help required

Dear members,
I am new to this forum and have joined to gain some valuable knowledge from you. I have no experience in electronics or programming but willing to learn. I am currently doing a small project to LED lighting system for my reef aquarium.
I am hoping to use 120 x 3 watts Cree star type bulbs. I have bought a LED 12V 400 watt driver/transformer with constant power supply. I would like to make 4 section in my lighting and each section will have 30 x 3 watts LED’s which means 90 watts worth of LEDs. If I use three different colour of LED’s each section, let’s say one red, two blue and 27 white. I would like to have same number and colour of LEDs in all four sections.

Now, the question which is mind baffling for me as I want to control all four sections independently from one programmable dimmer controller. I can buy a programmable dimmer controller but it could only work with max 144 watts worth of LEDs. I don’t really want to buy 3 or 4 seprate dimmer controllers to run all dimming functions.
All I want is to have one programmable dimmer controller which could control the speed or colour temperature for my 360 watts worth of LEDs at the same time.

Could anyone help? I am more than happy to pay someone if they can do programming for me.

Thanks guys.

So… You want four independent banks of LEDs that can be dimmed? You want to be able to control the dimming and the speed of dimming? An arduino could be used as a controller to do this. Then it could switch four transistors (they’d have to be reasonably decent ones. 90 watts of 12V is 7.5 amps). The transistors would all need heatsinks to be able to dissipate the sort of power running through them. In situations like this it’s common to put all four transistors in a row or grid and heatsink them all with the same heatsink assembly.

Such a four bank dimmer could be constructed reasonably cheaply if you can do the soldering and layout yourself.

You also may be able to use the PWM outputs of the Arduino if your LED driver has a PWM input. Many do and it’s directly compatible in the products I’m familiar with. The Arduino has 6 PWM outputs. You can also control the on/off of your LEDs with the digital IO pins on the Arduino as many LED drivers also have an on/off input pin.

Can you provide the model/part number/manufacturer of the LED driver system you have or are looking to purchase? With that info, we may be able to better help you.


Hi there,

I can’t find 400 watts LED driver but have found 300 watts one and link to the product is here.

Since I cannot find any waterproof 400 watts LED power driver I have decided to go with 100watts x 4 power drivers to run four different sections in my lighting fixture. Link and information on the 12V 100 watts LED driver is here
I am more than happy to have 4 sections and to run each section from 12v 100watts LED driver. I can put them all in one array and have them mounted on heat sink to be on safe side.

I have been looking at this programmable dimmer controller but it can only work with max 144 watts. Link to the product can be found here,

Please look into the download just below the product for functions.
The LED I will be using are Cree or Luxeon 12volt 3 watts x 120 bulbs un total. Each section will house 30 x 3 watts LED bulbs of three different colure but some will have different Kelvin output rating.
Link to the product is as following

As explained in my question, I would like to control all four sections from one programmable dimmer controller which could run all 360 watts worth LED’s and let me have the control over all sections. I would ideally like to lit a certain section of the light fixture. Let’s say if I have 4 sections and in each section there are 30 LED’s
1 x red
4 x blue
25 white with different Kelvin rating.
Let’s say it’s 8am … 1 red and 4 blue to come on at low speed and gradually increase to full for the next 20 minutes. After first 20 minutes I would like my red LED to go off but at low speed (within 2 minutes). I would like my blue LED’s to stay on for next one hour, yet no other colour LEDs ON. Once the first hour has passed I would like my white LED’s to come on, let’s say 9AM. It has to be soft start or with slow colour temperature or speed. At this point I would still like to have blue LEDs ON at full. Now lets say white LEDs have a gradual colour speed going upwards for next half an hour (9:30), full white ON. Once all the white has reached their full colour speed or temperature I would like to have my blue LEDs OFF.
Now I would like to have my white LEDs switched ON till, lets say 8pm. Once 8pm hits, I would like my RED LED to come one and white LED to go down with set colour speed or temperature. Once white LED’s reached half of their full intensity and RED LED still ON. I would like my BLUE LEDs to come ON at lower speed and once blue and red has mixed halfway though. I would like my white lights to go OFF altogether. Once both RED and BLUE are at max speed, then I would like to dim the RED led for next 10 minutes until it goes off altogether but blue LED still ON. I would like to keep blue LED ON for next one hour and 10pm total switch OFF.

I hope I have not asked too much and some of requests may not even make any sense to you.
I am more than glad to answer any of your questions if needed.
Just to let you know that I am building my own DIY LED reef lighting system and would like to replicate sunrise, mid noon, sunset and night modes to match what happens in nature.

I hope you can help and sorry about all waffling…

For what it sounds like you want to do you’d need a separate channel for each color and for each bank. If the red, blue, and white lights need to be independent then that’s three channels. If each of the four banks must be independent then you have four sets of three channels or 12 channels in total. You could do this with four of the linked programmable dimmers.

Yes, I think this is the only way I could think off. To do the functions on dimming side what you are suggesting is to buy 4 x 100 watts LED drivers and then have individual programmable dmmer controllors which I mentioned in the post. What you are saying that if I want to run three colours LEDs then I need to make 4 channel per section (90 watts) and then control it from an indivdual driver and dimmer controllor.
This means 4 drivers and 4 dimmers or have I got the wrong end of the stick?

Please help… :-/ :-/ :-/

Yes, unfortunately the level of control you are looking for is only going to happen if you have 12 controllable channels. The controller you linked to is three channel so you’d either need four of them or something with at least 12 channels.

Hi, Thanks for the kind help and I am very greatful for all your feedback.

Now, I kmow that I was on the correct path lol. Would anyone knows where I could buy or look for 12 channel controllor?

Thanks for the help. You can always PM me.

Kind regads

Just a few minutes ago, I added this 16-channel PWM thread to my favorites:

It may be what you are looking for. Then you just need the driver for each of the 12 channels.

IS there any place on this forum where would could chat?

I am not too sure what you are trying to say, I am really sorry but I am not very good at these things. So what you are saying that if I have one 400 watts LED driver then one of your programmable Ardunio could run all of my four sections in my system? Or, are you saying that I need 4 x 100 watts transformers and then create 3 channel from each driver which means 3 x 4 = 12 channels and then connect to Ardunio to control all dimming function according to our requirements. Of course Ardunio has to be programmed but can programmable Ardunio be used with 4 x 100 watts drivers from one command centre (Arduino). Or can I buy one 400 watts LED driver and then run it from single Ardunio?

help please…

Lets define some nomenclature for clarity:
The transformer provides raw power to the system
The driver delivers and manages the power to the LEDs based on what the controller tells it to do
The controller sends signals to the drivers to control brightness or turn LEDs on and off
The Arduino can be your controller or it can control sub-controllers
The 16-channel PWM chip is an accessory to the Arduino that gives you more of what you need to properly control your project.

Given your example above: 4 sections of LEDs, each section has 1 red, 2 blue and 27 white LEDs and you want to control each color separately.

Then you would need:
4 drivers that each handle one LED (3 watts) for the red
4 drivers that each handle two LEDs (6 watts) for the blue
4 drivers that each handle 27 LEDs (81 watts) for the white
For a total of 12 channels.

OR if you just want to control all of the same color as one channel:

1 driver that can handle 4 LEDs (12 watts) for the red
1 driver that can handle 8 LEDs (24 watts) for the blue
1 driver that can handle 108 LEDs (324 watts) for the red
For a total of three channels.

If you go with 12 channels, you’ll need 4 x 100 Watt transformers - one for each section

If you go with three channels, then you’ll need three different transformers (maybe only one or two) that can handle those wattages. Also, you won’t need the 16-channel PWM chip because the Arduino has 6 PWM outputs.

There are more details to consider, such as how many LEDs can be in one series string and how many of those strings you need to make, and other things too. But this should break it down well enough to get started.

Hi thanks…So, firstly I need LED driver rather than transformer as I need to dim my lighting or am I wrong again. I have looked at your example and what I understand is that I need only 4 x 100 watts LED drivers if follow the first example. Let’s say my LED driver is 100 watts and I will control one section 90 watts in total. Now I got one section ready, 1 x red with its own connection direct to the driver, 2 x blue connected to the same driver, 27 x white connected to the same driver.

Now I have 3 LED light colour all connected to the one 100 watt LED driver. Now I repeat the same process, setup wise having 4 identical lighting sections with 3 colour LEDs and 90 watts per section.
Now! Would I be able to supply power to all drivers from one mains supply and then add Ardunio to control all four sections and have no sub dimmer controller? How much power of LEDs can Ardunio handle or does it not make any difference in Ardunio case?

I am sorry if I am repeating the same question over and over again. I am not getting the grips and really want to learn.

Thanks for your help.

With all due respect, the level of confusion you are having leads me to believe you may be attempting a project that is too difficult for your skill level. In order to succeed in this project you should be able to determine on your own what basic components are necessary and understand what those components can do.

I suggest for you to try a few smaller projects and become familiar with how the Arduino works, how it can control LEDs and how to power and control large arrays of high power LEDs before attempting a project of this scale.

I wish you the best of luck!

Thanks, I think this would be the best way… Would you be able to help me if I want to run just 1 x 90watts portion of my LED lighting fixture and write a little programme for me? I would like to have 1x red, 2 x blue, 27 x white lights and then run from Ardunio to control. I need a small programme written to support the functionality I wish to employ.

Thanks for the lovely advice and help.

Well, programming is my weakest skill right now. I come from a hardware world and I’m only recently using the Arduino stuff. Try looking over the examples and set up some small tests to get a feel for how the code works. You’ll probably be able to figure it out on your own just from the examples.