LED Rainbow - RGB LED PWM Controller Construction - Easy to Build




Step-by-step, easy to follow instructions on the building of a LED Rainbow RGB LED PWM Controller. Only a minimal amount of parts are needed, along with a PIC processor, and you can construct one of the most amazing LED controllers available.

The system is capable of driving either RGB LEDs, or individual Red, Green and Blue LEDs to produce stunning effects.

The bare PCB, kits of components, code necessary to program into the PIC controller are all available from the http://www.pcboard.ca/kits/led_rainbow/ support site at www.pcboard.ca.

Full details on the LED Rainbow, along with user guides, display sequence summaries, programming information for the PIC processor along with full customization details are all freely available on the support web site.

If you have a well stocked bench with components, you can easily build up this project in an afternoon.

Step 1: Background Information

The LED Rainbow is a dedicated Pulse Width Modulation (PWM) controller which generates color changing effects with RGB LED lighting products. The circuit controls three outputs, each which has the ability to run an LED segment, and with three segments, is a natural for the control of RGB LED arrays.

Sequences are fully customizable and are contained in the microcontroller, which has the ability to strobe, cycle and fade the lighting, creating a massive palette of over 16 million colors using Pulse Width Modulation (PWM) technology. Each output has a resolution of 8-bits, which gives each color a range of 256 intensities and when the three colors are mixed together, a full rainbow of color combinations is possible.

With a minimal parts count, the LED Rainbow is very economical for the hobbyist to build, using industry standard components and running off of a standard 12v-15v power supply. The 2" (51mm) square board is a double sided construction with a detailed silk-screen which aids in the placement of the components.

Step 2: Getting Organized - Identifying All the Parts

Looking at the LED Rainbow board, you can see really just how simple of a design it is - but don't let the simplicity fool you as to how powerful it is.

The board measures only 2" x 2" (51mm x 51mm), is a double-sided design (meaning there are circuits or traces on each side of the board) and has a high-contrast silk-screen (the white lettering and drawing) on the top to indicate the layout of all the components and their orientation.

When assembling the board, you should do it with one component at a time, usually starting with the smallest and lowest components closest to the board. Keep in mind that some components are polarized or must go in a certain way.

Start by laying out the board and setting aside all the components in preparation.

Remember.. Full documentation on this product is available from the http://www.pcboard.ca/kits/led_rainbow/ support web site.

The parts needed to assemble the board are as follows:

Resistor 1/4 watt, 5% Carbon Film:
(3) 1K ohm (brown-black-red-gold) R1, R2, R3

(1) 33uF 50v Electrolytic Capacitor C1
(-) Optional - .1uF C2
(1) .1uF C3

(1) 1N4002 D1
(1) LM78L05 5 volt regulator TO-92 Case U1
(1) LED Rainbow Processor U2
(3) STP36NF06 N-Channel MOSFET Q1, Q2, Q3

Sockets, Headers, Connectors and Switches:
(1) 8-pin DIP Socket U2
(1) PCB mount pushbutton switch S1
(1) Optional - DC Power Jack P1

Step 3: Lets Start Building

The first step in laying out the kit is to have a clean work surface, with your components set aside and easily identifiable. We will not be going in to detail on soldering and assembly techniques here, Google is your friend and you should be able to find some best practices out there.

All soldering will be done on the back of the board (the side opposite to where you place the components. All the holes are plated through, so you only need to solder them on the back-side and the electrical connection to the front will be automatically made for you.

Take care in soldering as this will determine if your project works or not.

If you have never soldered before, you may want to look to a friend, or even consider purchasing a fully assembled and tested board.

Step 4: Assembly Step 1: Diode D1

Position D1 (1N4002) diode. You will notice a silver/white bar on the diode. This is the Cathode and should match the silk-screen on the PCB. Ensure that the bar on the diode is towards the bottom of the component. Solder in D1 now.

Step 5: Assembly Step 2: Regulator U1

Now place the LM78L05 Regulator at U1. Notice that the device has a half-circle flat side on it. The flat side should face towards the bottom of the board, again matching the silk screen on the PCB. Solder in U1 now.

Step 6: Assembly Step 3: Capacitor C3

We can now move on the C3, the .1uF Capacitor. This capacitor is not polarized, so it can go in either way. Solder in C3 now.

Step 7: Assembly Step 4: Capacitor C1

The next component to go in will be C1, a 33uF Electrolytic Capacitor. It is important that you watch the markings on this component. Normally, the negative lead is marked on the outside, with a minus (-) sign. Ensure that you do not put it in backwards on the PCB. The negative lead should not go in the hole on the board with the plus sign is. Install C1 now, double check it is in properly and solder it in place.

Step 8: Assembly Step 5: Resistors R1, R2 and R3

We now move on to the three resistors at R1, R2 and R3 which are 1K ohm resistors and have a color code on them of brown-black-red-gold. Resistors are not polarity sensitive so these can go on any way. Bend the leads so you have the resistors standing on end and solder R1, R2 and R3 into place.

Step 9: Assembly Step 6: Pushbutton Switch S1

It is now time to install the push button switch at S1. This switch is not polarized, but it will only fit into the board one of two ways. The switch is actually wider than it is tall, so try it both ways to see which way it fits best. You will know you have it in the correct position when it will push into the board with a little force. Go ahead and solder in S1 now.

Step 10: Assembly Step 7: IC Socket U2

Now position the 8-pin IC socket at location U2. This is the socket which will hold the PIC Processor LED Rainbow controller. You can now solder into place socket U2.

Step 11: Assembly Step 8: MOSFETs Q1, Q2 and Q3

It is now time to install the three N-Channel MOSFETs (STP36NF06) at Q1, Q2, and Q3. MOSFETs are sensitive to static, so use care when handling them - treat them with care. The MOSFETs have a metal panel on their backs which is a heat sink. You will want to match up the heat sinks with the solid white pattern on the PCB silk screen. Once you have them positioned, you can go ahead and solder in Q1, Q2 and Q3.

Step 12: Assembly Step 9: Optional DC Power Jack at P1

We can now move ahead and install an optional Power Jack at P1. This jack allows for a standard wall adapter to be used to power the LED Rainbow PCB. The hole pattern on the board is standard and can accommodate virtually any power jack you may have. If you have this component, you can now go ahead and install it at P1.

Step 13: Assembly Step 10: Install LED Rainbow Controller

The final step in the assembly of the board is to insert the LED Rainbow controller into the socket at U2. The controller must be placed into the socket with Pin 1 facing upwards. Pin 1 is identified on the chip by a small indentation on the chip in the corner - this is used to signify Pin 1. If you insert the processor is backwards and apply power, you run a good chance of damaging the processor. You can now install the controller at U2.

Step 14: Congratulations - Your Board Assembly Is Complete!

Congratulations. You have finished building your LED Rainbow controller system. Now you can connect up your RGB or individual Red, Green and Blue LEDs to the board. Your completed board should look like ours below.

Step 15: Lets See It in Action

We have prepared a short video of the LED Rainbow in action. This is an example of building the unit into a standard home lamp with a frosted globe on top. The results were truly remarkable and is very popular with everyone who see it.

We have seen the LED Rainbow used in a number of different applications, including Halloween and Christmas decorations, used as a lighting controller in home theatres, even used on limousines to control the outer and inside lighting. The possibilities are endless, let your imagination free.



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    25 Discussions


    3 years ago on Introduction

    www.pcboard.ca/kits/led_rainbow/led_rainbow_v3.pdf on this link i m getting the page u have requested not found please give schematic of circuit


    4 years ago on Introduction

    Looks good!

    I'm not sure what I need to customize the PWM sequences. Somewhere else, I found the exact same code that you have on your support site, the code that has delay (in milliseconds), wait, and RGB (and it ends each block or sequence with 255). Except, over there, you can copy and paste some sample code into a dynamic page that shows you what the colors and patterns will be (So I can figure out HOW to make the effect I want). They don't sell the rainbow setup with mosfets - and it'll be awesome with the power of mosfets!

    Do we need to program it via picaxe? Or is there another way? Also, I assume my computer does not have the program to open up the code (which I hope is the same as that above - want to create a multicolor flame). Will the instructions tell me how to do the process of getting all the hardware and software together?



    4 years ago on Introduction

    How about a copy of this in PDF format on the product website for those of us that have purchased the product from the website.

    I would like to put this on my tablet to read and printing the entire to PDF (view all steps) comes out messed up. I am not sure if it is just Chrome and/or I that is having the printing problem, or it it is Instructables way of pushing people to give them money for a premium account. tia.


    5 years ago on Introduction

    Say i want to use two 3w leds to be controlled by the same board. or maybe say 3. what should i do? wire the red-green-blue sides in series in all the leds and make sure the transistors can handle the power+increase the size of the supply?


    5 years ago on Introduction

    how can i connect 14 star type rgb LED in single driver, whether its possible or not..?


    7 years ago on Introduction

    anyone already do the layout for de pcb?...

    someone can share it? thank u!


    7 years ago on Introduction

    The pinouts on the schematic appear to be mislabeled. Pin 3 should be Vin and pin 1 should be Vout, Since the pins are reversed, I'm thinking that Vcc and Vdd should be reversed as well. Also, what voltage should appear at the output terminals?


    8 years ago on Introduction

    Can someone identify what type of cap C3 is? In the parts photo it looks to be a blue tantalum. In several other photos it looks like a brown mylar. Thank you.

    2 replies

    Reply 8 years ago on Introduction

    You can use whatever type of .1uf non-electrolytic capacitor you might have around in your component supply chest.



    8 years ago on Introduction

    This is a great project, and the different effects are awesome :-)
    It worked first time to my amazement!
    I hope to install it somewhere permanent soon., like a kitchen glass splash back or behind the tv for mood lighting. Designing the pcb was a little tricky !
    Thanks for sharing,


    Reply 8 years ago on Introduction

    Full documentation and schematics are available here: http://www.pcboard.ca/kits/led_rainbow/led_rainbow_v3.pdf


    9 years ago on Step 14

    Whats the maximum input power: voltage and amps? and whats the maximum output voltage and amps per color? thanks


    9 years ago on Introduction

    hi! i love this one but i dont see where can i find the board circuit :S can anyone help me whit this? i really wont to do this! thanks in advance! PS: i love this!