail to her 1st ever birthday party pretty soon. "provided shes not all craby due to not having a nap"

22nd July 2012, 18:37
It's microusb not mini USB.

And it's standard, should find one easy enough on the other bay and cut it up

Sent from my iPhone using Tapatalk. Please excuse any crazy auto corrects or lack of detail (links to info sources)

22nd July 2012, 18:40
you can get the microusb cables in pound land there the samsung/blackberry cables

22nd July 2012, 18:45
2 for a quid on eBay, including shipping.

Don't know how they do it.

Sent from my iPhone using Tapatalk. Please excuse any crazy auto corrects or lack of detail (links to info sources)

22nd July 2012, 19:09
already have some, not an issue really. was just making sure it was the correct one.

What length of cable are you wanting ?
"for both"

cos im home now and ready to do the dirty

22nd July 2012, 19:18
Hiya! Yeah it's standard micro USB alright.
I think cable lengths for both should be 7 inches long to be on the safe side. Rather too long than too short :)

Cheers mate! Really appreciate this. Looking forward to seeing what you come up with.

PS. Don't forget wiring for on/off switch if you can. :thumbsup:

22nd July 2012, 19:43
well where is this on off switch going?
do you wanted mounted on/in the brick casing so its all contained..

Or do you want it free hanging on a live wire swinging about freely in a manner that will allow you to mount it your self els where, but could leave a live wire exposed out of the brick casing if something breaks..

"i think you can tell from my choice of wording which i would prefer" but that up to you.

22nd July 2012, 20:07
I see no reason for you to worry over the extra Amperrage.
Look at my example over the 'regular' Pi thread.http://www.amibay.com/showthread.php?t=26180&page=21
I got me an el-cheapo Solar panel which outputs 2600mAh, and was able to drive the Pi, with SD and USB keyboard + mouse.
Although it's a BIN from evilbay, i'll let you realize if it's' suitable for you or not. Look for a description of 2600mAh Solar Panel External Battery Power Charger.
I understand this will not cover your display needs, but you can't beat 'free power'! :)

22nd July 2012, 20:55
i wired it up..
i waited for input on a power switch but never recived it so i didnt add one..
(also not sure if i actualy had one spare to use to be honest)

The power out or the lcd i Guessed the size of it. from a picture "looked pretty small" Hope i used the right size.

22nd July 2012, 22:43
i wired it up..
i waited for input on a power switch but never recived it so i didnt add one..
(also not sure if i actualy had one spare to use to be honest)

The power out or the lcd i Guessed the size of it. from a picture "looked pretty small" Hope i used the right size.

Hi Shambles. Many thanks for this! I added pictures of the connector that is actually used by the LCD TV. I'm afriad yours looks a bit small, however, I suppose I could remove it and cut mine and wire it on if it turns out to be the wrong size. Just not sure how to figure out which wire is positive and which is negative :Doh:

I really do need wires out of the supply to attach to the case for wiring up to an on/off switch though. Again about 7 inches should suffice.

Let me know how you get on!

22nd July 2012, 23:07
you could use 1 of these


22nd July 2012, 23:29
the wire i used the live is surronded by a white case and the ground wire surrounds it then bothe are surrounded by a white case. so thats easy to figure out.

il have to rummage for an on off switch cant guarantee i have one. but il look if you really need it.

22nd July 2012, 23:49
Thanks guys that's great. Shambles you don't need to add a switch. I can add it myself. I just want the wiring to be available for me to wire it up when I've built the case itself :thumbsup:

23rd July 2012, 00:37
il just add a simple break inline just before the fuze.
that should be a prety safe situation for you. But it will be on the live line. so dont go twisting the wires together to test it as they will be pumping out 240v

il use a yellow wire for live and white for ground for you.

il have it ready in about 10 mins or so id imagine. but il update the thread or pm you tomorrow after some errands.

23rd July 2012, 11:04
Thanks! Looking forward to it.

Let me know what I owe you and give us a PM with your payment info etc. :thumbsup:

23rd July 2012, 15:45
ok. I found an old rocker switch..
I dont rate it and i recomend you replace it.
I have tested it and it works. But i dont trust it dangeling like this.
I added some hot glue to the exposed terminals of it to insulate it. and il also tape it up some. But i dont like 240v being insulated by hot glue and tape. so replace it and make me feel better knowing you wont get electrocuted..

I chose to use the crappy rocker switch on the basis that a relitivly un safe rocker switch whould inevitably be safter than a live wire.

any way here is a little vid of what i cobbled together for you.
Im pretty sure its what you asked for.

you may be thinking. "oh that rocker switch is fine i wont need to do anything"

but you may notice mounting it could be an issue due to the face being bigger than the body, and it actualy being solderd to the wires.


23rd July 2012, 21:38
Cheers for that Shambles. I'll ensure I put a better switch on there. Any recommendations? Perhaps a 2A switch? I quite liked that one Johnim URL'd earlier from fleabay.

Otherwise, top job mate!
Send me your info so I can pay you and give you my postal addy :thumbsup:

Oh and one more thing: Thanks for taking this on for me. You guys have given me good ideas for future mods.

Money sent to Shambles as well as postal info. Cheers mate!

25th July 2012, 01:49
when it comes to this sortr of thing im more than able to help, but id usualy leave it to some one els who may well have more experience in doing this stuff..
But seeing as i already had something that was a simple solder job to modify i had no issues doing it.

Any way the item is boxed up and ready to go. payment was recived "slightly more than agreed on, so thanx for that"
and my wife is heading off to some meeting about how she was treated in the labour ward tomorrow so she can drop it off on the way.

as for the switch.

i used a 120v 6A /240v 3A switch.
2amp should be fine. but id probably advise 3amp. ths switch is on the 240v line.
there is a fuse in the brick itself but that is on the other side of the riocker switch.. so remember that the yellow wire is the live wire. and that is direct from the power. the only fuse you have for the yellow wire before the switch is in the plug stuck to the wall..

Probably would have been safer to put the fuse on the other side, but the hole to solder the wire in to would not have been adequate to accept a wire that i deemed capable of handeling that sort of voltage.

29th July 2012, 01:29
I added some hot glue to the exposed terminals of it to insulate it. and il also tape it up some. But i dont like 240v being insulated by hot glue and tape. so replace it and make me feel better knowing you wont get electrocuted..

Hey mate.

It arrived yesterday (friday), thanks. Unfortunately the lcd tv connector is way too small to use, so I will have to pull it out and use the spare connector you supplied (thanks for that). I just don't know which wire should be wired up where, ie how will I know I'm connecting ground to the outside of the connector and 12v to the inside of the connector? I suppose once I pull off all the hot glue and expose that area I will be able to tell, or will I need to open up the brick casing too? Sorry for the n00b questions, but I don't want to mess it up, making all your work for naught. :picard

31st July 2012, 04:58
Just do a simple solder job on one end, mate.