Power Supply for LEDs?

[Mr. Microscope]

Hello All,

I'm planning an LED build with one of four configurations (likely one of the first two, possibly option three or four after I get my true violet LED's from nanotuners). I have two power supplies. They are 12 volts 1.2 amps.

Will they be enough for these setups?

3 Cree XR-E's on a 1000mA dimmable BuckPuck and a 12 volt DC fan on one power supply.
2 Cree XR-E's on a 1000mA dimmable BuckPuck and 1 Cree XR-E on a 500mA dimmable BuckPuck on the other power supply.

4 Cree XR-E's on a 1000mA dimmable BuckPuck and a 12 volt DC fan on one power supply.
2 Cree XR-E's on a 1000mA dimmable BuckPuck on the other power supply.

3 Cree XR-E's on a 1000mA dimmable BuckPuck and a 12 volt DC fan on one power supply.
2 Cree XR-E's on a 1000mA dimmable BuckPuck and 3 Cree XR-E's on a 500mA dimmable BuckPuck on the other power supply.

4 Cree XR-E's on a 1000mA dimmable BuckPuck and a 12 volt DC fan on one power supply.
2 Cree XR-E's on a 1000mA dimmable BuckPuck and 2 Cree XR-E's on a 500mA dimmable BuckPuck on the other power supply.

Thanks in advance!
Mr. M

 

[Mr. Microscope]

Anyone?

I also have this 18 watt 4.9 Amp from an old laptop. Says AC adapter. I thought we needed DC adapters..?

 

[stage3-S4]

Pretty much the best way to go about is that Cree XR-Es have a forward Voltage(Vf) of around 3.6v-3.7v at 1000mA. So I wouldn't put more than 3 of them in series with a single 12v power supply. Vf would be around be around 3.4v for 500mA. Again I wouldn't put more than 3 of them in series with a 12v power supply. I would just buy a new 24v power supply with around 3 amps of current so you can run multiple led arrays. With a 24v you can run 8 LEDs on one array. Since they are connected in series the forward current will be the same for all LEDS (1000ma or 500ma depending on the regulator used). Refer to the specs sheet of the XRE for more information:
http://ledsupply.com/docs/cree-xre.pdf

 

[Mr. Microscope]

Thank you stage3-S4! Will I be okay with the 3 leds and the 12 volt fan on one PS?

 

[stage3-S4]

Thank you stage3-S4! Will I be okay with the 3 leds and the 12 volt fan on one PS?

You should be ok, just make sure you wire up the fan in parallel with the LED array so that it gets the full 12v. Since its a 1.2 amp power supply you should have 1 amp for the LED array and an extra .2 amps for the fan which I cant imagine being that much. Just check the current draw before you connect it. I'm also assuming you are just going to use a small 60mm computer fan for this which will be more than enough.