DLD Lab 1st Experiment : Verification of Logic Gates

Students, you have to write this experiment in your  RECORD.

EXPERIMENT: 1 LOGIC GATES

AIM:- To study and verify the truth table of logic gates

LEARNING OBJECTIVE:-

 Identify various ICs and their specification.

COMPONENTS REQUIRED:-

 Logic gates (IC) trainer kit.

 Connecting patch chords.

 IC 7400, IC 7408, IC 7432, IC 7406, IC 7402, IC 7404, IC 7486

THEORY:

The basic logic gates are the building blocks of more complex logic circuits. These logic gates perform the basic Boolean functions, such as AND, OR, NAND, NOR, Inversion, Exclusive-OR, Exclusive-NOR. Fig. below shows the circuit symbol, Boolean function, and truth. It is seen from the Fig that each gate has one or two binary inputs, A and B, and one binary output, C. The small circle on the output of the circuit symbols designates the logic complement. The AND, OR, NAND, and NOR gates can be extended to have more than two inputs. A gate can be extended to have multiple inputs if the binary operation it represents is commutative and associative. These basic logic gates are implemented as small-scale integrated circuits (SSICs) or as part of more complex medium scale (MSI) or very large-scale (VLSI) integrated circuits. Digital IC gates are classified not only by their logic operation, but also the specific logic-circuit family to which they belong. Each logic family has its own basic electronic circuit upon which more complex digital circuits and functions are developed. The following logic families are the most frequently used.

TTL _Transistor-transistor logic

ECL _Emitter-coupled logic

MOS _Metal-oxide semiconductor

CMOS _Complementary metal-oxide semiconductor

TTL and ECL are based upon bipolar transistors. TTL has a well established popularity among logic families. ECL is used only in systems requiring high-speed operation. MOS and CMOS, are based on field effect transistors. They are widely used in large scale integrated circuits because of their high component density and relatively low power consumption. CMOS logic consumes far less power than MOS logic. There are various commercial integrated circuit chips available. TTL ICs are usually distinguished by numerical designation as the 5400 and 7400 series.

AND gate

                       

The AND gate is an electronic circuit that gives a high output (1) only if all its inputs are high.  A dot (.) is used to show the AND operation i.e. A.B.  Bear in mind that this dot is sometimes omitted i.e. AB

OR gate

                      

The OR gate is an electronic circuit that gives a high output (1) if one or more of its inputs are high.  A plus (+) is used to show the OR operation.

NOT gate

                       

The NOT gate is an electronic circuit that produces an inverted version of the input at its output.  It is also known as an inverter. If the input variable is A, the inverted output is known as NOT A.  This is also shown as A', or A with a bar over the top, as shown at the outputs. The diagrams below show two ways that the NAND logic gate can be configured to produce a NOT gate. It can also be done using NOR logic gates in the same way.

NAND gate

                      

This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate.  The outputs of all NAND gates are high if any of the inputs are low. The symbol is an AND gate with a small circle on the output. The small circle represents inversion.

NOR gate

                                        

This is a NOT-OR gate which is equal to an OR gate followed by a NOT gate.  The outputs of all NOR gates are low if any of the inputs are high.

The symbol is an OR gate with a small circle on the output. The small circle represents inversion.

EXOR gate

                                 

The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both, of its two inputs are high.  An encircled plus sign () is used to show the Ex-OR operation.

EXNOR gate

The 'Exclusive-NOR' gate circuit does the opposite to the Ex-OR gate. It will give a low output if either, but not both, of its two inputs are high. The symbol is an EX-OR gate with a small circle on the output. The small circle represents inversion.

PROCEDURE:

1. Check the components for their working.

2. Insert the appropriate IC into the IC base.

3. Make connections as shown in the circuit diagram.

4. Provide the input data via the input switches and observe the output on output LEDs.

PIN CONFIGURATION OF IC’s :

RESULT: -