Luxeon Rebel 145 lumens output

I plan on getting 4 cool-white luxeon rebel each producing 145 lumens output at the typical voltage. I will be using a 9V (6 AA batteries) as a power source but I do not know if the resistance I calculated is correct. Each LED needs 3.6 Vf @ 700 mA in order to produce 145 lumens. The amount of resistance needed after using the OHM law is 7.714 Ohm. Can someone verify if this is correct? If so, which resistor should I get to connect the LEDs together?

How do you plan on wiring them? SLEDs should always be connected in series, giving a total Vf of about 14V, way more then the provided 9V. Instead of a resistor you'd be better off with a driver such as one of the Luxdrive buckpucks or a Taskled(.com) LED driver. Also, can you make your own PCB's? The Rebel is f@#*$ing small, I couldnt solder it at home for sure.

where did you get them and how much did they cost?!!

maybe you can calculate the needed resistor here:
http://www.metku.net/index.html?path=mods/ledcalc/index_eng

They are made from lumileds. You can purchase them on lumileds.com

http://lumileds.com/images/productphotos/ingan_web.jpg

heres a picture of them

I decided to change my LED setup. I decided to go big. I'm setting up a 16 LED luxeon rebel lamp for my salt water aquarium. The voltage supply is changed to 16 volts, 3.6 Vf from the LEDs @ 700mA . My LEDs setup is going to be in parallel. 4 LEDs each column, a total of 4 columns. I used the resistor calculator from the link above and calculated a resistance of 2.7 Ohm needed per led per column. Does anyone know where I can purchase these resistors? I tried radioshack, but couldn't find any.

I can't help you out, but it sounds like you are gonna have one sick aquarium light when you are done

Brum said:

How do you plan on wiring them? SLEDs should always be connected in series,

Click to expand...

Just curious, can I ask why?

They are made from lumileds. You can purchase them on lumileds.com

Click to expand...

I don't think they supply in small quantities to end-users

kanarie said:

I don't think they supply in small quantities to end-users

Click to expand...

They do, actually. I was surprised, but they do deal with end users. You can order a single LED from them.

In general, you don't design a circuit *then* go out to source components with exact values to match it. You see what components are available on shelves, then you design a circuit to use off-the-shelf components.

Scott Packard said:

In general, you don't design a circuit *then* go out to source components with exact values to match it. You see what components are available on shelves, then you design a circuit to use off-the-shelf components.

Click to expand...

Or design the circuit, then analyze how badly it would suck if you used the nearest standard value components , often using Monte Carlo techniques to vary component values if some parameters are really critical.

PS - Here's a table of standard resistor values - 27 is there, but not 2.7.
http://www.rfcafe.com/references/electrical/resistor_values.htm

I'll be darned - Vishay makes a 2.6 ohm?
http://www.vishay.com/resistors-discrete/metal-film/res0-1/

*crap*

I probably made a mistake thinking I would have 16V as a power supply because I tried finding adapters for 16V and I don't think radioshack makes adapters in 16V. So I'm changing it to 15V power source.

LED
Vf of LEDs - 3.6V
mA of LEDs- 700 mA

Power Source
15vdc adapter - 15V

The link suggests that I need one (1 Ohm) resistors per LEDs series in each column, a total of four columns. So I need to get atleast four (1 Ohm) resistors for the setup.

Can someone verify if this is correct?

Thanks.

4 LEDS at 3.6Vf = 14.4V.
15V supply minus the 14.4V required leaves .6V.
.6V divided by .7A = .857Ohms.
.6V times .7A gives you .514Watts

You would need (4) .857 Ohm resistors, one in each 4 led branch. Each resistor will dissapate a little over .5 watts so you would want at least a 1 watt or more resistor at each location.

You will be driving 4 strings of leds at 700ma meaning your power supply will have to be able to supply at least 2.8 amps at 15 volts.

bascerballer4 said:

I decided to change my LED setup. I decided to go big. I'm setting up a 16 LED luxeon rebel lamp for my salt water aquarium. The voltage supply is changed to 16 volts, 3.6 Vf from the LEDs @ 700mA . My LEDs setup is going to be in parallel. 4 LEDs each column, a total of 4 columns. I used the resistor calculator from the link above and calculated a resistance of 2.7 Ohm needed per led per column. Does anyone know where I can purchase these resistors? I tried radioshack, but couldn't find any.

Kind regards,


Chingy

Click to expand...

If it's a reef aquarium, you're gonna kill every life form in it. Stick with the trusty HQI lamps. The only natural light source for marine aquariums.

If you are running 4 parallel banks of 4 in series then one bank will draw 700ma and have 16V. 4 leds at 3.6Vf is 14.4V, so you need to drop 1.6V at 700ma across the resistor, which is also in series with these 4 LEDs. Each bank of 4 LEDs will need its own resistor, so 4 in total. Now 1.6V at 700ma gives 2.28ohm and 1.12Watts, a little different to the answer you got.
Vishay make a 2.2ohm and a 2.7ohm rated at 2.5W, They can be bought in Europe at
http://rswww.com/
and cost £4.32 for 10. Part numbers 485-1571 and 485-1593
Hope that helps.

Hows that possible? Too bright? It's only putting out 2320 lumens. 6000k to 10000k color temperature. I don't think it'll damage them at all.

whoops, typing too slow, out of date already. Dropping so few volts across the resistors means that any fluctuation in power supply voltage mostly gets to the LEDs which can draw quite a bit more for a little extra voltage, they are best run on constant current.

bascerballer4 said:

Hows that possible? Too bright? It's only putting out 2320 lumens. 6000k to 10000k color temperature. I don't think it'll damage them at all.

Click to expand...

I didn't say that that quantity of lumens would kill them (that don't even comes close of the output of a proper reef tank illumination ). The problem is,
LEDs lack the proper light spectrum necessary to support the marine life, that's why HQI's are used in this type of aquarium. Your are not rasing a pet iguana, marine tanks are a whole lot more serious.