Another CXA3050 thread

[luvdemshrooms]

Between the spare reflectors/hood I have on hand and that "other" CXA3050 thread... I was inspired. This unit is for flowering so 2700K LED's were used. Alas, the CRI is 80 as none better was to be found.

I bought the 4.9" X 26" heat sink from heatsinkusa and proceeded to mill. This is the result:

I drilled and tapped some 6-32 holes and added some .089 holes to run my wires through. A thin film of heat sink grease and some 6-32 truss head stainless screws... Edit: Do NOT mount your LED's this way. They fail prematurely. I was cheap and didn't buy the mounts. Do not make the same mistake.

No mods were made to the hood so it can be used for it's original purpose should I desire.

Using a hand built driver I'm running 1.6A through the LED's. The temperature of the LED runs between 37 - 39c with a 400cfm 250cfm fan blowing. Using my crappy old light meter (lux only) showed that:

1. 600w HPS was hitting 1000 lux at 2 feet.

2. My new LED unit hits 1500.

The meter may not give accurate readings as I haven't had it checked but it was used for comparison only.

I was concerned that the tube would interfere with the light output, but when measured at the same (yet unrecorded) distance on the bench there was a roughly 10% improvement when the unit is inside the tube. I chalk that up to the reflector.

Current draw? 220 watts.

 

[3dDream]

Very cool! Nice job!

 

[sammyz2646]

Excellent job man! You made some very smart choices and several things you did are very crafty! I'm loving the heat sink, loving the fact you've made it a multi-cob unit, love the smart wiring holes and screws to tie down the cob (w/ adhesive). Your plants are going to love this.

But the BEST part of this light, IMO is the convection cooling that you engineered here, using the cool tube.

You my friend, have inspired me, and I want to thank you for laying many mental seeds, if you will. . . . This gives me lots and lots of thoughts. . .


GREAT JOB !!

 

[Firebrand]

Nice job, your engineering and fabrication look professional. Subbed.

 

[sammyz2646]

You might put a small carbon filter, (even a old used one), on the intake end, as to prevent debris of any kind coming through the COB area. Have you measured any temperatures?? I'll bet it's running NICE AND COOL with that kind of airflow behind it.

Another thought, is to use your fan plug wisely. luvdemshrooms probably did, but just be smart if you build this, or simply wire things up as to "protect" your COBS from something stupid. Maybe a constant wired together with the power.
Stupid meaning----- For example, using 2 separate timers and say one got a bit off, and somehow the fan did NOT come on in time, (or at all), to cool as per design.

I'll bet that heat sink could dissipate the heat nicely, for SOME time, without any assistance. How long?, I'm curious. Especially inside that tube

Again, this design by luvdemshrooms is very, very, smart

 

[luvdemshrooms]

A carbon filter is in place. What other peoples noses can't detect, is beneficial to me.

As for the temperatures, from the original post... "The temperature of the LED runs between 37 - 39c with a 400cfm fan blowing."

The fan runs off the same timer as the LED's and while it's not shown in the picture (because I was too lazy to take more), there is a 80° thermostat located between the leftmost LED in the pictures and the socket for the HPS bulb. That is to say, at the end of the heat sink furthest from the fan. My thought on the location being that the air flow warms a bit more as it passes each LED, theoretically that would make the spot I located the thermostat the hottest location on the heat sink. Unless the fan fails I can't imagine it ever getting hot enough to trip the thermostat. Cree say's the temperature for the CXA3050's should be kept below 85°.

As a side note, Cree added a pad where it is suggested that temperature measurements be taken. In the close-up shot of the single CXA3050, just below the upper left screw, you can see a pad. This is the spot.

I took a reading there until the temperature stabilized. Then I attached the thermocouple to the heat sink right next to the LED. There was less than a half a degree difference between the two spots.

I was unwilling to take chances with $36 LED's so no passive cooling was attempted.

Thanks for the kind words. You probably realize this but it was your thread that inspired me to try the CXA3050. I'd been playing with XML's for awhile with good, but not great, results. The CXA3050 blows them away. So thanks for your inspiration.

Two additional thoughts.

1. Cree now makes a CXA3590 which has almost double the output of the CXA3050. 11000ish lumens at 124lm per watt.

and

2. Newark Electronics has the CXA3050 on sale at $30 until the end of the month.

 

[sammyz2646]

Yeah, I was drooling over the CXA3590 too, but it seems that you need to order a min. of 100 to even get your foot in the door. Kind of a bummer, but time will remedy that, if it already hasn't. Plus new stuff will be coming out all the time .


I am really enjoying toying with these Cree's, and even the colored Chinese COB's, and I want to do a "hybrid" Chinese/Cree build in a hood like you have built.

I feel like building off each others ideas will not only benefit us, but everyone else who may be interested and not yet been introduced to these LED's and their potential.
Got to keep the word out there and promote that EYE PROTECTION, as we only have one set of eyes.


Those temps are really low, and I am no engineer, BUT, with that kind of airflow behind your cooling, making the design effectively an "active" cooling system, theory says that you would be able to under- engineer the size of the heat sink and go with something smaller than you would normally think, due to the additional cooling provided by so much airflow, providing you with EVEN better engineering opportunities using a spare hood as used here. Are you needing to save that socket ? Is that why you chose to leave it in there?

Like I said, this little design is spawning many ideas . . . . . . .

 

[morgandecaptain]

I have some CXA3070 Z4 3000k's that I'm running at 1.4a and over 39% efficient at 52 watts,they are amazing. I saw someone over at RIU that has some of the CXA3590's and they are a bit bigger than the CXA3070's.

 

[luvdemshrooms]

Those temps are really low, and I am no engineer, BUT, with that kind of airflow behind your cooling, making the design effectively an "active" cooling system, theory says that you would be able to under- engineer the size of the heat sink and go with something smaller than you would normally think, due to the additional cooling provided by so much airflow, providing you with EVEN better engineering opportunities using a spare hood as used here. Are you needing to save that socket ? Is that why you chose to leave it in there?

Like I said, this little design is spawning many ideas . . . . . . .

With the heat sink that wide the edges touch the inside of the flanges which keeps the LED's "suspended" above the tube bottom, even without bolting the heat sink in.

The socket was left in for one reason only. The vent flange at the socket end is riveted in. While the socket is screwed to the flange, two of the nuts are inaccessible without removing the flange. I didn't want to drill the rivets out to do so. As I have a milling machine cutting the heat sink seemed the best way to go.

I'm a careful guy and I wanted to be able to return the hood to it's virgin state if I so desired (or if it didn't work out as I thought it would).

 

[luvdemshrooms]

I have some CXA3070 Z4 3000k's that I'm running at 1.4a and over 39% efficient at 52 watts,they are amazing. I saw someone over at RIU that has some of the CXA3590's and they are a bit bigger than the CXA3070's.

I looked at those but my mind was set on 2700K. Lead time for the 2700K 3070 is 11 weeks with a 55 piece minimum. I'm unable to wait. It's a personal failing.

 

[hempfield]

I looked at those but my mind was set on 2700K. Lead time for the 2700K 3070 is 11 weeks with a 55 piece minimum. I'm unable to wait. It's a personal failing.

Mabe because 2700K is very hard to build for CREE, and they are in fact 'rejection ' COBs and they need to manufacture a lot of 3000K COBs to get enough '2700K' to fulfill an order.

Don't forget that even assisted by computers and robotic systems, each individual COD is build , tested, measured and selected by hand and this is a time consuming process.

 

[3dDream]

Mouser has the 2700k cxa3590 for $72.72.

I hope that every 10,000 hours I can slap on whatever is the latest cob and get more lumens with the same amount of heat.

 

[luvdemshrooms]

In the case of the 3590 you may not be able to just "slap on" a better LED.

The 3050 is a 37 volt, the 3070 are 38.5 volt, the 3590 are 77 volt. (all forward voltage numbers) You'd likely need new drivers and the footprint is bigger.

Digi-Key offers the same LED for $56. Now, if only they actually had some!

 

[luvdemshrooms]

Well, just for laughs I attempted to order some of the 2700K CXA3590-0000-000R00AD27F from Digi-Key.

Current Lead Time
Quantity Expected Ship Date Estimate
2 5/28/2014

Let's see what happens.

 

[luvdemshrooms]

I am so very weak.

Couldn't get a commitment from one supplier so I ordered 4 of the CXA3590's 2700K from Mouser.

 

[Firebrand]

Couldn't get a commitment from one supplier so I ordered 4 of the CXA3590's 2700K from Mouser.

What kinda price did you get?

And please, tell us how many watts you'll be looking to make and what you'll use for a driver.

 

[luvdemshrooms]

Alas, 72.72 each. That's the price of my impatience.

I build my own drivers and will be running 1.4A through the LED's. I normally try and stick close to Cree's current test specs for longevity. However, seeing how well my system works to keep the temperature down I'm going to disregard their current test of 1.2A and go with 1.4A. That works out to 109+ watts per. As they're rated at a current max of 1.8A, I'm pretty comfortable with the 1.4A.

 

[Firebrand]

Thanks for the reply, I snooped around, saw the 70+$ prices.

1.4 amps @ 78 volts? I'm learning, I hope pass this test.

Also, you build your own drivers? That deserves a thread of its own, I would really like to have a discussion on that.

Do you start with a bridge rectifier or voltage controller or an autotransformer? I know a scant little about this from working around motorcycle electronics as a youth, British bikes in particular, Zener diodes and rectifiers and such, I sure like learning more.

 

[luvdemshrooms]

78 volts is right. That's just an estimate though until I actually have one of those beauties in my hands.

First... a fuse! Then a diode bridge. A Mosfet, diode, inductor, some resistors, couple of capacitors and a SOIC-8 Hi Brightness LED driver.

 

[luvdemshrooms]

Edited OP to reflect correct fan airflow of 250cfm.

Anyone know how to do a "strike through"? Tried brackets with the word strike and with just a "s". No joy either way.