NAND Gate

                        Hello students once again welcome back. In last post we learn about OR gate in this post we will learn about NAND .
                        NAND gate is nothing but 'Not - AND gate '. It is combination of AND gate and NOT gate . Output of AND gate is given as input to NOT gate and Output of NOT gate becomes Output of combination i.e. NAND gate .When gate has n inputs it is called n-bit NAND gate. Output of NAND gate is high(1) when anyone of input is low(0).
                     When both inputs are high(1) ,output is low(0).IC 7400 is known as Quad Dual input NAND gate.In Boolean Algebra NAND gate is known as universal building block.
                     Symbol and truth of two bit NAND gate is as follows:-

                    That's it . In next post we will learn about NOR gate.

                         

OR gate

                 Hello students once again welcome back. So in last post we had learned about NOT gate and in this post we will learn about OR gate .
                OR gate has 2 or more inputs. When it has n inputs it is called n bit OR gate . Defination of OR gate is "Output is High(1) when anyone of input is High (1) ", i.e. it recognizes the input word which contains (1) and output is low when all the inputs are low(0) . Trick remember the truth table is that OR gate is similar to Disjunction in Maths.
In Boolean Algebra '+' indicates OR addition . The symbol '+' is read as OR . IC 7432 is known as Quad Dual Input OR gate .
                 The symbol and truth table of OR gate is as follows:-

                  That's it for today . In next post we will learn about NAND gate.

NOT gate

                       Hello students once again welcome back.In last post we have learned about AND gate. In this post we will learn about NOT gate. 

NOT gate has only one input and ouput. Output is not input .ie. Output is compliment of input . For example , when input is high(1) , output is low(0) and vice versa. IC 7406 is hex inverter. NOT gate is also called as Inverter. In Boolean Algebra over bar (-) indicates NOT gate. Symbol of NOT gate and truth table is shown below:-

 This is about NOT gate . In next post we will learn about OR gate.

Introduction to Logic Gates

                     Hello student's I hope you have started studying 12th HSC electronics. Some of you might have read some lessons. I will tell you about logic gates in easy way.
                     For a time being consider gate as our lock which we use in our day to day life. When does it open? Obviously when we put key of that lock . Here key is our input and lock is out put . Similarly in logic gates we give some inputs to get some output .
                    Now question arises why we need logic gates? Answer is in computer there are several components. By using this components we can get 10 different states but this states are not well defined but 2 well defined states can be obtain from these components, so we use Boolean Algebra i.e. two states Algebra. Logic Gate uses Boolean Algebra. In computer and microprocessors logic gates are used for various purposes for example counting , addition,substraction,multiplication,divison,etc.
                    Logic Gate is device which has one or more inputs but only one output. Output is high when input word is recognized by gate just like when we put proper key of lock it open i.e. it opens , output is low when input is not recognized by gate just like when we put wrong key in lock it doesn't open. In logic gate output high is denoted by 1 and low output is denoted by 0
                   There are two types of Logic :- 1) Positive Logic and 2) Negative Logic
                  In positive logic input 1 is shown by more positive of two voltage levels and 0 by other voltage level. For example if input voltages are 0 and 5 then 1 is represented by 5 and 0 is represented by 0 . If inputs voltages are -5 and 0 then 1 is represented by 0 and 0 is represented by -5.
                In negative logic 1 is represented more negative of two voltage levels and 0 is represented by other voltage. For example if voltages are 0 and 5 then 1 is represented by 0and 0 is represented by 5. If two voltage levels are 0 and -5 then 1 is represented by -5 and 0 is represented by 0
               There are 3 fundamental logic gates :-1) AND gate 2) NOT gate 3) OR gate .
               We will see in details of these 3 gates in my next blog. Thanks for reading!!