In this project we will make automated room with different type of sensors. In which we will use different type of sensors. We will use Intruder, Temperature,Gas,LDR and Fire sensors. IR for Checking indtruder. LDR for lights. Moisture for garden water pump control. Fire sensor for security purpose.
A GSM modem will be attached serially using Max232 with the Micrcontroller. To SMS alert for any detection.
It will detect the signal sensor then it will give signal on indicator and we will use 16*2 LCD for display fault on LCD. Here in this project we also show that how we detect a LPG gas or any type of gases and if we detect a gases then alarm is on, doors glasses will open or doors will open and the same time lcd display shows the gas detection display . lpg gas sensors are for future point of view, because of increasing cost of petrol, most of car owner are using LPG gas car kit/ If the gas is detected then relay is off and break the supply of gas applied to the vehicle or we can control any type of electrical connection on or off by this relay operated logic.
Main part of this project is gas sensor.
Here we use TGS gas sensor. This sensor is a 6 pin sensor . Top and bottom of the sensor is covered with 100 mesh stainless stell wire cloth. The heart of the sensor is the cylindrical form in the middle of the unit. The cylinder is a ceramic material with the SnO2 material deposited on its surface. The heater coil is located inside the ceramic cylinder. The heater has a resistance of 38 ohms.
Output of the gas sensor is connected to npn transistor and the ic 555 as a monostable trigger ic. Sensor gives high signal to npn transistor. Transistors emitter is connected with ground. And collector connected with NE555 timer. Timer gives output to npn transitor. Second npn transistor gives low signal to mcrcontroller. We know microcontroller default o/p is high.As the sensor is detect a gas then ic 555 activate automatically and then output of the ic 555 is connected to the microcontroller circuit.
In the microcontroller circuit we use ic 89s51 controller. Use of this is is to control the one or many relay logic and at the same time show the message on the lcd display. If no gas is detected then display shows a everything is ok . If the gas is detected then show a warning message on the screen and at the same time relay off the supply unit.
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
In ldr circuit we used two transistors npn 548. we get two inputs at base of first npn transistor. A variable resistance of value 5k connected with base of first tr.
Second input to transistor is connected to vcc via LDR. LDR is of 50ohm when get max. light at base of LDR. When npn will get high signal at basethen it will get activated. Transoistors collector is connected with VCC and emitter connected with base of other npn transistor. Now other npn transistors collector connected with microcontroller and emitter connected with ground. It connected with pin 1.4 of mcu.
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.