I am such a guy who loves his thing very much and specially i don't like any one coming to my work space without my prior knowledge,mostly if the persons are my sibling or young kids.I need a way to make an alarm to help me protect my space and guard it properly.
But buzzer are too low in volume to implement.Until i got this . A freaking loud siren from DNA technology.
It was so loud that i had to wear plugs before i had to turn it on.
I just loved it but also needed to decrease the volume of the siren , which i achieved by using a pwm ,which i will explain later.
I coded a simple sketch in arduino to input from a ultrasonic sensor and if their is somebody near 100 cm of my workplace it ativates the alarm and stays on still the person is present.

Hey everyone,
My project uses the Microsoft Kinect for the Xbox 360 and a human biped robot. I always see companies making humans able to control biped robots, but they always make the user wear sensors. So I thought, why not create a cheap prototype of being able to control a biped robot, but just standing in front of a camera and moving around? So that't exactly what I did!
http://devpost.com/software/shadowbot-azure

The Spiderbot is an imitation of the "Transformers". It is a RC quadruped robot and has two modes of operation: spider and vehicle, just like the robots in "Transformers". It is Arduino-based and controlled by Android phone using Bluetooth. It does not have any kinematic calculation inside. The robot cannot be played on rough ground as it needs to slip slightly. You should check out the Youtube video demonstration first!
Hope you like it!