High power LED's

Using Arduino General Electronics
1

Hi everyone.

I've got three of these these high powered LED's http://www.dealextreme.com/p/3w-led-emitter-on-star-multicolored-rgb-4530 that I want to drive from my Arduino. I bought these LED drivers http://www.dealextreme.com/p/amc7135-1050ma-regulated-circuit-board-for-diy-flashlights-20-pack-3201 to power them but I believe they require 3.6~4.5V inputs.

Basically, I want to PWM and put each colour on the 3 LED's in parallel so I can turn all three RED's on at the same time, all three Blue's on at the same time, you get the idea ;). The driver would work fine for that testing with battery but now I want to move to having the Arduino and the LED's powered by the same power supply. I'm thinking of getting a 12V power supply http://www.ebay.com.au/itm/AC-110-240V-DC-12V-2000mA-2A-Power-Supply-Adapter-AU-plug-/300646685254?pt=AU_Electronics_Accessories_Power_Boards_Cables&hash=item45fff05a46#ht_2768wt_938 that should give me 24W to play with. The LED's will take 9W, the Arduino not much more, giving me heaps of spare.

The question is, using a 12V power supply like this... if my LED driver won't be any good. How do I drive it? Any links to something to buy that would fit the bill would be awesome.

Cheers,
Scotty O

2

I just noticed someone doing the same thing I am with 1 of these LED's Arduino + 3W RGB LED - YouTube

If I used the same driver they're using http://www.dealextreme.com/p/mr16-1-1w-320-350ma-constant-current-regulated-led-driver-8-40v-input-13553 but used 9 of them with a 12V 2A power supply (instead of the three in his video) would that work just as well?

3

It is not clear if those LEDs are common anode or common cathode. Likewise it is not clear if that last driver is a constant current sink or constant current source.
To be clear you need a constant current sink with a common anode LED
Or
A constant current source with a common cathode LED.

The first combination is more common.
You need three constant current drivers per LED, there is no way to put these LEDs in series.

Probably not the answer you were looking for but those links do not describe what they are selling very well. You could always try and ask the seller the question.

4

It is not clear if those LEDs are common anode or common cathode.

Look at the picture of the LEDs... you see R+, G+, B+, and - on the PCB. I would guess at common cathode from that.

The drives are based around the AMC7135. The data sheet quotes:

350mA constant sink current.

and there are three on each "chip" (as dealextreme call it). Even so, DE quote

  • 4W 1050mA (+/- 10%) Regulated Power Output

So I don't know what they're on about there... (yes, that is 3 chips worth of sink - but power output?! The chip sinks!)

5

What if I got these http://www.dealextreme.com/p/mr16-1-1w-320-350ma-constant-current-regulated-led-driver-8-40v-input-13553 (looks like they are what that guy on YouTube used.)

I'm thinking if I got 9 of them express posted, they could drive the 3 RGB LED's

6

majenko:

It is not clear if those LEDs are common anode or common cathode.

Look at the picture of the LEDs... you see R+, G+, B+, and - on the PCB. I would guess at common cathode from that.

The drives are based around the AMC7135. The data sheet quotes:

350mA constant sink current.

and there are three on each "chip" (as dealextreme call it). Even so, DE quote

  • 4W 1050mA (+/- 10%) Regulated Power Output

So I don't know what they're on about there... (yes, that is 3 chips worth of sink - but power output?! The chip sinks!)

One of the comments on the deal extreme site was:
The screen is wrong, + and - symbols are interchanged. This LED is common anode. Simply change your transistors from NPN to PNP.
Each color draws a different current, so you cannot use a common resistor.

Sorry if I'm a little n00b at all this

7

One of the comments on the deal extreme site was:
The screen is wrong, + and - symbols are interchanged. This LED is common anode. Simply change your transistors from NPN to PNP.

One more reason cheap isn't always good...

8

majenko:

One of the comments on the deal extreme site was:
The screen is wrong, + and - symbols are interchanged. This LED is common anode. Simply change your transistors from NPN to PNP.

One more reason cheap isn't always good...

That was on the LED :P.. if I've already bought them and want to use them though...

9

I've already bought them and want to use them

So definitively find out what way round they are.
Take a 470R resistor (or somewhere between 220R and 1K), connect the common end to +5V and the resistor to ground and touch the R, G and B LEDs in turn. If they light up they are common anode.

If the don't connect the common end to ground and the resistor to +5V if it lights up it is common cathode.

The you can begin to look for the correct type of current driver.