Second part of project
COMPONENTS USED
Gates:
Following are the gates used in project:
Nand gates: These gates which we used in project are made from the transister transister logics.These gates are embebbed in 7400 series. IC no. for the nand gate is 7400. This IC contain 4 two input nand gate. The ground voltage is given to the 7th pin whereas supply voltage is given to the 14th pin. The numbering is started in anticlockwise from the cut. The truth table for nand gate is:
A0 A1 Output
0 0 1
0 1 1
1 0 1
1 1 0
Not gates:
Not gate is also called an inverse gate because it inverse the input. IC no. for the not gate is 7404. It contain 6 two input not gate. Truth table for the not gate is
Input output
0 1
1 0
Selector switch:Selector switch is a rotating switch. It is many input one output switch.It select the particular input and fed it to the output. In our project we have three output from the logic circuit so one output is selected at a time with the help of selector switch.
Relay:Relay is a powerful component in the electronic world. It acts as a switch. It operates on logic operations. Relay consist of a copper coil. The output of any logic circuit is given to the relay. It consist of four pin. One pin is connected to the neutral, one is connected to the main 220V supply and other two is connected to the output of the logic gates. It works on the principle of magnetic field. When the output of the logic circuit is one means 5V, then a magnetic field is produced inside the coil. Due to this magnetic field a magnetic force occur. This force attract the iron piece which is mounted above the centre of the coil. As a result the circuit is completed and a relay gives a output of 220V. when the output of the logic gates is zero then 0V is applied to the relay. Therefore no magnetic field is produced inside the coil and relay acts as a open circuit.
Water pump:
Water pump is simply used to push the water from the ground to the tank. Water pump is off many types depending upon its types on the basis of size, wattage etc. A tripical used water pump is a rotating blade type pump. When the blades inside the pump is rotated then the pump release water with a high pressure.
Transformer:
We used step down transformer in our project. This transformer step down the 220V of AC supply to 5V. Thus the number of turns in the secondary winding is less then the number of turns in primary winding.
Diodes:Diode act as a switch. When the postive side of the battery is connected to the p side of the diode then it act as a closed switch but when the postive terminal is connected to the n side of the diode then it acts as a open switch.
Capactor:Capactor is used to store the charge. It allow the DC supply but block the ac supply. Thus it is used as a filter for the dc supply. In our project it is used in rectifier circuit for filter the dc output.
Bell:Bell is used simply to alert the consumer. Its one terminal is connected to the positive dc supply other is connected to the A3 terminal of the tank. When water rises to the A3 terminal then it is grounded and the circuit is completed and bell vibrates.
WORKING
Working with gates: Initially when the tank is empty then all the four pins in the tank are open. These open pins are acts as 1.Let us consider the case of output Q1 because other case of Q2 and Q3 are similar to the Q1. Output Q1 depends upon the two input that is A0 and A3. lets suppose the initially output of Q1 is zero. This output is fed back to the gate G6. The other input of the G6 is the output of G6’ not gate, which is zero thus the two inputs of the G6 is zero so the output of the G6 (which is nand gate) is 1. This output of G6(which is1) is fed back as the input of G5, other input of the G4 is also 1( as open pin A3 act as 1). So the output of the G5 which is Q1 is zero. Thus the output of the logic circuit is zero. When the output of the logic circuit is zero then relay acts as a closed switch (because initially the spring of the relay completed the circuit. The circuit only break when the magnetic field is produced. This magnetis field oppose the spring force and relay acts as open circuit) Therefore relay, switch on the motor and the tank starts filling.
Now suppose the initial output Q1 is 1. This output is fed back as the input of the G6. Other input of G6 is already 0. so the output of this nand gate is 1. This output is fed back as the input of G5 whose one input is already one. So output Q1 is again zero. Thus unless the initial conditions the output depends upon the pins A0 and A3 when the tank is empty.
When the motor starts running, the level of the water in the tank starts rising. When the level reaches the pin A0, it become zero because water is grounded. Again the output of G6’ become one,and one input of G6 is 1 and other is zero(feed back input). Thus the output of G6 become one. This output is fed back as the input of G5 thus the two input of G5 become one and the output become again zero. Thus motor runnig althrough water level reaches to A0.
When the level reaches to A3 ( whose one pin is already one) its one input become zero and the output of the Q1 becomes 1. when the output of the logic circuit is one then the relay acts as open circuit. Thus motor stops.
Again when we use the water, therefore water level starts decreasing. when the water level decreases from A3, one input become one. Initially when the level of the water is on A3 the output is one. So when water falls from this level, this output is fed back(which is one). Thus the two inputs of G6 become one, and output become zero. This zero is fed back as one input of G5(whose one input is one). Thus output of G5 again become one and the motor remain stops at this condition.
Now when the level decreases from A0 then again all the condition discussed above is applied(which we applied when the tank is empty). And the output of Q1 become zero and the motor starts running.
RESULTS
WHEN WATER RISES
A0 | A1 | A2 | A3 | Q1 | Q2 | Q3 |
1 | 1 | 1 | 1 | 0 | 0 | 0 |
0 | 1 | 1 | 1 | 0 | 0 | 0 |
0 | 0 | 1 | 1 | 0 | 0 | 0 |
0 | 0 | 0 | 1 | 0 | 0 | 0 |
0 | 0 | 0 | 0 | 1 | 1 | 1 |
WHEN WATER FALLS
A0 | A1 | A2 | A3 | Q1 | Q2 | Q3 |
0 | 0 | 0 | 0 | 1 | 1 | 1 |
0 | 0 | 0 | 1 | 1 | 1 | 1 |
0 | 0 | 1 | 1 | 1 | 1 | 0 |
0 | 1 | 1 | 1 | 1 | 0 | 0 |
1 | 1 | 1 | 1 | 0 | 0 | 0 |
PURPOSE OF THREE OUTPUTS:
When we select the output Q1, it means that motor is only on when the tank is empty completely.
When we select the output Q2, it means that motor is only on when the water level in the tank is 1/3. Thus when the water level decrease from 1/3 level of the tank, motor automatically on and fil the tank again.
When we select the output Q3, it mean the motor is on only when the water level in the tank is 2/3.
ADVANTAGES
These three output is given to the selector switch. The selector switch selects only one output at a time. Thus we select the output level according to our need. For example in some areas there is lot of electric cuts, so they want their tanks filled with water all the time because of lack of regular electricity. So in our circuit they select the output Q3. The advantage of this is that, the level of water in their tanks will always above two third of the tank.
SOURCE OF DC SUPPLY:
A step down transformer is used. This transformer step down the 220V of ac to 5V. This 5V is given to the to the wheatstone bridge. Wheatstone bridge consist of 4 diodes and a capacter. Two diodes are set with same polarity whereas the other diodes are set with different polarity as the arm of the bridge. When the cycle of the ac is positive, the two diodes is forward biased whereas other two are reversed biased. The output is taken across the capactor which gives the pure dc supply.
ROLE OF LED:
Full form of LED is light emitting diode. When LED is forward biased it glows. So these LED ars used to indicate the level of the water. We give 5V to all the LED and other pin are dipped in 5 different levels in water. LED only glows when the water reaches the pins. Thus the level of the water is determined with the help of these LED’s.
ELECTRIC BELL:
Electric bell is used for the indication of the tank filled signal. To take the advantage of this bell, it depends upon the interest of the user because it is connected to the on\off switch. If some one does not want any bell signal, then they switch off the bell. One input of this bell is directly connected to the positive terminal of dc supply whereas the other input is connected to the A3 pin. When the water reaches the level A3, this terminal is grounded and the circuit of the bell is completed.
MANUAL ON \ OFF SWITCH:
This switch is introduced for more advantage of the user. When this switch is on then the motor on directly and at this condition the logic circuit is off. This is done with the help of the two way switch. When we switch on the motor manually then the logic action off automatically. And when we switch off this manual switch then the logic circuit operates automatically.
ADVANTAGE OF THIS MANUAL SWITCH:
Suppose someone know that the light is gone after 10 minutes and he wants to fill the tank before the electricity gone. So at this condition, the manual switch is very helpful. To take more advantage from this manual switch, switch on the bell.
POWER SWITCH:
Power switch is simply used to isolate the circuit from the main, when we don’t used this circuit.
APPLICATIONS
It is very useful circuit in case of areas facing electricity problems. It will help a lot due to its automatic on/off operation and there is no necessity that tank must be empty to start the motor, but can be adjusted to one-third or two-third of level.
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