Instructables

Building a Sentry Gun with Laser Trip Wire System and Arduino

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Picture of Building a Sentry Gun with Laser Trip Wire System and Arduino
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*NOTE* THIS PROJECT IS DONE BY A GROUP OF STUDENTS FROM SINGAPORE POLYTECHNIC UNDER FYP SUPERVISOR TEO SHIN JEN.

Concept:
Trigger gun when laser is blocked by intruding object.

Note:
Tilting is included for expandability but not used in this project.

Skill Level:
Basic soldering and basic metal works

Things You Need:
Toy Gun(Any will do, preferably a semi-auto)
Continuous Rotation Servo Motor
Servo Motor
Servo Arms and Wheels
Arduino
Metal Sheets
Ball Bearings
Bolts
Nuts
Screws
Rubber Washers
Cable Tie
Copper Wire
Copper Strip Board
Pins
Sockets
Resistors(1K Ohm)
Light Dependent Resistor
Potentiometer(20K Ohm)
NPN Transistor(2N2222)
 
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Step 1: Building the Frame

Picture of Building the Frame
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Cut the metal sheets into 6 rectangular pieces(4 of equal length, 1 long, 1 short) and 2 square pieces.
Below are the dimensions we used:
4x 6”(inch) by 2”
1x 10.5” by 2.4”
1x 2.5” by 2.4”
1x 10” by 10”
1x 9” by 9”

Feet(6” by 2”):
Bend the 4 metal piece 90 degrees at the 2” mark and make  screw holes(at least 2) at the shorter end.
[Image 1]

Base(9” by 9”):
Make screw holes that match your feet’s at 4 corners of the metal piece to mount the feet and a hole in the center for the pivot(the hole size depend the bolt you’re using).
[Image 2]

Gun Support(10.5” by 2.4”):
Bend the metal piece 90 degrees at the 2” mark and the 6.5” mark to form a deformed U. Make screw holes(at least 2) at shorter end  and 4 holes at the other end to mount your servo.
[Image 3]

Turning Panel(10” by 10”):
Make screw holes that match the gun support’s at one corner of the metal piece and one hole in the center for the pivot(should be slightly larger than the pivot but smaller than your ball bearings).
[Image 4]

Servo Mount(2.5” by 2.4”):
Make a hole at one end to fit into the pivot and 4 holes at the other end to mount your servo.
[Image 5]

Step 2: Trigger of the Gun

Picture of Trigger of the Gun
Mount one of the servo to trigger the gun
We secure a small servo with a short servo arm onto toygun.
Tobor 2.01 year ago
use this with: http://www.instructables.com/id/Arduino-Controled-Nerf-Vulcan/ and chaos is sure to follow
The_N00b1 year ago
I hate this there are lots of good or funny ideas but i don't find any part of the project i hate germany -.-
Would like more/better video. This is unclear about what's happening in the vid. Great project, we'd like to see it working fully!
dasxodnes (author)  omalachowski2 years ago
Thanks for your comments. I have added a small description for each of the video to help the viewer better understand what I'm trying to show.
Thanks, that is helpful. You may consider setting up something of a more complete example of the project working. Something where a person walks in front of the wire and is squirted with water or illuminated with light. While I can see that your project works, it would be more satisfying for a few of you to put together a video that shows it working in a more dynamic way.

Are there any film students at your school or a school nearby? Maybe they need a sentry gun for a spy video...
bthjehiel2 years ago
Very well done.
rinusdamen2 years ago
How do you make these nice pictures with the broadboard and servo pictures? Is there a program to make them?
http://fritzing.org/
Thank you very much !
;)
chailiyh2 years ago
nice work.perfect idea.
menahunie2 years ago
*NOTE* THIS PROJECT IS DONE BY A GROUP OF STUDENTS FROM SINGAPORE POLYTECHNIC.

Since owning a gun in that country is illegal and more likely if caught with one would be either dead or a very long prison sentence.

I did similar project and used a toy robot arm to hold the paint ball pistol and used a video camera using software that detects motion and the gun would point at where the motion is detected and fire.
This project you do the same with a radio shack light beam used in stores at their doors..
@ rinusdamen: It is Fritzing. Go to - fritzing.org