Automatic Room Light Controller with Visitor Counter
Automatic Room Light.docx
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A ordinary automatic room power control circuit has only one light sensor. So when a person enters the room it gets one pulse and the lights come ‘on.’ When the person goes out it gets another pulse and the lights go ‘off.’ But what happens when two persons enter the room, one after the other? It gets two pulses and the lights remain in ‘off’ state. The circuit described here overcomes the above-mentioned problem. It has a small memory which enables it to automatically switch ‘on’ and switch ‘off’ the lights in a desired fashion. The circuit uses two LDRs which are placed one after another (separated by a distance of say half a meater) so that they may separately sense a person going into the room or coming out of the room. Outputs of the two LDR sensors, after processing, are used in conjunction with a bicolor LED in such a fashion that when a person gets into the room it emits green light and when a person goes out of the room it emits red light, and vice versa. These outputs are simultaneously applied to two counters. One of the counters will count as +1, +2, +3 etc when persons are coming into the room and the other will count as -1, -2, -3 etc when persons are going out of the room. These counters make use \of Johnson decade counter CD4017 ICs. The next stage comprises two logic ICs which can combine the outputs of the two counters and determine if there is any person still left in the room or not. Since in the circuit LDRs have been used, care should be taken to protect them from ambient light. If desired, one may use readily available IR sensor modules to replace the LDRs. The sensors are installed in such a way that when a person enters or leaves the room, he intercepts the light falling on them sequentially—one after the other. When a person enters the room, first he would obstruct the light falling on LDR1, followed by that falling on LDR2.
Main idea behind this project is to measure and display the number of persons entering in any room like seminar hall, conference room. LCD display placed outside the room displays this value. And when number of persons inside the room are zero, power supply inside the room can be cut using a relay interface.
This project consist of following blocks
We are going to implement the Person counter module using a 2 transmitters and 2 receivers. We are going to use Infra-Red transmitters because infrared beams are not visible to human eyes. Transmitter used are IR LEDs
We are going to use a Infrared receiver. It is a active low device which means it gives low output when it receives the Infrared rays.
This is the CPU (central processing unit) of our project. We are going to use a microcontroller of 8051 family. The various functions of microcontroller are like
I. Reading the digital input from two infrared receivers and calculate the number of persons from them.
II. Sending this data to LCD so that the person operating this project should read the number of persons inside the room.
III. Sensing the password using keypad and to check whether it is a correct password or a wrong password and rotate the stepper motor if the password entered is a correct password.
IV. Sending the data to the computer using serial port. This data consist of number of persons inside the room and the status of entered password (Correct/wrong)
We are going to use 16x2 alphanumeric Liquid Crystal Display (LCD) which means it can display alphabets along with numbers on 2 lines each containing 16 characters.
5. PC Interfacing:
We are going to use max 232 IC for pc interfacing, the values of number of persons inside the room and the status of entered password (Correct/wrong) will be sent to pc.
Application and Advantage:
1. Can be used in various rooms like seminar hall, where the capacity of room is limited and should not be exceeded. Project will display the actual number of persons inside the room.
2. Can be used in conference room, study rooms in colleges.
1. We can send this data to a remote location using mobile or internet
2. Voice alarm system can be added to indicate that room is full & persons can’t enter inside.