Similar to Burglar alarm project, this is also one type of security system, where instead of observing some one auspicious in a particular area, the system will focus on the security of one single object like Jewellery box, moneybox, mobile phones, camera and so on. It is very similar to the burglar alarm project, Just you have to change one line in the code and remaining things including circuit diagram are same.
I highly recommend you to read the Burglar alarm tutorial before proceeding.
Below is the Video, with will explain you the working of this project.
I hope that, you have clear understanding about the circuit through this video. I have not given a seperate circuit diagram to you people because i want you to understand the working and not just see and make circuits. But after this video, you could still not figure out how to make circuit on this board or at your custom board then for that, i have made a small PDF file for all the steps you should follow, while making this circuit. you can download this file from here. With this, you can also download the codes of 8051 microcontroller interfacing and specially the code for this project on this git link.
Changes in code of alarming system
Below given code snippet of this project. The code for this project is absolutely same as of Burglar Alarm code. Study & download that code and do these changes explained to run that as Item protection.
Here you can see that alarm variable which is holding pin to trigger alarm ON is equated to negation of input signal comming from IR sensor. It means if there is some object (usually caliberated) in front of sensor, then it will be quite menas alarm will not be triggered and viceversa. There is only passing of input data to alarm and LEDs. There is no much data processing by 8051 in this version of alarming system.This is also not so reliable for industries, but my main aim, is to give you enough knowledge to configure 8051 microcontrollers for input, output and a systematic code arrangement. But it will give you experience to make a reliable application with good programming styles and higher microcontrollers and libraries.
I hope this article helped you. Please feel free to comment below or contact me, for any query. :)