My son and I built this motion sensitive animatronics prop of an alligator head in October of 2003. I am publishing ths story on Instructables for the first time.

The Idea
First of all, before I talk about the project itself, let me first explain why I decided to write about it and put it up on the website. Yes, appearing on Larry King Live is my ultimate goal. Obviously, this puny project is not going to make it happen. I wanted to write about it to tell the folks that regardless of what you see on "This Old House" and "Monster Garage", if you don't do something on a regular basis, or as a part of your profession, simple tasks can become a project. It can be very frustrating. However, the end results are very rewarding.

My son and I have been an avid fan of Discovery and TLC on the cable. We have enjoyed shows like "Monster Garage", "Junk Yard War", "American Choppers", and "The Movie Magic" (I think that's the right name of the show). All these programs have inspired both of us in terms of creativity, and having fun while creating something. I have been thinking about building an animatronics piece for some months. My original idea was to create a motion sensitive dinosaur head, which would open its mouth and breathe fire. I mentioned this to my colleague, JR sometime in September of 2003. I also told him, I wanted to finish the project by the Halloween (in the same year). JR, an electrical engineer by education, is a walking encyclopedia of engineering knowledge. How can a man with a baldhead hold so much of information, just baffles me. JR with his wisdom, right away advised me to cut down the scope of the project. He suggested making a motion sensitive alligator head instead, a comical alligator head. His point was to focus on the mechanics of the project and use stuffed toy from Toys R Us for the head. I conceded and the Project Alligator was conceived.

The Team
Let me set the record straight. Though I am an electrical engineer by education, I am no craftsman. My son volunteered to be the creative talent behind the mould and the paintwork. Considering that I scored only 17 marks out of 50 in my arts class in 8th grade, I gladly gave him the job of the creative director. Apart from JR, there are two other people who should be mentioned here. My buddy, Nasir, who is a master craftsman in woodworking projects, provided some pointers with the movement mechanism. My friend Venu provided company for beer at various brain storming sessions at the local bar. By the way, Bud, Coors, and Miller brands are NOT thought provoking beers. Last but not the least, there are many of you, the web surfers, who provided valuable suggestions in the mechanical design and the choice of material for the mould. I got help from the following newsgroups:

rec.models.scale and rec.models.railroad

I decided to include the following functions:

Alligator should open its jaws based upon motion and close it. This cycle should continue until the motion stops.
Its eyes should light up while the jaws are in motion.
It should create effect of exhaling fire by blowing air on confetti wrapped light.

After Thoughts
The project was definitely way over budget because I bought material in large quantities because I did not know how much I needed. I justified buying tools, which I perhaps will not use again. However, every bit of this experience was a MasterCard moment, priceless.

After After Thoughts
After making this beautiful piece of work, like a fool, I sold it on eBay for $100. Three years later, in December of 2006, when I got really bugged by thought that I should never have sold it, I contacted the buyer. To my surprise, not only I was able to contact him, I managed to buy the gator back from him. So, Anthony, thanks so much for being a great human being.

Step 1: Components

These basic components were purchased from surpluscenter.com and Home Depot.

In the picture below I have:
1. A 12 Volts power supply
2. Motion sensitive lights
3. Limit switches (2 of them)
4. Four pole double throw relays (2 of them)
5. Blower
6. 17 RPM gear motor
<p>Hey, thanks man! Helped me get inspired for a full character, and you made it really easy! Great job!</p>
Thank you for the kind comments. Good luck with your project!
I like the idea and the implementation. The Intro was way too long and actually told the whole Instructable while the steps were too short and vague. It would have been nice to split up the Intro into the steps and include more detail on the construction. The video was okay, but I'd have sent the kids to another room. They were very distracting from the intent of the video.
To be fair, when the video was filmed, some 4 years ago, I doubt kabira had heard of Instructables. It's lucky he filmed that stage at all!
Thanks Vegas. Good tips. I have implemented them.
Nice project... What is controlling the blower? I am unable to view the video, Does the blower start when the mouth is open? Didnt see anything in the electrical diagram about that. I am planning on building something similar for halloween... thinking about using a vaporizor/humidifier to push out moist breath...perhaps I can add something to the water for stinky Dino breath... Also for other people interested, you can get similar motion sensors that are used for alarm systems that use 12 to 14 volt dc power... this way you can use batteries and make it more portable.
Thanks for the comments. The blower motor is connected to the same circuit as the main jaw opening motor. The only difference is that blower motor does not change direction. Good luck with the Halloween project. I looked around for 12V motion sensor circuit. There were a few available, but were expensive compared to the one I used from Home Depot ($14).
Would you mind explaining what these components are please? They look very nice but if someone were to wish to replicate the finished product they wouldn't know what the parts they need to get are.
Ah, very well then. Thank you.

About This Instructable




Bio: I am an electrical engineer by education and a software developer by profession. I am like building electro-mechanical models. I also like grilling and barbecuing ... More »
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