How gate work

Logic gate

 The digital circuit which follows the logical relation between input and output voltages. Its system is depend in only two numerical input i.e. 0 or 1 here 0 refer to low and 1 refer to high. In this gate there is only one output for one or more than one input. There are different type of logic gate they are 

1) OR gate 

2) AND gate

3) NOR gate

4) NAND gate

1) OR gate
It is the logic gate which provide the high output if one of the input is high. It has two or more than two input and only one output. It can express as Z=X+Y.

Explanation of OR gate

The circuit diagram of OR gate using two diode D1 and D2 as shown in figure. A and B are input and Y is output. Here  0 potential mean 0 state and positive mean 1 state. The operation of OR gate is explained as follows:

• When A is 0 volt and B is also 0 volt then the diode D1 and  D2 don't conduct current hence there is no flow of current through the diode as well as load resistance Rl. So output is low i.e   Z=X+Y=0+0=0.
• When A is 0 volt and B is +5V volt then the diode D1  don't conduct D2 conduct current hence there is flow of current through the diode D2 as well as load resistance Rl. So output is high i.e Z=X+Y=0+1=1.
•  When A is +5V volt and B is 0 volt then the diode D1 conduct current but D2 don't conduct current hence there is flow of current through the diode D1 as well as load resistance Rl. So output is high i.e Z=X+Y=1+0=1.

• When A is +5V volt and B is +5V volt then the both diode conduct current hence there is flow of current through the diode as well as load resistance Rl. So output is high i.e Z=X+Y=1+1=1.

2) AND gate

 It is the logic gate which provide the high output if both the input is high. It has two or more than two input and only one output. It can express as Z=A.B

Explanation of AND gate

The circuit diagram of AND gate using two diode D1 and D2 as shown in figure. A and B are input and Y is output. Here  0 potential mean 0 state and positive mean 1 state. The operation of OR gate is explained as follows:

• When A is 0 volt and B is also 0 volt then the diode D1 and  D2 don't conduct current hence there is no flow of current through the diode as well as load resistance Rl. So output is low i.e   Z=X+Y=0+0=0.
• When A is 0 volt and B is +5V volt then the diode D1  don't conduct D2 conduct current hence there is flow of current through the diode D2 as well as load resistance Rl. So output is high i.e Z=X+Y=0+1=1.
•  When A is +5V volt and B is 0 volt then the diode D1 conduct current but D2 don't conduct current hence there is flow of current through the diode D1 as well as load resistance Rl. So output is high i.e Z=X+Y=1+0=1.

• When A is +5V volt and B is +5V volt then the both diode conduct current hence there is flow of current through the diode as well as load resistance Rl. So output is high i.e Z=X+Y=1+1=1.

3) NOR gate

 It is the logic gate which provide the high output if  both the input is low. It has two or more than two input and only one output. And the logic gate provide low output if both then input is high. Its work as shown in the given truth table. Its can be express as X = A+B.

Explanation of NOR gate

The circuit diagram of NOR using two diode D1 and D2 as shown in figure.A  and B are input and X is output. Here  0 potential mean 0 state and positive mean 1 state. The operation of NOR gate is explained as follows:

• When A is 0 volt and B is also 0 volt then the diode D1 and  D2 conduct current hence there is flow of current through the diode as well as load resistance Rl. So output is low i.e   X = A+B=0+0=1.
• When A is 0 volt and B is +5V volt then the diode D1 and D2 don't conduct current hence there is no flow of current through the diode as well as load resistance Rl. So output is low i.e X = A+B=0+1=0.
•  When A is +5V volt and B is 0 volt then the diode D1 and D2 don't conduct current hence there is no flow of current through the diode as well as load resistance Rl. So output is low i.e X = A+B=1+0=0.

• When A is +5V volt and B is +5V volt then the diode D1 and D2 don't conduct current hence there is no flow of current through the diode as well as load resistance Rl. So output is low i.e X = A+B=1+1=0.

4) NAND gate

 It is the logic gate which provide the low output if  both the input is high and if one of the the input is low then its output is high. Its can be express as AB=A+B.

INPUT		OUTPUT
A	B	A NAND B
0	0	1
0	1	1
1	0	1
1	1	0

Explanation of NAND gate

 The circuit diagram of NAND gate using two diode D1 and D2.A  and B are input and Q is output. Here  0 potential mean 0 state and positive mean 1 state. The operation of NAND gate is explained as follows:

• When A is 0 volt and B is also 0 volt then the diode D1 and  D2 conduct current hence there is flow of current through the diode as well as load resistance Rl. So output is low i.e   AB=A+B=0+0=1.
• When A is 0 volt and B is +5V volt then the diode D1 and D2 conduct current hence there is flow of current through the diode as well as load resistance Rl. So output is high i.e AB=A+B=0+1=1.
•  When A is +5V volt and B is 0 volt then the diode D1 and D2 conduct current hence there is flow of current through the diode as well as load resistance Rl. So output is high i.e AB=A+B=1+0=1.
• When A is +5V volt and B is +5V volt then the diode D1 and D2 don't conduct current hence there is no flow of current through the diode as well as load resistance Rl. So output is low i.e AB=A+B=1+1=0.