Stealthy LED Project - help wanted

[Jopedijoo]

Hey there!

Hey there!

I still don't have the soldering equipment ready, been busy thinking.. I got the whisper fan finally powered, it's quiet and nice, but maybe not that quiet. It got me thinking...

I have another closet that's built into the house. It would need a bit fixing up, some plywood on the walls etc. to make it airtight but it would be situated better sound wise. To use that I would have to give up my plans to have two separate growing chambers, but maybe it's not totally necessary. Might have to cut some corners here..

After new walls etc. the dimensions of the closet would be around 16x28 inches and height around 4-5 feet depending where I want to set the roof. I was thinking of making a slightly smaller closet inside the bigger one so I could have the ventilation proper and have the air coming out from top of the "inside" cab and have the "real closet door" ajar so that the air could move. And maybe have the Mastech and other drivers on top of the "inside cab" to cut the heat. Stealth enough for me I reckon...

I was also thinking that if I only have one cab and I already have two 10x10" heatsinks I could use both of them! Maybe first put one blue in the middle and four reds around on both of them. So I'd have 8:2 R:B. If it seems too much blue I could add maybe two or four more reds. This way I wouldn't have problems driving the blue(s), I could use a PLN-30 or PLN-60 for two blues. And if I only had 5 emitters on each sink I might not even need fans at all!

The guy that I got the hint for this whisper fan was using a 150W HPS with this 80CFM fan in a small cab and doing good. I reckon the 8:2 setup would do good also. If I'd add two to four emitters more, I don't know if there would be enough ventilation then.. I guess I'd have to try with the 8:2 first and see how high the temperature goes..

What do you think?

 

[Weezard]

Chill!

Chill!

"I guess I'd have to try with the 8:2 first and see how high the temperature goes..

What do you think? "

I think, that's good thinking!
150W. on a 10" heatsink will start out OK.
In time, the heat accumulates without moving air.

So, it would depend on the ventilation in your cabinet.
If I were a betting kine guy, I'd bet that you'll need a fan on it.
Most I could get out of my Frankenlight without a fan was 15 minutes 'fore the temps got me worried.
Hot LEDs are inefficient and Vf. will change with heat.
A resistor will increase in value as the heat increases.
This is not the case with semiconductor junctions.
R. will drop and I. will increase.
As I. increases so does the heat.
When it reaches the "tipping point", thermal runaway will put yer lights out.
Best to keep leds as as possible in any case.
Anything over 50 C. will shorten their lives and waste Watts.

Anyway, that's what I think.

Aloha,
Weeze

 

[Jopedijoo]

"I guess I'd have to try with the 8:2 first and see how high the temperature goes..

What do you think? "

I think, that's good thinking!
150W. on a 10" heatsink will start out OK.
In time, the heat accumulates without moving air.

So, it would depend on the ventilation in your cabinet.
If I were a betting kine guy, I'd bet that you'll need a fan on it.

Yep, by reading your DIY things, that's what I figured out: need a fan for 150W on one sink. Then I thought that maybe by spitting the 8 reds and 2 blues on two 10" heat sinks and then maybe no fans...

But you are right I think. There's not much lost if I put a fan on the sink, once again a lot might be if I don't.

Well, if I decide to use both sinks for a 2 x (4+1) I could test the temperature at 4+1 to see if the sink exceeds the 50 C for example.

Or just stick 'em 8+2 on the same grill and simply use a fan.

 

[giblets]

I am a dumbass. It finally occurred to me that these 15W leds are like a "bare emitter"; not 'on a star.' Next time I do this I'm going epoxy each led to its own individual chunk of heat sink stock. Then drill a mounting hole in each. Basically, make a thermally conductive mounting bracket for each emitter; something that functions like a star.

If I drill and tap some extra holes in the main heatink, I can move the leds around however I might want them- even to a different heatsink. If I used something like aluminum bar stock the emitters could be swung right outside the main sink profile for wide coverage...

Any suggestions for material?

 

[Weezard]

Or...

Or...

You could mount a fan with a 50 C. thermal switch in series.
I used them on the cake pan light and it cycles on and off.
The pan has 4 and 1 but the pan is relatively thin and has to deal with the heat of the LM317s as well.
Still, it's about a 50% duty cycle and the fan is very quiet.
I have to look to see if it's spinning.

Then you are covered, either way.
I think the switches were less than a buck ea.

But wait! There's more!
It's also a mini light mover.
Everytime it kicks on, the light rotates a little in the opposite direction.
Gives me a tad more penetration with the deep red as the shadows shift.

Now, how much would you pay!?

Put away your pocket book, it's free!

(Acording to the new money math.
What was 3, is 2.
What was 2, is 1.
And what was 1 is nothing!
So, it's free, only a dollar.)

I do like the idea of splitting the leds between the 2 sinks.
More flexible.

Aloha,
Weeze.

 

[Weezard]

sure.

sure.

I am a dumbass. It finally occurred to me that these 15W leds are like a "bare emitter"; not 'on a star.' Next time I do this I'm going epoxy each led to its own individual chunk of heat sink stock. Then drill a mounting hole in each. Basically, make a thermally conductive mounting bracket for each emitter; something that functions like a star.

If I drill and tap some extra holes in the main heatink, I can move the leds around however I might want them- even to a different heatsink. If I used something like aluminum bar stock the emitters could be swung right outside the main sink profile for wide coverage...

Any suggestions for material?

Gold or Silver is best for heat conduction.
Next comes Copper.
It's mo' betta da Aluminum but a bear to work with.
It eats taps.
However, once you get some holes drilled, self-tapping metal screws work a treat.
Weeze.

 

[Weezard]

Aloha "Dumbass"

Aloha "Dumbass"

I like it!
You just gave us a great idea!

Da "home-made "stars" got me thinkin'.
So I posted the following on da "Calling out to Weezard" thread.
Though I might post it here as well;

"I just had a stoner thought.

Got a pile of peltier devices that I intended to use as active heatsinks.

Until I found out how much current they draw. Ouch!

Got a dozen of them on the shelf.

They work both ways.

Heat one side, and/or cool the other, and it acts like a thermocouple and generates current.



Then your idea of mounting the 15s on homemade "stars" got me thinkin'.

We're eating Watts to remove heat with the fan.



Perhaps we should stop seeing the heat as a waste product and put it to work for us.



Here's what I propose.

Epoxy one, or two 15 Watt Ledengin emitters to the chip side of the peltiers.

Then bolt the fin sides to a large heatsink with a fan.

Use the temperature difference to generate enough current to run the fan!

As the fan cools the big 'sink, it "bootstraps" the fan power a little more as the temp. difference increases.

Does that sound semi-sane.



I'll have to buy some emitters to try it with and see how many units it would take to run a fan.

Ambient can get to 90F. here so a 50 degree difference would have to suffice.

If it works, it's self regulating!

And, dare I say, rather elegant.

That's why I call this MMJ, Cogito."



Aloha.



Weezard

 

[giblets]

Perhaps we should stop seeing the heat as a waste product and put it to work for us.

Good point. Lotsa folks adding huey's this time of year when they could evap some H20 off something already hot, like a light. I'm just not up to suggesting the average reader put a pan of water on his HID, too many ways for that to go wrong. But yeah, reconverting energy that's just in the wrong "form" makes sense, absolutely.

I'll have to buy some emitters to try it with and see how many units it would take to run a fan.

Well, unless you just want an excuse to pick up some more emitters you could just see how 'hot' you need to get the peltier in order to produce the current. Need to get past the "stall" point on the fan motor, though...

Edit: Meant "humidifier," not dehuey. Forsa habbit.

 

[Weezard]

Odd. that pic. will not display.

 

[giblets]

You mean the red x-in-the-box at the end of my posts? That's where I deleted the avatar pic from my sig. If I forget to hide the sig, that's what it does now.

 

[Jopedijoo]

Hi guys!

My vacation is almost over and not much has happened with this project. I'm so slow with my moves that when I think I have my plans ready the situation isn't the same no more...

As I have just the 6 reds, I was going to order two or four more from Mouser.. But as it happens to be, the 660 reds 15 watters are now obsolete. I should have listened to you and ordered more more quickly Now that I'm stuck with 6 reds and two blues maybe I'll make one light using 6 reds and 1 blue and the other blue for the other light accompanied by maybe 6 10 watters. Dunno..

I have to find out if I can get some 15 watters someplace else, don't know if I'm gonna have much luck...

What I have accomplished is the closet. It's almost finished and the fan with a scrubber also. It's working quite good and is quiet enough. Will have to hope it does good with the lights too and is able to keep temps down...

The closet came to be 18"x30" and the height is 5 feet with all new walls and a door.

I like your idea of making our own "stars" from the 15 watters! If I got it correctly you take a small thin sheet of aluminum (cheapest material I guess), make a couple of holes for screws, epoxy the emitters on the sheet. Drill small holes to the heat sink. Take some thermal paste and put that between the heat sink and the sheet of aluminum. Then screw some self tapping screws to attach the things proper...

How are those self tapping screws? Never used them.. Can you use the same holes (and the screws?) on the heat sink again if you want to move the emitters or something?

What about those peltier devices? Do you think it could work? Sounds cool anyhows.

Kinda bummed about not having no more 15 watters. Have to be more quick next time and not like there they go..

 

[Weezard]

Damn self-tapping screws keep waking me up.

Damn self-tapping screws keep waking me up.

"How are those self tapping screws? Never used them.. Can you use the same holes (and the screws?) on the heat sink again if you want to move the emitters or something?

Yes, once the threads are cut, you just have to be careful not to crossthread on susequent screwings.

What about those peltier devices? Do you think it could work? Sounds cool anyhows.

Well, they work, but at what cost.
They double the power consumption!
Costs a watt, to cool a watt.

Like I said
I'm going to try using them backwards.
I'll put them in the heat path and see how much power they produce.
If it's enough to spin a fan, I'm stoked!
Maybe I should get off my butt and start testin'?

Aloha,
Weezard

Kinda bummed about not having more 15 watters. Have to be more quick next time and not like there they go.. "

You can try Ledengin dot com for an alternate source and you can query Mouser.
Seems that when Mouser gets enough inquiries on the 660's, Ledengin whips up another batch.

 

[Jopedijoo]

Yes, once the threads are cut, you just have to be careful not to crossthread on susequent screwings.

All righty then, got to find some of those screws...

Maybe I should get off my butt and start testin'?

Sure, test ahead! I should start to do some tests of my own too, though first I need to quit dreaming and wake up from this hibernation of mine...

You can try Ledengin dot com for an alternate source and you can query Mouser.
Seems that when Mouser gets enough inquiries on the 660's, Ledengin whips up another batch.



I asked Mouser, no reply yet. Found another place also for LedEngins, Farnell Electronics. They seem to have everything else but not those deep red 15 watters.

 

[Jopedijoo]

Darn!

Darn!

I tried LedEngin, Mouser, Farnell and a couple more places for those 15W deep reds, no luck... No more anytime soon. Well, can't blame anyone but myself.

I guess I just have to go with 10 watters, even though they cost as much as the 15 watters and are on stars. Was there a thing with the stars that you have to solder first and then mount? So I guess you should mount them mechanically with screws like them self made stars we've been talking about here? No epoxy needed then I suppose...

Light #1: 6 reds (15w) and 1 blue (15w)
Light #2: 6 reds (10w) and 1 blue (15w)

6 reds (15w): Mastech
6 reds (10w): PLN-60
2 blues (15w): PLN-30

 

[Jopedijoo]

I just realized I can't drive those 10 watters with MeanWells, any suggestions?

 

[Jopedijoo]

I just realized I can't drive those 10 watters with MeanWells, any suggestions?

Well, I suppose I could drive the 6 15W reds with two PLN-60s and use the Mastech for those 10 watters...

 

[Weezard]

A'ight!

A'ight!

Well, I suppose I could drive the 6 15W reds with two PLN-60s and use the Mastech for those 10 watters...

Isn't it amazing what you can figure out just by thinking?

Well done!

Weeze

 

[Jopedijoo]

Isn't it amazing what you can figure out just by thinking?

It sure is amazing ! I usually tend to overthink which I sometimes compensate with underthinking, like in this case...

See ya later... when I'm really ready with this piece

 

[MeanBean]

sorry guys, my question may sounds stupid to you. But is Led growing viable?

I thought they didn't have enough power...

Sure they do! Check out the grows in my sig.

 

[dabbler]

You guys have mentioned using a red incandesant bulb for supplemental lighting, there are two types, there is Transparent Colored Bulbs and Ceramic Colored Bulbs, and then you can get the red cfl ones - which one do you advise? if possible post a photo of the one you use.
Would they be of any use in a cfl grow? ( sorry I have not yet converted to LEDs but I am researching)

Many Thanks

Dabbler