DIY LED grow lights experiences

Ohhhh....

I thought it was a much more complicated point, LOL

I think I am minimizing losses to inverse square law, too... (by being able to put panel closer) which, being exponential, is probably one of the most important factors, right?

Or is my brain playing tricks on me?

green surfer said:

totally agree with SDS

another way to do it would be to use SSL150s at the center of the lamp and SSLs80 at the sides

Click to expand...

Also true ...

SnotBoogie said:

Ohhhh....

I thought it was a much more complicated point, LOL

I think I am minimizing losses to inverse square law, too... (by being able to put panel closer) which, being exponential, is probably one of the most important factors, right?

Or is my brain playing tricks on me?

Click to expand...

True........

green surfer said:

totally agree with SDS

another way to do it would be to use SSL150s at the center of the lamp and SSLs80 at the sides

Click to expand...

To give more detail,

This all came about because i bought a VERY CHEAP heatsink which is too good to waste... 20 x 20 x 7.5 cm (big fins)

Active cooled, that much surface area is way way more than you need in a 20cm^2 area, so my thought was to use 150's and cover double or so...

80° is the half angle, with SSL80 you can keep plants at 7 inches, its not a very narrow angle.

I like 150° for vegging and cuttings, for flowering personally I prefer SSL80, for the punch and penetration.

Designing & building a led grow panel ,was and is one of the most intriguing ,
fascinating and joyful experiences I've ever had ..(at least for me ,personally )
And keep having ....

But it is also one of the most multi-aspect and difficult tasks ever taken ....
(at least by me ...Oh-ohh ..My EGO speaks ,once more ? )

Even when , I had massive help and guidance by the best ..( Search for " Guod " at ..Cannapedia ... ) ...

Still ..
I F@(kin' -Absolutely LOVE IT !!!

To the point ....

Wide angle led lens allow for more "spaced apart" led arrangement ...( because of better light ' blending ' ) ...
'Cause of that ,cooling ,somewhat ,becomes easier ... (no hot spots ,no need for massive cooling of small heated/heating area,as with small mcpcbs -packed leds )

So ,passive cooling with the right heatsink becomes more feasible ....
(See Astir panels .... Same heatsink used for GD-SDS ,but PASSIVE ,cooling only 24 leds at ~320mA_ 120°-130° half angle )

While using narrow angle lens ...

1) Either panel distance from plants has to increase,with leds kept at a certain (minimum ) distance ,
with each other on to the heatsink _and passive cooling used ...
( I.e. like with led street lighting fixtures -luminaires )

Or ..

2) Leds have to be closely packed / arranged on the mc-pcb / heatsink ....
...
Passive cooling is out of question then ....*


....
!

P.S. / Edit : Doubting my shelf ,now ....
My Alter-Ego ,taking over ....

*
-Yeah ?
If that's true ,Mr I-Know-Everything ....
What about Osram's Prevaled spots then,dude ?
[video=youtube;LJN-CiSJHrw]http://www.youtube.com/watch?v=LJN-CiSJHrw[/video]
......


?
Anyone ?

hehe!
I ordered mine this eve...

PetFlora said:

I was looking at heat pipes, comes with 2-3 cooling fans. Don't know how much wattage each can handle but 3/$80 seems cheap, even if each only dissipates 40w multi-chip (either a single or maybe 4 @ 10w...) , this should be a viable DIY project.

Click to expand...

EDIt: 4000cm2 surface area.... rated for 215 TDW

stardustsailor said:

2) Leds have to be closely packed / arranged on the mc-pcb / heatsink ....
...
Passive cooling is out of question then ....*

Click to expand...

not totally agreed, it is related to the number of leds, current, substrate thermal properties, thermal transfert

i did many experiments with my veg lamps, with passive cooling, with a thermal probe at the solder point, and i found the limits of power that i could run on my heatsinks.

For ex, finaly i went with 6 leds 3CW/3R, 17V 500mA, 47,5x19x200 mm junction temp (under 55°) with black anodised
5 leds 1CW/1RB/3R 13V 500mA same heatsink not anodised...
...

distance between leds is important, 10-12mm is fine to keep a closely packed engine and to avoid hot spots. It is related with substrate quality too, this one is very important. For ex with sinkpad technology ...

compact engine will make an homogeneous light, good colors mixing

pinbloc heatsink are very nice too, but not cheap. They are made with almost pure aluminium, they are perfect for one engine/ one heatsink

http://www.pinbloc.com/pages_english/home.htm



with just a little air flow they have very high thermal properties.

Look at this pcb ....=>..

Forget about the color arranging ..

Black is copper ...

Anything "out of the usual/ ordinary " ....?

A small ...detail ..that makes a great difference .....

Hint :


Ambient Temp : 21 ° C
-Fans at lowest speed/setting ..( ~ 1500 rpm )
-36 leds at 700mA ...
-non anodised heatsink 200x160x40 mm ( AA 1060A al. alloy )
- >10 hours of continuous operation
.....Pcb temp at led side(in contact with led case side,of an outer row led )* : 37° C
Center of heatsink ( at base _ fin side )* : ~22-23 °C


*( K type thermocouple / kapton+alum tape used ,as suggested by Osram .
I'll post later about it.Have to go ,now ...)

< 5oz grower (which lasts ~ 12 months)
!!!!!!!

Now I feel jealous ....

My needs are at average 3~4 oz ( 90-120 gr ) ...per month ......

Yeap,I need 36~48 oz per year ...
At average ...The last 15 years now ...
Well...
What can I say ?
I'm a stoner ...

...
....


So ...

Type K thermocouples are the "right" ones for use in DIY led designs ..

More info at Osrams "Application Notes " :

-Measuring of the Temperature Profile during the
Reflow Solder Process
&
-Temperature Measurement with Thermocouples


..
The-cheap- one I use ...
It does it's job just fine .....
More than fine ...

green surfer said:

pinbloc heatsink are very nice too, but not cheap. They are made with almost pure aluminium, they are perfect for one engine/ one heatsink

http://www.pinbloc.com/pages_english/home.htm

View attachment 2620087

with just a little air flow they have very high thermal properties.

Click to expand...

" .....A pin fin heat sink is a heat sink that has pins that extend from its base. The pins can be cylindrical, elliptical or square. A pin is by far one of the more common heat sink types available on the market. A second type of heat sink fin arrangement is the straight fin. These run the entire length of the heat sink. A variation on the straight fin heat sink is a cross cut heat sink. A straight fin heat sink is cut at regular intervals.

In general, the more surface area a heat sink has, the better it works.[SUP][3][/SUP] However, this is not always true. The concept of a pin fin heat sink is to try to pack as much surface area into a given volume as possible.[SUP][3][/SUP] As well, it works well in any orientation. Kordyban[SUP][3][/SUP] has compared the performance of a pin fin and a straight fin heat sink of similar dimensions. Although the pin fin has 194 cm[SUP]2[/SUP] surface area while the straight fin has 58 cm[SUP]2[/SUP], the temperature difference between the heat sink base and the ambient air for the pin fin is 50 °C. For the straight fin it was 44 °C or 6 °C better than the pin fin. Pin fin heat sink performance is significantly better than straight fins when used in their intended application where the fluid flows axially along the pins rather than only tangentially across the pins...."


.....

http://en.wikipedia.org/wiki/Heat_sink




& ....

http://en.wikipedia.org/wiki/Fin_(extended_surface)

..
Photometric => Radiometric .............
Radiometric => Photometric ...

stardustsailor said:

http://nuventix.wpengine.netdna-cdn.com/wp-content/uploads/2011/09/Nuventix-SynJet-Guide-for-Osram-PrevaLED-Modules-1.4.pdf

Quite of a combo Fan-Heatsink ,huh ?

Click to expand...

Nice....

You will buy one and take it apart for us, then?

stardustsailor said:

< 5oz grower (which lasts ~ 12 months)
!!!!!!!

Now I feel jealous ....

My needs are at average 3~4 oz ( 90-120 gr ) ...per month ......

Yeap,I need 36~48 oz per year ...
At average ...The last 15 years now ...
Well...
What can I say ?
I'm a stoner ...

Click to expand...

Fortunately, I have no pain issues to deal with, other than I am a pain- in- the- ass by nature. I go days without smoking. I simply forget

I just enjoy growing and experimenting. Being pragmatic (and with low funds), I put my mind to simplifying/streamlining grow techniques.

It should be very nice to make an .XLS file to calculate the radiometric efficiency with the spectrum curve.

If i have some time I will do it. But may be someone here has something like that?

I remember that knna made an xls calculation but i don't know if it is about what i'm talking about