Power


#1

I’m looking to power my Picade from a single outlet like others have done… I’ve done some research and ordered this:

Looking at the specs I think it should work, and is the same spec adn the power block I’m currently using (12v 1500ma output)… However it doesn’t seem to be powering the screen properly (12.1 screen). It comes on but it’s VERY dim and only really working on 1 side… I assume it’s not getting enough power.

I quickly knocked up the USB to Barrel cable myself and it’s not great, do you think it’s the badly made cable? If so I’ll order a proper one form Ebay.

Thanks.


#2

Do you have a multimeter handy? If so check the voltage and current for the screen and see what its drawing. Its possible whatever smart technology that that uses doesnt recognise the connection so will only pass through the standard usb powe (dumb cables are often limited to 500ma or less)


#3

Unfortunately I don’t have one :(

I might have to RMA it :(


#4

I suspect that your homebrew cable isnt allowing the power requirements of the 12.1" screen, which i belive is 12v at 1A. This might not be the case but frankly my advice would be to grab a cheap multimeter and check the current and voltage being supplied. You can get a cheap one for ~£5-10 or so and you dont need extreme accuracy.


#5

I’ll try that, thanks.


#6

I tried that same setup and the 12.1 inch screen was just too dim. Not enough power. I just resulted in plugging two cords. I was thinking of just putting a small power strip inside and plug the cord from the 12.1 inch display and the picade into it and just plug 1 cord to the outlet when I use it.

rav


#7

its just strange that the PSU i’m using at the moment is 1.5a and works perfectly :(

I guess not all amps are equal :)


#8

Confused? Does the display need 12V or 5V for power? And what voltage are you powering it with? If it needs 12V and you only feed it 5V that would explain why its dim and doesn’t work.


#9

from what I saw on the one they sold before it is 12v at at least 2.1a. I used that barrel usb plug and it got super hot but it did work.


#10

I wouldn’t be trying to power a 12V device with only 5V. Bad things are likely to happen.


#11

I think it should work fine but the weak spot is the USB to barrel
adapter… Let be clear I think i explained it wrong. Once I went
directly from the display to the power source using the USB 3.0 12v 2 a
slot it was too dim. Then when I used that USB to barrel adapter it worked
fine. The issue was it got too hot. I was afraid to damage something or
fire. So I stopped using it.


#12

I think, these QuickCharge devices are able to provide more than 5V only to devices that communicate with the charger in a certain way. If you are plugging in a “dumb” USB to Barrel cable, you are getting only 5V.


#13

USB 3 is 5V not 12V. So unless there is an up converter between the USB slot and barrel connector, your not getting 12V into the displays power jack. A picture of the hookup would help greatly.


#14

The one I bough has a Quick Change 2 port which provides 12v at 1.5a so i’m not sending 5v to the screen, I’m sending 12v.

I’m guessing it’s the cable I’m using, I thinking of either RMAing the PSU or buying a cable and seeing if that works… Can’t decide which. I only have 10 days to return it but it will take longer than that to receive delivery of the cable :(


#15

Ok, never heard of those? 12V will destroy most 5V USB devices.


#16

Yeah it’s all a little tricky. I don’t mind plugging in 2 plugs to play for a bit. At least I got a powerblock and power button so I can safely turn off the pi. To me that mattered more.


#17

The power supply for one of those small form factor PC’s should do the trick. It would be smaller than a full ATX power supply and have +12V and +5V with decent current capacity.

EDIT: You’d have to do some wiring modifying, but it would get you down to one AC wall plug.


#18

Hi

Is the current quoted for all outputs or individually?

Cheers

Paul


#19

It should be the same deal as a PC ATX PS, the current is listed for each voltage. You may have to Google the part number to get the detailed info.


#20

I would wager that this is absolutely not the case. No USB port should ever under any circumstances naively supply 12v.

To actually get 12v out of a USB Power Delivery supporting port, you need to use a “USB Power Delivery” certified, electronically detectable cable.

Apparently this detection happens entirely over V-BUS, and isn’t part of the USB Host<->Device negotiation, which is something I had assumed would be the case. Depending on how this happens (Apple used a small micro-controller in the end of their chargers to switch between low and high voltage) it might be possible to botch up a cable that requests 12v.

I’m trying to find this out. But… sheesh the USB 3.1 spec is an 80MB zip that downloads excruciatingly slowly =/ usb.org are clearly using servers as old as their port :D

Edit: Darn-it, the hub uses “Qualcomm Quick Charge 2.0” which is not USB Power Delivery. The above still mostly applies, though.

Unfortunately “Qualcomm Quick Charge 2.0” is a proprietary specification, the details of which are probably known only to Qualcomm and to manufacturing partners under NDA, so the chances of hacking up a cable that successfully tricks the “Qualcomm Quick Charge 2.0” port into sending 12v are slim to none.

Or… maybe there’s hope: http://hackaday.com/2016/12/13/bitbanging-qualcomm-charge-controllers/
… apparently “Quick Charge 2.0” is not as closed as I thought!

Oh and people are sniffing USB Power Delivery, too: https://www.reclaimerlabs.com/blog/2017/5/16/example-usb-power-delivery :D

TLDR: No. The Aukey PA-T1 most definitely does not output 12V unless you connect a “Qualcomm Quick Charge 2.0” supporting device. Fortunately, if you’re sufficiently motivated you can pretend to be one and request 12V. See: http://www.hackvlog.com/2016/12/bitbanging-quick-charge-2.html - the guy uses the same brand of hub, too :D