Super easy DIY LED micro grow light
- Thread starter bassclef
- Start date
bassclef
Active Member
It is not very big--I believe 4x4" if I remember correctly. I can't comment specifically on LEDs with contacts you are describing... if that is truly the case my guess is that you could use either. Maybe someone else can chime in on that one. The problem with contacts on the bottom is that you risk touching it directly to the heatsink. Just make sure your thermal pad is big enough, or use LEDs that don't require reflow soldering!
My large heatsink is around 6x10 I think, but it has 35 2" fins so that increases the surface area by a lot. So you calculate the heatsink surface area, and use the numbers I gave in the guide to see how many LEDs you can safely run. If you plan a fan blowing directly at/on the heatsink, you can use a smaller one. And if you use copper, you can reduce the size even further as it's thermal conductivity is nearly twice that of aluminum. But it's more expensive and heavier. I use the bigger light for flowering, hence the dominance of red.
bassclef
Active Member
To help answer some questions I've gotten and to make the thread more informative, here's a redux of the notes that I took while reading knna's thread over at seedmine. It's biased toward the DIY construction side so I've updated it with a little info about the technology and LEDs in general. It's not totally complete, but maybe it will help explain things in more detail.
DIY LED LAMP CONSTRUCTION
Three basic parts needed for a LED lamp
I. LED lights
II. Heatsink
III. Driver
Mounting LEDs together
Materials needed to mount
Wiretwo types
Dielectric Kapton tape
Mounting process
As a general rule, space LEDs at least one inch apart
Place two strips of Kapton tape on the flat part of heatsink
Place a dot of adhesive on thermal pad
Apply gentle pressure while LED is drying, fully dry after a few hours
The two different LED types used in growing (Red & Blue/White) react differently to increased current (amps). Red lights increase output linearly when driven with more current, up to a point. Blue/White LEDs, however, lose efficiency when driven past their rated current. On the other hand, Blue/White LEDs fare better when overheated, while Red will lose light output faster if not properly cooled. Thus, sometimes red LEDs have lower mA numbers on spec sheets to avoid heat. More importantly, it is why proper heatsinking is important: Reds provide the most important light spectrum during flowering, so keep them cool!
Excess humidity can damage blue/white LEDs so keep them in airtight packages before soldering. Red LEDs are not as susceptible to humidity, but its safe to keep them in a sealed bag anyway.
Osram Golden Dragon 660nm (designed for horticulture)
Radiant power (light output) increases linearly: 1.75mW @ 700mA; 2.25 @ 1000mA
Radiant power drops greatly after reaching about 40C (104F)
Max permissible current/temperature is 1000mA @ 90C (194F)
At high light densities, prefer to increase whites, not blues
DIY LED LAMP CONSTRUCTION
Three basic parts needed for a LED lamp
I. LED lights
A. Available online, should be 1-3 watts each (at least)
1. Two types for grower: AlInGap (reds/oranges) and InGan (blues/whites)
a. AlInGap more sensitive to heat, thus InGan can take more current
B. Red/blue spectrum best for flowering
1. Starting ratio 5R:2W:1B for flowering (veg plants less picky)
C. Sold in BINs
1. Batches that come off assembly line: determines brightness level, can make significant difference in overall effeciency
2. Brighter bins preferred, although sometimes cannot choose unless buying in large amounts
C. Dont buy cheap LEDs
1. Check datasheets for light output and efficiency graphs
2. Osram Golden Dragon Plus LEDs
a. 12 Red, 2 Royal Blue, and 3 White 3500Ks (as used in Pinstripes array running on same string at 500mA)
II. Heatsink
A. Dissipates heat from LEDs
B. Necessary to maintain peak LED brightness and longevity
C. Use nine square inches (50 cm2) of heatsink for every watt of LED used
D. Use 27 square inches (150cm2) of heatsink if not using fans
E. Anodized aluminum preferable material
1. Found on window mountings, discarded electronic parts
2. Should have fins to increase surface area and a flat surface for mounting
Lower thermal resistance = better heat/electric conductivity
Aluminum thermal conductivity: 210 W/k
Copper thermal conductivity: 386 W/k
III. Driver
1. Converts AC (three-prong outlet) power to LED-friendly DC power
2. Look for constant current drivers, not ones that use resistors
3. Available on Ebay an other online retailers
4. Philips and Osram two respectable makers
Mounting LEDs together
Materials needed to mount
Wiretwo types
Solid monofilament wire to connect LEDs together
Standard wire to connect LEDs to driver
Solder gun and tinDielectric Kapton tape
Electrically isolates LEDs
Thermal adhesiveAllows mounting of LED directly to heatsink
Increases heat transfer to heatsink
Should also be dielectric
Apply very thin layer when mounting
TweezersUseful when handling small parts
Copper tapeNot required, but useful when soldering leads
Results in stronger construction and avoids problems if thermal pad adhesive fails
Thermal pads
Thermal pads
Used to cushion the LED against and transfer heat to the heatsink
Mounting process
As a general rule, space LEDs at least one inch apart
Place two strips of Kapton tape on the flat part of heatsink
The two strips should be of equal length and run in parallel
Align tape so that the space between parallel strips is equal to the width of one LED
The tape must be below any part of LED that is electronically connected, usually the sides of the LED
Cut a thermal pad to the size of a LED and place it between the Kapton tape stripsPlace a dot of adhesive on thermal pad
Apply gentle pressure while LED is drying, fully dry after a few hours
The two different LED types used in growing (Red & Blue/White) react differently to increased current (amps). Red lights increase output linearly when driven with more current, up to a point. Blue/White LEDs, however, lose efficiency when driven past their rated current. On the other hand, Blue/White LEDs fare better when overheated, while Red will lose light output faster if not properly cooled. Thus, sometimes red LEDs have lower mA numbers on spec sheets to avoid heat. More importantly, it is why proper heatsinking is important: Reds provide the most important light spectrum during flowering, so keep them cool!
Excess humidity can damage blue/white LEDs so keep them in airtight packages before soldering. Red LEDs are not as susceptible to humidity, but its safe to keep them in a sealed bag anyway.
Osram Golden Dragon 660nm (designed for horticulture)
Radiant power (light output) increases linearly: 1.75mW @ 700mA; 2.25 @ 1000mA
Radiant power drops greatly after reaching about 40C (104F)
Max permissible current/temperature is 1000mA @ 90C (194F)
At high light densities, prefer to increase whites, not blues
Kill a Watt
Well-Known Member
nice tutorial
mewk69
Active Member
This is EXACTLY the kinda info I was after!
I've been looking to throw in say 4 high powered LEDs into my pc box, to compliment the cfls. Have been hunting everywhere for some basic info on the howtos of getting it all wired up. You sir, are a star. +rep for an awesome tutorial.
And a vote to have this stickied too!
I've been looking to throw in say 4 high powered LEDs into my pc box, to compliment the cfls. Have been hunting everywhere for some basic info on the howtos of getting it all wired up. You sir, are a star. +rep for an awesome tutorial.
And a vote to have this stickied too!
Boatguy
Well-Known Member
Been working on a light of my own, and wish i had found this when i started.
Few things to add for anyone looking to start this project.
- If you want to get an idea of the spectrum you will wind up with check bmlcustom led website. The website has a tool that shows you the light spectrum based on the led's you choose.
-Heatsinkusa sells heatsinks all sizes, cut to order
-Meanwell led drivers have adjustable ranges of constant current and voltage to accommodate a variety of led setups, they also have some with dimming. Ledsupply.com has a tool for choosing your led driver based on how many leds you need to run.
-Blue and red leds almost always have different forward voltages, so in order to run both on one panel you will need to get creative with the wiring or use 2 drivers.
My light is going in a modified wine fridge. Its 40 leds at 3.5w a piece, but actual draw is only around 50 watts. 3 drivers with dimming so i can adjust as needed. The leds are Cree xpe http://www.mouser.com/new/cree/cree-horticultural-lighting/ .
Just make sure you get the emitters already attached to the thermal star. I have 40 bare emitters and thermal pads that i now have to attach with a diy hotplate.
Good luck and i hope this helps folks get it done faster than me.
Few things to add for anyone looking to start this project.
- If you want to get an idea of the spectrum you will wind up with check bmlcustom led website. The website has a tool that shows you the light spectrum based on the led's you choose.
-Heatsinkusa sells heatsinks all sizes, cut to order
-Meanwell led drivers have adjustable ranges of constant current and voltage to accommodate a variety of led setups, they also have some with dimming. Ledsupply.com has a tool for choosing your led driver based on how many leds you need to run.
-Blue and red leds almost always have different forward voltages, so in order to run both on one panel you will need to get creative with the wiring or use 2 drivers.
My light is going in a modified wine fridge. Its 40 leds at 3.5w a piece, but actual draw is only around 50 watts. 3 drivers with dimming so i can adjust as needed. The leds are Cree xpe http://www.mouser.com/new/cree/cree-horticultural-lighting/ .
Just make sure you get the emitters already attached to the thermal star. I have 40 bare emitters and thermal pads that i now have to attach with a diy hotplate.
Good luck and i hope this helps folks get it done faster than me.