Infrared Based Four Wall Security System

Group- 80ETC-6, Kiit UniversityAnkush Sinha Ray, roll no- 1120008

INTRODUCTION• In the industries security system is one of the

important part. It is also required to safe guard the industry from unauthorized entry of vehicles and man.

• In this project the care is taken to design an industrial security system, in which a four zone is protected. 

• This zone control is designed with IR-based system. There are four Infrared sources stationed at different corners of the boundary line. The infrared light sources are LEDs connected to maintain an un-interrupted link between the transmitter and receiver in the normal condition. The Infrared-based system is very much advanced and works very much accurately. This type of devices are designed and marketed by the different multinational companies.

•What is Infrared Radiation?•Infrared (IR) radiation is

electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. Infrared radiation spans three orders of magnitude and has wavelengths between approximately 750 nm and 1 mm.

Circuit Description Power supply• Basically the power supply used for the

transmitter and receiver is arranged from a battery. Along with the battery the power supply requirement are +12 Volt and +5Volt

•The power supply is basically consisting of three sections as follows

•Step down section•Rectifier Section•Regulator section

1) IR TRANSMITTER:

•IR LED •The IR LED is also light emitting diode but

the junction is made out of such material that the transition of electron between the bands emits quanta of energy( E=h) having a particular frequency which is having a particular characteristic. When a diode emits a particular characteristic signal having frequency in the range of infrared then, that diode is called a infrared emitting diode

2) The IR detector diode is the device, which sense the IR signal. This diode is normally connected in reverse biased condition in series with a resistance to limit the PIV. The resistance connected in series develops an I x R drop across it and that drop increases as the intensity of IR signal. There is coupling capacitor to couple IR Data and reject the ambient signals

3) A photo diode is light sensitive device the junction of the photo diode is such that it generates carriers when the lights fall on it. There are different type of diodes, which generates carriers in different magnitudes at different frequency this depends on the nature and doping of the junction

Operation• the photodiode is used as signal (data) detector purpose

to detect the IR signal (data) from the IR transmitter LED section. Whenever the signal is transmitted from the IR transmitter LED, the signal is received at the photodiode receiving section. The receiving signal is very weak in strength, for that we used an amplifier. The output of the photodiode is given as input to a Op-amp ( LM393) through a resistor, which is configured as a comparator and the reference voltage is set at non-inverting terminal of the operational amplifier. There is a 10K variable resistor which is connected between +12 Volt and Ground and the variable terminal is connected to the OP-AMP for providing the threshold value. The out put of the LM393 swings in between +Vsat and –Vsat, even for a small variation of signal across the threshold value.

• That output signal is not compatible with the Microcontroller because of the high current; that output from the Op-amp is given to the signal conditioning i.e. the signal is given to the base of the transistor through a base resistance between 1K – 43K and the collector is connected to Vcc = +5Volt in series with a 10K resistance and the output is taken from the collector.

• The output of the photo diode voltage (3v) goes to the input of the comparator. In the comparator we have set the voltage say 3.5Vto the inverting terminal. In this case inverting terminal is greater than the non-inverting terminal. That means output of the comparator is LOW i.e, the infrared is absent at the photodiode. If the infrared is present at the photo diode,

• the corresponding voltage will increase. That voltage goes to the input of the non-inverting terminal(which is a reference voltage) of the OP-amp (lm393) which is configured as a voltage comparator. In this comparator we have set the voltage say 3.5V to the inverting terminal. In this case non- inverting terminal is greater than the inverting terminal. That means output of the comparator goes to +Vsat is HIGH. We have connected a led indicator ckt at the o/p of the comparator to indicate the high low condition of comparator.

•Future Expansion:•This project can be developed with Micro

controller and can be interfaced to PC for controlling the large numbers of zones with multiple sensors. Many other features such as vehicle counting system, Visitor counting system can be introduced.

•Conclusion: This project has functioned satisfactorily

in the laboratory condition. It may require slight modification to make suitable for working in the out door conditions. The results obtained are well below the level of experimental Errors.