Archive for October 31st, 2009

I had great fun this Halloween with a silly string shooting spider!  My plan was to use an Arduino micro-controller developer board to control my son’s “Teenage Mutant Ninja Turtle” RC car that already shoots silly string.  I didn’t get the spider to actually squirt the silly string but when you’re looking at a big black spider and something shoots silly string at you from the same direction it scares you just the same. 

I was inspired to do this 4 hour marathon build by a blog posting by Eric on www.Instructables.com. Eric created a silly string shooting pumpkin which was so incredible I just had to build a spider for Halloween that did the same.

My major problem was that once I heard about Eric’s pumpkin I only had a day to get the supplies and about 4 hours of free time to wire-up something, code it and get it out in the front yard before the kids started coming for tricks or treats.

Here is a component breakdown of the final prop.

• The red dot and arrow point to the RC car hiding under a bush.
• 2) RC car remote control.
• 3) Relay used by pin 2 on the Arduino to fire the remote control’s silly string button.
• 4) Arduino board: Duemilanove with ATmega328 Purchased from adafruit.com
• 5) Small blue servo to yank on the spiders leg: TowerPro SG-50.
• 6) Two red LEDs for spider eyes. Not on the spider I know, I ran out of dev time
• 7) Parallax Ping))) sonar sensor, held up with helping hands.
• 8 ) Big black spider

 
I originally wanted the string to shoot from the spider’s behind but I really didn’t have time for that so I hid the RC car in the bushes behind the spider and loaded it with a fresh can of silly string.  All I really had to do was get the Arduino to sense somebody getting to close to the spider’s face and then “POW!” fire the silly string using the car’s remote control.

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