Description

Long straight lines of LED luminescence is nice, but sometimes you may want to light up something that has an unusual shape, or is not so linear. This is where the 12mm diffused flat digital RGB LED Pixels can come into play. This cool strand of 25 NeoPixels fit nicely into 12mm pre-drilled holes of any material you like.

This tutorial is dedicated to making a LED Light Box. I wanted the box to be equally as interesting during the day as it was at night. If you decide you make your own, feel free to be as creative as you want !! However, if you lack artistic acumen, you may need to source a minion or two.

Parts Required:

LED Circuit:
• Arduino UNO (or compatible board)
• 12mm Diffused Flat Digital RGB LED Pixels (Strand of 25)
• PowerTran 5V DC 4A Plugpack with 2.1mm tip
• 2.1mm Screw Terminal, DC Power Line socket
• Breadboard
• Breadboard jumper wire
• 330 ohm resitor
• 4700uF 16V Electrolytic Capacitor (Jaycar Cat No. RE6243)
• 6 Pole PC Mount Pluggable Header (Jaycar Cat No. HM3106)
• 6 Pole PC Mount Pluggable Terminal Block Socket (Jaycar Cat No. HM3126)

Project Box:
• Boyle Medium Craft Timber Box With Catch
• 12mm drill bit (and drill)
• ELC Acrylic Paint Antique White 100mL
• Micador Acrylic Paint Sets
• J.Burrows Acrylic Paint 200mL Glitter Sugar Cube
• ELC Rhinestone Assorted 500 Pack

Arduino Libraries and IDE

Before you start to hook up any components, upload the following sketch to the Arduino microcontroller. I am assuming that you already have the Arduino IDE installed on your computer. If not, the IDE can be downloaded from here.

The FastLED library is useful for simplifying the code for programming the NeoPixels. The latest "FastLED library" can be downloaded from here. I used FastLED library version 3.0.3 in this project.

If you have a different LED strip or your NeoPixels have a different chipset, make sure to change the relevant lines of code to accomodate your hardware. I would suggest you try out a few of the FastLED library examples before using the code below, so that you become more familiar with the library, and will be better equipped to make the necessary changes.

If you have a single strand of 25 Neopixels with the WS8201 chipset, then you will not have to make any modification below.

ARDUINO CODE:

Arduino Code Description

The code above will generate a randomised raindrop pattern on the NeoPixel LED Light box, however I have written code for a few more LED animations. These animations were written specifically for this light-box setup. In other words, once you have hooked everything up, you will be able to upload these other LED animations to the Arduino board without any further modification to the hardware/wiring, and yet experience a totally different light effect. You can find the code for the other animation effects by clicking on the links below:

1. Breathing effect
2. Ripple effect
3. Clock effect
4. Rotation effect
5. Sweep effect
6. Spiral effect
7. Lightning effect
8. Paparazzi in the Rain effect

Hooking it up:

Power requirements

Each Neopixel LED can draw up to 60 milliamps at maximum brightness (white). ie. 20 mA for each colour (red, green and blue). Therefore you should not try to power the LED strand directly from the Arduino, because the strand will draw too much current and damage the microcontroller(and possibly your USB port too). The LED strand will therefore need to be powered by a separate power supply. The power supply must supply the correct voltage (5V DC) and must also be able to supply sufficient current (1.5A or greater per strand of 25 LEDs).

Excessive voltage will damage or destroy your Neopixel strand. The LEDs will only draw as much current as they need, however your power supply must provide at least 1.5A or greater for each strand. If you chain two strands together, you will need a 5V 3A power supply.

Neopixel strand connection

There are 25 Neopixel LEDs per strand. Four of the wires at each end of the strand are terminated with a JST connector. The red wire is for power (VCC), blue wire for ground (GND), yellow wire is for Data, and green wire for Clock. A spare red wire (VCC) and a spare blue wire (GND) are attached to the ends of each strand for convenience, however, I did not use either. Please double check the colour of your wires... they may be different.

If you want to attach the LED strand to a breadboard, you can cut the JST connector off and use the Neopixel strand wires. Alternatively, if you would prefer to preserve the JST connector, you can simply insert jumper wires (or some male header pins) into the JST connector, and then plug them into the breadboard as required.

Each neopixel LED is individually controllable using two pins on your Arduino. The strand is directional. i.e. There is an INPUT side and an OUTPUT side. The strand should be connected such that wires from the microcontroller are attached to the INPUT side of the first neopixel. The arrows on each LED show the direction of data flow from INPUT to OUTPUT. The arrow on the first NeoPixel should be pointing towards the second NeoPixel, NOT towards the breadboard.

Other considerations

As a precaution, you should use a large capacitor across the + and - terminals of the power supply to prevent the initial onrush of current from damaging the Neopixels. I used a 4700uF 16V Electrolytic capacitor for this purpose. According to Adafruit, a 1000uF 6.3V capacitor (or higher) will also do the trick. You may also want to consider a 330 ohm resistor between the Arduino Digital pin and the strand's DATA pin.

If you want to power the Arduino using the regulated 5V external power supply. Disconnect the USB cable from the Arduino, and then connect the positive terminal of the power supply to the 5V pin on the Arduino. Be warned however, that excess voltage at this pin could damage your Arduino, because the 5V regulator will be bypassed.
 
Providing the USB cable is NOT connected to the Arduino, it should now be safe to plug the power supply into the wall. This setup will allow you to power the Neopixel strand and the Arduino using the same power supply.
 
WARNING: Never change any connections while the circuit is powered.

For more information about these NeoPixel strands, you may want to visit the Adafruit site. Adafruit was the source for most of these NeoPixel Strand precautions.

Fritzing diagram

The following diagram demonstrates how to connect the NeoPixel Strand to the Arduino and to the External 5V power supply.

This diagram was created using Fritzing

Connection Instructions

LightBox assembly

You will need to drill a 12mm hole into the craft timber box for each LED on the strand. It is worth taking the time to make accurate measurements before drilling the holes.
 
I made 12 holes for the outside circle pattern (12cm diameter), 6 holes for the inside circle pattern (8cm diameter), and a hole in the centre. I also made two holes at the front of the box, two on the left side, and two on the right side. I made one last hole at the back of the box for the 2.1mm DC power line socket.
 
Therefore you should have a total of 26 holes in the box. 25 of the holes are for the Neopixel LEDs and one for the external power supply socket.

The lid of the box is about 19.5cm x 14.5cm long, which makes for a very tight squeeze. Probably too tight, because you have to account for the inner dimensions of the box. The inside of the box is used to house the Arduino, breadboard, the chipset side of the LEDs and cables/components. The inner dimensions of the box are 18cm x 13cm. Therefore, the housing for the LED chipset PCB (1.8cm x 2.5cm) prevented the box from closing. I used a Dremel to carve out the space required to close the lid.

Each LED is approximately 8cm apart on the strand, however, if you are really keen, you could cut the wires and extend them to any distance you require. But keep in mind that each LED is mounted on a small PCB (with a WS2801 chipset).You will therefore need to leave a minimum of 2cm between each 12mm hole to accomodate the size of the PCB+LED. If you plan carefully, you can probably squeeze a couple of LEDs within a distance of 1cm... but I would recommend that you give yourself a bit more room, because the PCBs are not square, and there is a good chance that you will have to start all over again.

In hindsight, I could have made the circle patterns a bit smaller, however I don't know if I could have packed these LEDs any closer. The diameter of the inner circle pattern must be at least 2cm smaller than the outer circle pattern. So I think "a bigger box" would have been the best option.

When the paint is dry, insert the LEDs into the drilled holes in number order.
You can see the end result below.

Project Pictures

These pictures show the Light box after it has been drilled and painted. The LEDs have been inserted into their respective holes, and all wires + Arduino + breadboard are hidden within the box.

Concluding comments

Once you start writing LED animations for the NeoPixel Lightbox, it is very hard to stop. The colour combinations

If you like this page, please do me a favour and show your appreciation :

 
Visit my ArduinoBasics Google + page.
Follow me on Twitter by looking for ScottC @ArduinoBasics.
I can also be found on Pinterest and Instagram.
Have a look at my videos on my YouTube channel.

This project would not have been possible without OpenLab's collaborative effort.
Please visit their site for more cool projects.

However, if you do not have a google profile...
Feel free to share this page with your friends in any way you see fit.

Description

Long straight lines of LED luminescence is nice, but sometimes you may want to light up something that has an unusual shape, or is not so linear. This is where the 12mm diffused flat digital RGB LED Pixels can come into play. This cool strand of 25 RGB LED pixels fit nicely into 12mm pre-drilled holes of any material you like.

This tutorial is dedicated to making a LED Light Box. I wanted the box to be equally as interesting during the day as it was at night. If you decide you make your own, feel free to be as creative as you want !! However, if you lack artistic acumen, you may need to source a minion or two.

Parts Required:

LED Circuit:
• Arduino UNO (or compatible board)
• 12mm Diffused Flat Digital RGB LED Pixels (Strand of 25)
• PowerTran 5V DC 4A Plugpack with 2.1mm tip
• 2.1mm Screw Terminal, DC Power Line socket
• Breadboard
• Breadboard jumper wire
• 330 ohm resitor
• 4700uF 16V Electrolytic Capacitor (Jaycar Cat No. RE6243)
• 6 Pole PC Mount Pluggable Header (Jaycar Cat No. HM3106)
• 6 Pole PC Mount Pluggable Terminal Block Socket (Jaycar Cat No. HM3126)

Project Box:
• Boyle Medium Craft Timber Box With Catch
• 12mm drill bit (and drill)
• ELC Acrylic Paint Antique White 100mL
• Micador Acrylic Paint Sets
• J.Burrows Acrylic Paint 200mL Glitter Sugar Cube
• ELC Rhinestone Assorted 500 Pack

Arduino Libraries and IDE

Before you start to hook up any components, upload the following sketch to the Arduino microcontroller. I am assuming that you already have the Arduino IDE installed on your computer. If not, the IDE can be downloaded from here.

The FastLED library is useful for simplifying the code for programming the RGB LED pixels. The latest "FastLED library" can be downloaded from here. I used FastLED library version 3.0.3 in this project.

If you have a different LED strip or your RGB LED pixels have a different chipset, make sure to change the relevant lines of code to accomodate your hardware. I would suggest you try out a few of the FastLED library examples before using the code below, so that you become more familiar with the library, and will be better equipped to make the necessary changes.

If you have a single strand of 25 RGB LED pixels with the WS8201 chipset, then you will not have to make any modification below.

ARDUINO CODE:

Arduino Code Description

The code above will generate a randomised raindrop pattern on the Arduino LED Light box, however I have written code for a few more LED animations. These animations were written specifically for this light-box setup. In other words, once you have hooked everything up, you will be able to upload these other LED animations to the Arduino board without any further modification to the hardware/wiring, and yet experience a totally different light effect. You can find the code for the other animation effects by clicking on the links below:

1. Breathing effect
2. Ripple effect
3. Clock effect
4. Rotation effect
5. Sweep effect
6. Spiral effect
7. Lightning effect
8. Paparazzi in the Rain effect

Hooking it up:

Power requirements

Each LED pixel can draw up to 60 milliamps at maximum brightness (white). ie. 20 mA for each colour (red, green and blue). Therefore you should not try to power the LED strand directly from the Arduino, because the strand will draw too much current and damage the microcontroller(and possibly your USB port too). The LED strand will therefore need to be powered by a separate power supply. The power supply must supply the correct voltage (5V DC) and must also be able to supply sufficient current (1.5A or greater per strand of 25 LEDs).

Excessive voltage will damage or destroy your LED pixel strand. The LEDs will only draw as much current as they need, however your power supply must provide at least 1.5A or greater for each strand. If you chain two strands together, you will need a 5V 3A power supply.

RGB LED pixel strand connection

There are 25 LED pixels per strand. Four of the wires at each end of the strand are terminated with a JST connector. The red wire is for power (VCC), blue wire for ground (GND), yellow wire is for Data, and green wire for Clock. A spare red wire (VCC) and a spare blue wire (GND) are attached to the ends of each strand for convenience, however, I did not use either. Please double check the colour of your wires... they may be different.

If you want to attach the LED strand to a breadboard, you can cut the JST connector off and use the LED pixel strand wires. Alternatively, if you would prefer to preserve the JST connector, you can simply insert jumper wires (or some male header pins) into the JST connector, and then plug them into the breadboard as required.

Each LED pixel is individually controllable using two pins on your Arduino. The strand is directional. i.e. There is an INPUT side and an OUTPUT side. The strand should be connected such that wires from the microcontroller are attached to the INPUT side of the first LED pixel. The arrows on each LED show the direction of data flow from INPUT to OUTPUT. The arrow on the first LED pixel should be pointing towards the second LED pixel, NOT towards the breadboard.

Other considerations

As a precaution, you should use a large capacitor across the + and - terminals of the power supply to prevent the initial onrush of current from damaging the RGB LED pixels. I used a 4700uF 16V Electrolytic capacitor for this purpose. According to Adafruit, a 1000uF 6.3V capacitor (or higher) will also do the trick. You may also want to consider a 330 ohm resistor between the Arduino Digital pin and the strand's DATA pin.

If you want to power the Arduino using the regulated 5V external power supply. Disconnect the USB cable from the Arduino, and then connect the positive terminal of the power supply to the 5V pin on the Arduino. Be warned however, that excess voltage at this pin could damage your Arduino, because the 5V regulator will be bypassed.
 
Providing the USB cable is NOT connected to the Arduino, it should now be safe to plug the power supply into the wall. This setup will allow you to power the RGB LED pixel strand and the Arduino using the same power supply.
 
WARNING: Never change any connections while the circuit is powered.

For more information about these RGB LED pixel strands, you may want to visit the Adafruit site. Adafruit was the source for most of these RGB LED pixel Strand precautions.

Fritzing diagram

The following diagram demonstrates how to connect the RGB LED pixel Strand to the Arduino and to the External 5V power supply.

This diagram was created using Fritzing

Connection Instructions

LightBox assembly

You will need to drill a 12mm hole into the craft timber box for each LED on the strand. It is worth taking the time to make accurate measurements before drilling the holes.
 
I made 12 holes for the outside circle pattern (12cm diameter), 6 holes for the inside circle pattern (8cm diameter), and a hole in the centre. I also made two holes at the front of the box, two on the left side, and two on the right side. I made one last hole at the back of the box for the 2.1mm DC power line socket.
 
Therefore you should have a total of 26 holes in the box. 25 of the holes are for the RGB LED pixel LEDs and one for the external power supply socket.

The lid of the box is about 19.5cm x 14.5cm long, which makes for a very tight squeeze. Probably too tight, because you have to account for the inner dimensions of the box. The inside of the box is used to house the Arduino, breadboard, the chipset side of the LEDs and cables/components. The inner dimensions of the box are 18cm x 13cm. Therefore, the housing for the LED chipset PCB (1.8cm x 2.5cm) prevented the box from closing. I used a Dremel to carve out the space required to close the lid.

Each LED is approximately 8cm apart on the strand, however, if you are really keen, you could cut the wires and extend them to any distance you require. But keep in mind that each LED is mounted on a small PCB (with a WS2801 chipset).You will therefore need to leave a minimum of 2cm between each 12mm hole to accomodate the size of the PCB+LED. If you plan carefully, you can probably squeeze a couple of LEDs within a distance of 1cm... but I would recommend that you give yourself a bit more room, because the PCBs are not square, and there is a good chance that you will have to start all over again.

In hindsight, I could have made the circle patterns a bit smaller, however I don't know if I could have packed these LEDs any closer. The diameter of the inner circle pattern must be at least 2cm smaller than the outer circle pattern. So I think "a bigger box" would have been the best option.

When the paint is dry, insert the LEDs into the drilled holes in number order.
You can see the end result below.

Project Pictures

These pictures show the Light box after it has been drilled and painted. The LEDs have been inserted into their respective holes, and all wires + Arduino + breadboard are hidden within the box.

Concluding comments

Once you start writing LED animations for the RGB LED pixel Lightbox, it is very hard to stop. The colour combinations

If you like this page, please do me a favour and show your appreciation :

 
Visit my ArduinoBasics Google + page.
Follow me on Twitter by looking for ScottC @ArduinoBasics.
I can also be found on Pinterest and Instagram.
Have a look at my videos on my YouTube channel.

This project would not have been possible without OpenLab's collaborative effort.
Please visit their site for more cool projects.

However, if you do not have a google profile...
Feel free to share this page with your friends in any way you see fit.

Project 3: RF Remote Control Emulation

In the first tutorial, I introduced the 433 MHz Transmitter and Receiver with a simple sketch to test their functionality. In the second tutorial, the 433MHz receiver was used to receive a signal from an RF remote. The RF remote signal was coded based on the pattern and length of its HIGH and LOW signals. The signals received by the remote can be described by the code below:

 
Code comparison table

The RF remote that I am using transmits the same signal 6 times in a row. The signal to turn the light on is different from that used to turn the light off. In tutorial 2, we were able to "listen to" or receive the signal from the RF remote using the RF receiver. I thought it would be possible to just play back the signal received on the Arduino's analogPin, but the time it takes to perform a digital write is different to the time it takes to do an AnalogRead. Therefore it won't work. You need to slow down the digitalWrite speed.
I would like to find out if it is possible to apply this delay to all 433 MHz signal projects, however, I only have one 433 MHz remote.

If the delay in your project is the same as mine (or different) I would be keen to know - please leave a comment at the end of the tutorial.

We are going to use trial and error to find the optimal digitalWrite delay time. We will do this by slowly incrementing the delay until the transmission is successful. The transmission is considered successful if the fan-light turns on/off. All we have to do is count the number of transmissions until it is successful, then we should be able to calculate the delay.

 

Parts Required

• Arduino UNO or compatible board
• Breadboard
• Wires
• RF Module (433 Mhz) - Transmitter and Receiver pair 
• Mercator Ceiling Fan/Light with Remote

 

The Transmitter Fritzing Sketch

 
 

RF Calibration - Arduino Sketch

I used an array to hold the RF code for light ON and light OFF. Each number within the code represents a specific sequence of HIGH and LOW lengths. For example, 2 represents a SHORT HIGH and a LONG LOW combination. A short length = 3, a long length = 7, and a very long length = 92. You need to multiply this by the timeDelay variable to identify how much time to transmit the HIGH and LOW signals for.
The short and long lengths were identified from the experiments performed in tutorial 2 (using the RF receiver). Each code is transmitted 6 times. The LED is turned on at the beginning of each transmission, and then turned off at the end of the transmission. The timeDelay variable starts at 5 microseconds, and is incremented by 10 microseconds with every transmission.
In the video, you will notice that there is some flexibility in the timeDelay value. The Mercator Fan/Light will turn on and off when the timeDelay variable is anywhere between 75 and 135 microseconds in length. It also seems to transmit successfully when the timeDelay variable is 175 microseconds.
So in theory, if we want to transmit a signal to the fan/light, we should be able to use any value between 75 and 135, however in future projects, I think I will use a value of 105, which is right about the middle of the range.

Video

  Now that I have the timeDelay variable, I should be able to simplify the steps required to replicate a remote control RF signal. Maybe there is room for one more tutorial on this topic :)

Update: Here it is - tutorial 4
Where you can record and playback an RF signal (without using your computer).

Project 3: RF Remote Control Emulation

In the first tutorial, I introduced the 433 MHz Transmitter and Receiver with a simple sketch to test their functionality. In the second tutorial, the 433MHz receiver was used to receive a signal from an RF remote. The RF remote signal was coded based on the pattern and length of its HIGH and LOW signals. The signals received by the remote can be described by the code below:

 
Code comparison table

The RF remote that I am using transmits the same signal 6 times in a row. The signal to turn the light on is different from that used to turn the light off. In tutorial 2, we were able to "listen to" or receive the signal from the RF remote using the RF receiver. I thought it would be possible to just play back the signal received on the Arduino's analogPin, but the time it takes to perform a digital write is different to the time it takes to do an AnalogRead. Therefore it won't work. You need to slow down the digitalWrite speed.
I would like to find out if it is possible to apply this delay to all 433 MHz signal projects, however, I only have one 433 MHz remote.

If the delay in your project is the same as mine (or different) I would be keen to know - please leave a comment at the end of the tutorial.

We are going to use trial and error to find the optimal digitalWrite delay time. We will do this by slowly incrementing the delay until the transmission is successful. The transmission is considered successful if the fan-light turns on/off. All we have to do is count the number of transmissions until it is successful, then we should be able to calculate the delay.

 

Parts Required

• Arduino UNO or compatible board
• Breadboard
• Wires
• RF Module (433 Mhz) - Transmitter and Receiver pair or the 315 Mhz version
• Mercator Ceiling Fan/Light with Remote

 

The Transmitter Fritzing Sketch

 
 

RF Calibration - Arduino Sketch

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128

/*    Transmit sketch - RF Calibration      Written by ScottC 17 July 2014      Arduino IDE version 1.0.5      Website: http://arduinobasics.blogspot.com      Transmitter: FS1000A/XY-FST      Description: A simple sketch used to calibrate RF transmission.            ------------------------------------------------------------- */  #define rfTransmitPin 4  //RF Transmitter pin = digital pin 4  #define ledPin 13        //Onboard LED = digital pin 13    const int codeSize = 25; //The size of the code to transmit  int codeToTransmit[codeSize]; //The array used to hold the RF code  int lightON[]={2,2,2,2,1,4,4,4,4,5,1,4,4,4,4,4,4,5,2,2,1,4,4,4,6}; //The RF code that will turn the light ON  int lightOFF[]={2,2,2,2,1,4,4,4,4,5,1,4,4,4,4,4,4,5,2,2,2,2,2,2,3}; //The RF code that will turn the light OFF  int codeToggler = 0; //Used to switch between turning the light ON and OFF  int timeDelay=5; // The variable used to calibrate the RF signal lengths.      void setup(){    Serial.begin(9600); // Turn the Serial Protocol ON    pinMode(rfTransmitPin, OUTPUT); //Transmit pin is an output    pinMode(ledPin, OUTPUT);     //LED initialisation sequence - gives us some time to get ready   digitalWrite(ledPin, HIGH);   delay(3000);   digitalWrite(ledPin, LOW);   delay(1000);  }         void loop(){     toggleCode();    // switch between light ON and light OFF     transmitCode();  // transmit the code to RF receiver on the Fan/Light          timeDelay+=10;    //Increment the timeDelay by 10 microseconds with every transmission     delay(2000); //Each transmission will be about 2 seconds apart.   }               /*----------------------------------------------------------------      toggleCode(): This is used to toggle the code for turning                     the light ON and OFF    -----------------------------------------------------------------*/   void toggleCode(){     if(codeToggler){        for(int i = 0; i<codeSize; i++){          codeToTransmit[i]=lightON[i];        }             } else{       for(int i = 0; i<codeSize; i++){          codeToTransmit[i]=lightOFF[i];        }      }     codeToggler=!codeToggler;   }                   /*-----------------------------------------------------------------     transmitCode(): Used to transmit the signal to the RF receiver on                     the fan/light. There are 6 different HIGH-LOW signal combinations.                                           SH = short high   or  LH = long high                                         PLUS          SL = short low    or    LL = long low    or    VLL = very long low                        -------------------------------------------------------------------*/    void transmitCode(){     // The LED will be turned on to create a visual signal transmission indicator.     digitalWrite(ledPin, HIGH);        //initialise the variables     int highLength = 0;     int lowLength = 0;          //The signal is transmitted 6 times in succession - this may vary with your remote.     for(int j = 0; j<6; j++){       for(int i = 0; i<codeSize; i++){         switch(codeToTransmit[i]){           case 1: // SH + SL             highLength=3;             lowLength=3;           break;           case 2: // SH + LL             highLength=3;             lowLength=7;           break;           case 3: // SH + VLL             highLength=3;             lowLength=92;           break;           case 4: // LH + SL             highLength=7;             lowLength=3;           break;           case 5: // LH + LL             highLength=7;             lowLength=7;           break;           case 6: // LH + VLL             highLength=7;             lowLength=92;           break;         }                      /* Transmit a HIGH signal - the duration of transmission will be determined             by the highLength and timeDelay variables */          digitalWrite(rfTransmitPin, HIGH);          delayMicroseconds(highLength*timeDelay);                    /* Transmit a LOW signal - the duration of transmission will be determined             by the lowLength and timeDelay variables */          digitalWrite(rfTransmitPin,LOW);          delayMicroseconds(lowLength*timeDelay);       }     }     //Turn the LED off after the code has been transmitted.     digitalWrite(ledPin, LOW);  }

I used an array to hold the RF code for light ON and light OFF. Each number within the code represents a specific sequence of HIGH and LOW lengths. For example, 2 represents a SHORT HIGH and a LONG LOW combination. A short length = 3, a long length = 7, and a very long length = 92. You need to multiply this by the timeDelay variable to identify how much time to transmit the HIGH and LOW signals for.
The short and long lengths were identified from the experiments performed in tutorial 2 (using the RF receiver). Each code is transmitted 6 times. The LED is turned on at the beginning of each transmission, and then turned off at the end of the transmission. The timeDelay variable starts at 5 microseconds, and is incremented by 10 microseconds with every transmission.
In the video, you will notice that there is some flexibility in the timeDelay value. The Mercator Fan/Light will turn on and off when the timeDelay variable is anywhere between 75 and 135 microseconds in length. It also seems to transmit successfully when the timeDelay variable is 175 microseconds.
So in theory, if we want to transmit a signal to the fan/light, we should be able to use any value between 75 and 135, however in future projects, I think I will use a value of 105, which is right about the middle of the range.

Video

  Now that I have the timeDelay variable, I should be able to simplify the steps required to replicate a remote control RF signal. Maybe there is room for one more tutorial on this topic :)

Update: Here it is - tutorial 4
Where you can record and playback an RF signal (without using your computer).