13-06-2012, 01:52 PM
AUTOMATIC PLANT IRRIGATION SYSTEM
Automatic plant irrigation system.pptx (Size: 478.67 KB / Downloads: 199)
INTRODUCTION
Irrigation is the key to a successful garden.
A transistor is used to drive the relay during the soil wet condition. 5V double pole – double through relay is used to control the water pump.
This project works with 5V regulated power supply.
Bridge type full wave rectifier is used to rectify the ac out put of secondary of 230/18V step down transformer.
7805 three terminal voltage regulator is used for voltage regulation.
This project uses regulated 5V, 750mA power supply.
FEATURES OF MICROCONTROLLER
8 Kbytes of In-System Reprogrammable Flash Memory
Endurance: 1,000 Write/Erase Cycles
Fully Static Operation: 0 Hz to 24 MHz
Three-Level Program Memory Lock
256 x 8-Bit Internal RAM
32 Programmable I/O Lines
Three 16-Bit Timer/Counters
Eight vector two level Interrupt Sources
RELAY
A relay is an electrically operated switch
Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts
The relay’s switch connections are usually contains COM, NC and NO.
NC = Normally Closed, COM is connected to this when the relay coilCOM = Common, always connect to this; it is the moving part of the switch is off.
NO = Normally Open, COM is connected to this when the relay coil is on
Relays can also be used to implement Boolean logic
COMPARATOR
Here electrodes acts as a sensors.
For different conditions we have different voltages
The different voltages are sensed by the comparator
Here we are using LM324 as a comparator
the water/liquid comes in contact with the electrode tip, a conductive path is established between the sense electrode and the tank wall/reference electrode.
This current is sensed, amplified and made to operate a relay whose contacts in turn can be used for annunciation/control.