The New Hobbyist

So now that the hard part was over (writing the animation sketch for my Arduino) I started on the fun part, making the Arc Reactor a wearable Halloween prop.

About halfway through my build I found a great post on building a prop Arc Reactor on Instructables by msraynsford which used most of the same materials I had picked for my own. Great minds think alike I guess…

I picked up a rectangular PCB at Radioshack to mount my LEDs to. It seemed like a secure way to keep everything in place while wearing it, plus an excuse to brush up on my soldering skills. I used a scroll saw to cut the PCB into a 4 inch round. Then mounted the LEDs on the board spaced in an even ring (note: the extra LEDs pictured on the PCB would have resulted in my Arduino turned into a pile of slag and were removed). I also used this time to drill a couple of holes in my Altoids tins for holding my 9v battery and Arduino board.

Cutting PCB to size

4 inch round PCB

LEDs mounted in a ring

After cutting the PCB to size I soldered the LEDs and resistors to the board and some lengths of hookup wire so I could feed them directly into the board for testing.

I had my fingers crossed the whole time and as you can see from the video everything worked just as expected. Somehow I managed to do it all without soldering my fingers together.

Now that I had a working board I cut off the ends of an old serial cable and used the 8 conductor wire to extend the hookup wire. I added about 2 feet of wire or enough to reach the battery pack I planned on keeping in my pocket and wired a 9 volt battery to the Arduino board for power. I also hot glued the hookup wires into the outputs on the Arduino board. From what I’ve seen online this is the best semi-permanent way to make connections on the board and comes off with a little rubbing alcohol. Then fit everything snugly into my two Altoids tins so I could easily fit the battery and Arduino around in my pocket.

Ready for soldering

Just enough wires for the job

The modeling plastic I used comes in a container as small white plastic beads. When heated with hot water they turn transparent and mailable like a firm clay. As it cools it returns to a very hard white plastic. Since this happens fairly fast I wasn’t able to take any pictures of the molding process. I used items I had around the house with shapes similar to what I wanted to see on the faceplate and pressed the plastic around them. Then while the plastic was still warm I stretched it around the sides of the PCB and allowed it to cool. After cooling it held on really firmly to the board. I also velcro’ed a pocket on the inside of a t-shirt to hold the arc reactor while I was wearing it. The Arc Reactor and Arduino ran for over 8 hours on one 9 volt battery (I left it on over night so I’m not sure of the exact time).

Below are pictures of the finished Arc Reactor.

And the final video

Overall I’m pretty happy with how it turned out. I’m planning on taking what I learned and trying to get my hands on some laser cut metal parts for next year. I’d like the Arc Reactor to look as cool outside of the shirt as it did inside.

After receiving my Arduino UNO and playing with it for a bit I realized I needed to pick a project with a goal if I really wanted to learn how to use it. Playing around with tutorials online is fun and all but I find trying to complete a project forces me to learn and retain a lot more information.

So after learning how to make LEDs blink, photocells collect data and piezo speakers buzz (thanks Adafruit!) I set my sights on a project with a due date one month in the future. Completion date? Halloween 2010.

Enter the Arc Reactor.

This seemed like a pretty reasonable project for an Arduino newbie considering it’s really just some glowing LEDs under a shirt. Plus who doesn’t like Iron Man?

So here’s my supply list…

Supplies:

Arduino Duemilanove (I didn’t know how hot gluing would work and didn’t want to sacrifice my UNO)
7 5mm White LEDS
Rectangular PCB large enough to cut into a 4 inch circle
Hook up wire
Length of 8 conductor wire (I used an old serial cable)
InstaMorph Moldable Plastic
Bread board
Resistors (150 ohm seemed to work OK)
Altoid tins for battery pack/arduino holder
Hot glue
9v battery + battery hookups
Gold craft wire
t-shirt with an internal pocket

After collecting everything I needed for the build I started working out the Arduino code. This could have been accomplished without the Arduino and static lighting but it’s so much cooler with animated LEDs!

The idea was to mount 6 LEDs in a ring shape around a PCB with one LED in the center. The animation sequence I came up with looks like this.

10 Scrolling LEDs (outer 6 only)
20 All 7 on (for 60 seconds)
30 Pulsing LEDs (outer 6 only)
40 All 7 on (for 60 seconds)
50 GOTO 10

I used the pulse with modulation (PWM) digital outputs on the Arduino to control the pulsing animation. There are only 6 outputs that support PWM so only the outer ring of LEDs pulse. Here’s a quick test video of the scrolling animation (note: I didn’t have any resistors after the LEDs. I don’t recommend this, despite what some websites say my Arduino was red hot after a few minutes).

The physical build of the Arc Reactor will be in a follow up post. I’ve included the code I used to animate the LEDs below. I’m sure this could have been done in a much more elegant way but I’m new to Arduino programming and it worked.

/*
Tony Stark

Built this in a cave, with a box of scraps

TheNewHobbyist 2010
http://www.thenewhobbyist.com
 */

// Initialize Variables
int blinkCycle = 0;
int newLed[7] = {3, 5, 6, 9, 10, 11};
int i;
int fadeCycle = 0;

void setup() {         
// Nothing needed, config mode? blink all LEDs?
}

void loop() { 

if (blinkCycle == 6) { // Skip blink if t's already run 6 times
  goto fade;
}

for (i = 0; i < 6; i = i + 1)  {
  
    // Blink array in order
    analogWrite(newLed[i], 255);
    delay(200); // change for slower blinking
    analogWrite(newLed[i], 0);
}
    
    if (i == 6) // If finished array...
    {
      i = 0; // start over
      blinkCycle++; // count times through loop

if (blinkCycle == 6) { // blinked x times already, LIGHT IT UP
    analogWrite(newLed[0], 255);
    analogWrite(newLed[1], 255);  
    analogWrite(newLed[2], 255);
    analogWrite(newLed[3], 255);  
    analogWrite(newLed[4], 255);  
    analogWrite(newLed[5], 255);    
    delay (60000); // wait between animations
}
    }

fade:

if (blinkCycle == 6) { 
Serial.println("DONE");
   
  for(int fadeValue = 0 ; fadeValue <= 255; fadeValue +=5) {  // fade in
    analogWrite(newLed[0], fadeValue);
    analogWrite(newLed[1], fadeValue);  
    analogWrite(newLed[2], fadeValue);
    analogWrite(newLed[3], fadeValue);  
    analogWrite(newLed[4], fadeValue);  
    analogWrite(newLed[5], fadeValue);      
    delay(30);                            
  } 

  for(int fadeValue = 255 ; fadeValue >= 10; fadeValue -=5) { // fade out
    analogWrite(newLed[0], fadeValue);
    analogWrite(newLed[1], fadeValue);  
    analogWrite(newLed[2], fadeValue);
    analogWrite(newLed[3], fadeValue);  
    analogWrite(newLed[4], fadeValue);  
    analogWrite(newLed[5], fadeValue);        
    delay(30);   
  }  
fadeCycle++;
if (fadeCycle == 6) { // if faded x times LIGHT IT UP
    analogWrite(newLed[0], 255);
    analogWrite(newLed[1], 255);  
    analogWrite(newLed[2], 255);
    analogWrite(newLed[3], 255);  
    analogWrite(newLed[4], 255);  
    analogWrite(newLed[5], 255);    
    delay (60000); // pause inbetween animations
}

}

  if (fadeCycle == 6) {
    blinkCycle = 0; // reset
    fadeCycle = 0; // reset
  }

}