DIY 10-CREE LED Light

[Splutter]

Hi folks! I had some spare time while waiting for my new 2ftx1.5ftx2ft tank to cycle and I decided to try my hands on some techie work.

I planned to run 10 3-watt LEDs in 2 groups of 5.


Some of the things that I ordered:

1. 10 x CREE XR-E 3 Watt LEDs
2. 30watt LED driver that outputs 18V and 2A
3. Acrylic sheets customized to size and pre-drilled with holes

Meanwhile, I went out to Sim Lim to get the following items:

1. Heatsink compound (Epoxy kind)
2. 10 x Heatsink
3. 2 x 80mmx15mm Fan
4. 2 x 80mm fan grill
5. Wires
6. Soldering Iron
7. Solder (Lead-Free)
8. 8 x 4Mx25mm bolts
9. 8 x 4Mx30mm acrylic bolts
10. 2 x Lighted rocker switches
11. 8 x Rubber grommets (washer)

Rest of the items from various shops:

1. 1mm aluminum sheet
2. Pre-cut and drilled acrylic sheets to form body

Now for some pictures!

Got a 1mm thick aluminum sheet to mount the LEDs


Marked the spots to drill holes for wiring. Note that the sheet isn't in great condition since I bought it from a neighbourhood store.


After drilling 4mm holes for wires!


After that, I had to wait for my LEDs and driver to arrive.....

[Navanod]

Nice. How do you plan to seat the light atop your tank bro?
I'm keen to DIY too but I'm still thinking if I should go order all the parts without actually having a plan on how to build and mount the thing

By the way, whats your reason for choosing XR-E instead of newer XP-Gs? And how do you plan to wire that 2A driver? Each group of 5 will get 1A?
Thanks

[cdckjn]

Cool DIY Job. If can, I want to do one as well.

[Splutter]

I'm actually going to house the plate along with all electronics in a acrylic box that I customised.

I chose XR-E because I've viewed many such DIY examples and it seems to be having a high rate of success. The new XP-Gs draw quite a bit more current and I don't really see the need for such brightness. Besides, they are more expensive too. Being my first DIY after such a long time, I'm a little scared to toast some expensive LEDs

Each group of 5 LEDs will get about 1A. So it's basically a parallel-series circuit. I know it's not best practice to do it this way, but the only drivers that come with suitable voltages for a full series layout are pretty expensive!

[Splutter]

Christmas came early! Each CREE LED is individually wrapped in bubble wrap


The LEDs themselves


After mounting them on the aluminum plate via thermal epoxy


The LED driver - unfortunately not very good (I'll explain later)


Heatsinks to be stuck on the back of the aluminum plate

[Splutter]

Testing connection - it works!


The 2 fans I got to cool things down. Both are rated at 12V, 0.09A from Nidec


The customised acrylic pieces - they cost quite a bit to order, nearly $130 =(


Screwing in my fans after drilling the mounting holes myself. I put in rubber grommets to dampen the vibrations as well.


Snapping in the lighted rocker switches. One for the lights and one for the fans.

[Cross]

Nice finishings with the acrylic. Hope to see the finished DIY soon! Don't mind me asking, is the led driver a constant current driver?

[tawauboy]

have you tried to measure the operating temperature of the leds?

[Splutter]

I wanted to source for a constant current driver but I couldn't get one easily. Looks like only Mean Well has it locally and it takes a while to order =( I had to settle for a normal power supply and I ran into some problem. I'll explain later as well.

I have no means of measuring the temperature of the LEDs but the whole setup was just a little warm to my touch even after running for 8hours straight. I think it's pointless to measure the LED temperatures unless you have the specific equipment to measure the node juncture of the pn gates of the LED itself. Based on the data sheet, those tiny points heat up to >100 degrees.

[Splutter]

So anyway, I ditched the idea of using this voltage regulator as the output voltage wasn't very stable. As I was running the circuit without any current limiting resistor, it led to unstable current load as well. The regulator died out after a while. I went back to the drawing table and opted for a dual AC/DC switching supply instead where I hooked up 5 LEDs + a resistor to a single regulator at 24v, 700mA.


Some of my calculations:

Voltage drop across 1 LED at 700mA = 3.5v
Voltage drop across 5 LEDs at 700mA = 5 x 3.5 = 17.5v
Voltage across resistor required = 24v - 17.5v = 6.5v
Resistance of resistor required = 6.5v/700mA = 9.285ohms
Wattage of resistor required = 6.5v x 700mA = 4.55w

Resistor eventually used : 10 ohms, 10 watts as I wanted to be on the safe side for heat dissipation

I also bought 2 new Mean Well switching regulators at SLT again.


Wired up everything according to this circuit diagram:

[Navanod]

I'm actually going to house the plate along with all electronics in a acrylic box that I customised.

I chose XR-E because I've viewed many such DIY examples and it seems to be having a high rate of success. The new XP-Gs draw quite a bit more current and I don't really see the need for such brightness. Besides, they are more expensive too. Being my first DIY after such a long time, I'm a little scared to toast some expensive LEDs

Each group of 5 LEDs will get about 1A. So it's basically a parallel-series circuit. I know it's not best practice to do it this way, but the only drivers that come with suitable voltages for a full series layout are pretty expensive!

I wanted to source for a constant current driver but I couldn't get one easily. Looks like only Mean Well has it locally and it takes a while to order =( I had to settle for a normal power supply and I ran into some problem. I'll explain later as well.

Wow, so the box would sit on the tank like a hood I assume? Where did you get the acrylic cut?
XP-G can be driven at the same amperage and still produce more light than the XR-E hehe, but you're right about the cost.
I saw a meanswell 48V constant 1amp driver that cost about $70 (plus shipping) online. Direct AC to DC too with PWM dimmer. Most likely to be getting that if my project does take off

[tawauboy]

...

I have no means of measuring the temperature of the LEDs but the whole setup was just a little warm to my touch even after running for 8hours straight. I think it's pointless to measure the LED temperatures unless you have the specific equipment to measure the node juncture of the pn gates of the LED itself. Based on the data sheet, those tiny points heat up to >100 degrees.

it's good to hear that the whole setup is just a little warm to touch. just ensure that the 2 fans are running to keep the led temperature low.

you do not need special equipment to measure the junction temperature. it can be calculate from the datasheets provided. these cree leds have a thermal resistance of about 8deg/w from p-n junction to solder point. so if you are running the leds at 3 watts, the temperature difference between the p-n junction and solder point is 24 deg. you can measure the temperature of the solder point.

you'll want to keep the p-n junction temperature below 80deg.

[Splutter]

Acrylic was from Dama. They should be pretty easy to work with.

tawauboy, thanks for that information. I'm still monitoring to see if there's any spike in temp.

[Splutter]

My girlfriend helped me with the acrylic construction and I think she did a very nice job =)


The acrylic bolts I got to screw in the tail plates


The new 10 Ohm, 10 Watt resistors I got to limit current


The new Mean Well voltage regulators - 24v, 700mA


How everything looks after powering up!

[neverwalkalone]

Nice journal, and great job on the DIY Bro Splutter. ;-)

Would you mind sharing the cost of the items you listed?

Agree with you that Current Regulators are a pain to source; and expensive - found some at Sim Lim Tower but there are too ex, mostly IP6x rated (waterproofed) which in my mind is not necessary..

Was contemplating building my own Current regulators using National Semicons (LM3404s) but haven't been able to find them (online are bulk orders)... open to hear what other Forummers have in mind on building such Current Regulators. I feel using using the 'ready made' regulators (buck pucks etc) are too expensive IMO.

[cdckjn]

Good write up on the details! Great and Nice looking Lights!

[tawauboy]

...

Was contemplating building my own Current regulators using National Semicons (LM3404s) but haven't been able to find them (online are bulk orders)... open to hear what other Forummers have in mind on building such Current Regulators. I feel using using the 'ready made' regulators (buck pucks etc) are too expensive IMO.

try looking at digikey and avnet express websites.
they offer small quantity purchases.

[illumnae]

I'm planning on using Buckpacks ordered from www.ledsupply.com

They seem pretty compact and affordable, and are efficient for just stringing sets of 5-6 LEDs, which will help in my eventual "automation" project using an Arduino, where I would like to light different banks of lights at different times.

[Splutter]

More views of the final product =)

[neverwalkalone]

try looking at digikey and avnet express websites.
they offer small quantity purchases.

Thanks Thomas. Forgot to check those sources - just relied on Google and NS' distributors...

Bro Splutter: Nice Full Tank Shot.
If I may comment - the hardscape is alittle too 'short' for the 2ft height IMHO.