It’s not rocket science

A while back I bought an Estes model rocket kit for my niece and nephew. Upon opening the package and seeing this

I thought, “Lame.”

So I set about making a custom launch controller. The idea behind the controller was to further spark the imagination of the kids. To that end, it has four ports, a countdown LED, and configurable launch patterns.

I wanted it to look somewhat retro and have lots of stuff to interact with prior to launching a rocket. The idea being to extend the amount of imagination time before igniting the rocket motor. It struck me that just pushing a button doesn’t give a kid a whole lot of time to play the role of the engineer in the launch room.

The controller has four different launch patterns controlled by the two switches at the top to the right of the on/off switch, a countdown LED, four switches at the bottom that provide safety override for the four launch ports and an LED ringed launch button.

The fifth port on the right side in the photo below is 12V in, the four on the left, are 12V out to the rocket’s electronic ignition fuses.  Hooking this up to a car battery works quite well.

The enclosure was designed in Autodesk Inventor and cut from 1/4′ (sides and bottom), 1/8″ (top) acrylic on Crashspace’s laser cutter.

Internally it’s controlled by an Atmel ATmega328 which drives transistors to switch the 12V out to the electronic ignition fuses, displays the LED pattern corresponding to the launch pattern, and runs the LED countdown.  There’s a small coin battery inside the case running the LEDs and arduino.

A mess of wires, with the eagle schematic I did just to keep my head straight while soldering everything up.

 

Software was written using Atmel’s AVRStudio.  e.g.  No arduino bootloader on that ATmega328 running an arduino sketch.  Straight up, old fashioned, C.

Living in the middle of a large metropolitan area, figuring out how to safely test the device was a challenge.  I initially used 12V auto light bulbs to verify the basics worked, but lets face it, that’s not nearly as fun as fire and smoke.  So I built a test rig, inserted some engines and had some fun.

Software can be found here: https://github.com/cmacfarl/LaunchController.git

~ by skatefriday on February 1, 2014.