Calling out to Weezard for LED advice

My friend, I've read your stuff here and at Steve F.'s site. I want to build a dedicated flowering lamp using Ledengin 15 watters. (4 reds, 1 blue, and possibly 1 warm white; LM 317's so I can tweak the ratios.) Essentially, a copy of your 4+1 cake pan lamp but built on a 4 x 18" finned heatsink so I can see what's going on under it.)

If I were to post my picks for power supply, resistor ratings / values, etc., would you critique and perhaps offer some guidance? I have already purchased the Mastech 3010 you've talked about.

Hoping you'll see this,
Crunchypants

Quote:

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Originally Posted by Crunchypants

My friend, I've read your stuff here and at Steve F.'s site. I want to build a dedicated flowering lamp using Ledengin 15 watters. (4 reds, 1 blue, and possibly 1 warm white; LM 317's so I can tweak the ratios.) Essentially, a copy of your 4+1 cake pan lamp but built on a 4 x 18" finned heatsink so I can see what's going on under it.)

If I were to post my picks for power supply, resistor ratings / values, etc., would you critique and perhaps offer some guidance? I have already purchased the Mastech 3010 you've talked about.

Hoping you'll see this,
Crunchypants

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Aloha, CP
Saw your post in KNNA's thread.
Answered it, sort of.
This is prolly a way mo' betta place for it though.
No wanna hi-jack da "bean counters" thread,ya :D

Happy to help, brah.
Dunno 'bout critique n guidance.
But, I'll kibbitz gleefully.:D

Let 'er rip.
Weezard

Oh, went and got the post from KNNA's thread.
Here, 'tis
"
The Herding instinct in Photons and micro-einsteins.
Quote:
Originally Posted by Crunchypants http://boards.cannabis.com/images/buttons/viewpost.gif
Weezard, I'm planning to homebrew a version of your 4+1 x 15w. light. :thumbsup:Looks like the Ledengin LED's have a 90-110 degree beam, though. Would you recommend additional optics or did the 15's work okay for you unmodified?

Mine are mounted in a deep aluminum cake pan which serves as a reflector.
Didn't find lenses for the ledengins but the 5Watt leds that I lensed are clearly better than the same configuration without the lenses.
Would call it proof if the red leds were identical.
The lensed set is 660nm., the un-lensed are 625nm.
Perhaps the difference in efficiency compensates.
Ah dunno.
I just ordered more lenses.
Will install them on the 625nm lamp and start taking pictures
of the progress.
If you find, say, 40 degree lenses that fit the 15W ledengin lens, please drop me a line.

Also, MPJA has a 28v. / 5.5A power supply (the 24v. is out of stock for awhile). I was thinking getting one to power 2 parallel legs of (2) 15w. 660's, with an LM317 on each leg. Am I just making extra work for myself by not running a 24v. supply into a single LM317 and parallelling (4) 660's off the 317? Seemed like a bit of current to push through a single 317, but I don't really know.

LM317 has a absolute maximum of 1.5A!
You might want to use an LM138 - 338 instead.

Driving an approximately. 12V led from a 28V supply will work well if you run the 2 parallel sets in series.
That will give you 4V headroom but would have to pass 2.1A.
That would require a pass transistor, etc.

So the LM138 series with a max of 5A. would probably serve better for ease of design.
Google the LM138 series for a quick and easy schematic.

The problem then is the blue led which uses closer to 15V, for peak efficiency.
I use 2 separate supplies because dissapating "excess" energy just rubs me the wrong way
My next ledengin lamp will have 2 Blues.
The goal here is to waste as little power as possible in the regulator.

I would like to underdrive the LED's slightly, and have some extra headroom in the build. Thanks!

Good idea!
I limit mine and use a thermal switch in series with the fan to keep everything under 50C.
Better Photons:Watts = less waste heat to deal with as well.

Easy lamp to build and it will work for flowering.
Mine covers app. 2 sq ft. and takes 2 or 3 weeks longer, start to finish, than HPS.
But the quality?
Wicked good!:stoned:

Let me know if I can help.

Aloha,
Weezard "

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This is prolly a way mo' betta place for it though.
No wanna hi-jack da "bean counters" thread,ya

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Point taken--I'll move my ignorance-fest back here.

I could have asked Knna, but then I'd have had to have someone explain his answer to me. :confused:

I had begun to think you weren't going to see this post, and at some point my eagerness overcame my sense of etiquette. Hope not to have offended anyone, and thanks again for your willingness to help.

Dang! I had just found some little finned heatsinks at Radio Shack for the 317 in the TO-220 package. Going to have to think about mounting strategies for the LM 138 after I read up on it more. Looks like a big power transistor with the case electrically hot. Gotta figure out how to deal with that. CP.

Quote:

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Originally Posted by Crunchypants

Point taken--I'll move my ignorance-fest back here.

I could have asked Knna, but then I'd have had to have someone explain his answer to me. :confused:

Tell me about it! :D

I had begun to think you weren't going to see this post, and at some point my eagerness overcame my sense of etiquette. Hope not to have offended anyone, and thanks again for your willingness to help.

Not at all. Best way to do it.

Dang! I had just found some little finned heatsinks at Radio Shack for the 317 in the TO-220 package. Going to have to think about mounting strategies for the LM 138 after I read up on it more. Looks like a big power transistor with the case electrically hot. Gotta figure out how to deal with that. CP.

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We're dealing with low voltage here so an electrically "hot" heatsink need not be a problem.
The Ledengin die appears to be well insulated.


Looks like you are serious about this.:cool:
Sorry, but I'm not used to someone who reads and retains everything they can find before they start asking questions.
I'm impressed! And flattered.


To me, this is a way of obtaining meds that I can not obtain through legal channels or afford on the street.
I don't worry myself about a nanometer here or a uE there.
I just want maximum yield for minimum cost.

You may be dissapointed with the single warm white led.
At least as far as "seeing what you are doing" goes
As you say the white led is a crippled blue led and will be swamped by the red and blue.
I am using a 120W CFL to supply any odd color that my girls may be "pining" for.
(Does it do any good?
Jury is still out on that. )
And still, even with a flash, getting a true color picture is accomplished only with the LEDs powered off.
Fer instance:
[attachment=o213252]

Here's a shot of the top of my light if you haven't already seen it;
[attachment=o213253]
Shouldn't be hard to improve on this mess.
It works, but it's far from elegant.

Am still running the last light array I built on my bench supply.
I plan on using an Laptop switching supply for it and getting my bench supply back to develop my next light any day now:)

I gotta ask, why "crunchypants"?

Aloha,
Wee Zard

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I am using a 120W CFL to supply any odd color that my girls may be "pining" for.
(Does it do any good?
Jury is still out on that. )

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About the time WhiskeyTango started adding supplements to his Procyons I began wondering if I could close that 2-3 week gap in finishing that everyone seems to have noticed with LED's. I added 2 x 13 watt cfl's and/or 1 x 24 watt T5HO (nominal 2 footer) to sweeten the mix. I tried both 3K warm and 6500 cool at alternate times, in a not-very-scientific way. Improvement didn't seem worth the added heat, and strangely, I thought the 6500 degree provided slightly better (still minimally better) results. So I guess I've proved to myself I don't need to fuss with adding white LED's to my lamp.

120 watts of CFL is another story; be interested to see the results of this experiment. What color temp are you using?

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I gotta ask, why "crunchypants"?

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Well, I was just trying to blend in by looking like a 19-year-old male with a chip on his shoulder. Before I registered at CannCom I lurked around the other boards for awhile, and a vaguely suggestive username seemed to be the norm. After I settled in at CannCom and read some posts and stickies by Stinky and Rhizome, I realized this community was much different than the recreational doper sites. (This impression was reaffirmed in the recent weeks when CannCom was down, and I revisited some of those "other" sites.)

At that point, I thought about picking a different username, but thought maybe the mods would see a "wise-ass" change his name without a single post and assume I was just a troll. I didn't want to get banned before I even started, so I just left it.

I never really planned on posting much, because the site elders were effectively advising all the noobs without my help, and I could answer my own questions by simply reading what's already been posted. But then SnS took the plunge with their LED grow, and heavyweights like Knna, you, and others started weighing in. CannCom became the unofficial clearinghouse for LED grow info, even more so than the GPL site.

If I had to do again, I would observe the CannCom convention of whimsical, grow-related handles and be "Foley R. Feading" or "The Dreaded Hermie." :D

Guess I should probably change it; no sense coming off like an adolescent in an adult community.

I feel more mature already, except I liked my Jan 2008 registration date. Color me noob! CP, now DH! :cool:

This is the stuff I wanted to mount my components on. I don't look forward to drilling it, though. The cake pan is looking better and better.[attachment=o213335]

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Originally Posted by Crunchypants

About the time WhiskeyTango started adding supplements to his Procyons I began wondering if I could close that 2-3 week gap in finishing that everyone seems to have noticed with LED's. I added 2 x 13 watt cfl's and/or 1 x 24 watt T5HO (nominal 2 footer) to sweeten the mix. I tried both 3K warm and 6500 cool at alternate times, in a not-very-scientific way. Improvement didn't seem worth the added heat, and strangely, I thought the 6500 degree provided slightly better (still minimally better) results. So I guess I've proved to myself I don't need to fuss with adding white LED's to my lamp.

120 watts of CFL is another story; be interested to see the results of this experiment. What color temp are you using?

It's actually 42W. CFL
The package hype claimed 120W. equivalent.
Was meant to be a tiny joke, but I forgot da li'l smiley on da end.:o

They list no color temp.:wtf:
It looks half way between warm and cool. I'd call it daylight.
I'm still at least 2 weeks from a bud density comparison.
but it did not "speed 'em up".

Well, I was just trying to blend in by looking like a 19-year-old male with a chip on his shoulder. Before I registered at CannCom I lurked around the other boards for awhile, and a vaguely suggestive username seemed to be the norm. After I settled in at CannCom and read some posts and stickies by Stinky and Rhizome, I realized this community was much different than the recreational doper sites. (This impression was reaffirmed in the recent weeks when CannCom was down, and I revisited some of those "other" sites.)

At that point, I thought about picking a different username, but thought maybe the mods would see a "wise-ass" change his name without a single post and assume I was just a troll. I didn't want to get banned before I even started, so I just left it.


I never really planned on posting much, because the site elders were effectively advising all the noobs without my help, and I could answer my own questions by simply reading what's already been posted. But then SnS took the plunge with their LED grow, and heavyweights like Knna, you, and others started weighing in. CannCom became the unofficial clearinghouse for LED grow info, even more so than the GPL site.

If I had to do again, I would observe the CannCom convention of whimsical, grow-related handles and be "Foley R. Feading" or "The Dreaded Hermie." :D

Guess I should probably change it; no sense coming off like an adolescent in an adult community.

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No worries, brah. I thought it was droll.

And your avatar is great!
Reminded me of my first stab at being the electrician, (or somebody like him), at about that age..
('cept I used a small, stainless steel, turbine blade that I held with a boxing glove.)
Jammed it in a broken socket 'cause I wanted to "magnetize" it.
Parental units were not amused.:D

So, it's time to outshine the Procyon.
Been saving my pennies and it's need to build some more Ledengin 15W arrays.

Been playing with an idea that involves 3/4" soft copper water pipe.
Want to coil it in a flat spiral, squish the spiral disk almost flat, sand and polish one side and attach the LEDs with thermal cement.
Then, if I hang it from the center I end up with a "cone-o-light"
Pumping water through the pipe and back into a res. will cool the leds and keep res. temps up in the winter for mainland folks.
I'll probably have to feed it from the tap and tie the output into my drip irrigation for the yard.
That will transport the heat out of the grow room.
Still a pipe dream, until I get to the plumbing supply store.

Howz your design coming?

Aloha,
Weezard

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Originally Posted by DreadedHermie

This is the stuff I wanted to mount my components on. I don't look forward to drilling it, though. The cake pan is looking better and better.[attachment=o213335]

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That's Aluminum.
Piece of cake to drill and tap.:)

Keep in mind, the current regulator/power supply does not have to share the 'sink with the leds if you use "fat" wire to feed the array.
I try to keep as much heat as I can outside the G.R..

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It's actually 42W. CFL
The package hype claimed 120W. equivalent.
Was meant to be a tiny joke, but I forgot da li'l smiley on da end.

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I get it. ;) I was about to suggest you call that setup a CFL-assisted-by-LED grow, though. :D

Quote:

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Been playing with an idea that involves 3/4" soft copper water pipe.
Want to coil it in a flat spiral, squish the spiral disk almost flat, sand and polish one side and attach the LEDs with thermal cement.

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Yep, have thought along those lines but am obviously working my way through some other details first. (Like building a basic, working light!) Rectangular aluminum stock with forced air cooling through the center seemed more realistic for me to attempt; my plumbing seems to cause flooding. :(

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Howz your design coming?

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Well, I think you just opened up some new possibilities. For some reason I was thinking the current regulators needed to be close to the load; I'd planned to mount 'em on the 'sink near the LED's. I prolly misinterpreted the data about filter caps needing to be close to the current regulator(s).

I had planned on keeping the power supply out of the grow area, but are you telling me I can keep the current regulators adjacent to the power supply? I could mount them in a separate case and keep the light nice and neat. This would also let me use the 338's in a TO-3 package, which seem much more popular, and look like they'd dissipate heat much better.

BTW, I don't see any "proper operation assumes adequate heatsinking" type disclaimers on any of the 338 family, unlike the LM317's. I also can't figure out what the voltage drop across the 338's is-- in one graph it looks like they'll want 1.5-2 volts at around 4 Amps. Help??:confused:

Hey, (duh) doesn't a power supply + current regulator = "LED driver?" Dang, I'm dense sometimes. Jes' call me "Pb.":rolleyes:

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Originally Posted by DreadedHermie

I get it. ;) I was about to suggest you call that setup a CFL-assisted-by-LED grow, though. :D

Yep, have thought along those lines but am obviously working my way through some other details first. (Like building a basic, working light!) Rectangular aluminum stock with forced air cooling through the center seemed more realistic for me to attempt; my plumbing seems to cause flooding. :(

Well, I think you just opened up some new possibilities. For some reason I was thinking the current regulators needed to be close to the load; I'd planned to mount 'em on the 'sink near the LED's. I prolly misinterpreted the data about filter caps needing to be close to the current regulator(s).


I had planned on keeping the power supply out of the grow area, but are you telling me I can keep the current regulators adjacent to the power supply?

Zackly!
The closer the better.
Eliminates the need for a tantalum cap on the input to the CCR. That in turn eliminates the need for a diode.
Same with the output of the CCR.
You do not need a capacitor because of the nature of the load.
With no output cap to reverse bias the regulator, no "protection diode" is needed. Keep it simple.
16 ga. wire would suffice, but I'd use 14 ga. stranded and a plug/socket right at the lamp.
I used a 4 pin hard drive connector with a seperate ground return for the Red and blue supplies.
The CCR will hold whatever current you wish when using thinner wire, but why waste watts in da wire?

I could mount them in a separate case and keep the light nice and neat. This would also let me use the 338's in a TO-3 package, which seem much more popular, and look like they'd dissipate heat much better.

You got it straight away!
Impressive.
It's gonna be fun working with you.:)

BTW, I don't see any "proper operation assumes adequate heatsinking" type disclaimers on any of the 338 family, unlike the LM317's.

Look harder, I'm sure it's there somewhere. :D
Might have to dissipate 16W. or more! So a heatsink is in order. And, in this case, bigger is better. :cool:

I also can't figure out what the voltage drop across the 338's is-- in one graph it looks like they'll want 1.5-2 volts at around 4 Amps. Help??:confused:

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If you allow for a 3 volt drop across the regulator and the 1.25V. drop across the sense resistor in your design, you should have enough headroom to keep the 338s happy.

Now, I'm havin' fun.
Weezard

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Eliminates the need for a tantalum cap on the input to the CCR. That in turn eliminates the need for a diode.
Same with the output of the CCR.
You do not need a capacitor because of the nature of the load.
With no output cap to reverse bias the regulator, no "protection diode" is needed. Keep it simple.
16 ga. wire would suffice, but I'd use 14 ga. stranded and a plug/socket right at the lamp.

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Okay, now I'm excited because I actually understand all that.

What I'm not sure about (among many other things) is what the 15w. 660's are actually going to be pulling current-wise. They're rated at 1500mA, so if I'm running them conservatively are they pulling a bit over an amp or so each, or are these things actually meant to be run at 750mA? (I'm cautious of power ratings, I remember audio amps that were in reality about 30 watts RMS being rated at 600 watts "intermitent peak-to-peak" or some other hogwash.):wtf:

If the reds are indeed capable of pulling an amp and a half each, my 5.5 amp power supply isn't as overkill as I'd thought.

Quote:

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Might have to dissipate 16W. or more! So a heatsink is in order. And, in this case, bigger is better.

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Dang! I hate to waste 16W., especially by turning it into heat! Can I improve my design? Maybe find a 24v. supply instead?

And I can think so much more clearly. :thumbsup:

This is why I have that bench supply! I can use it to see what my LED's want to be fed, and buy a power supply that fills that need.

The LM138 is good for higher temps than the 338 (150 C. vs, 125 C.) so I'll use those. Found some real sporty dedicated heatsinks for the TO-3 package. My driver will look like the Batmobile, or perhaps the Nautilus (esp. if I do any plumbing! :D)

So, Weezard, my last question, hopefully, before I start buying components for the red circuit, is:

What watt rating to I need for R1 and R2? It seems like folks are using a 5K ohm Radio Shack pot for R2. These are only rated at a half watt. However, I see some devices on your light that look like 7W resistors. How much juice is going through the R1-R2 resistor combo?

Mouser has a 5 watt wirewound pot-style variable resistor for only $4, but only up to 2K ohm. Would you recommend recalculating R1 value and using resistors/pots rated at 5 watts, or are half-watt parts sufficient here? I know the LM138 is going to have to handle some heat, but what about R1 and R2? Are they putting the brakes on any significant current flow, or are they just reference / sense components? And what the heck is a sense resistor, anyway? :confused: (Well, that was more than one question, I guess.):D

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Originally Posted by DreadedHermie

And I can think so much more clearly. :thumbsup:

This is why I have that bench supply! I can use it to see what my LED's want to be fed, and buy a power supply that fills that need.

:D:D:D Goodonya!

The LM138 is good for higher temps than the 338 (150 C. vs, 125 C.) so I'll use those. Found some real sporty dedicated heatsinks for the TO-3 package. My driver will look like the Batmobile, or perhaps the Nautilus (esp. if I do any plumbing! :D)

So, Weezard, my last question, hopefully, before I start buying components for the red circuit, is:

What watt rating to I need for R1 and R2? It seems like folks are using a 5K ohm Radio Shack pot for R2. These are only rated at a half watt. However, I see some devices on your light that look like 7W resistors. How much juice is going through the R1-R2 resistor combo?

Mouser has a 5 watt wirewound pot-style variable resistor for only $4, but only up to 2K ohm. Would you recommend recalculating R1 value and using resistors/pots rated at 5 watts, or are half-watt parts sufficient here? I know the LM138 is going to have to handle some heat, but what about R1 and R2? Are they putting the brakes on any significant current flow, or are they just reference / sense components? And what the heck is a sense resistor, anyway? :confused: (Well, that was more than one question, I guess.):D

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A sense resisror is so called because it hooks to the sense input of a regulator.

Here's how the LM317 CCR circuit works;

The lm317 is designed to be a variable voltage regulator
and it "wants to see" 1.25Vdc between the output pin and the ADJ/Sense pin. before it will begin regulating anything.
We take advantage of those facts for our current regulator.
We tie a restor to the output pin and draw the current to our load through that resistor.
If we run a wire from the load side of the resistor to the adjust pin, that pin will sense the voltage drop across the resistor.
So, ohm's law.
If we want a 1 ampere current limit, we use a resistor value that will drop 1.25V at 1 amp.
Once the adjust pin senses 1.25v.it regulates voltage to keep that voltage drop, and thus the current, constant.
1 A. X 1.25 V. = 1.25 W.
While a 2 watt resistor would suffice, a 5 or 10 watt resistor will run cooler and thus regulate tighter.
I had some 10 Watt, 1 ohm power resistors laying around so I thermal glued them to the heatsink.
Overkill? Perhaps,. But overkill is a good thing in this case .
Gives me about 1.2A. which is exactly what I wanted.
Seems to be the sweet spot in photons per watt.

What is this R2 you speak of?
The current limit configuration only requires one resistor.
[attachment=o213372]
And, I think this all applies to the 138 series as well.

It's very simple.

Here's where I'm getting that R2 stuff:[attachment=o213389]

[attachment=o213390]


Here's the TO-3 heatsinks:[attachment=o213391]

Looks like R2 is like a trimmer to make the voltage variable(?). Of course, once it's dialed in you can measure the resistance the pot's providing and replace the pot with a fixed resistor, unless you want to be able to change how much your blues are putting out, for example. Somehow I think PWM might be more efficient at doing this, but I'm not that far along yet.

[attachment=o213392]

What about this bad boy? (The 12v. version.) Looks like all the goodies are built-in. A little pricey, and maybe marginal headroon for 4 660's. Would you still need CCR's on top of this?

Quote:

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Originally Posted by DreadedHermie

Here's where I'm getting that R2 stuff:[attachment=o213389]

[attachment=o213390]

Oh, O.K., those configurations are for regulating voltage.

We want to regulate current.

Lose R2 completely, we don't need it.
And R1 should be about 1/2 an ohm. for 2 amps or 1/4 ohm for 4 amps.
If you can't find the exact value you want, you can always wire larger values in parallel.
2. 1 ohm resistors in parallel = 1/2 ohm, etc.

The schematic in my last post is complete.
One regulator, one resistor, no "salad". :jointsmile:
It's all you really need for a non-inductive, non-capacitive load.

Here's the TO-3 heatsinks:[attachment=o213391]

Looks like R2 is like a trimmer to make the voltage variable(?). Of course, once it's dialed in you can measure the resistance the pot's providing and replace the pot with a fixed resistor, unless you want to be able to change how much your blues are putting out, for example. Somehow I think PWM might be more efficient at doing this, but I'm not that far along yet.

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Quite right! PWM is a better choice, but, in a pinch, a high current low resistance trimmer with a limit resistor will work for varying current.

You might be over-thinking the CCR part.:D

Disclaimer:
This works a treat with the LMx17 series and should work just as well with the LMx38. But, I have yet to try it with the x38s.

See easier that you thunk, ya?

Weezard

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You might be over-thinking the CCR part.

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Yes, I am positively devoted to overthinking (everything) now, not after I've smoked $150+ of LED's!:eek:

Quote:

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The schematic in my last post is complete.
One regulator, one resistor, no "salad".
It's all you really need for a non-inductive, non-capacitive load.

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Very elegant in its simplicity. Without your guidance I would be making this way harder than it needs to be. Thanks again!


BTW, read somewhere you're on nursing duty this week. Please give my best to your patient, and I hope you're better at nursing than I am at EE. :)

I found a CRAZY thick aluminum cake pan last night, 13' x 9", except it's also non-stick. What's your take on grinding the teflon off so I can epoxy to it?

Quote:

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Originally Posted by DreadedHermie

[attachment=o213392]

What about this bad boy? (The 12v. version.) Looks like all the goodies are built-in. A little pricey, and maybe marginal headroon for 4 660's. Would you still need CCR's on top of this?

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Dude!
You didn't say you had a fat budget.:D

Hell yes! That will work.
That's exactly what I would use if a had 2 pennies to rub together.:)
I'd use the 120Vac input unit and be done with it.
It is truely all you need besides leds, wire, and a heatsink

They are PWM based.
Very little power wasted as heat
Just buy, plug, n play.

I only reneck my own supplies because I have to choose between toys and food. :(
(Sometimes the toys win. Keeps me from gettin fat, ya?):D


So rich!!;)
Must be nice.:smokin:


Aloha nui.
Weezard

Quote:

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Originally Posted by DreadedHermie

Yes, I am positively devoted to overthinking (everything) now, not after I've smoked $150+ of LED's!:eek:



Very elegant in its simplicity. Without your guidance I would be making this way harder than it needs to be. Thanks again!


BTW, read somewhere you're on nursing duty this week. Please give my best to your patient, and I hope you're better at nursing than I am at EE. :)

I found a CRAZY thick aluminum cake pan last night, 13' x 9", except it's also non-stick. What's your take on grinding the teflon off so I can epoxy to it?

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I'd be very careful.
When Teflon is heated past 4 or 5 hundred degrees F. it produces a poisonous gas.
Not powdered Teflon, an actual gas, so wearing a grinding mask is not gonna save ya.
It WILL kill birds, so it can't be healthy for people.
If you do this, sand the Teflon off by hand, outdoors, down-wind and very slowly.

We seem to be leapfrogging messages:D.

Ciao
Weeze

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I'd be very careful.

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Thanks. I think that real heatsink stock is the way to go.

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You didn't say you had a fat budget.

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Not so much, but the power supply I'd use would be around $75.[attachment=o213400]

By the time I get the 338 heatsinks ($10, plus $10 more for shipping, plus $10 ea. for the 338's, the led driver is actually cheaper. Certainly neater, as well. Think I'm ready to start ordering. Do ya think I should do a build log?

Quote:

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Originally Posted by DreadedHermie

Thanks. I think that real heatsink stock is the way to go.

Yeah, that!

Not so much, but the power supply I'd use would be around $75.[attachment=o213400]

By the time I get the 338 heatsinks ($10, plus $10 more for shipping, plus $10 ea. for the 338's, the led driver is actually cheaper. Certainly neater, as well. Think I'm ready to start ordering. Do ya think I should do a build log?

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Build log?
Why not?

Grow log?
Abso-freakin-lutely!
Be a good way to give back to the boards that gave so much to us.

On that Driver, the 100-12 might not cut it.
I'd vote for the 60-15 or the 100-15 for the 12-13 volts the red leds are going to want.
My blue wanted 13.8 V. if I remember correctly:stoned: but you won't be able to run it off the same driver.:(
(Reds n blues have different Vf. for a given current.
That would confuse your driver.)
Of course 2 $80 drivers is an option, but you might be able to use one 100-15 driver on the blue with dropping resistors in series with the red leds to shave the difference.
Something to think about.

Aloha,
Weezard.

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you might be able to use one 100-15 driver on the blue with dropping resistors in series with the red leds to shave the difference.

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Nope, I want to run separate drivers for the reds and blues. Using resistors and creating waste heat just seems sloppy to me. If it were a real small lamp it'd be different.

Actually, I've been planning to build two lights, 75-90 watts each. So if I overbuy for the blue driver I can power the blues in both lights with a single driver, yes? I just wanted to build one light at a time so I can work out any kinks before I do the second one.

One thing I noticed, the specs for the PLN-60 and PLN-100 are nearly identical in the 12V versions. The higher voltage PLN-100's begin to outrun the PLN-60's, but the 12V PLN-100 is only rated at 60W. :confused:

The data sheet for the red 630's (I don't think there's one out for the 660's yet) led me to believe they'll want 11.4 volts MAX if I remember right. But you described a trick somewhere for determining what LED's want by using your bench supply. Might have been just turning the thing up until it kicks over to current limiting. Haveta look around for that. Seems wise to experiment with the bench supply before actually purchasing the driver so I get it right. And, I can use the bench supply to drive the LED's, too. :D

But your suggestions are right on the money. Keep 'em coming!:thumbsup:

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Using resistors and creating waste heat just seems sloppy to me. If it were a real small lamp it'd be different.

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Not only did that sound kinda snobby, it's not really what I meant. :stoned: What I was thinking was: only if the difference in voltage requirements of the reds vs. the blues is small, does shaving a volt or two with resistors make sense. :thumbsup: Indeed, in that circumstance, dropping the blues a bit with a resistor may be the wisest solution--especially if bringing in a separate power supply is problematic.

I just got used to planning for a worst-case scenario based on the data sheets for the LEDs. Depending on what bin the dealer decides to send you, it looked like it was very possible to wind up with blue LEDs wanting a full 4 volts more than the reds. :( I guess I resigned myself to thinking that was what I was gonna wind up with.

But Weezard, I guess you've been tellling me your blue and red 15 watters are not that far apart in their voltage requirements. That opens up new possibilities (like judicious use of resistors). Sorry, I'm dense sometimes! :i feel stupid:

Aloha DH

Kinda waitin' 'til you have the LEDs in hand and can use the variable supply to label them with the actual Vf, at the current you want.
You can use the variable voltage function and increase the voltage until you reach the target current. Or you can use CC mode if you turn the voltage all the way up and adjust current up to the target and, in either case, just record your meter readings.
Should come out the same regardless of the approach, ya?

Theory is lots of fun, but, once you have actual facts in hand, design kinda handles it'self.:cool:

Once we know what is, we'll know what needs to be.
No wasted speculation, now mind be mo' free.
Once you've whittled many paths down to 2 or 3.
'tis then, the path that you will choose, seems obvious to me.:D

Sorry!
It happens.:jointsmile:

Weezard

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Once you've whittled many paths down to 2 or 3.
'tis then, the path that you will choose, seems obvious to me.

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Quite right. It's just that I whittle a lot faster than I can type! ;) Sorry if I seem to be going several directions at once (wait a second, I ALWAYS go several directions at once! :thumbsup:) but you've given a LOT of good ideas, some of which required some quick self-education on my end. Seems like if, after considering all the reasonable possibilities, I keep coming back to the same place, that I'm getting real close to the "answer." Thanks to you, I do have a very clear (although "adjustable") picture of where I'm going with this.


I think I've figured out the order I need to acquire parts to make sure they all play nice together. (Although, deep in my heart, I am lusting after that 100-15 driver! :D) Getting as much as possible from few vendors saves a bit on shipping, too.

Already ordered:

1) Arctic Silver epoxy, plus the 2-part cleaning solution set. I'm expecting some kinda grease, anti-oxidant coating, or something like that to be on the heat sinks. ($23.23 shipped)

2) Two 8.5x 13" sections of that heavy heatsink. Grand total with shipping: $62.55. Should be here by Wednesday. Decided to get the sinks together to save shipping, but just building one light right now.

I want to mount two 92mm fans right against the fins of each heatsink, like the 80mm is mounted on the Procyon. I just need to confirm that the mounting holes for the fan line up with gaps between the fins. Once I know what fans I'm using, I can put in the order for the LED's and get finger guards for the fans on the same order. (Later next week.) :dance: Once I get the LED's I can measure 'em and decide on a PS. (Although I REALLY want a 100-15. Did I mention that? :D)

Meanwhile I'll play with the sinks a bit to see how they balance, etc. to decide how to mount the flying hardware (prolly just use ringbolts). MIGHT be nice to be able to hang the light "sideways" too, although I don't plan to use it that way.



Anyway: I believe each heatsink is over 5 lbs. of aluminum. I was planning ("no gotta calculate, overkill will do jus' fine";)) to run (2) 12V 92mm fans gently on a 9V wallwart to keep the junctions as happy as possible. Is this crazy overkill? Is that enough heatsink where a wise man wouldn't even use a fan? You mentioned a thermal switch on your lamp. Are you actually able to get by with passive cooling? Or is the switch doing something other than kicking in your active cooling, like shutting things off above a certain temp?? I'd like to see how you have that set up.

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Kinda waitin' 'til you have the LEDs in hand and can use the variable supply to label them with the actual Vf, at the current you want.

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Yes. Your guidance will be critical here. Little apprehensive about firing them up the first time, and I don't even own 'em yet! (See avatar.)


:confused: :what: :confused: :silly: :stupid:

Quote:

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Once we know what is, we'll know what needs to be.
No wasted speculation, now mind be mo' free.
Once you've whittled many paths down to 2 or 3.
'tis then, the path that you will choose, seems obvious to me.

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Weezard, your knobs clearly go all the way to "11." ;)

You done one-upped the Bard.

You leave me no choice but to reply in Haiku. This is for you, and I call it, "Elegy to some LEDs:"

Tiny sparkling lights
Struggle under current load
Poof! A smoky death.

Regards,
Hermie-san. :stoned:

No worry brah.
Evah li'l t'ing, gone be jus' fine:jointsmile:

Quote:

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Originally Posted by DreadedHermie

Weezard, your knobs clearly go all the way to "11." ;)

You done one-upped the Bard.

You leave me no choice but to reply in Haiku. This is for you, and I call it, "Elegy to some LEDs:"

Tiny sparkling lights
Struggle under current load
Poof! A smoky death.

Regards,
Hermie-san. :stoned:

---

Haiku?
Youku!

I call him.
"Tomorrow."

Shards of pure color
Grew large buds with magic rays
Tonight we smoke bliss.


Weezard-san
:stoned::stoned::stoned: to the tits.:cool:

Weezard, you're a true renaissance man. What a lovely haiku. Mine was rather bleak by comparison. :(

Not sure I get "Tomorrow" unless it's this one:
"Creeps in this petty pace from day to day
To the last syllable of recorded time"

I got impatient and ordered the LEDs just now. 2 blues and 5 reds. And at only .80 each I took a chance on a couple finger guards.

I'd like to squeeze 5 reds on the light but the power supplies I'm looking at seem best to drive 4. (Did I mention that 100-15? :D :D :D )

So, maybe I'll use red #5 in the next build.

Also found some PMD controllers at Quickar. There's one for $10 that looks like something I saw on your lamp, prolly that blue controller that you jumpered around after it fried. Those might be useful, unless they're failure-prone. :angelsmiley:

The thermal glue arrived, too. The 92mm fans do line up (to miss) the fins. I am thinking now about cramming 6 reds in a domino-6 pattern and centering the blues in the middle. Weezard, is that "too much light" in a small area?

[attachment=o213587]

[attachment=o213588]

I could fit 4 fans on this thing......

[attachment=o213589]

Is that too much light?

Now, that's just crazy talk.:D

I like the 6 n 2 setup.
You can go from 3:1 R:B to 6:1 with the flip of a switch.
Though a dimmer would give the control that you want.
I like the centered blue array as well.
Blue triggers phototropism and we want the terminal bud to seek the center of the light.
2 fans should be jus' fine.
Depends on how hard you drive the leds.

Once they are mounted on the sink, you can light 'em up with the variable supply, and see how a passive sink handles the heat.
If it stays under 40 degrees C. you don't really need a fan.
Between 40 and 50 C. in the first hour?
Add a thermal switch in series with the fan to conserve power.
Over 50 degrees in a the first hour of burnin?
Hardwire both fans.

On that PWM.
Prolly the same one that I fried.
Can't blame the device though.
I pushed my luck with a fraction of a volt over the max rating.:o

(Li'l tiny Zards make big dumb mistakes alla time)

Nobody's prefect
Weeze

The server just got overloaded, or so it claimed, and ate my post! Gotta start saving work as I go, maybe.
Anyway, the first heatsink is all drilled and tapped. Ordered (4) 92mm fans.

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I like the 6 n 2 setup.

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Me, too! 6 it is! :D

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You can go from 3:1 R:B to 6:1 with the flip of a switch.

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I need some help here. If I just switch a blue LED out of the circuit won't the driver attempt to deliver the current (that was split between the blues) to the single blue?

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If it stays under 40 degrees C. you don't really need a fan.
Between 40 and 50 C. in the first hour?
Add a thermal switch in series with the fan to conserve power.
Over 50 degrees in a the first hour of burnin?
Hardwire both fans

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Thank you so much. I needed that info badly. Is there a way to get an accurate enough reading without buying an IR thermometer? And, do you have a part# or description of the thermal switch I might need?

Thought of another possible layout. [attachment=o213685] Thoughts? LED's should be here Thursday! :D:D:D Thanks for all your help. This is fun! :thumbsup:

Quote:

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Originally Posted by DreadedHermie

The server just got overloaded, or so it claimed, and ate my post! Gotta start saving work as I go, maybe.
Anyway, the first heatsink is all drilled and tapped. Ordered (4) 92mm fans.


Me, too! 6 it is! :D

I need some help here. If I just switch a blue LED out of the circuit won't the driver attempt to deliver the current (that was split between the blues) to the single blue?

Sorry, works fine with C.V. forgot we were dealing with C.C. here.:o
You are correct, switching one out would make the supply increase the voltage to try to keep the current constant.
Once you exceed Vf.max, poof! All bus' up!
All da magic smoke gets loose an' he no work now.:rastasmoke:


Thank you so much. I needed that info badly. Is there a way to get an accurate enough reading without buying an IR thermometer? And, do you have a part# or description of the thermal switch I might need?

Candy thermometer will work and an educated fingertip will serve you well during burn-in.

As for thermal switch. I just hit E-bay and typed "thermal switch" into the search engine.
They are cheap and plentiful.
Won't hurt to hardwire the fans until you know if you actually have need of the switches.
They are easy enough to add later.

Thought of another possible layout. [attachment=o213685] Thoughts? LED's should be here Thursday! :D:D:D Thanks for all your help. This is fun! :thumbsup:

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My pleasure!
It was on my way.:D

Aloha
Weeze

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Sorry, works fine with C.V. forgot we were dealing with C.C. here.
You are correct, switching one out would make the supply increase the voltage to try to keep the current constant.

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I think those Mean Well's I want are CV and CC, if that makes any difference.

Let's say I have 13V @ 4800 mA going to 4 blue LEDs in parallel. Each blue is drawing ~1200mA, yes? Now, I switch one blue out of the circuit. Do the remaining 3 blues divide the 4800mA if the voltage remains at 13V?
That's the part I'm not sure about. Maybe a safe way to check it would be "backwards," like setting things safely for one LED and switching a second one INTO the circuit, and seeing what the driver does in response?? :stoned:

Quote:

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Originally Posted by DreadedHermie

I think those Mean Well's I want are CV and CC, if that makes any difference.

Let's say I have 13V @ 4800 mA going to 4 blue LEDs in parallel. Each blue is drawing ~1200mA, yes? Now, I switch one blue out of the circuit. Do the remaining 3 blues divide the 4800mA if the voltage remains at 13V?

No.
If the voltage remains constant, each led will still draw 1.2 A. for a total of 3.6A.

I = E/R
If we change R. and keep I. constant, E. must change.
If E. is held constant and we change R., then I. must change.
etc.
It's the LAW. :D

That's the part I'm not sure about. Maybe a safe way to check it would be "backwards," like setting things safely for one LED and switching a second one INTO the circuit, and seeing what the driver does in response?? :stoned:

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Once you've tested and recorded Vf. and I. for each individual LED, you will know if one will try to "hog" the current.
(A led with significantly lower Vf. will draw more current than it's neighbor.)
That's why we never try to run paralleled leds at or near I. max.
With luck, all your emitters will be within .01 V. and it will not be an issue.
So, bring them up one at a time to 1.2A and record the Vf.
We can then make minor adjustments as needed.:cool:

Gotta run.
zooooom.
W.

Finally. I'm making some jigs by cementing 2 washers together, so I can epoxy the LEDs to the heatsink without putting pressure directly on the lens. :)

I'm gonna glue first, then wire. Weezard, is 20 guage stranded wire enough to supply each individual LED?

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Originally Posted by DreadedHermie

Finally. I'm making some jigs by cementing 2 washers together, so I can epoxy the LEDs to the heatsink without putting pressure directly on the lens. :)

I'm gonna glue first, then wire. Weezard, is 20 guage stranded wire enough to supply each individual LED?

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I would not do that!

Actually, I did just that.:o
But, I won't do it again.
Solder before you mount ,or buy a honkin big soldering iron.:D

The heatsink steals the heat and soldering then becomes a chore.

20 guage stranded will do jus' fine for short runs.
For long runs, I'd use 16 gauge stranded.

The PCB is so flexible, can't I just lift up the solder pad end and slip something between the pad and the heatsink while I solder? I've only just now attached one LED and only cemented pad behind the emitters, not the entire body of the device.

Seemed easier than having the thing squirm around while I try to attach the wires, then fighting the wires while I try to glue the LEDs down(?)