LED Plant Growth Light





Introduction: LED Plant Growth Light

My LED plant growth light has been an effort in my new found hobby; gardening.
I have been extremely intrigued by the whole urban gardening movement, and my
dream is to help bring it indoors. So here is the part of my efforts that involves LED's.

Step 1: Tools & Materials

(A) Soldering Iron
(B) Cutting pliers
(C) Breadboard

(1) LED's, lots of them. (Ive been using these: white, blue, and red ones.)
(2) Resistors ( I have changed resistance as needed.)
(3) Solder
(4) Wire
(5) Circuitboards (Size depends on how many LED's you want use.)
(6) Power supply components
(7) Spray on Insulation (Optional)

Add some patience and imagination, and you'll be one your way to create something
 awesome with your own two hands.

P.S. Don't forget a hammer and some elbow grease to get you out of the tough spots.

Step 2: Breadbording

It probably does not need to be said, but always remember that your body can be
very conductive with the right accidental conditions. Always respect any electrical
safety guidelines that you've learned. If you don't know any, goandlearnsome.

I always like to check my LED and resistor combinations with my breadboard.
It ensures that not only the LED's and power supply are in working order, it will
also allow to tweak with your resistances before you commit to soldering. My first
LED light uses a total 34 LED's. I chose to use 12 white LED's, broken up into 4
strings of 3 LED's. Each string has a 220 ohm resistor soldered to the anodes
of the LED string. Same goes for the remaining 3 blue, and 3 red LED strings.
However since i used 11 blue and 11 red LED's. Their strings had to be two 4
LED, and one of 3 LED, strings for each color.

Once you've verified your components, you'll be ready to move on to permanently setting
those components on a circuit board of you choice.

Step 3: Chosing Various Paths, and Soldering Them.

Now that you've got working components its time to decide how to lay out your
components within the confines of your chosen circuit board. I should also mention
that being able to etch your own PCB design probably saves a lot time and second
guessing. I however lack that skill still, so I decided to use the leads from my LED's
and various other components to make the solder connections.

I setup my power supply first, making sure to keep the components close together
and well aligned to limit any wires crossing that should not cross. But also leaving
enough space for the resistors to fit as well. Make sure that the components are
connected in the right order like when you verified on your breadboard. Once you made
your layout decision, you're ready to solder the power supply into place.

Now your ready to lay out your LED's according to the strings we verified in our
breadboard. Figure out the most efficient way for all the LED's to fit in the circuit board
string by string. Once you've visualized where the leads are going to fit your ready 
to cut the excess leads and solder the components as you see fit. Remember to solder
the anodes to the resistors and the cathodes to your negative  coming from your power
supply. This is the step that requires much patience and imagination.
Once you've got your first string soldered, run power to it and make sure it lights.
This step is probably unnecessary, but it sure saved me a lot of second guessing.
I powered every string after I soldered it, this is how I noticed that I had flipped an
LED so it was not getting power on more than a few occasions.

Keep soldering until you run out of the strings of LED's that you prepared previously.
Once you finish those you pretty much have your finished product.

Don't be afraid to play around with your lay outs prior to soldering them. As you can see
on my both my later light versions I took some very different paths. Use both sides of
the circuit board; that doubles your working area and makes your lead runs much cleaner
and less likely to cross and short circuit your design.

Step 4: Finishing and Enjoying Your New Light.

Well now that you are finished with soldering and you've verified that you haven't crossed
any wires its time to doll up your new light. I decided to use a spray on insulator to add
protection to my bear leads. This will also block light from escaping upwards and therefore
your plants get more photons to feed on. Ive also looked into adding Mylar around my clay
pots to have more photons bouncing around the plant. But be careful to not make the Mylar
tube too tall for you risk reducing the plants air supply.

Or you can even start using your light as is. I guarantee that the results will impress you
and your plants much more than you might expect. I have been growing Jalapeño plants
for a bit over a month and a half in some potting soil with some very impressive results.

Step 5: Update!

Here's a few more pics of the progress Ive had. As you can see, Ive cleaned up alot of the clutter and moved the lights up the ceiling. Everything is much easier to clean and more accessible. 



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    i wanted to ask does that light really increase plant growth or was it just for fun.

    This is a very old instructable. For anyone interested on trying something similar but more up to date I suggest to use your Google-Fu with the key words [ led driver ic constant current ] and check out the chip manufacturer suggestions for DIY circuits.You also could just pick up a prebuilt module for a few bucks if you are not so adventurous.

    If you are thinking of building a diy grow light please take note of this.
    Each and every led needs to be atleast 1watt each. Anything below that will be useless so don't use old leds out of toys or old boards, they simply will have too little Total lumens versus lumens per watt. You need atleast 10mm LEDs with 1watt per LED to supply enough light to the plant anything lower will not work. A good combination is a pannel made from 75% 1watt red high brightness leds, 20% 1watt blue high brightness leds and 5% 1watt amber high brightness leds. somewhere in the region of 660nm for red and 460nm for blue
    There is also no effective difference in penetrative power for horticultural purposes between a 1W LED and a 3W LED. So anything over 1watt is just wasted. This means brightness has very little to do with the benefit you will get once you use 1wat leds. Don't confuse this with a pannel made from say 20 LEDs rated a 10watt as to one with 10 LEDs rated at 10watt. As the 20 watt pannel will use the useless 0.5watt leds verses the 10watt pannel that uses 10x10watt 1watt LEDs that are ideal. This has been tested and proven that 1watt single LEDs have great benefit to plants and anything less is just a waste of time and has no benefit at all to plants. The same applies with going brighter than 1watt has no benefit either.
    Hope that may help some of you. Especially if you are growing indoors.
    Also LEDs are more efficient than any other form of grow lighting available.
    The commercially available LED growlights outperform all other growlamps from HID lamps to including high pressure sodium (HPS) and metal halide (MH) lamps.
    So prepare to see other grow lamps become obsolete as LED growlight take over.

    Would you please provide your source for the info above? Given approximately the same luminous efficiency (not efficacy), 10W total should give you the same light output regardless of the power rating of the individual LEDs. The high power ones (1W/3W/5W) just seem to be heavily heat-sinked, not some special design. The light density depends upon the power as well as the half-power angle (angle of spread). Why can't you just put the 3W higher up than the 1W to get the same amount of light per sq ft?

    I've also seen different info on ratio of red to blue. The research I saw said something like 200:1 of red to blue and cited two different red wavelengths that need to be included for best results.

    I understand that we have to be careful around electricity. When electricity is near water, you should plug it into GFCI outlets. If your indoor garden does not have GFCI outlets, you can get GFCI extension cords. Depending on how hot your LED's run, it is not a bad idea to add a tip over sensor so it turns off when it falls over.

    I really want an LED grow light too. I just ordered some 3W royal blue and deep red LED's. To make it simple, you can use flexible clamp lamps for LED's that fit standard fixtures but this method is bulkier and more expense is needed.

    Are you sure you're clear on the concept ofwww.instructables.com ? Because I think you may be more at home at www.wherecanibuyoverpricedcrapicould buildbetterandcheapermyself.com.  

    Just sayin...  ;-)

    good, you have a great yield

    Good Job! If my tone sounds critical, I apologize in advance. I just want to share some information with whomever might read this. This is just free information.

    If I build a LED grow-light I will do a few things differently. For anyone considering a similar project, here's what I would recommend:

    1. The most common Red LED is made of GaAs and has a wavelength of 625 nm. This isn't bad, but it isn't ideal for plants. A "super-Red" or "deep-red" LED emitting a wavelength of 660 nm is better (FYI the LED material will have "Al' or "P" in addition to the "GaAs") . These are harder to find, and may cost a bit more, but in theory they are worth the trouble to obtain. Order from a site like digikey.com or mouser.com or even superbrightleds.com where they actually list the wavelength and other useful spec's.

    2. Use high-brightness LEDs that can handle at least 700mA to 1 Amp of current or more, because they put out a lot more light for the money.

    A note on heat... Make sure the thermal pad on the LED is *soldered* to a copper heat spreader that you have first tinned with solder. For a surface-mount part, you will have to use a hot-plate or frying pan, or hot-air gun, or oven to reflow the solder. The Cree website has pdf documents on how to do this. It is often easier to just buy high-brightness LEDs that come pre-mounted on a hexagonal "star"-shaped circuit board with mounting holes and everything. These typically have an aluminum core, which makes an excellent heat spreader, so then you only have to put heat-sink compound on the back of it and screw it down to a heat-sink, or you can just epoxy the whole thing down semi-permanently.

    2. Use a higher voltage power supply, like 12 or better yet 24 volts. This allows you to put more LEDs in series. Since so you can always guarantee that all LEDs in the string are carrying the same current, less resistors are needed. The whole thing will be more efficient, and produce less heat, and keep your electric bill down.

    4. The voltage regulator probably isn't necessary, even if your power supply is "unregulated". You can probably get away with using smaller resistors if you just add up the voltages of all the LEDs in a given string, and adjust the number of LEDs per string to get as close as possible to the power supply voltage. To do this it helps to mix and match LED colors in the string, just make sure that you don't exceed the LED's current rating. Ohm's law says that the resistor value in ohms that you should use is:
    R = (Vs - V_LED) / I_LED

    Where Vs is the power supply voltage,
    V_LED is the sum of the LED voltages in the string, and
    I_LED is the current in amps that the LEDs are rated for

    If V_LED is just slightly less than Vs then you will only need a very low value resistor, like 1 ohm or less, assuming a 1 amp string. You shouldn't need to drop more than a volt or so across the resistor. If you're dropping over 2 volts, why not just add another LED instead?

    Just calculate the proper resistor value for each string, and after you've built the circuit, measure the current through each string with an ammeter to make sure the current does not exceed the LED's spec.

    I hope this helps. When I get organized enough to build a light-source and take photos, I'll try to put together an 'ible.

    I suspect that all those capacitor in series with the supplies (both at the "in" and the "out" of the regulator) will prevent the circuit to work : you probably want to mount them in parallel, from the pins to ground.
    The diode also seems to be reversed.
    Three white LEDs can be powered from 9V directly witha few Ohm resistor in series (220 seems a lot). The same for blue LEDs.
    Also, same type LEDs seems to receive different current...
    I suspect your schematic needs some clean up !