Intro: 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 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.