12.1" Screen / Pi power


#1

So since the Pi needs 5v and the 12.1" screen needs 12v, does anyone have a nice suggestion for a circuit to power both from just the 12v power lead?

Something like this?


#2

I’m gonna try and do it with this:


#3

I used something like this on my Picade Maxi

http://www.ebay.co.uk/itm/HDD-POWER-SUPPLY-AC-12V-5V-2A-FOR-HARD-DRIVE-MOLEX-EU-/320705061192?hash=item4aab82e148

and one of these to get the power to the rpi http://proto-pic.co.uk/usb-microb-plug-breakout-board/?gclid=Cj0KEQjwo7auBRCOtoqn_s-G7aMBEiQAxArNrJKTtsVQjdhgzzglxx4eBTqV-iwba3phxi_UqpOs70AaArYZ8P8HAQ


#4

The DC-DC converter looks like a good option though too.


#5

That Molex power supply looks like a really great solution!


#6

Just ordered a Picade with the 12.1" screen! Once it’s all set up and working ok i’ll probably give the molex power supply a go.
I assume for the Pi you could just solder the 5v and GND from the HDD supply to an existing Micro USB cable, leaving the data cables disconnected, and with the 12v, similar process but solder the 12v and GND to a cable with barrel connector for the screen. Would this work ok?


#7

I suspect you’d be best place grabbing a female molex connector and soldering onto that, so your power supply is unhacked and easy to disconnect.

But yes, you can just hack a Micro USB cable onto the 5v rail, and a barrel jack onto the 12v.

Oh and it says 2A, does that mean 2A total, or 2A for each? I’m guessing the latter, but it may make a difference.


#8

I believe it is 2A for each, looking at another picture of the PSU elsewhere it certainly seems to indicate this.

As for using a molex to plug into the power supply, good idea! Will something like this do it?


#9

That looks like the one!


#10

I just used something like http://www.ebay.co.uk/itm/20CM-4Pin-IDE-Molex-Male-to-SATA-Female-Power-Plug-Cable-For-HDD-Hard-Drive-Disk-/400920991522?hash=item5d58c0d722 and cut off one end (Connected +5v/round to a the board with micro usb connector, and connected driver board cable to the +12/ground


#11

Possibly cleaner to solder directly into a new molex connector though, but I had some molex cables handy, so just used one of them.


#12

I haven’t even built my Picade yet as it’s only just been delivered, but have sorted out the power supply for both screen and Pi in advance, and it works.

I bought this: http://www.ebay.co.uk/itm/320705061184?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT and this http://www.ebay.co.uk/itm/390888442414?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT - then reused a USB cable and old PSU cable. Didn’t actually solder the wires onto the molex pins in the end as it was too fiddly for me, but crimping them hard seemed to work just as well and kept everything in place. Then I just tidied up a little with tape at the ends (no heatshrink available) and some other cable wrap. Can always improve it later but it’s fine for now.

Only thing I would mention is that power supply has only one ground pin at the connector end, so I had to put both the 12v and 5v ground connections onto this pin, which was a fiddle but it was ok once they were in there.

Here’s a pic:


#13

I’ve used a similar method to Movisman. I purchased this PSU http://www.amazon.co.uk/dp/B003TRT7FA/ref=sr_ph?ie=UTF8&qid=1442957193&sr=1&keywords=phobya but got it considerably cheaper from a local supplier. Then I used a Molex “Y” splitter I had from a PC PSU stripped the 2 connectors off, cut down a Micro USB cable and soldered it to one and then got a 2.1mm DC connector from Maplins for £2.50 and connected that to the other.

I finished building my Picade last night and connected the power up today and it worked like a treat first time.


#14

There is a nice 4-port USB power supply that can work from wide voltage range, including 12V. So, you can have 12V power for display and also use the same power for USB Power Adapter. From 4 USB ports you can power Pi, USB HDD, USB cooler or whatever else you need.


PiCade customisation questions
#15

Hi all, this is my first post. I just put my picade together & I was wondering if a UK plug with dual USB slots would work & power both screen & Pi sufficiently


#16

It really depends on the quality and output of the UK plug. Judging by our past experience of plugs and socket adaptors with USB ports in them I’d reckon probably not ( they’re generally terrible ), but if you already have one you could give it a try since it shouldn’t cause any harm.


#17

Hi,

Just to share an update on my PSU effort from last year (posted above) to power both Pi and Screen off one plug - finally I got chance to improve this. I was getting the odd ‘rainbow’ warning where the voltage must have just been dropping a little too much on occasion. I silenced it as it was only popping up maybe once or twice per session, but always figured I should look at it one day.

So in an attempt to solve the problem, I completely did away with all molex adapters, used a different USB cable which only carried power (no data - just more convenient when stripping cables), and shortened the USB cable by well over half to reduce any unnecessary resistance. On the last effort I was overly conservative with cable length. I then had a friend help me solder each wire together, heatshrink the individual wires and then put one big piece over the lot. Looks a lot cleaner now and the connection is obviously more solid. Here is the result:

Most importantly, no more rainbow so I now have full confidence in the cabling. Doing away with the molex, shortening the cable and directly connecting everything has obviously helped.

Just thought i’d share.

Cheers


#18

I bought this as a simple solution:

It’s pretty small and hides in the cabinet nicely. Works like a charm with my 12 inch screen. I get an occasional power warning if I pump the volume right up, but never have any screen problems. I also fitted an inline switch to the power cable for convenient power killing.


#19

I like that Rav power usb power bank. I found a newer model that has one quick charge 2.0 port that can do 12v 2A and the other 3 can do 5v 2.4A. In your opinion will that work? I want to use the quick charge port for a 12.1 inch screen and others for pi3, led usb strip, and still one strip left.

Quick Charge 2.0 RAVPower 40W 4-Port USB Quick Charger with iSmart for Galaxy S7/S6/Edge/Plus, Note 5/4, LG G4/G5, Nexus 6 and more (Black) https://www.amazon.com/dp/B018S6X92I/ref=cm_sw_r_other_apa_pvDExb7RC8YXQ

Also use this from the USB 2.0 port to the 12.1 inch screen.
LANMU
1M USB DC 5V To DC 9V 12V 2.1mm X 5.5mm Module Converter DC Barrel Male Connector Jack Power Cable Plug (5V To DC 12V)


Power
#20

Just wanted to mention to anyone else who finds this thread that this may be an option. I’ve ordered one:
https://www.amazon.com/Generic-Volt-Barrel-Power-Cable/dp/B00304DZ7I/
It appears to be completely passive, so if you plug the USB side into a 12-volt source, like the QuickCharge port on the RAVPower device, I imagine it will pass that directly to the display panel. Time will tell.