Home Security System

To make the home security system components two circuits have been developed. One is using infrared diodes for detecting intrusion, and the other is using a heat sensor to detect fires. Both the circuits have been mounted on bread boards and a there is a plan to design a PCB in the future. For the home automation part two android apps have been developed using Google’s App Inventor Beta software. One providing a GUI for controlling of various devices and the other controlling the devices based on location entered by the end user.

While deciding about the major project, the main consideration was to make something that would be practically useful and could be utilized in our daily lives as well as various diverse fields. Theft has increased a lot in today’s world and not everyone can afford costly security system. We have tried to make cheap and effective security system. Today cell phone has become an integral part of our life and through this security system we can get security alert on our mobile phone in case of any incident say LPG leak, theft, fire irrespective of where we are.

LPG gas sensing Fire sensing Theft sensing GUI for controlling of home devices Location based automatic controlling of home devices Heat Sensor (Thermistor):A thermistor is a type of resistor with resistance varying according to its temperature. The word is a combination of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self resetting overcorrect protectors, and self regulating heating elements.

An Obstacle Sensor is an Infra Red light sensor and it senses any object which comes in the path of its IR rays. Operational Amplifier:An operational amplifier, often called an op-amp , is a DC-coupled high-gain electronic voltage amplifier with differential inputs and, usually, a single output. Typically the output of the opamp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.

High input impedance at the input terminals and low output impedance are important typical characteristics. Optocoupler:- There are many situations where signals and data need to be transferred from one subsystem to another within a piece of electronics equipment, or from one piece of equipment to another, without making a direct ‘ohmic’ electrical connection. Often this is because the source and destination are (or may be at times) at very different voltage levels, like a microprocessor which is operating from 5V DC but being used to control a triac which is switching 240V AC.

In such situations the link between the two must be an isolated one, to protect the microprocessor/microcontroller from over voltage damage. These use a beam of light to transmit the signals or data across an electrical barrier, and achieve excellent isolation. Optocoupler typically come in a small 6-pin or 8-pin IC package, but are essentially a combination of two distinct devices: an optical transmitter, typically a gallium arsenide LED (light-emitting diode) and an optical receiver such as a phototransistor or light-triggered diac.