DIY LED spot light build

[iamweasel]

Riiight, I've been planning this build for ages now and I finally got all the bits together that I need. (I won't mention that someone who will remain nameless, threw away the first batch of LEDs I ordered)

We've all seen those ridiculously over-priced LED light bars:
http://www.rigidindustries.com/product-p/eseries30.htm

Well, here's a guide on how to build your own LED spots. I'm building two spots - not a light bar, but the parts I'm using would perfectly suit a rectangular lightbar.

This setup will (in theory) generate the same amount of lumens as the 30" $1000 lightbar above (12000lm). I know I know, lumen values aren't a direct measure "brightness". Luiminous intensity - "brightness" - is a factor of how those lumens are focused
....Aaaaanyway, the optics I've chosen give similar beam angles to the Rigid Industries (R.I. for future reference) light bar , so the 'brightness' should be comparable.

Parts:

• 12 x CREE XML T6 LEDs
• 12 x Ledil optics (each spot: 2x 8° spot, 2x 14°x46° oval, 2x 6°x24° oval)
• 2 x PC cpu heat sinks (Aluminium is really expensive here, so this was the only cost effective option, but I found a few US heatsink companies on Google)
• 1 x constant current power supply (I'll describe this in detail later)
• switch
• relay
• thermal paste
• 3mmX9mm self-tapping screws
• wiring

Plus whatever materials you choose to make the housing out of. I'm going to replicate the Renegade lightbar spots. Here in SA Renegades only have 2 spots on the lightbar, so I'm adding the two center ones.
I'm gonna use fibre glass to recreate the OEM shape.
If you wanted a R.I. style lightbar, you can find lots of aluminium extrusions at your local hardware store that would work.

The cost? about $100.

The LEDs:

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The Heatsinks:

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The optics laid out on the heatsink:

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As you can see above, the optics definitely lend themselves to the RI style lightbar. I'm pretty sure they use the same optics.

The optics come in these holders:

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Some of my calculations to determine the required beam angles:

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The sketch on the left is a top-down view, showing the beam width at certain distances: 50m, 100m and 200m. I aimed for a 20m-wide beam at each of those distances. I'll have to wait for a trial run to see if my speculations on these beams angles are correct.

The optics are cheap though - about $1 a piece - so changing the beam angles is no biggie - cheap and easy.

Circuit diagram of the power supply:

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I'll be tweaking this to run 3 LEDs in series, not 2 as show here. LEDs need a constant current, so this bit is crucial. I looked all over the net for a suitable DC-DC transformer, but ended up with the plan to make one from a circuit design I found online.

Step 1: Prepare the heatsinks for the LEDS
The heatsinks I ordered had a ridge on them which I had to grind down.
The smoother/flatter the better the heat transfer will be. Each of these LEDs is 10W, so good heat dissipation is necessary.
Decide on a layout and drill holes for the LEDS:

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Step 2: prepare the optics
I wasn't able to get hold of Ledil optics specifically for the Cree XML LEDs, so I ordered ones for a similar Cree LED. A bit of Dremel-work was necessary...
Typically the LEDs would be screwed directly to the heatsink, but this can cause shorting issues between the LED, screws and heatsink.
What I decided to do, is screw through the optic holders and LED board, into the heatsink. like this:

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That's as far as I got this weekend...
Next steps:

• Solder the LEDs into circuits of 3 LEDs in series.
• Test using a 220v power supply connected to the mains (I bought one specifically for this. Puts out 36v @ 3A.)
• TEST I'll post some videos/pictures
• Build and test the 12v power regulator
• Test again using the Jeep's power
• Build the enclosures
• Assemble!

Shout if you have any questions

 

[iamweasel]

Part 2

I had to make a second modification to the optics holders to make space for the wires when when the LEDS are wired up. I made a hole in opposite ends of the optics (the grey one between the heatsinks)

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You can also see some pieces of wire I cut for connecting up the LEDs

Wiring in place:

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All soldered up:

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I connected the LEDs in 6 sets of 2 in series. But as I write this, I just remembered it was supposed to be 4 sets of 3 in series :favorites68::favorites68::favorites68: Mother:favorites68: :favorites68:ing son of a :favorites68:

*sigh* wooooosa

So each spot will have two arrays of three LEDs, not three arrays of two LEDs as show in these photos.
The reason for this is each LED requires 3.6v and three in series means a total forward voltage of 10.8v, so the power supply has a smaller voltage drop to regulate (from the Jeep's 13ish volts). The power supply is crucial to regulate voltage/current fluctuations from the alternator.

Well I'll carry on describing what I did. Next weekend (or during the week if I find time) I'll rewire. This is not the end of the world, as you'll find out shortly...

Here you can see two LEDs properly mounted and another two with a blob of white thermal paste on the underside. This is necessary for proper heat conduction to the heatsink

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One done:

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Two done:

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Now the wiring mistake I mentioned above is a bit of a moot point, because after finshing the above assembly, I decided to test the LEDs, only to discover that three are dead. Joy. So unfortunately I'm gonna have to order some more which, thanks to the fantastic SA postal service, will take about 4 weeks.

In the mean time, I'll transfer all the good LEDs to one spot and rewire with 3 in series.

While I'm waiting for the new LEDs to arrive, I'll start on fabricating the housings.

Til next time...

 

[BIRDMAN]

can't wait to see how this turns out. you can get LED light bars for a fraction of the costs you're looking at but this will still be cooler and cheaper yet!

 

[iamweasel]

Thanks Birdman.
I mad a torch with one of these LEDs and it's incredibly bright! I can't wait to see what 12 look like :icon_twisted:

I'm also gonna prototype a projector LED light for a possible headlight repalcement

 

[BIRDMAN]

here's some pics i took last week of my setup just to give you motivation

All off

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Low Beams:

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20" LED bar

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[iamweasel]

Cool, thanks for the pics! Hopefully i'll be able to post something similar soon...

 

[BIRDMAN]

i'm looking forward to it.

 

[theroofable]

sweet.

 

[iamweasel]

I found today that the LEDs actually all work - it was my dodgy soldering that stopped some from lighting up.

I rewired them to three-in-series (4 strings of three LEDs) and I'm still struggling with shorts when the LEDs are screwed down. The star shaped circuit board they are on is aluminium, so if the screws aren't perfectly straight they make a short between the aluminium circuit board and the aluminium heatsink. Frustrating.
Should have that sorted tomorrow though. Then for a (hopefully successful) power up...

Here I had connected the 4 series circuits connected, so all 12 LEDs in series. This was just for testing with my 220v power supply

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You can also see the different optics. Shinier ones are the spots, the more opaque ones are the oval beam

 

[BIRDMAN]

looks good so far...

 

[Ry' N Jen]

Can't wait to see the finished product!

 

[iamweasel]

LED there be light!

Excuse the corny title, but I'm super chuffed to get them all lit up.
Took a while, but I solved the shorts. My modifications to the LED screw holes caused some shorts...

This is with all LEDs connected in series for testing with the 220v power supply:

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et voila!

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Night time photos to follow...

 

[Ry' N Jen]

So far so good Adam!

 

[Sandman]

I'm anxiously waiting on the end result!
Where did you order the XML T6 LEDs from?
I'm building a similar lightbar but with the Cree 2W 180lumen LEDs and my biggest problem is finding the correct reflectors.

 

[iamweasel]

hi Sandman, I've been doing some work on this project in the last few months, but not much. It's been slow going. Having a baby will do that :smokin:

I also ended up with 4 dead LEDs for some unknown reason, so I'm waiting on yet ANOTHER order from DX.

I ordered the XMLs from Deal Extreme:
Tools: Diy Tools, Parts Accessories, Diy Tool, Diy Manual - Free Shipping - DealExtreme

Only problem with delivery to SA is that EEEEEverything from them seems to get caught at customs.

Cutter Electronics are also a good source with good service, but they only offer free shipping on large orders:
Cutter Electronics

Here are some pics of the power supply I made recently. It will (should) provide constant current/voltage to the LEDs despite fluctuations caused by the alternator. The circuit diagram is at the beginning of this thread.

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Each of the white wires is the positive for a pair of LEDs. The negative connections for each pair will all connect to " LED -'ve "

 

[Sandman]

What is the max power or Amp output on the power supply and how is the PC heatsink working for the cooling?

I'm fitting 30 of the 180lumen cree's on a lightbar (when the order arrives) but I'm sceptical if the power supply unit can handle around 60watts

DX's orders take for ever, my last order took 7weeks.
I have found that by adding the Drop Shipment and Gift Service to the cart, the shipment dodges customs' VAT charge.
Drop Shipment and Gift Service (Removes DX logo from package) - Free Shipping - DealExtreme

 

[iamweasel]

Are you using the same power supply schematic I'm using (http://www.simple-electronics.com/2011/09/high-current-led-driver-using-fet.html)? It looks quite flexible, provided you get the resistor values right.

I really struggled to find an appropriate constant current power supply for 12-14v with the desired voltage output AND the right current.

Which Cree LEDs are you using? 180lm are probably 3W right? so you're probably working off around 700ma, which was easier to find than 3000ma for the XMLs.

You can have a look here for power supplies:
RS | world-leading distributor of electronic, industrial and maintenance, repair and operation products.
Mantech Electronics | Leader in Electronic and Industrial Components, Tools, Test and Measurement
RABTRON | Supplier and Importer of Electronic Components
also try searching for DC-DC converters