Physics Investigatory Project

2014Physics Investigatory Project

CONTENTS PAGE NO.

1. Certificate2. Acknowledgement3. Aim of the project4. Objective5. Summary6. Introduction7. Experiment Apparatus Theory OR GATE AND GATE NOT GATE Procedure8. Application of Logic gates9. Bibliography

Certificate

This is to certify that ________________________________________ has satisfactorily completed his chemistry investigatory project as prescribed by the AISSC course during the academic year 2014-2015.

Teacher in chargeDate:

Internal Examiner External Examiner

Acknowledgement

I would like to sincerely and profusely thank my chemistry teacher MR.________________________(Physics), for his able guidance and support in completing my project.

I would also like to extend my gratitude to the principal MR______________________________________ for providing me with all the facility that was required.

Last but not the least, I would extend my gratitude towards all teaching and non teaching staff of ________________________________________ and towards my friends who has supported me to complete this project.

___________________________

Objective : To design an appropriate Logic Gate combination for a given truth table.

Summary : Since the 1990s, most logic gates are made inCMOStechnology (i.e. NMOS and PMOS transistors are used). Often millions of logic gates arepackagedin a singleintegrated circuit.There are severallogic familieswith different characteristics (power consumption, speed, cost, and size) such as:RDL(resistor-diode logic),RTL(resistor-transistor logic),DTL(diode-transistor logic),TTL(transistor-transistor logic) andCMOS(complementary metal oxide semiconductor). There are also sub-variants, e.g. standard CMOS logic vs. advanced types using still CMOS technology, but with some optimizations for avoiding loss ofspeeddue to slower PMOS transistors.Non-electronic implementations are varied, though few of them are used in practical applications. Many early electromechanical digital computers, such as theHarvard Mark I, were built from relay logicgates, using electro-mechanicalrelays. Logic gates can be made usingpneumaticdevices, such as theSort berg relayor mechanical logic gates, including on a molecular scale. Logic gates have been made out ofDNA(seeDNA nanotechnology)and used to create a computer called MAYA (seeMAYA II). Logic gates can be made fromquantum mechanicaleffects (thoughquantum computingusually diverges from Boolean design).Photonic logicgates usenon-linear opticaleffects.In principle any method that leads to a gate that isfunctionally complete(for example, either a NOR or a NAND gate) can be used to make any kind of digital logic circuit. Note that the use of 3-state logic for bus systems is not needed, and can be replaced by digital multiplexers.

Introduction : Inelectronics, alogic gateis an idealized or physical device implementing aBoolean function; that is, it performs alogical operationon one or more logical inputs, and produces a single logical output. Depending on the context, the term may refer to anideal logic gate, one that has for instance zerorise timeand unlimitedfan-out, or it may refer to a non-ideal physical device(seeIdeal and real op-ampsfor comparison).Logic gates are primarily implemented usingdiodesortransistorsacting aselectronic switches, but can also be constructed using electromagneticrelays(relay logic),fluidic logic,pneumatic logic,optics,molecules, or evenmechanicalelements. With amplification, logic gates can be cascaded in the same way that Boolean functions can be composed, allowing the construction of a physical model of all ofBoolean logic, and therefore, all of the algorithms andmathematicsthat can be described with Boolean logic.Logic circuits include such devices asmultiplexers,registers,arithmetic logic units(ALUs), andcomputer memory, all the way up through completemicroprocessors, which may contain more than 100 million gates. In practice, the gates are made fromfield-effect transistors(FETs), particularlyMOSFETs(metaloxidesemiconductor field-effect transistors).Compound logic gatesAND-OR-Invert(AOI) and OR-AND-Invert (OAI) are often employed in circuit design because their construction using MOSFETs is simpler and more efficient than the sum of the individual gates.Inreversible logic,Toffoli gatesare used.

Experiment:

Apparatus Required: The following things required are 2 Batteries 6 Volts 2 Switches Torch bulb and connecting wires Connecting WiresTheory: The three basic logic gates and their combination are the building block of the digital circuit.

OR-GATE : The symbol and the truth table for OR-GATE are shown in figure 1.

Figure 1 Inputs Outputs

ABY= A + B

000

101

011

111

AND-GATE : The symbol and truth table for AND-GATE are shown in figure 2.

Inputs Outputs

ABY= A + B

000

100

010

111

NOT-GATE :

The symbol and truth table for NOT-GATE are shown in the figure 3.

InputOutput

AY=

01

10

.

Procedure:

1. Write product term for each input (minterm) Combination where Boolean function has output 1. While writing minterm, complement that variable whose vaiue is 0. Otherwise write it in direct form (without complement).2. Add all the minterms to obtain the Boolean function.3. Draw the circuit using BASIC LOGIC gates. Example: - (a)

XYFMinterm

001

010-

100-

111X.Y

The Boolean function F (X,Y) is obtained as;-

F(X, Y) = + X.Y.*. Logic circuit is:

(b)

XYZF Mintern

0000

001

1 Z

010

1 Y

0110

100

1 X

1010

1101 XY

1110

The Boolean function F(X, Y, Z) is given as:

F (X, Y, Z) = X + X +XY.*. The logic circuit is

Some Common Applications of Logic Gates:

During the course of discussion about various digital logic gates, we have mainly discussed about the design, property and operation of them. In this article we will look at variousapplications of logic gates. Their applications are determined mainly based upon their truth table i.e. their mode of operations. In the following discussion we will look at theapplications of basic logic gatesas well as many other normal logic gates as well.Application of OR gateWherever the occurrence of any one or more than one event is needed to be detected or some actions are to be taken after their occurrence, in all those cases OR gates can be used. It can be explained with an example. Suppose in an industrial plant if one or more than one parameter exceeds the safe value, some protective measure is needed to be done. In that case OR gate is used. We are going to show this with the help of a diagram.

Application of OR gate:

The above figure is a typical schematic diagram where an OR gate is used to detect exceed of temperature or pressure and produce command signal for the system to take required actions.Application of AND gate:There are mainly twoapplications of AND gateas Enable gate and Inhibit gate. Enable gate means allowance of data through a channel and Inhibit gate is just the reverse of that process i.e. disallowance of data through a channel. We are going to show an enabling operation to understand it in an easier way. Suppose in the measurement of frequency of a pulsed waveform. For measurement of frequency a gating pulse of known frequency is sent to enable the passage of the waveform whose frequency is to be measured. The diagram below shows the arrangement of the above explained operation.

Application of AND gateApplication of Ex-OR/Ex-NOR gateThis type of logic gates are used in generation of parity generation and checking units. The two diagrams below shows the even and odd parity generator circuits respectively for a four data.

Parity generation using Ex-OR/Ex-NOR gates

With the help of these gates parity check operation can be also performed. The diagrams below show even and odd parity check.Parity check using Ex-OR and Ex-NOR gates

Figure (a) shows the parity check using Ex-OR gates and the figure (b) shows the parity check using Ex-NOR gates.Application of NOT gate or InvertersNOT gates are also known as inverter because they invert the output given to them and show the reverse result. Now the CMOS inverters are commonly used to build square wave oscillators which are used for generating clock signals. The advantage of using these is they consume low power and their interfacing is very easy compared to other logic gates.

Square wave oscillator by using a ring configuration: The above figure shows the most fundamental circuit made of ring configuration to generate square wave oscillator. The frequency of this type generator is given by

Bibliography1. Website www.wikipedia.org www.google.com www.yahoo.com

2. BOOKS: Comprehensive Practical Manual Pradeeps New Course Chemistry Dinesh Companion Chemistry for Class 12 NCERT Class XII