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Topic # 148840 2-Jul-2014 16:54

Hello,


Trying to power a Raspberry Pi with an attached screen. Requires an adapter, don't know much about the technical term of what type of socket, but all the old modems in our house (as well as our new one) accept the same connector as the one I need. All of them are between 9 - 12V / 1 - 2 A so I believe they are incompatible. 

Manufacturers said it required 6V but the adapters they provide (5V / 3A) ran max output at 5.5V and worked fine with the screen. So I'm looking for a power adapter that fits the bill.

The nearest thing I could find was DSE selling this, max output 5.4V. It is quite expensive though. Seeking recommendations about where to find a power adapter, and maybe some advice on how to pick one safely (and if someone could tell me the type of connector based on my description, that'd help).   Thanks

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  Reply # 1078787 2-Jul-2014 17:35
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How many do you want?  5V 3A is what I have designed into our new product http://livestock.tru-test.com/en-nz/indicators/xr5000

As for the connector, I can probably attach one for you.  We have a number of PIs at work so I can check the connector.  But it is your risk if 5V is not enough, just saying.




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  Reply # 1078941 2-Jul-2014 22:27

Thanks for the help, I only need one.

If it can output at least 5.5V then it should be safe to use. The screen attaches via an LVDS / HDMI converter. There is a picture of it here connected to a Raspberry Pi (black cable bottom right). I'd prefer something that wasn't cut up and tweaked, but was designed for this kind of socket. 

Can you identify what kind of connector that is based on the photo? Like I said, it is used on all of the 4 different brands of modem / router we have. The socket is about 5 or 6 millimetres width/height with a silver pin in the middle. The pin is kind of thick, probably no bigger than 1 millimetre, maybe slightly smaller.

I don't mean to insult you by asking, but I feel I should just for peace of mind:  I trust the adapters are supplied from a reliable source? Wouldn't want anything unsafe, have to be careful about power adapters and chargers these days.

How much would you want for 1 adapter to be sent to Chch?


 
 
 
 


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  Reply # 1078970 2-Jul-2014 22:57
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It's a fairly high amperage / voltage ratio and not something you find often. The Linksys PAP2T comes with just such an adapter... had to buy another one this week thanks to a power surge.

 

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  Reply # 1078973 2-Jul-2014 23:06
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That picture has a 5.5mm outside diameter DC socket, the pin can either be 2.1 or 2.5mm which are not really interchangable. A 2.5mm plug will go into a 2.1mm socket, but will have a crap connection and drop out on every wiggle etc. The other way wont fit. Many things use a 2.5mm for their 5v inputs so people dont plug higer voltage wall warts into them, but its really only possible to know for sure by measuring it.




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  Reply # 1079037 3-Jul-2014 02:42

insane: It's a fairly high amperage / voltage ratio and not something you find often. The Linksys PAP2T comes with just such an adapter... had to buy another one this week thanks to a power surge.

 


But from where did you buy it? D:

the pin can either be 2.1 or 2.5mm which are not really interchangable.


What do you mean? The width of the metal pin inside the socket or the width of the connector on a power adapter?



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  Reply # 1079052 3-Jul-2014 06:21
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Rough guess $10 for the power adapter, will check at work today.  And I can give you a copy of all the compliance certificates if you want, world wide.  Tru-Test is one of the top electronics exporting manufacturers in the country ;-).

Measure the voltage while the display is turned on, i.e. while there is a load.  With no load the voltage can be slightly higher.

As others said, there are different size centre pins.  I'll do a decent job of fitting the connector, but need to know which one.  What is the make/model number of the LVDS converter?  Also, I'm interested in buying one as we needed it a couple of years ago when we developed the above mentioned product.




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  Reply # 1079054 3-Jul-2014 06:41
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Looking around there's a similar looking board at Chalkboard Electronics. The spec for that is 5v at least 2 amp. You seem to have an adapter lined up but if it didn't need 3 amps that would give more options.

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  Reply # 1079074 3-Jul-2014 07:45
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This. More here. I've bought from sicom before, no problems at all.




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  Reply # 1079454 3-Jul-2014 15:35

timmmay: This. More here. I've bought from sicom before, no problems at all.


Thanks, that looks like a good solution if I can't get one Niel.

 

Bung: Looking around there's a similar looking board at Chalkboard Electronics. The spec for that is 5v at least 2 amp. You seem to have an adapter lined up but if it didn't need 3 amps that would give more options.


Yeah thats it, I have their new 14" screen with their LVDS/HDMI converter. 5.5-6V is what was recommended, they ship a 5V 3A adapter with it for extra but only with UK or US plug so I didn't bother.

Niel: Rough guess $10 for the power adapter, will check at work today.  And I can give you a copy of all the compliance certificates if you want, world wide.  Tru-Test is one of the top electronics exporting manufacturers in the country ;-).

Measure the voltage while the display is turned on, i.e. while there is a load.  With no load the voltage can be slightly higher.

As others said, there are different size centre pins.  I'll do a decent job of fitting the connector, but need to know which one.  What is the make/model number of the LVDS converter?  Also, I'm interested in buying one as we needed it a couple of years ago when we developed the above mentioned product.



Sounds good. I'm not sure what else I can provide to help identify it better, except that it is from Chalkelec. This is the page for buying one, but I'm not sure if it is the same one they are using for the new screens (I suspect it is, but it is worth mentioning they've been re-designing a lot of their products recently):

 

http://www.chalk-elec.com/?page_id=1280#!/~/product/category=3094861&id=14647633

 

The product I have:

 

http://www.chalk-elec.com/?page_id=1280#!/~/product/category=3094861&id=36248806

 

LCD backlight requires 6V voltage as per datasheet. We made tests in our lab and found that backlight works stable with voltage down to 5.3V. Our optional AC/DC adapter can provide 5.5V, so it will work seamless with this LCD. Please, take note if you are going to use own power supply.

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  Reply # 1079681 3-Jul-2014 22:34
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As I suspected, the higher voltage is required for powering the backlight.  The LVDS driver runs off 3.3V logic with a voltage regulator, it is only the backlight that needs more.  Sorry, mine will not do 5.3V, it is specified 5.0 +/- 5% no load and minimum 4.6V at 3A load.  Essentially it complies with the USB spec but higher power which is required to charge our battery at the same time as running the product.  From the web site I could not find anything to confirm the diameter of the connector centre pin.  Best option if you can't measure it exactly is to buy a universal power adapter with interchangeable DC connectors.




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