In this project we will use IR sensors to detect the person.We will detect movement of person. If person detected then it will automatically switch on ATM Lights and it will trigger the message “ Some one detected.
We will use Microcontroller 8051 or AVR controller for this purpose. AVR is modified controller after 8051.
Fire detection circuit- In Fire detection circuit we used thermocouple as a sensor. Thermocouple works at nearly 70 deg to 90 deg. If it detect high temperature in your car ( that can be in engine). Then thermocouple get expanded. And give low signal to microcontroller. It is connected with the microcontroller at pin 1.3
as there is no water sensor available in the market. We used twires for water connectivity purpose. One wire is connected with mcu at pin no p1.2 and other wire connected with ground. It give low signal to mcu when connected to each other via water.
It can be used for moisture check in mats and rain detection.
IR circuit :
There is one transmitter and other reciver. Transmitter is IR LED of size 5mm.
We bias in forward bias. i.e. positive is connected with VCC via 470E resistance. And –ve is connected to ground.
In reciver side we used IR photodiode. It works in reverse bias. Negative of IR connected to positive and positive end is grounded .we take output from negative pin of sensor. We used 10k E pull up resistor to make negative end sensor high. When they are in front of each other theb it will give low signal to mcu.
Gas sensor interface.
Schimtt trigger circuit.
Relay on/off control
IN the gas sensor interface we use gas sensor as a input logic. We attach one ic 555 as with this sensor . Here ic 555 work as a monostable timer. Sensor output is connected to the ic 555 pin no 2 via npn transistor. Pin no 2 is a negative trigger ic. When sensor activate then positive output is available and this positive output is converted into negative with the help of the NPN transistor. Output of the NPN transistor is now connected to the pin no 2 of the ic 555. Pinno 4 and 8 of the ic 555 is connected to the positive supply. Pin no 1 is connected to the ground pin. Pin no 7 is the output pin. Pin no 6 and 7 is the time constant pin. Pin no 6 and 7 provide a time constant option. When ic 555 works then output is available on the pin no 3 . Now this output is switching by the further NPN transistor.One led is also connected to the transistor circuit. Output of the npn transistor is available on the collector point. This output from the collector of NPN is now connected to the microcontroller pin no 1 which is port p1.0. Pin no 40 of the controller is connected to the positive supply. We supply a 5 volt regulated power supply on this pin. For regulated power supply we use one step down transformer . Step down transformer step down the voltage from 220 volt ac to 9 volt ac. This ac is converted into dc with the help of the rectifier circuit. Here we use two diode as a full wave rectifier. Output of the rectifier is now converted into 5 volt regulated supply with the help of 7805 regulator. IC 7805 regulator provide a 5 volt constant supply to pin no 40 of the ic. Pin no 20 is connected to the ground pin. LCD is connected to the port 0. Here we use 2 by 16 lcd for display. 2 by 16 means 2 line and 16 character.
Two output is available from the controller from port P2. One output is buzzer and second output is relay output. Buzzer is on when circuit sense a gas and relay switch off the supply chain.
To control a relay we use two transistor circuit. Output from the controller is drive the pnp transistor through 1 k ohm resistor. Collector of the pnp transistor is connected to the npn transistor through 1 k ohm resistor. Collector of the NPN transistor is connected to the relay coil directly. . Here relay is for the switching purpose only . As the transistor is on relay is on and relay break the contact of supply chain.