Auto Switch Water Pump

Auto-Switch Water Pump Project Objective: The project aims to make circuit that can auto turn on and of a water pump corresponding to the water level of the tank. Description: For the water below level A, the switch is turned on For the water between level A and B, the state of the switch is unchanged For the water higher than level B, the switch is turned off. All these work is done automatically. The water level is sensed by two sensors, denoted as A and B The states of parts in the circuit: Sensor B 0 0 1

Sensor A 0 1 1

B 0 0 1

A 1 0 0

Switch 1 No change 0

The state of the sensors is corresponding to the water level: 1-the water is higher than the sensor level 0- the water is lower than the sensor level The state of B, A is the logic level of the sensors output, 1-high, 0-low Circuits: The circuits for the sensors:

The power used for the circuit is 5V DC Then how can we make a circuit that makes the output as the truth table above. The answer is quite simple, we use a RS flipflop.

The truth table for a RS flipflop is:

Mode of Op Set Reset Hold Undefined

R 0 1 0 1

S 1 0 0 1

Q 1 0 No change undefined

Q’ 0 1 No change undefined

Then we will let R= B and S= A, Switch = Q We will get the desired operation states.

For the switch to drive the water pump, we use a transistor and a Relay

MY4N OMRON 6V

U1 4 3 6 7 12 11 14 15 5

S0 R0

Q0

S1 R1

Q1

S2 R2

Q2

S3 R3

Q3

2 9 10 1

R1

Q1 H1061

2.2K

E 4043

Unfortunately, I don’t have a RS flipflop but a JK flipflop instead. So I decide to used my JK flip flop to implement this circuit The truth table of my 4027 Dual JK flip flop is shown in fig.03

Fig.03 Truth table of th 4027 Dual JK flipflop

According to the truth table, I designed my circuit as follow:

Fig.04 The circuit using 4027 Dual JK flipflop

This circuit is draw and test on Electronic Workbench Copyright© Interactive Image Technology Ltd , and fulfills the requirement I test the circuit on real board, and it works well The out put of the 4027 reacts right corresponding to the level water This project is succesful. Designed and report: Thu Nguyen van Department of Automatic Control Hanoi University of Technology Hanoi Oct 8th 2008