A system to control the regime of irrigation based on the water needs of the soil without any human intervention.

1. given by:
OYEDIRAN TOBILOBA JOSEPH
10CK011291
Electrical and Electronics Engineering
Friday 10th April, 2015

2. 1. INTRODUCTION
2. AIM AND OBJECTIVES
3. METHODOLOGY
4. SYSTEM DESIGN
5. RECOMMENDATIONS
6. QUESTIONS AND ANSWERS

3. WHY THIS PROJECT ? ?

5.  Humans always had to be involved. Someone
has to be present, either continuously or
intermittently. Such time could be used for
something else!
 A lot of water is wasted in the process as there
is no way to ensure that the water actually get
to the roots of the crops. There is not even
enough water in the world for humans yet!

6. Design an irrigation system that can
autonomously control the irrigation process
and conserve water while at it.

7. • Develop a sensor to determine when irrigation
is necessary
• Develop a control circuit (the brain of the
system)
• Develop a pumping and delivery channel for
the irrigation water
• Develop a power supply unit for the system

8.  A moisture sensor was constructed to model
the electrical resistance of the soil;
 A regulated 12 volts power supply unit was
constructed to power the system;
 The control circuit was implemented using
operational amplifier and timer;
 And the pumping subsystem consisting of a
submersible low-noise micro water pump was
constructed using a small dc-operated motor.

10.  Power Supply Unit
 Step down transformer : turns ratio 16:1;
15V output
 Diode bridge
 Filtering capacitor : 2200uF
 Voltage regulator: LM7812 ; 12V output
 Noise cancelling capacitors : 0.1uF
 Unit output 12V = control circuit supply
voltage = pump’s driving voltage

12.  Moisture sensing
 Modelling soil electrical resistance
 Inverse relationship between soil moisture
content and electrical resistance
 Calibration indicated 100kilo ohms as the
sensor’s dry point for most soil samples.
 Sharp sensitivity
 Specs: probes’ length = 6cm
separating distance = 4cm
totally dry soil resistance = 1-2 mega ohms

14. The Control Circuit

19. 15.0
8.0
2.5
5.0
3.0
1.5
12.0
7.5
2.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
40 50 60 70 80 90 100 110
Irrigation
time
(seconds)
Level of soil dryness (%)
Graph of irrigation time against percentage of soil dryness
clay soil
sandy soil
loamy soil

20. For the large scale implementation of this project:
 a more powerful motor should be used;
 the control circuit be implemented using a
microcontroller in order to accommodate more
than one sensor;
 where homogenous irrigation is needed and
the crops cover every part of the area, the drip
means of irrigation should be modified into a
sprinkling system
 where there is possibility of presence of water
around where the control box is located, the
mode of power supply should be implemented
using detachable, rechargeable batteries.