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Power Requirment
#1
Hi,
Im a newbie to some of this - so please be gentle!
I got my AllPixel via the KickStarter project and it arrived safe and well, parts soldered on and Python installed (even though the AVR driver was a pain!) - running Win7 64Bit.

I bought a strip of LED's from Ebay (Item: 151643082419) - however im a bit confused about the power.
Looking at the LED's I have 150 LED's @ 9 watt per meter, giving 45W, another video says allow 20%, so im looking for a 5V 60W transformer.

This is where the problem starts, most of the LED transformers are 12v, also most are listed on EBay from China.
The only one ive found close is Ebay Item : 231529048788

Please can anyone recommend a transformer I can use ?

Thanks
Mike.
#2
Hi Mike! Happy to help out Smile

Power always is a little confusing with these.

First... You are definitely doing the right thing to assume extra power! Smile Never run your supply at max for long.
That being said, it's a little more complicated than that because the rated power for the strip is with every pixel at full white. Odds are, you aren't going to really do this most of the time. So it is technically possible to get away with a power supply rated LESS than what your strips say. Just be aware of what kind of animation you are running and back off on the brightness if you can. In bibliopixel, that's as easy as:

Code:
led.setMasterBrightness(64) #1/4 full brightness

I have a handful of both of these around and they work quite well for 5m strips of LEDs:

http://www.amazon.com/dp/B00MOAR0M0/
https://www.adafruit.com/products/658

Beyond about 10A@5V you generally have to go a little more industrial and can't find enclosed wall adapters like that one.

Something like this works great, if you are OK with wiring on your own plug:

http://www.amazon.com/gp/product/B00N751734/

It's good for 40A and should power several hundred LEDs. But, please be careful... that's exposed mains power! I recommend covering the wiring terminals with electrical tape or similar to make sure nothing can touch the power input terminals.

The key on ebay is to search for "5V switching". All the items in that link ship from the USA Smile

I also buy a ton of stuff from MJPA. Their prices are great as are the power supplies.

Hopefully that should provide you with some decent options Smile
#3
Hi - Many thanks for the reply - although the links you provided are not available in the UK, but using the information I did find this:-
Ebay Item : 360879332663 (5v 150w) which is in the UK
Thanks for your help
Mike.
#4
Hello there,

sorry for reviving such an old post, but i decided not to open a new topic for a similar question.

I'm currently  thinking about building some kind of led wall washer. I want to drive the LEDs with a RasPi and  an AllPixel. For LEDs i thought about getting 5m of this 60 led/m strip. according to the strip description, it requires 0,3W/Led what means 90W for all 300LED on the strip. If i'm not wrong that would mean i require a power supply with 18A @ 5V.

According to the AllPixel description it only allows up to 5A on its DC Power jack. 

Thats the point where i need some help... could you suggest how to do the power supply?


Thanks in Advance! Smile
#5
Dodge, you are correct. 18A is what you should plan for with that strip. One thing to note, however, is that that 18A is ideal and at full white. Most of the time an animation is going to draw 30-60% max power... but we still recommend planning for being able to do max power.

What we recommend for applications like this is using the PowerTap (http://www.seeedstudio.com/depot/AllPixel-Power-Tap-Kit-p-2380.html). This allows easily splicing in up to 5A of power every so often. Since it makes a nice round number, I would recommend doing this every 75 pixels. So, the first 75 powered direct from the AllPixel and then 3 PowerTap boards along the rest of the strip. But it also depends on how you are going to mount your strips.

Another option is to divide the strip into two sections and then power each from both ends. You could use two smaller, 10A supplies this way if you wanted to (NEVER mix the power rails of two different supplies! but remember to tie the grounds together!... this is what the PowerTap does).

Basically, you are going to have to splice in power at 4 places minimum. The reason the AllPixel and the PowerTap are limited to 5A is because we have found that to be the maximum you can run before the voltage drop on the strip is to great and the lights start to have problems. So don't just think you can wire a 20A supply direct to the strip and bypass the AllPixel... you'll just end up with more than half the strip not working because of the voltage drop.
#6
Hello Adam,

thank you for your reply. I'll see how i will solve that for me. i thougt it would be possible to power a full strip with one supply - good that i asked! Smile


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