Question 5~12v 2amp power supply specification?

[PB97]

I've just brought a 9" pi compatible display and it says that it requires a 5~12v 2amp power supply.

I'm currently using it with a 5v 2a usb phone charger with ausb to 5. 5mm adapter cable, the cable is too short and if I try to use a usb extension cable it won't power on, presumably due to voltage drop. I've tried 3 cable under a meter and it's the same for all of them. So the cable is not faulty.

I have a 12v 2a mains power supply with 5.5mm jack on it and much a longer cable. Presumably 5~12v means that I can use any power supply in that range?

I'm 99.999 percent sure but I just want to check.

 

[OldSurferDude]

If the display is the only component that you're powering with the power supply, you should be OK. In order to be as certain as you, I'd need to see the schematic of the display to ensure that 12V doesn't get onto the RPi.

Also, cheap 12V supplies can have huge ripple and/or rely on its internal resistance / load resistance to get an approximate 12V out; in other words, they rely on the device voltage regulator for proper power regulation. I have noticed that a lot of devices use regulators that are spec'd up to 15VDC input, but it's a bad design to rely on the absolute spec.

OSD

 

[PB97]

It's a cheap Chinese display, so no schematics. It seems to run OK on 5v, except for when I try to use an extension cable, with all that I've tried the screen flashes slightly but won't turn on. I had the same issue when I tried using a sub 5v power supply.

 

[OldSurferDude]

This is always the problem with the devices of this quality. Some work great and some can "let the magic smoke out"

Consider it an an experiment. No experiment fails because the object of the experiment is to gain knowledge. You will learn at least one of the following: It works. It doesn't work. It doesn't work and also fries your display. It doesn't work, fries your display and RPi.

If your are concerned about the latter, (I would be), a less risky method would be to use an Orange Pi (~$30 as opposed to $150).

Please share the knowledge you gain. And post a link to the source of the display.

Good Luck

OSD

 

[PB97]

If you open the box there is an equal chance of tbe cat being

1 dead
2 alive
3 your crazy x girlfriend with a carving knife

 

[PB97]

Here are some images of the control board.
Link

 

[OldSurferDude]

I have less experience with this board than you, thus I must leave you to your own devices.

Your adventure starts by googling the label of the board "PCB800099". It quickly takes you to this page. It is important that you read and take whole heartedly the section "Contacting me about this board"

In finding a solution to your challenge, you will learn much about how to find solutions on your own. Approach each shred of knowledge with respect and healthy healthy skepticism. Also respect the people that have taken the time to write up their findings, for they are the ones that will guide you, though it is unlikely they will hold your hand.

And honor those that have led you to a solution by writing up and publishing the steps you took to arrive there. In doing so you will gain respect yourself.

Good luck!

OSD

 

[PB97]

I have less experience with this board than you, thus I must leave you to your own devices.

Your adventure starts by googling the label of the board "PCB800099". It quickly takes you to this page. It is important that you read and take whole heartedly the section "Contacting me about this board"

In finding a solution to your challenge, you will learn much about how to find solutions on your own. Approach each shred of knowledge with respect and healthy healthy skepticism. Also respect the people that have taken the time to write up their findings, for they are the ones that will guide you, though it is unlikely they will hold your hand.

And honor those that have led you to a solution by writing up and publishing the steps you took to arrive there. In doing so you will gain respect yourself.

Good luck!

OSD

But... I'm lazy

I want easy answers delivered to me in bite sized peices that mean I won't have to think for myself or take responsibility for anything. Like when I was in college and twitter told me how to feel about stuff.

 

[PB97]

To be fair, I'm just pluging in a power cable and an hdmi cable to use this to display sensor readings and pretty pictures, so my needs are pretty much just plug and play. No hacking or tinkering.

I only have a first generation pi.