# How to drive 8 leds at 10watt-12vdc each..



## Murphy625 (Jan 28, 2014)

So maybe I should have just asked this question from the start instead of trying to design my own power system without any LED experience.

I bought 10 high powered LED's off ebay.. They are SMD chips that run 1050ma at 9 to 12 vdc each.. They are considered to be 10 watts.

What is the cheapest way to power all 10 of these? It would seem to me that hooking them up to a 12vdc source (atx pc computer power supply?) and using series resistors in front of each led chip would be the cheapest. 
But people seem to frown on that for a variety of reasons.

Been looking around on ebay and have found constant current modules for about $5 each but I'd have to purchase one for each led chip.. that adds a lot of money to the project so I'm wondering if I'm not considering all my options.

Any help on this???


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## hydropower (Jan 28, 2014)

The resistor solution is bad because the current you get depends on the voltage drop over the LED's and as you already wrote it varies from 9 to 12V. That's about 25%!!! Saying that resistor is cheaper is only valid if your LED's are cheap because you will pop them like popcorn! (a bit exaggerated, but you get the point)
What's the power in the eBay modules? You can possibly run a couple of LED's in parallel or series depending on the regulator. 

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## Murphy625 (Jan 28, 2014)

There doesn't seem to be a good solution. None of the ebay modules seem to be a perfect solution..
My chips are 10w, 9-12vdc and want a max of 1050ma... 

This one only provides 900ma.. on the up side, I could still use the computer power supply unit and running at a lower amperage would probably extend the life a bit.
http://www.ebay.com/itm/Constant-Cu...274?pt=LH_DefaultDomain_0&hash=item19e1a5af22


This one is nice.. I could probably hook up two of the LED's in series and power it with 24 volts.. but where am I going to get 24 volts @2 amps from?
http://www.ebay.com/itm/5A-Constant...960?pt=LH_DefaultDomain_0&hash=item4acf06bc00


This one almost seems to be the best so far.. Its a 30w driver but only puts out 30 to 34 volts. If I hooked up 3 of my leds in series, I'm wondering if he 30 to 34 vdc would be enough.
http://www.ebay.com/itm/Newly-30W-W...8803078?pt=US_Light_Bulbs&hash=item4860a0e786


What is everyone else doing? Are LED's still restricted to flashlights and gimmick projects? I thought this was going to be straight forward for the most part..


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## poolman966554 (Jan 28, 2014)

just did a quick browse on ebay and found this. if you wanted to run them at max amperage, i think this should work for you. 
http://www.ebay.com/itm/100-Watt-Wa...ing_Parts_and_Accessories&hash=item3f2f2345c3
12v out @ 8.33A = 8x leds in parallel @ 1.04A each

Edit: I also found this which is cheaper: http://www.ebay.com/itm/100W-Watt-H...ing_Parts_and_Accessories&hash=item2a2f00755d

But that will require you run a total of 9 leds in 3s3p to run them at 36v @ 1A

Care to post the datasheet for these leds? maybe a better guess could be made.


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## Murphy625 (Jan 28, 2014)

poolman966554 said:


> just did a quick browse on ebay and found this. if you wanted to run them at max amperage, i think this should work for you.
> http://www.ebay.com/itm/100-Watt-Wa...ing_Parts_and_Accessories&hash=item3f2f2345c3
> 12v out @ 8.33A = 8x leds in parallel @ 1.04A each
> 
> ...



I'm confused. How does either of those differ from a regular pc power supply? Neither of them seem to be constant current or current limiting... 

Further confusion.. if you have a 12 volt supply at 3 amps and you run 3 leds (9 to 12 vdc) in parallel and one of them burns out, wouldn't the others suck up the extra amperage and burn out also? I realize this wouldn't be the case with a series resistor, but at that point, we're back to the PC Power supply arraignment again..

What am I missing here?


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## 18650 (Jan 28, 2014)

Murphy625 said:


> So maybe I should have just asked this question from the start instead of trying to design my own power system without any LED experience. I bought 10 high powered LED's off ebay.. They are SMD chips that run 1050ma at 9 to 12 vdc each.. They are considered to be 10 watts. What is the cheapest way to power all 10 of these? It would seem to me that hooking them up to a 12vdc source (atx pc computer power supply?) and using series resistors in front of each led chip would be the cheapest. But people seem to frown on that for a variety of reasons. Been looking around on ebay and have found constant current modules for about $5 each but I'd have to purchase one for each led chip.. that adds a lot of money to the project so I'm wondering if I'm not considering all my options. Any help on this???


 I'm no expert myself but I think buying a constant current driver that outputs at least 100 watts. Something like a Meanwell HLG-120H-C1050 but these are not cheap at over $100.


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## poolman966554 (Jan 28, 2014)

poolman966554 said:


> Edit: I also found this which is cheaper: http://www.ebay.com/itm/100W-Watt-H...ing_Parts_and_Accessories&hash=item2a2f00755d
> 
> But that will require you run a total of 9 leds in 3s3p to run them at 36v @ 1A
> 
> Care to post the datasheet for these leds? maybe a better guess could be made.



i made a mistake on this link, copied the wrong tab.. 
meant this one: http://www.ebay.com/itm/100W-Consta...198?pt=LH_DefaultDomain_0&hash=item417664a776

Also im with 18650, as i am also still learning. Agreed on meanwell, but $$


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## Murphy625 (Jan 28, 2014)

18650 said:


> I'm no expert myself but I think buying a constant current driver that outputs at least 100 watts. Something like a Meanwell HLG-120H-C1050 but these are not cheap at over $100.



What am I missing here? That's a 12vdc supply that puts out 1050ma.. Your suggesting I purchase one of those for each of the LED's I'm installing? How would that one supply power 4 or 6 or 8 leds that are 9-12 volts @1050ma each?


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## DIWdiver (Jan 28, 2014)

LED strips have internal resistors, and are designed to be driven with a voltage source.

Bare LEDs are NOT suitable for driving with a voltage source, which is why we build LED drivers. But you already knew that.

What you have may be three LEDs in series in a single package, or it may have 12 in a 3S4P configuration. It may or may not have resistor(s) in it as well. That will make a huge difference in how you want to drive it. Most likely it does not have resistors in it, but if it does then it greatly simplifies driving it.

I agree the e-bay supplies posted look like they are probably voltage regulators, meant for driving LED strips, not current drivers meant for driving resistorless LED arrays.

A module like this can work with a regular power supply to add a current limit to it: http://usd.dx.com/product/power-led...er-supply-module-cc-cv-901156788#.UuhLe40o7AU

Of course, it's only 3A output, so you'd need 3 of them (put 3 LEDs on each of 2 of them, then 2 LEDs on the other), but they are cheap.

Here's one that could do all 8 LEDs in a 2S4P configuration: http://dx.com/p/100w-car-notebook-boost-power-supply-module-led-driver-157473#.UuhNYY0o7AU. Or here's a cheaper one without the housing: http://dx.com/p/dc11-35v-to-11-35v-...rter-step-up-power-module-247963#.UuhQlo0o7AU


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## poolman966554 (Jan 28, 2014)

Murphy625 said:


> What am I missing here? That's a 12vdc supply that puts out 1050ma.. Your suggesting I purchase one of those for each of the LED's I'm installing? How would that one supply power 4 or 6 or 8 leds that are 9-12 volts @1050ma each?



look at this
http://www.meanwell.com/search/HLG-120H-C/HLG-120H-C-spec.pdf

If you look at 'constant current region' it gives a voltage spread. That voltage is 74V-148V. so that means you can connect all leds in series (which will be 96V, and within voltage range of unit))

also notice 'CURRENT ADJ. RANGE'. the current available is adjustable by a potentiometer inside the casing. adjustment from 525ma - 1050ma


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## Murphy625 (Jan 28, 2014)

DIWdiver and poolman....

Now I get it!! It is exactly what I thought.. I did not notice the meanwell spec sheet but it appears as though it does have enough voltage to push through several of the LEDs.. 

DIWdiver, the Leds I bought do not seem to have any internal resistors.. its just a 1 inch square surface mount chip with, I think, 9 leds inside. 

So, at this point, I'm leaning towards using the ATX power supply and then purchasing some constant current modules to put in front of each LED... That drives the cost up to around $5 per 10w led.. but I'm ok with that... 

Thanks everyone! Big help!!


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## 18650 (Jan 28, 2014)

Murphy625 said:


> DIWdiver and poolman.... Now I get it!! It is exactly what I thought.. I did not notice the meanwell spec sheet but it appears as though it does have enough voltage to push through several of the LEDs.. DIWdiver, the Leds I bought do not seem to have any internal resistors.. its just a 1 inch square surface mount chip with, I think, 9 leds inside. So, at this point, I'm leaning towards using the ATX power supply and then purchasing some constant current modules to put in front of each LED... That drives the cost up to around $5 per 10w led.. but I'm ok with that... Thanks everyone! Big help!!


 The driver I listed above is an AC-DC driver. If you're hooking it up to ATX power supply I think you would need to buy a DC-DC driver. These are a little cheaper.


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## Murphy625 (Jan 29, 2014)

18650 said:


> The driver I listed above is an AC-DC driver. If you're hooking it up to ATX power supply I think you would need to buy a DC-DC driver. These are a little cheaper.



Because of you guys, I found the almost perfect driver.. Its a Mean Well LPC-60-1050.. output is 9 to 48 vdc and should be enough to power 4 of my 9-12v leds @10watt each . Cost is about $24 so that make it an all-in-one solution in an IP68 house and only adds $6 to each diode.. a bit pricey, but can't beat the perfect configuration.

When I started this thread, I never even heard of "Mean Well"... 

Thanks!


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## awardblvr (Sep 22, 2015)

Murphy625 said:


> Because of you guys, I found the almost perfect driver.. Its a Mean Well LPC-60-1050.. output is 9 to 48 vdc and should be enough to power 4 of my 9-12v leds @10watt each . Cost is about $24 so that make it an all-in-one solution in an IP68 house and only adds $6 to each diode.. a bit pricey, but can't beat the perfect configuration.
> 
> When I started this thread, I never even heard of "Mean Well"...
> 
> Thanks!



OK... SO I have a couple of these... Now I would like to add dimming to a few in-series 10W LED's. The recommended method is to use PWM (Pulse-Width-Modulation... varying duty cycle of a 100Hz or more... turning on and off power to the LED very fast.)

Can a constant-current power-supply like this handle its output being PWM'd to add dimming capability? Or does it take a special power supply / driver designed to do just that?


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## DIWdiver (Sep 22, 2015)

Some can, some can't. You definitely shouldn't do it on the input side of one that wasn't designed for it, but some can handle a PWM dimmer between the driver and the LED.

Some of the Meanwell drivers have dimming inputs (either analog or PWM), but this is not one, and the manufacturer does not discuss dimming this one.

Unfortunately, unless someone knows the inner workings of this particular driver, I don't think you're going to find anyone to recommend dimming it.


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## SemiMan (Sep 24, 2015)

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