Super simple high power LED driver

This Instructable will show you how to built a Constant Current for high power LEDs, using only two components.

High power LEDs are getting cheaper and cheaper, however the constant current drivers, to drive them are pretty expensive.

Here, I'll show you how to built a simple and cheap, yet very effective constant current source.

The image shows the constant current driver hooked up to a 1W white Luxeon LED.

EDIT: This LED driver supports PWM, which means that you can control the brightness of the LED(s). Those fancy and expensive drivers doesn't support that. I'll post some schematics and applications as soon as i have time.

Step 1 Get the Parts.

Here is a list of the the things you'll need.

a LM317 Regulator.
a Resistor (see next step).
a Heatsink for the LM317 (you don't need one as big as mine, I just took one i had laying around).
some Luxeon, or other brands of high power LEDs (see next step too).
some Wire to hook it up.
it will be a good idea to use a heatsink for the LED as well.

Comments

[nigel cox]

What input voltage are you using in this circuit please, thank you Doc Cox

[chse720]

i am wanting to power an LED that requires 16.2V and between 1.5-2.5A. I would like to use a current of 2A for this project, how would i go about doing this and power source would you suggest? i would like to use a dewalt rechargeable 18V battery

[zami]

Thnx for the gr8 article.It really helps.I have a question.
I m making a 90W Led panel,Using 1W led(rating 350mA,3.2V)
In which design shud i make it??

And for Led lights panel,Constant current source is better or Constant Voltage source??????
n do the series or parallel combinations of LEDs affect the efficency or temperature of the panel....


Please Email me the design at
[e-mail]

[ironsmiter]

So, when it comes to circuit design, I can be a bit addlebrained.

What's the advantage(besides power savings) of the modded PWM version ov, say, using a variable resistor in THIS circuit.

To control brightness.

Or am i confusing voltage and amperage yet again?
(sorry, bast my normal bedtime)

[markee2]

Nice instructables. No doubt this is one of the simplest LED driver. Its only limitation is current is limited only up to 1.5A. 
I found a  very cheap LED driver that claims can drive up to 10A current
I dont know know and never tried building it building it, here is the circuit
copied from a site
http://www.simple-electronics.com/2011/09/cheap-power-led-driver-circuit.html

here is the sites circuit

[PabloMDP]

Hi, i have 4 leds 10w (9 - 11v 1amp) and i have a 12v 10amp power supply. Can i make a driver only with one LM1084IT-ADJ? I want to dimmer the leds with one control. Thanks!!!

[Avaruushirvi]

From datasheet ==> "The LM1084 is a series of low dropout voltage positive regulators with a maximum dropout of 1.5V at 5A of load current. It has the same pin-out as National Semiconductor's industry standard LM317."

So you cannot use full bright!

[PabloMDP]

Sorry, i have another question. What happend if i put 4 leds in parallel, 1 amp each led, all with only 1 regulator LM1084IT-ADJ, (0.3 ohm resistor) and 1 led is damaged. In this case, the other leds work at 1.33 amps? Thanks, and sorry for my english.

[Avaruushirvi]

IF that one led shorts, then 4 apms go through it... And If it open then it's go just as you suspected!

[burton2663]

im looking for a 1 watt luxeon led driver to maximize brightness when connected to the outputs of the vu meter lm3915, an actual schem would be nice tnx

[eugenehaller]

 AI, I am amazed that you are still diligently answering comments two years after you you made your instructable.

I am trying to build this, but I am using two 10w LEDs with a Vf of 3.6 and a current consumption of 2800 mA. For the life of me I can't figure out what regulator to use. Any ideas? 

[yugang]

Hi Eugenehaller,

could you help me in designing a circuit for lighting 10 w power LED or 1*10 watt leds..

Thanks,

Yugang

[valveman]

Use an LM338 it is rated to 5A.

[seethasub]

you have to add a PNP power transistor with IC to incease its current rating.

(Transistor 2N6111 On Heat Sink with LM317 ) 

 

 

 

 

 

 

 

 

 

 

 

[Artificial Intelligence]

Hi, sorry for not replying. I must have missed your comment. I have not tried using 10W LEDs with the LM350, but I don't think it's a very good idea, because when I use the LM317 (1500mA max) to drive a LED that just uses 700mA, it gets very hot and needs a pretty big heatsink. This happens because both the LM350 and LM317 are pretty inefficient, so they "burn off" the power as heat. For very high power LEDs, you might be better off with a more efficient regulator. Try the LM1084IT-ADJ. It costs more than the LM350, but it's more efficient and can handle up to 5 Amps. It has the same reference voltage and pinout as the LM350/317, so you can use my instructable with it.

[doransignal]

try using a LM350 it is rated at 3 amps or 3000 ma

Lee

[aekara]

i need help of powering a 30w high power led



 THE LEDhttp://cgi.ebay.com/30W-White-High-Power-2100LM-LED-Light-Lamp-Bulb-A_W0QQitemZ220708010099QQcategoryZ163866QQcmdZViewItemQQ_trksidZp4340.m263QQ_trkparmsZalgo%3DSIC%26its%3DI%252BC%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D10%26pmod%3D220693236934%26ps%3D63%26clkid%3D5621333683761900258

CAN I USE THE LM317 OR I NEED A DIFIRENT VOLTAGE REGULATOR

THE INPUT POWER WILL BE 16V

[yugang]

Hi,

could you please help me in designing to light 10w power led or 1w * 10 led?

I appreciate your help!

Yugang

[macnomad84]

DATA SHEET
http://www.national.com/ds/LM/LM117.pdf

"The LM117 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 1.5A over a
1.2V to 37V output range."

P = V * I = 16 Volts * 1.5 Amp = 40 W

I think you can. Go for it. Someone correct me if I'm wrong. Gonna keep reading this DS...

[ngwanhoe]

I anyone could show me a simple circuit for :-

Input voltage : DC 4.8V - 5.6V
Led : 3 X 3w Leds, working voltage 4v - 5v each led, so had to wire in parellel.
Prefered current : 0.8A - 0.9A

Now I am just using resistor to do the job.

Please email to [e-mail]

Thanks a million.

[Jayvis Vineet Gonsalves]

You can wire the LEDs in Series and for the resistor, you can use a 1.56 ohm resistor if you desire 0.8A of current. Use the schematic given in the instructable.

[ngwanhoe]

Thanks Vinet,

If wire the Leds in series then I would have to put in 8v - 15v power supply. Don't have space for so many batteries.

[pandyaketan]

My projects might provide simple answers to your complex issues...

reg
ketan
--------------------------------------------------------
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May the rulers go by the path of justice.
May the best of men and their source always prove to be a blessing.
May all the world rejoice in happiness.
May rain come in time and plentifulness be on Earth.
May this world be free from suffering and the noble ones be free from fears"
---- Vedic blessing

[broxlin]

Hi!
I have 50 blue and 50 white leds, here are the spec:
" http://i1104.photobucket.com/albums/h329/broxlin/Proiect%20Diamant/Blue.jpg " and " http://i1104.photobucket.com/albums/h329/broxlin/Proiect%20Diamant/White.jpg ".
This will be the light for my reef tank.
I want to make 2 or max 4 lamps, if it's possible, so one circuit for 25 / 50 leds.
If I put less leds, the number of sources will be higher and the cost the same.
How can i make it better?
Thanks!

[Jkirk3279]

Hi.

I've been studying this subject.

This regulator seems just what I'm looking for. Not tuned in yet on the "constant current" concept though.

I want to drive twenty 1 watt LED's in series. Each uses 2.79 volts and 350 mA.

So if I drove them in parallel I'd need 2.79v but a staggering 7 amps !

I asked an electronics teacher and he said "run them in series".

So then you need 28 volts but only 350 mA for 20 watts, plus a balancing resistor.

Very little power wasted.

As I understand it each LED sees 350mA, but the voltage pressure drops progressively until finally it hits the resistor.

[mjhilger]

The voltage drop across any LED is dependent on the junction temprature. The temp will rise as they are driven in higher power. And, the voltage change between dim and fully bright is small (compared to the drive voltage). However the current to light output is relatively consistent. One should drive LED's via current to protect longevity and operation. Because each LED of the same part number, from the same manufacturer batch will vary its exact voltage per current, you cannot run LED's in parallel; there is no way to regulate the current to each in this manner. So you must drive them in series to maintain control to drive near peak output.
The constant current concept is a consistent way to safely drive power through the LED's one or many. You are correct the voltage goes up on your supply demands, but the constant current (or current regulator) provides the proper power control.
Hope that helps to explain constant current concept

[TheNuclearWatermelon]

Ugh! The LM317 is the most common current regulator circuit ever! I hate it's 3v dropout! Why can't anyone show us a simple boost circuit like the LM3410?

[ovven]

Great guide, really useful. I am trying to rig up a system of 11 high power LEDs, with a forward current of 350 mA and a forward Voltage averaging 3.5 V.
would it be best to run these all with different drivers or all in series or a mixture and also what would be the best regulator for the system. I'm nearly at the point of comprehending all of this but thats not the same as understandingit to a competant enough level to make it, just yet.

Cheers

[morphious69]

hi. I am wondering if you could use a couple of these for higher power like what is consumed by the 10 watt or higher LEDs? can they be adjusted to put out the higher voltages needed like 12 or 24 volts and just be expected to supply the amount of amperage they can handle but multiply this by having several of them in parallel so as to add more amps?

[Electroinnovation]

Could this handle 2 1W white leds? and if so would i put them in a parallel or a series circuit?

[LEDismylife]

To anyone who knows, how can I extend my LED output from 700mA to 1000mA? should i change just the regulator?

[oli1122]

Could i do this for a 10W Led of 1000ma???

[SRWitt]

Lets see if you're still answering questions. So I'm building an array of 3w Leds in red, yellow, and blue.

I'm planning on using the LM1084it-adj vs the LM317.

So far I've figured based on datasheets @ 700ma, I should have about 2v total drop with the 1084 (1.25adj+ ~.8@700mA). Is this correct?

My source is going to be a computer PSU converted to a benchtop PSU, using the 12V out. Based on my LED's datasheets, I should be at about 2.2V per Red or Yellow @700ma, based on this, the 1084 will be dissipating 1.2V@700mA with 4 red or yellow LEDs wired in series (total of .84W). For the blue I've figured ~3.6V for 700mA, with 2 in series the 1084 would have to drop ~2.8V@700ma (1.96W).

Forgive me, I am a relative newb to electronics, does my math seem correct? Am I misinterpreting the datasheets when it comes to how much voltage the 1084 drops under varying loads?

[peterbeihoffer]

Hi I need some help. I am trying to design a high powered LED light. I want to put together 10X 1W high power LEDs. I was thinking of using 10 topledlight # BY1W-WH they have a DC Forward Voltage (VF): 3.0V ~ 3.8V, and a DC Forward Current (IF): 350mA ~ 400mA. I was wondering what the simplest and easiest way to wire this. Could I just use 1 10w driver? any help or tips would be much appreciated. Thanks

[WingmanSVT]

Im a bit confused about using this circuit with LEDs wired in series. I have 2, 3 watt LEDs wired in series, each has a forward voltage of 3.8 max and 700 ma. What resistor would i need to have between pin 2 and 3 on the LM317?

[jon1888]

does anyone know what it would take to power a 50w 24v-26v

[TheWhatnought]

Hey, is this usable for some of the really high current emitters? I'm trying to find a cheap, only on/off CC driver for a 3.86V 2800mA LED. I'm also trying to drive it off of a 12VDC supply. Any suggestions?

[pedroalaray]

Hi could you take a look at this circuit I've planned out? I think it would work but not sure if I should order the bits thank you Peter

http://farm4.static.flickr.com/3339/4629373728_186cbc5e3f_o.jpg

[Joshus]

Hi, I have been messing with DC power supplies for some time. Can I just use a bridge rectifier with my 110V ac at home followed by your design? How could I acomplish this? Thank you so much for all of the information! Reading your instructable and answers to questions has helped me ALOT!

[Rusdy]

 After many googling and forums, I've found this inexpensive current source, with wide AC inputs (110-240VAC). Link is here

(If the link doesn't work, just type "current source" on the linked website, www.dealextreme.com, and browse for the correct input voltage)

I just received it today, so haven't managed to tried it myself, but googling the driver's datasheet (AP3706), definitely a true current source! The product is rated to 350mA, but if you're good with electronics, you can change the Rsense (which I only can guess at the moment which one on board) to suit