Check out some solid advice about getting the right power supply for your LED projects, from Kean at Hacking Light:

Something easy to forget when building you own electronics it the importance of a good power supply.  Equally important is power distribution (wiring).

The LPD8806 LED strip we are using runs best off 5V, but will actually pretty well anywhere between about 3V and 6V, with obvious brightness changes. But the controller (Olimex OLinuXino i.MX233 Micro/Maxi, or Raspberry Pi) is quite a bit fussier, and really wants 5V +/- 5% (4.75V to 5.5V), without too much noise or ripple.

The LED strip draws about 50mA per LED at full brightness, so our 52 LED set up can potentially draw over 2.5 amps! And you want to allow another 200mA to 400 mA for the CPU and WiFi (lower value for Olimex Micro, higher value for Olimex Maxi or Raspberry Pi).

So you’d think that a 5V 3A supply should be fine, and all will be well. But it isn’t quite that easy. The Freescale i.MX233 really does not like its 5V supply going below 4.7V, or it will restart due to brown-out detection. I expect the Raspberry Pi is much the same, although I didn’t experience any problems with them during development.

For example we found that the output of a common 5V 3A plug pack could easily drop to maybe 4.8V above 2 amps. Add in some common 24AWG wire plus some connectors, and you can easily lose another 100mV or more.

Read More.

It’s great to see someone noticing the extra care Adafruit takes sourcing power supplies for our store! Dean solved his challenge by using our 10A power supply!

5V 10A switching power supply

This is a beefy switching supply, for when you need a lot of power! It can supply 5V DC up to 10 Amps, running from 110V or 220V power (the plug it comes with is for US/Canada/Japan but you can use any plug adapter for your country, or just replace the cable with a standard figure-8 cable)

The output connects to a 2.5mm DC plug but its a ‘springy’ type so you can use it in 2.1mm jacks as well. There’s a green LED indicator lamp as well.

These will be great for people who want to power 5V LED strips or a lot of motors for a CNC project. Using a separate supply like this can be easier than trying to modify an ATX power supply as its smaller, quieter and has a plug on it ready to go!

• 5V up to 10A output
• 110V-220V input
• Comes with 2-prong US/Canada/Japan – for other countries use a basic plug adapter. 112cm (44in) long cable
• 2.5mm output plug, but will also work with 2.1mm. 110cm (42in) long cable
• Body size is 5.5″ x 2.4″ x 1.3″ (14cm x 6 cm x 3.3 cm
• Weight: 0.925 lb / 420g