26 | Page CERTIFICATEThis is to certify that of class XII has satisfactorily completed the project on LOGIC GATES under the guidance of during the session 2013-2014. VALUED BY TEACHER EXTERNAL EXAMINERPRINCIPALDATE: ACKNOWLEDGMENTI'd like to express my greatest gratitude to the people who have helped & supported me throughout my project. I m grateful to our schools PHYSICS facultyI thank for her continuous support for the project, from initial advice & encouragement to this day. Special thanks of mine goes to my colleagues who helped me in completing the project by giving necessary information on the apparatus used in this experiment, made this project easy and accurate.I wish to thank my parents for their undivided support & interest who inspired me & encouraged me to go my own way without which I would be unable to complete my project. At last but not the least I want to thanks my friends who appreciated me for my work & motivated me.CONTENTIntroduction ExperimentAim 10 Apparatus 10 Theory 11 Procedure 16Circuits Prepared 22Observations 24 Result 26Bibliography 27INTRODUCTIONLogic Gates:A gate is a digital circuit that follows curtain logical relationship between the input and output voltages. Therefore, they are generally known as logic gates gates because they control the flow of information.The five common logic gates used are NOT, AND, OR, NAND, NOR. Each logic gate is indicated by a symbol and its function is defined by a truth table that shows all the possible input logic level combinations with their respective output logic levels.Truth tables help understand the behavior of logic gates.(i) NOT gate (Inverter)This is the most basic gate, with one input and one output. Produces a 1 output if the input is 0 and vice-versa. That is, it produces an inverted version of the input at its output.AY=A0110(ii) OR GateAn OR gate has two or more inputs with one output. The output Y is 1 when either input A or input B or both are 1s, that is, if any of the input is high, the output is high.ABY=A OR B(A+B)000011101111(iii) AND GateAn AND gate has two or more inputs and one output. The output Y of AND gate is 1 ,only when input A and input B are both 1. It kind of looks for the minimum of the two signals.ABY=A AND B(A.B)0000101001111 Some Basic Logic Gates and Their Truth TablesCircuit diagramsAND GATEOR GATENOT GATEExperimentAIMTo design and simulate basic logic gates and to design an appropriate logic gate combination for a given truth table.APPARATUSA project boardTwo N4007 diodesTwo LED A 9v battery with a connectorTwo BPJ-BC547 transistorsTwo 100, three 560 resistors Connecting wiresTHEORYThe three basic logic gates and their combinations are the building block of the digital circuit.1. OR gateAB A+B 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. CIRCUIT DIAGRAM: 2. AND GateA A.B BThe AND gate is an electronic circuit that gives high output only if all inputs are highCIRCUIT DIAGRAM :3. NOT GateThe NOT gate is an electronic circuit that produces an inverted version of the input at its output. It is also known as an inverter.A ACIRCUIT DIAGRAM: 01 PROCEDUREDesign of basic logic gates.DESIGN OF AND GATECOMPONENTS: Two p-n junction diode, A LED, A 100 resistorsCONSTRUCTION: An AND gate can be realized by connecting the diodes as shown in the figure. A resistance of 100 is connected in series with the LED to prevent its malfunction.PROJECT BOARD CIRCUIT:GROUNDHIGHDESIGN OF OR GATECOMPONENTS: Two p-n junction diode, A LED, A 100 resistorsCONSTRUCTION: An OR gate can be realized by connecting the diodes as shown in the figure. Here also there is a need for a 100 resistor in series with LEDPROJECT BOARD CIRCUIT:DESIGN OF NOT GATECOMPONENTS: A transistor, two LEDs, three 560 resistors.CONSTRUCTION: not gate circuit can be realized by connecting an NPN transistor as shown in the figure. The base of the transistor is connected to the input through resistance of 560 and emitter is connected to the negative terminal. The collector is connected to the positive terminal and the output voltage at collector is with respect to negative.PROJECT BOARD CIRCUIT:123Ground High line1=2=3=600Logic gate combination for given truth table1. Write product term for each input (minterm), Combination where Boolean function has output2. While writing minterms, complement the variable whose value is 0 otherwise write it in the direct form (without complement).3. Add all the minterms to obtain the Boolean function.3. Draw the circuit using basic LOGIC Gates.So we, choose the given Truth Table.ABY=A.BY0001010110011110The Boolean Function F(x,y) is obtained as:F(x,y)= X.Y+X.Y+XY= Y+XY = (X+Y)(Y+Y) = X+Y = (XY) So, our expression reduces to that of a NAND Gate logic (Not of AND).LOGIC CIRCUIT IS:F=(x.y)x CIRCUIT DIAGRAMHigh lineGround Circuits Prepared:-AND gate OR gate NOT gateNAND gate OBSERVATIONSStimulation of AND gate The following conclusions can be easily drawn from the workingof electrical circuit:a)Ifbothswitchesareopen(A=0,B=0)thenLEDwillnot glow, hence Y=0.b)IfSwitch one switch is openand the other is closed (A=1,B=0 or A=0,B=1)thenLEDwillnotglow, hence Y=0.c)IfswitchA&Bbothclosed(A=1,B=1)thenLEDwillglow, Hence Y=1.Stimulation of OR gate The following conclusions can be easily drawn from the workingof electrical circuit:a)Ifbothswitchesareopen(A=0,B=0)thenLEDwillnot glow, hence Y=0.b)IfSwitch one switch is openand the other is closed (A=1,B=0 or A=0,B=1)thenLEDwillglow, hence Y=0.c)IfswitchA&Bbothclosed(A=1,B=1)thenLEDwillglow, Hence Y=1.Stimulation of NOT gate a)IfswitchAisopen(i.e.A=0),theLEDwillglow,henceY=1.b)IfSwitchAisclosed(i.e.A=1),theLEDwillnotglow,henceY=0.Stimulation of NAND gate a)IfSwitchA&Bopen(A=0,B=0)thenLEDwillglow,henceY=1.b)IfSwitchAopenBclosedthen(A=0,B=1)LED willglow,henceY=1.c)IfswitchAclosedBopenthen(A=1,B=0)LED willglow,henceY=1.d)IfswitchA&Bareclosedthen(A=1,B=1)LEDwillnotglow, hence Y=0Result:Basic logic gates were designed and simulated and logic circuit was prepared for the given truth tableBIBLIOGRAPHY:-WikipediaElectronic devices and circuits by J B Gupta Conceptual physics by G C AgarwalEncarta