A SOIL MOISTURE SENSOR FOR AUTOMATED MICRO IRRIGATION SYSTEM

摘要

The invention relates to a soil moisture sensor for automated micro irrigation system comprising a tensi-meter having a porous cup (1) and connecting tube (2), the said connecting tube is attached to a hole in the bottom cap (4) of a cylinder (3), the said cylinder contain a piston (5) attached to a piston rod (6) and said piston rod protruding out through a hole in the top cap (7) of the said cylinder and other end of said piston rod is threaded (13) for use of a nut ( 12) to contain assembly of springs (8) and a brass plate ( 10) with washers (9, 11) and a brass strip ( 14) fixed to said cylinder such that said brass plate and said brass strip make electrical contacts to each other, said brass plate is connected by wire ( 15) to the negative terminal of a 6-V battery (7) and said bras strip is connected by a wire ( 15) to the terminal E of a 6-V relay ( 21), said 6-V relay provided with five ports ( A to E), Ports B and C are connected by wires to the motor ( 18) of the pump and the Port D is connected by a wire to the said brass strip of the sensor throuh a three port switch ( 22) , and port D is connected by a wire { 15) to the positive terminal of said 6-V battery.