Calling out to Weezard for LED advice

OK.
Moving right along.
Got the leds mounted to the heatsink.
[attachment=o215763]
Running some burn-in tests with my bench supply while I wait for that slow boat from China.
[attachment=o215765]
Here's a 45 degree lens.

(Oops. I'll insert the lens pics in the next post.)

Only gained 25% when I used these with the reds.
Not worth the heat increase.
Same lens on the blue led doubles the lux reading at 12"!

Am waiting for some 60 degree lenses for the reds
Meanwhile back on the photon pharm.
[attachment=o215766]

More later.
Prolly much later.

Weezard

I am with you in spirit, my brother. :thumbsup:

No smoke so far.:thumbsup:
Oh yeah, here are the missing lens photos:
[attachment=o215816]
[attachment=o215817]
Still waiting for the 60 degree lenses.
I'll use the extra 45s for the 5 Watt array.

Not a lot of construction details because it's all in the pictures.
Buy 'em glue 'em wire 'em.
Well, actually setting the current limit can be tricky.
If anyone is actually following this, I'll be happy to walk them through it when the time comes.

Monitor died this morning.
Gotta hunt down a new one.
It's always sumpin'.

Weezard

Slapped 3 muffin fans on the back and dialed in 10.4 amps by adjusting the constant VOLTAGE supply.
[attachment=o216159]
So we can cook 'em a little and watch for current drift.
Still waiting for the right fan so I can kick it up a notch.

Weeze

Quote:

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Originally Posted by Weezard

Slapped 3 muffin fans on the back and dialed in 10.4 amps by adjusting the constant VOLTAGE supply.
[attachment=o216159]
So we can cook 'em a little and watch for current drift.
Still waiting for the right fan so I can kick it up a notch.

Weeze

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How hot does the heatsink get without the fan?

Quote:

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Originally Posted by voodoojnky

How hot does the heatsink get without the fan?

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Don't know, actually.
That would be a costly experiment.
Led death is the upper limit with no airflow!:(

These leds are eating about 150 Watts.
Unlike most sources of light, leds do not radiate much heat with the visible light, so we have to dispose of the heat produced by moving it away from the emitters as efficiently as possible.
With no heatsink, these pups would pop in a fraction of a minute.
With a heatsink and no fan it would take a while, but the heat extracted from the emitters has to go somewhere.
If we don't remove it from the 'sink faster than we generate it, it's a matter of time before component failure.
I did run the first blush without a fan but after 5 minutes the sink had reached 100 degrees F. that's 20 degrees above ambient.
3. 80mm. muffin fans keep it under 90 F.

I've ordered several fans and will use the quietest one that does the job.
I'm still testing for creeping current now to see if I can safely run this without adding 12 Constant current drivers.
IF, it is stable with one central constant voltage source, we're done and will not need the dimmers or the CCs

My "brick" of 5 Watt emitters on a smaller heatsink had enough current drift to worry me so I re-did it yesterday adding 3 LM317 current regulators;

[attachment=o216168]

Slowed it's fan to about 1/4 speed and let it cook.
After 1 hour my heatgun said 120 F.
:microwave:
At 1/2 speed it's at 90 F. and still all but silent.:)
More than I can say for the Chinese UFO.:(

Today, I use the "brick" to play with lensing.:weedpoke:

Aloha,
Weezard

Fan caught my fingertip.
That's gonna leave a mark! :(



Had a plan to draw air up from the light using reflectix to route the air.
Put a shroud around the 'sink to draw the air in from the sides and up past the power supplies.

Looked great, on paper.:(
My tempgun said 97 F.
My finger said, "That tempgun is lying to ya!"

"In theory, theory and practice are the same thing.
In practice, they are not!" <sigh>

Tore it all apart and started over.
Now have the fan about an inch above the 'sink with the air blowing down.

[attachment=o216428]

[attachment=o216429]

Much mo' betta;
About 90 degrees F. after one hour.
It's a 30V. fan running on 12.5V.
Not silent, but quiet enough for a bedroom.
Leds are pulling 14.5 Amps.
About 150 Watts is the total led draw.
I'll know the total power used in 24 hours or so.
Now I'll let it cook for a few days and then re-test for current draw.

Luxmeter says 90k at 2 inches.
So, without lenses, I should get about 22k Lux at 4"

Plants stop growing under 90k of white light.
I'll be testing to see how much red/blue is "too much".
These light meters are calibrated for visible light though.

So, all that these readings are good for, is a relative comparison between 2 similar arrays.
Once this array is in service I'll compare readings with my 5 Watt led arrays.

More pics later.

Weezard

Weezard, a few months back I caught the tip of my thumb in one of my computer fans and it sliced / ripped off half the nail, along with some tissue. Painful incident, and a long, painful recovery due to my volunteer work providing low-cost pelvic exams to deserving young actresses. :D I do believe if I'd have caught it right I would have amputated part of a digit. :eek:

When I was deciding what fans would line up with the fins on my heatsink I always mentioned finger guards. That injury was why. Sorry, I should have warned you more directly. Hope you're not permanently maimed. Those suckas are much more dangerous than hot McBurger coffee. Maybe we could have a class-action lawsuit? (Or, in my case, a "no-class" suit...)

Plaintiffs:
"Eddie 2-fingers"
"Lefty"
"Stubbs" etc., etc.

Be back soon. Have been having technical (electrical) issues at work, repairing old ("vintage" would be flattery) stuff as it pyro-detonates. (And I know what you're thinking... but I'm totally passive in this and just doing easy diagnostic and repair. I will admit to having burned up enough leds to finance a date with a starlet-turned-callgirl, but I am not causing THIS.) And, I busted my Fluke trying to get a reading while perched an a....well, never mind.

It's not that I'm accident-prone. Not at all. I just attempt things sometimes that a person with better judgement would not. :rolleyes:

Thanks for the build log, though. I will have many questions. Hermie.

P.S. ifyoutakeenoughmeatoffyourthumbyoucan'tusethespace bar:stoned:

Your point is, er, was almost taken.
Mine was not. Just a moments owie.:thumbsup: See?
But it did take a divot out of the nail.
(You have to look real close)

Dropped everything and installed the fan guard.:o

[attachment=o216516]

Going kinda ballstothewall with this array design.

Got no current limit, so temperature control is mandatory.
Did not like the dimmers, too easy to "bump the potentiometer up, even with the knob removed.
Had marked a max. position and thought about replacing the potentiometer with a pair of resistors. But also noticed how hot the un-heatsinked, triac inside was getting.
Sealed in a heavy plastic box with no ventilation.:wtf:
(<Sigh> Guess that's why it was dirt cheap on e-bay.)

Quit trying to double-duty the fan and decided to remote the supply and give it it's own fan.
Then remembered a trick from the '50s
When us po' kids needed a sub 1 ohm, high wattage resistor.
We rolled our own out of nichrome wire.
Had a chart of resistance per foot of different gauge wire.

So, I'm thinkin' I need to drop my Vin. to the dimmers so the MAX out is 10.8 Vdc. Then, I can turn it down to change the B:R , have minimum heat dissipation in the dimmers and a, "do no harm", upper limit.

So I figure I've got 12 amps to work with. Should be easy to calculate, for some folks. :(

But, no worry, true to my redneck roots, I just grabbed 6 feet of 16 guage lamp cord, ran it between the supply and the sink, whipped out my meter and plugged her in.

Blind pig got good nose, brah.:D
Nailed it! :thumbsup:1st try.
Dimmers at max.= 10.82V.
'bout 1.25Amps per lamp.

Using 16 gauge, instead of 14 gauge lets me do some crude current regulation as well.
If the current load increases, so does the voltage drop in the supply line.
The heat is spread out evenly in the 6 feet wire which does feel a tad warm to the touch.
And now I can mount the 12V. 21 A. and the 15V 2.5 A power modules near the exhaust fan in the bloomery and take some weight and heat off the lamp.

Just put it into service today and found spider mites!
Guess I let my no-pest strip get 4 months old.
Ran right out and bought some fresh ones.
No want dese buggahs building a resistance.

They prolly rode in on a trojan clone.
(Geeks bearing gifts on the ides of April...)

Good to hear from you.

Feel free to take me to task for my less than conventional electriciacating.:rastasmoke:

Many hands make light work.

Wee Zard

What are the dimmers doing in the circuit now? Is there a voltage drop across them at wide open? I can't believe 6 ft. of 16ga would drop the voltage that much. I will pretty much have to take yer word for it, though, since I dropped my freakin' Fluke! :mad: