LED colors combination?

xenia2 · 06/13/2013, 07:39 PM

Hi guys,

I am planning to build a light fixture for the Elos mini, think of using 18 LEDs all together with two power supply (one of each strings).

However I am not sure how to pick the combination number of LEDs. Such as how many white (cool or neutral), how many blue (blue or royal or combination of both). Any help is greatly appreciated

cmpaue · 06/13/2013, 08:25 PM

1cw:1rb at least, desirable 1cw:2rb

Eud · 06/13/2013, 08:38 PM

4RB, 2NW, 1 OCW(which includes DR, Cy, CB), 2 430nm violets

hllywd · 06/14/2013, 07:58 AM

I've had mine running for about 3 years now, 50/50 Cree XR-E CW and RB. To do it again, or update my fixtures I would at least switch out half of the CWs for NWs to add some red spectrum. I would not add individual red LEDs, but that's just an opinion.

xenia2 · 06/21/2013, 05:26 PM

Thank you all for above suggestions :-)

I have another question, related to the Meanwell driver, I took the follow paragraph from rapidled.com site:

"To figure out how many LEDs a driver can run, you’ll need two pieces of information: the driver’s voltage range and the voltage required by the LED at the given current level that you would like to run the LEDs at. As an example, the LPC-35-700 driver has a voltage range of 9-48V. The XP-G Cool White LED requires 3.05V at 700mA (remember this is the current output of the LPC-35-700 driver). Thus, the minimum number of LEDs required is 9V divided by 3.05V. 9/3.05 = 2.95, thus we round up and the minimum number of LEDs is 3. For maximum LEDs, we divide 48V by 3.05V and get 15.74. We round down and get 15 LEDs. Typically we play it safe and thus on our product page we list the range on the LPC-35-700 driver as ~3-14 LEDs. Keep in mind the voltage required by each LED can be quite different so you may need to do these calculations for each of your strings."

According to above example, the minimum LEDs you can use are 3 and max are 15. Let say if you're using the min of 3 LEDs, how does the driver distinguish the output voltage between a 3 LEDs vs. 15 LEDs?

jlholimon · 06/21/2013, 06:19 PM

It doesn't, you have to configure the output voltage at 9 volts. From the specs on the meanwell website there are methods, using a PWM controller or for another series there are internal poteniometers that you adjust.

It is a good idea to test this with a multi-meter before hooking up to your leds though or

, shorts, and general unhappiness will occur.

xenia2 · 06/21/2013, 06:41 PM

I looked at the specs. but it doesn't specify any kind of voltage adjustment for LPC-35-700 driver?

jlholimon · 06/21/2013, 07:44 PM

The description is too brief for my electrical knowledge (something I have learning about a lot for my own LED build), but I would have to guess that either you have to have a voltage regulator after the power supply to drop it down to what you need or there is some other mechanism no mentioned in the item spec.
If you look at and LDD-LS (the drive I think is in your unit), read note 4 "Output voltage will always step down by 3 volts from input DC voltage". This makes me thing that your output is fix and you have to use something else to regulate it down.

DrawnToBeaches · 06/21/2013, 07:57 PM

you don't have to adjust anything, there are other drivers, the led draws a certain amount of volts at a certain current. the driver wouldn't be doing its job if it didn't pump it correctly without your assistance. but for that specific combination of led and driver min is 3 max is 15. you have so many drivers to choose from same goes for leds. don't limit yourself by those numbers but also don't expect to run a single low wattage led on one driver. also recommend looking at the meanwell ldd-h drivers, clay-boa has them very cheap and they rule for smaller projects like yours. very easy to use and are dimmable from 0-100%, but I think they still have a minimum number of leds per string. I am not blowing smoke up your butt either I have a box full of those drivers.

06/13/2013, 07:39 PM	#1
xenia2 Registered Member Join Date: Aug 2003 Location: Northampton, MA Posts: 437	LED colors combination? Hi guys, I am planning to build a light fixture for the Elos mini, think of using 18 LEDs all together with two power supply (one of each strings). However I am not sure how to pick the combination number of LEDs. Such as how many white (cool or neutral), how many blue (blue or royal or combination of both). Any help is greatly appreciated

06/14/2013, 07:58 AM	#4
hllywd Premier World Traveler Join Date: Nov 2000 Location: Ohio Posts: 4,293	I've had mine running for about 3 years now, 50/50 Cree XR-E CW and RB. To do it again, or update my fixtures I would at least switch out half of the CWs for NWs to add some red spectrum. I would not add individual red LEDs, but that's just an opinion. __________________ "The moment you doubt whether you can fly, you cease forever to be able to do it..." J.M. Barrie Current Tank Info: 210 AGA RR, Apex, 3x Kessil A360W & 2x 80W T5s, GEO 618 Ca Rx, BM220 CS2 skimmer, Tunze 6100s, 42" ETSS/AE Tech refugium/sump

06/13/2013, 08:25 PM	#2
cmpaue Registered Member Join Date: Apr 2013 Posts: 8	1cw:1rb at least, desirable 1cw:2rb

06/13/2013, 08:38 PM	#3
Eud Registered Member Join Date: Aug 2012 Location: Maryland Posts: 414	4RB, 2NW, 1 OCW(which includes DR, Cy, CB), 2 430nm violets

06/21/2013, 05:26 PM	#5
xenia2 Registered Member Join Date: Aug 2003 Location: Northampton, MA Posts: 437	Thank you all for above suggestions :-) I have another question, related to the Meanwell driver, I took the follow paragraph from rapidled.com site: "To figure out how many LEDs a driver can run, you’ll need two pieces of information: the driver’s voltage range and the voltage required by the LED at the given current level that you would like to run the LEDs at. As an example, the LPC-35-700 driver has a voltage range of 9-48V. The XP-G Cool White LED requires 3.05V at 700mA (remember this is the current output of the LPC-35-700 driver). Thus, the minimum number of LEDs required is 9V divided by 3.05V. 9/3.05 = 2.95, thus we round up and the minimum number of LEDs is 3. For maximum LEDs, we divide 48V by 3.05V and get 15.74. We round down and get 15 LEDs. Typically we play it safe and thus on our product page we list the range on the LPC-35-700 driver as ~3-14 LEDs. Keep in mind the voltage required by each LED can be quite different so you may need to do these calculations for each of your strings." According to above example, the minimum LEDs you can use are 3 and max are 15. Let say if you're using the min of 3 LEDs, how does the driver distinguish the output voltage between a 3 LEDs vs. 15 LEDs?

06/21/2013, 06:19 PM	#6
jlholimon Registered Member Join Date: Jun 2012 Location: Morrisville, NC Posts: 46	It doesn't, you have to configure the output voltage at 9 volts. From the specs on the meanwell website there are methods, using a PWM controller or for another series there are internal poteniometers that you adjust. It is a good idea to test this with a multi-meter before hooking up to your leds though or , shorts, and general unhappiness will occur.

06/21/2013, 06:41 PM	#7
xenia2 Registered Member Join Date: Aug 2003 Location: Northampton, MA Posts: 437	I looked at the specs. but it doesn't specify any kind of voltage adjustment for LPC-35-700 driver?

06/21/2013, 07:44 PM	#8
jlholimon Registered Member Join Date: Jun 2012 Location: Morrisville, NC Posts: 46	The description is too brief for my electrical knowledge (something I have learning about a lot for my own LED build), but I would have to guess that either you have to have a voltage regulator after the power supply to drop it down to what you need or there is some other mechanism no mentioned in the item spec. If you look at and LDD-LS (the drive I think is in your unit), read note 4 "Output voltage will always step down by 3 volts from input DC voltage". This makes me thing that your output is fix and you have to use something else to regulate it down.

06/21/2013, 07:57 PM	#9
DrawnToBeaches Registered Member Join Date: Jul 2011 Posts: 266	you don't have to adjust anything, there are other drivers, the led draws a certain amount of volts at a certain current. the driver wouldn't be doing its job if it didn't pump it correctly without your assistance. but for that specific combination of led and driver min is 3 max is 15. you have so many drivers to choose from same goes for leds. don't limit yourself by those numbers but also don't expect to run a single low wattage led on one driver. also recommend looking at the meanwell ldd-h drivers, clay-boa has them very cheap and they rule for smaller projects like yours. very easy to use and are dimmable from 0-100%, but I think they still have a minimum number of leds per string. I am not blowing smoke up your butt either I have a box full of those drivers.