Introduction: 60W 30€ Dimmable LED Grow Light

Picture of 60W 30€ Dimmable LED Grow Light

!! Working with electricity could always be dangerous, so be careful and protect yourself! If you have no experience in working with electricity learn the basics first.!!

We like growing things. As we want to grow plants like pepper,tomatoes or pumpkins, we have to start most of our seeds indoors. To give them a head start, we built our own cheap LED grow lights to enhance plant growth and to get healthier plants.

3 Challenges:


We searched for the cheapest components with good quality to make our project feasible for a small budget.


LEDs consume much less energy than conventional lights, but that was not enough. We also made sure to use red and blue LEDs with the right wavelength to maximise efficiency


Heat is a big problem for LEDs but because of the usage of a large surface and thermal glue, it was not necessary to mount a fan.

Step 1: Materials

Picture of Materials

Step 2: Idea

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Plants do not require the full spectrum of light. The wavelength with the best absorption rate is between 450 - 480 nm (blue) and 650 – 700 nm (red). To save energy, we only use these two colors and just add small quantities of white light (full spectrum). Nobody knows, what the best configuration is and to be sure that our plants get enough light we added these white LEDs. This works fine for us, but you can test your own configuration if you want to.

Step 3: Preparation of the Metal Surface

Picture of Preparation of the Metal Surface

At first you have to clean the metal sheet and the backside of the LEDs. It is important that the surface is free from oil. therefore, use a bit of alcohol.

Draw helping lines on the metal for the right positioning of your LEDs. This will help you a lot in the next step.

Step 4: Gluing

Picture of Gluing

Use the thermal glue and glue all LEDs to the metal surface. You can stick to our plan or test your own configuration. Do not use too much glue. A thin layer is better than too much glue.

Step 5: Drill the Holes and Place the LM2596

Picture of Drill the Holes and Place the LM2596

Drill the holes to place the LM2596 as well as one hole in every edge to be to attach the light later were ever you want to. Mount the LM2596 to the surface.

Step 6: Change the Output Voltage (dim) of the LM2596

Solder the power wires to the LM.. Use a multimeter to check the output voltage. One LM should have 19.6V (for blue and white LEDs)and the other one 15.4V (for the red LEDs) You can change the output voltage by screwing the screw on the blue element on each LM2596.

Step 7: Soldering

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Do the soldering, stick to the plan. If you have no experience in soldering, please learn the basics first. Otherwise it is possible to harm yourself or the building parts. So be cautious!

Step 8: Does It Work?

Picture of Does It Work?

Connect the growlight to the power supply and check whether it works. Now you can install the lights wherever you want to.

I hope you have enjoyed this instructable. If you have any question feel free to ask me. I will answer you as soon as I can.


mschroeder14 (author)2016-12-08

were your LEDs effected (fading light, burning out, etc.) buy not having any heat distribution?

zyzu (author)2016-11-12

Question does this LM2596 give u a constant current of 350ma I don't wish to damage my leds

zappenfusen (author)2015-10-12

Resistors for protection of Leds might be a good idea. 1 ohm resistors were made for this.

Team Z (author)zappenfusen2015-10-13

You could be right, but we trust in the LM2596. Until now, we have no problems with this issue. Of course, if there occur problems, we will let you know ;)

zappenfusen (author)Team Z2015-10-15

At the price of the LEDs replacement would be cheap but have you ever heard of thermal runaway? I know nothing about the LM 2596 but Led drivers offer current control as well as voltage which with solid state devices is pretty important. Are y'all located in Sweden? Instructables has gotten huge in the past few years. In the town, State, Nation I call home you start ordering the items on your parts list and you start hearing strange clicks on your phone line. Nah, I ain't paranoid but found out the hard way the authorities call growing "manufacturing" with a possible 10 year hiatus from life as we know it.


Team Z (author)zappenfusen2015-10-15

We are not located in sweden ;). Our arrangement works fine. Please inform youself about the LM2596, it is also called "buck" and I think it works similar to an LED driver. We regularly control temperature which is always very acceptable. Don`t try to grow illegal plants and there is no need for you to be paranoid or afraid I think :D

zappenfusen (author)Team Z2016-07-08

What? Me worry?

zappenfusen (author)2016-07-08

Don`t try to grow illegal plants and there is no need for you to be paranoid or afraid I think :D

Ah to be a member of the Great Society of "Earth People". We common folk driven by base desires blaming actions on basic lack of control will one day be deemed non-essential and the birth of a drug free, Utopian society will finally dawn. Ingesting the green stuff may be a little rough though! All people are created equal, some a little more equal than others though. Like pigs.


Najn_arte (author)2015-11-14

I was thinking, if I use a Christmas LED light string with the blue, red, and white LED lights instead of soldering, would it work? I am just thinking it could be a no-soldering method, although I would still have to glue the lights to the metal plate. What do you think?

Team Z (author)Najn_arte2015-11-23

not a good idea, you need the right wavelength.

bcLong (author)2015-11-07

Trying to put together my own plans but I'm new to electricity. My thinking was that I need a direct current driver for my leds but you're only using the step down converter. So if I want dimmable leds do I still need the direct current driver? Or does the step down converter do everything?

Team Z (author)bcLong2015-11-08

The step down converter does everything.

Zheka163 (author)2015-10-26

Prompt brand hot glue with which you have pasted the LEDs? I never heard of such a glue. More interested in a current consumption you get and how you can use the LM2596 make it stable for LEDs is very important.

milkcartonkid (author)2015-10-11

last I knew blue was the main color they need for growing and your only suppose to introduce red to start the flowering and grow the fruit or vegetable. over all nice nice instructable :)

Team Z (author)milkcartonkid2015-10-11

Thank you =) Yeah I have read something similar, but nearly all grow lights you can buy have significantly more red LEDs. I think there `s still a lot of research to be done to figure out the best configuration. It is also true, that different plant species prefere different wavelength. Because of those uncertainties, we`ve added the white LEDs. There are so many meanings about what is the best configuration and all meanings differ. Would be great to have a reliable source. We have also built 3 slightly different grow lights varying in power consumption and LED ratio, but all with more red than blue. I think because life developed out of water, plants are so good in using blue light. But as soon as plants began to grow on land, they also started to use red light. Aquarium lights should just consist out of blue LEDs, I think. All in all, complicated topic and a lot possibilities to try out.

milkcartonkid (author)Team Z2015-10-11

just tryin to help you out, ive always used blue florescent bulbs. but is there any chance you've checked how much power it uses per hour?

Team Z (author)milkcartonkid2015-10-13

Currently, we are running the grow light at the lower end of the voltage area, to test a few things out.

P = U*I

2.2V*0.7 = 1.54W (red LED)

3.4V*0.7 =2.38W (blue LED)

3.2V*0.7 = 2.24W (white LED)

All in all: 35.28 W ==> 0.03528 kw/h

andb41 (author)Team Z2015-10-23

Hello I'm planning to built a similar grow kit but i'm confused with the power supply. What is limiting the current?

thank you for your instructable

milkcartonkid (author)Team Z2015-10-11

look under the right color

Team Z (author)milkcartonkid2015-10-13

Thank you for the info=)

Najn_arte (author)2015-10-12

I thought LEDs didn't heat up. Is heat really a problem?

Team Z (author)Najn_arte2015-10-13

LEDs are still converting more than 80% of their consumed energy into heat. Without a heatsink, they would be destroyed very soon. That is the reason we used 3W LEDs instead of for example 10W LEDs. We`ve also built a spotlight with a 100W LED and used the Cooler and the fan of a desktop PC =) Heat is the biggest problem of LEDs.

Najn_arte (author)Team Z2015-10-13

I see. Maybe that is the problem I am having now. My plants don't look as healthy as they did when I had them with the neon light and outdoors. Of course, outdoors light beats all, but we are about to go below zero in here, so outdoors is no longer an option until spring.

If I just put a red glass or film under the light to make it red, will it be the same as if I buy an actual red LED?

Team Z (author)Najn_arte2015-10-14

No it wouldn`t be the same, it would make it worse, because plants are able to use the different wavelength of light (white is a combination of different wavelength, for example when you put red, green and blue light together, it appears white (RGB)) if you filter the blue and the green light out of a white LED, only the red light remains with just 1/3 of the power. What kind of light do you use at the moment and for which plants do you use it ?

Najn_arte (author)Team Z2015-10-15

I have one terrarium with one desk-lamp neon light. It wasn't working until I learned that the neon light has to be really close to the seeds for them to grow. I also have another terrarium with 2 LED light bulbs. These are 7.5W Each bulb provides about 2700 Kelvin and the terrariums are about 60 cm long, 30 cm wide, and 30 cm high.

This spring, I started lettuces in a terrarium with neon light, and it worked better than in all my previous attempts of growing lettuces without any light but the one from the windows, which is not enough because my house faces north.

When the lettuces had four leaves, I moved them outside to a mini greenhouse, and they were doing fine throughout the summer. I started another batch of lettuce seeds last week in that same terrarium, but I still don't see anything growing.

In the terrarium that has the LEDs I put a basil and the lettuces that I had in the mini greenhouse outside, two marigolds that were also outside, and a seed starter.

The basil and the lettuces seem to be drying, so I took them out of there to see if it is because of the LEDs since you mentioned that they give too much heat. The lamp doesn't really feel hot to the touch, just warm, but I guess the plants know better.

Another option I have considered is just going to a pet store and buying one of those lights for the terrariums for critters, but not the hot light, just the "natural" light.

Team Z (author)Najn_arte2015-10-15

Thank you for the description. I will try to help you. There are a few problems. First, your NEON lights work better for your plants because I think their color temperature is about 5000 Kelvin. This is ok but not very good becuase those lights waste to much energy in comparison to LEDs. If you run them in the long term, it might be cheaper to build or buy a LED grow light with the right color spectrum (to save energy cost). Second, 2700 Kelvin are not sufficient for your plants (Different light colors trigger different things, I think warm white is used for flowering, but this is a really complicated topic). If you want to use white LEDs, make sure to use those with a color temperature similar to daylight. 5500 Kelvin and above (cold white). It is much better to use red and some blue LEDs with the right wavelength (check the instructable above) of light because plants do not require the same light as humans (all other wavelength waste energy and waste money in the long term). Third, you need more power. You need at least 3 times more light in comparison to your current setup. I think heat is not the real issue here, because you have bought your LEDs in a store and I hope they use suitable heatsinks. Basil needs more water, I think. To germinate lettuce, make sure that the soil is moist enough and doesn`t dry out. Maybe it is too warm for the lettuce to germinate. I think some salads do not need high temperatures and fail to germinte if it is too warm. But I am no expert in growing lettuce;) If you have a big window with natural light, place it there until you have improved your setup.

Najn_arte (author)Team Z2015-10-15

Thanks for all your advice. I thought that 2 LEDs with 2700K each would add up to the approx 5500K (newbie). I am not too knowledgeable when it comes to electricity, so what I have done is get good-looking lamps for cheap at thrift stores and the LED bulbs at Home Depot. The bulbs were not easy to find because this lamp has a smaller type of socket, so I couldn't use standard-size bulbs. It used to be part of a flush-mount lamp that came with a blue glass screen and incandescent bulbs. I discarded the screen and the incandescent bulbs and I just use the light fixture on top of the terrarium. I lost my iPad so I have no way to post pictures but it looks quite well. My concern is that the LED lights in your instructable look above my skills, but I may be putting them together and trying to understand step by step.

Team Z (author)Najn_arte2015-10-15

If you don`t have any experience with soldering, it would be better to buy some grow lights =) They aren`t very expensive and will help your plants to stay alive =)

Najn_arte (author)Team Z2015-10-15

I have done some soldering but not really for electrical stuff. I have put together one or two wires to make a small repair here and there, but I have never built something like this. I may try to make it anyways. I will let you know.

Team Z (author)Najn_arte2015-10-16

Cool =) I think it is really about the soldering. All other steps aren`t complicated at all.

Najn_arte (author)Team Z2015-10-17

I guess I can only know if I can do it by trying, so I will try!

DIY Hacks and How Tos (author)2015-10-10

Great grow light setup.

Thank you =)

tomjasz (author)2015-10-12

How did you come to the prices? you show 5.74€ (50 pieces quantity) in fact it's $23USD plus shipping!

Team Z (author)tomjasz2015-10-12

You just need 14 of them for this light. When you buy larger quantities, you get a discount. It is better to buy a few more, so you can use them for other grow lights and try out some different configurations.

About This Instructable




Bio: This channel is used by my brother and me. We like building and learning new things and want to share it with you! I am ... More »
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