Halloween prop 2015

It was early September when a friend approached me about a Halloween costume project. “I heard you could augment a gun prop with LEDs!”  Intrigued, I encouraged her to elaborate more. She wanted to recreate the character, Rocket, from Guardians of the Galaxy to rest on her shoulder while she was dressed as something else.  Then she mentioned using a puppet for the raccoon and the project took a life of it’s own.

I had 6 short weeks to augment a Nerf Blaster with a sequence of LEDs, animate the head of a raccoon puppet, and make an industrial backpack to go along with the gun.  I drafted an overall plan for this attempt:

The Gun:

3 bright White LEDs ( 80mA each) for inside the barrel.

2 Purple LEDs for the tip of the muzzle

10 orange LED’s distributed to the chambers and butt of the stock.

The Backpack:

1  Blue Circular Bar-graph LED (with 16 LEDs)

1 tri-color LED

Racoon Puppet:

2 Red LED’s for the eyes

1 mini position servo 180 degrees for head movement

2 condenser microphones for the ears

I wanted a firing sequence that would start at the backpack with the tri-color LED cycling through it’s rainbow while the circular Bar graph started up. At about halfway around the circular bar-graph, a few of the orange LEDs will start to light up ( flames). At full circle, the bright white LED’s in the barrel would fire a sequence of 3 pulse with the purple LED’s as an effect on the muzzle. Then the rest of the Orange LED’s would all be lit ( after burn) while the Circular LED cycles down.

For the Raccoon, his eyes would stay lit. The intention was to have him noise activated. If the left ear picked up a noise  louder than the right ear, move head to the left. The same for the right and if the sound was loud ( a clap or shout) the firing sequence for the gun would start. That was the intent anyway. The problem was the sampling rate for the analog input was not what was desired with all the other functions happening and no time allowed for optimization.  It will be a follow-up feature. Instead I used it for randomization of the head and firing sequence which made it less like an automaton from cheesy restaurant.

Due to limited time, I decided to basically use an Arduino DUE because it had 54 GPIOs to cover the 32 LEDs I wanted to sequence and still have room for the servo and the condenser Microphone pickup. I spent a considerable amount of time soldering current limiting resistors for the LED’s as well as a transistor driver for the larger and brighter white LED’s which would be too much for an Arduino’s GPIO.

Each LED had heat shrink and wire run all down to the base of the NERF Blaster and came together in a ribbon cable that fed back into the backpack.  On the Backpack ( sorry limited pictures before I handed off to the owner), I had to carefully solder the resistors and feed them through holes. I took apart a Dewalt large capacity chalk line to create the industrial pack for Rocket. The wind-up hole was perfect for the color LED and the Circular LED fit perfect around it.  All of this was thread through the outer casing and then soldered them onto  a board on the inside and another ribbon cable mated with the Arduino.

I only had a mini servo. To maximize the movement, I created a metal frame from a robotic’s mechanical assembly kit and mounted it on the spindle of the servo. I tested the proper placement inside the puppet and found the ideal placement was inside the nose of the raccoon to get the most movement.

I coded up the arduino and ran several tests with 3 AA batteries.  I was able to get about 4 to 6 hours of life before the batteries needed to be changed

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I had a working Halloween prop for my friend in time for her to do some last minute augmentations ( she made is jump suit). She took it up to Salem MA to join in the fun. She got a lot of strange looks and wonderment from her little animated Rocket.