A PROJECT WORK ON

A PROJECT WORK ON. DIGITAL CLOCK BY D.VIJAYA LAKSHMI(110519468026) K.POOJA(110519468042) K.KEERTHANA (110519468045) K.UMA MAHESHWARI (110519468057) K.RISHI VARSHA (110519468053) Under The Guidance Of MR. P. JOHSON BABU JAGRUTI DEGREE & PG COLLEGE (Affiliated to Osmania University) Narayanaguda , Hyderabad -500029 2021-2022.

CONTENTS. Abstract Objective Introduction Features of the project Uses of Digital Clock Advantages and Disadvantages What is IC? IC Specifications Decade Counter IC74LS90 IC74LS93 IC74LS47 IC555 Astable and Monostable Software Required Result And Discussion References Conclusion.

ABSTRACT. The aim of the project is to design a Twenty Four hour Digital Clock that displays the time digitally in contrast to an analog clock, where the time is indicated by the positions of rotating hands. With the help pf counters and decoders a digital clock to display time in hours, minutes and seconds. Digital clock has a counter that receives a clock signal from any source. The counter triggers the counter next to decimal and sends it to Seven Segment Display. The counter triggers the counter next to it when it resets. Seven segement display is very common and efficient option for displaying decimal value. The project focuses on building a digital clock with simple gates and flipflops ,counters with sequential logic rather than any programming based element..

OBJECTIVE Digital time clock counts hours, minutes, seconds, months, days and even years digitally. The objective of this project is construct a device that will display the time in seconds, minutes and hours . In addition to this, it will also display time. We can also set the time using the switch. 1.To build a digital clock successfully gaining all the required knowledge. 2.To know about the working of each and every component and their role in the circuit. 3.To apply our knowledge and understanding into practice..

INTRODUCTION At this time most peoples in the whole world use an automated digital clock in their everyday use. Starting from the hand watch we were to those huge street clocks every one of us are dependent on the display the make. In 21th century time being more than money, regarding this change our hobbies of checking our time every minute is dramatically increasing. About 99% of todays digital clocks are made using microcontrollers which make them more hand able from the rest, those we can set the time to start any minute or second we want and also set an alarm for reminder so that the system will store the value in a memory and then when the time reaches the alarm will be on. As the microcontroller consists almost all the logical devices external logic gates doesnt exist. In order to be used properly and for a long life usage digital clocks must cover a very small place as much as it could but the size of most of the digital clocks manufactured this time is unexpectedly increasing as the use the give increases. This are the list of problems that exists in todays digital clocks. *An extensive range of large. *Use of independent LED matrix digital for the display that takes a huge space in the circuit and a lot of matrix code in the controller. *Displays only hour and minute. This makes use they give us limited on the range given. *Not easy to maintain. When the clock gets damaged some cant tell where the problem is easily, on the microcontroller or on the microcontroller or on the other driver ICS. *Very costly..

FEATURES OF THE PROJECT. An extensive range of large. Use of independent LED matrix digital wall for the display that takes a huge space in the circuit and a lot of matrix code in the controller. Displays only hour and minute. This makes the use they give us limited on the range given. Not easy to maintain. When the clock gets damaged some can’t tell where the problem is easily, on the microcontroller or on the other driver ICS. Very costly..

USES OF DIGITAL CLOCK. Digital clock I can be very small and inexpensive devices. They are often incorporated into all kinds of devices such as cars, radios, television, microwave ovens and cellphones etc..

ADVANTAGES AND DISADVANTAGES OF DIGITAL CLOCK. Advantages: It’s is light and compact. The first thing you can expect from a digital clock is a more accurate time-sheet that is extremely hard to forge that gives accurate tracking of employee hours. Secure records-most employee attendance software is cloud-based. This means that any information accumulated by a digital clock will be stored in the cloud. In short, employee time-sheets cannot be misplaced or lost, and unauthorized persons cannot access the records Easy tracking-with a digital clock, employee time tracking records will not only be accurate, safe and secure, it will be extremely easy to track the exact number of hours each employee has logged in. Exact time resume-if there is any power failure, there will not be any time display on the clocks. But as soon as the electric power resumes, the clock will show the right time automatically. Disadvantages: The disadvantages are that they depend on electricity (or)batteries where as some non digital clocks need only be wound. One of the Disadvantage of digital clock is the fact that it cuts off interpersonal communication..

WHAT IS IC? An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny MOSFETs (metal–oxide–semiconductor field effect transistors) integrate into a small chip. This results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete electronic components. The IC's mass production capability, reliability, and building-block approach to integrated circuit design has ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world of electronics. Computers, mobile phones and other home appliances are now inextricable parts of the structure of modern societies, made possible by the small size and low cost of ICs such as modern computer processors and microcontrollers.

IC SPECIFICATIONS. An integrated circuit, or an IC, is a miniature circuit made up of thousands or even billions of transistors. It can be described as a set of electronic circuits fabricated on a semiconductor material. Usually, this material is silicon. The integration of MOS transistors leads to chips being faster, smaller in size, and less expensive than conventional circuits created with discrete components. IC design can be categorized into digital and Analog chip design. Analog chips include the design and manufacturing of operational amplifiers, oscillators, PLLs, etc., whereas digital chips include FPGAs, SoCs , ASICs, etc. Due to the complexity of modern ICs, which has around a billion transistors on one chip, EDA tools are used for design, verification, and test. EDA stands for Electronic Design Automation and is used for the design of electronic systems, including Printed Circuit Boards (PCBs). Each step of the design flow has a dedicated EDA tool to perform the required functionality. EDA tools add flexibility to the chip design. The flowchart below illustrates the steps involved in manufacturing a chip, from system specifications to tape-out..

DEACADE COUNTER. A circuit decade counter is one that counts decimal digits rather than binary. A decade counter may have each (that is, it may count binary – coded decimal, as the 7490 integrated circuit ) or other binary encodings. A decade counter is a binary counter that is designed to count to 1001. An ordinary four-stage counter can be easily modified to a decade counter by adding a NAND gate as in the schematic to right. It counts from 0 to 9 and then resets to zero..

IC74LS90. IC 7490 is a 4-bit, ripple-type decade counter. It consists of four master/slave flip-flops, which are internally connected to form a divide-by-two section and a divide-by-five section. Each section has a separate clock input to change the output states of the counter on a high-to-low clock transition. The output states do not change simultaneously due to the internal ripple delays. Therefore the decoded output signals are subject to decoding spikes and should not be used for clocks or strobes.IC 7490 can count the binary numbers from 0000 to 1001. After 1001 it gets reset and again starts counting. As the IC 7490 gets reset after counting ten numbers, it is called MOD10 Decade Counter. IC 7490 is a decade counter IC which can generate output code in BCD . It is an Asynchronous Decade Counter IC. IC 7490 can count the binary numbers from 0000 to 1001. After 1001 it gets reset and again starts counting. It is called a BCD counter because its ten state sequence is that of a BCD code and does not have a regular pattern, unlike a straight binary counter. Then a single stage BCD counter such as the 74LS90 counts from decimal 0 to decimal 9 and is therefore capable of counting up to a maximum of nine pulses..

SPECIFICATIONS. Typical power dissipation: 45mW High count rates: 42MHz Choice of counting modes Input Clamp Diodes Limit High-Speed Termination Effect • Supply voltage: 5V Operating Ambient Temperature Range: –55 to 125°C.

PIN DIAGRAM. Pin No. 1: CLKB - There are two clock input pins in IC 7490. It is one of them. Pin No. 2: R1 - It is the reset pin to reset the circuit to start the counting again. Pin No. 3: R2 - It is also the reset pin. Pin No. 4: NC - It is not connected to the circuit. Pin No. 5: Vcc - It is the positive power supply pin. Pin No. 6: R3 - It is the Reset pin . Pin No. 7: R4 - It is also Reset Pin. Pin No. 8: Qc - Output Pin 3. Pin No. 9: Qb - Output Pin 2. Pin No. 10: GND - It is the Negative power supply Pin. Pin No. 11: Qd - Output Pin 4. Pin No. 12: Qa - Output Pin 1. Pin No. 13: NC - Not connected to the Circuit. Pin No. 14: Clock input pin.

TRUTH TABLE.

INTERNAL CIRCUIT DIAGRAM.

APPLICATIONS. Mainly IC 7490 is used in the digital counter circuits. IC 7490 also used in digital timers and clocks. IC 7490 is used in automatic controller circuits..

IC7493. IC 7493 is a 4bit binary counter IC, it is composed of 4 JK Flip Flop. Out of which 3 are connected together and 1 is alone, it is consists of a mod 8 counter and a mod 2 counter. Together they make a mod 16 counter..

BINARY COUNTER. A Binary Counter is a serial digital counter that counts ten digits. it resets for every new clock input. As it can go through 10 unique combinations of output, it is also called as “Decade counter”. A binary counter can count 0000, 0001, 0010, 1000, 1001, 1010, 1011, 1110, 1111, 0000, and 0001 and so on. A 4 bit binary counter will act as a decade counter by skipping any six outputs out of the 16 (24) outputs. uses of binary counter Normally binary counters are used for counting the number of pulses coming at the input line in a specified time period. The binary counters must possess memory since it has to remember its past states. As the name suggests, it is a circuit which counts..

FEATURES AND SPECIFICATIONS. Typical Operating Voltage: 5V Output High Voltage: 3.5V Output Low Voltage: 0.25V Operating Voltage Range: 4.5V to 5.5V Output current when high: -0.4mA Output current when low: 8mA CKB and CKA input clock frequency: 32MHz and 16MHz resp. CKA and CKB pulse width: 15nS and 30nS resp. Available in 14-pin PDIP, GDIP, PDSO packages Function: Counter Product type: Binary.

PIN DIAGRAM. INPUT NC 13 14 INPUT RO(I) RO(2) QD GND 11 10 7493 NC vcc 0B Qc NC Qc NC hackatronic.com.

PIN CONFIGURATION. Pin No Pin Name Description CKB Clock Input B R0(1) Master Reset Input 1 R0 (2) Master Reset Input 2 NC No Connection VCC Supply Voltage NC No Connection NC No Connection Qc Output Pin 9 Qb Output Pin 2 GND Ground Pin Qd Output Pin 4 12 Qa Output Pin 1 NC No Connection CKA Clock Input A.

TRUTH TABLE.

INTERNAL CIRCUIT.

APPLICATIONS. Used for creating long timing period Astable frequency divider or counter circuit Timing related applications Used in projects where Microcontrollers should be avoided Pulse counter or frequency divider.

IC 74LS47. The 7447 are Low Power Schottky BCD to 7-Segment Decoder/Drivers consisting of NAND gates, input buffers, and seven AND-OR-INVERT gates . They offer active LOW, high sink current outputs for driving indicators directly. Further, the IC7447 IC is the BCD to seven segment converter whose design and operation are based on Boolean algebra and logic gates. The seven-segment display has four input lines and seven output lines. A display decoder is applied to convert BCD code to the seven-segment code..

SEVEN SEGMENT DISPLAY.

IC 555. The IC 555 is configured as Astable multivibrator whose pulse can be controlled using given 100K pre-set resistor. You have to adjust the pre-set and bring the pulse of IC 555 to 1 Hz. There are two blinking LEDs which can be inserted in between the hour and minute digits. All the circuit is power at 5V. 555 timer is used in almost every electronic circuit today. For a 555 timer working as a flip flop or as a multi-vibrator, it has a particular set of configurations. Some of the major features of the 555 timer would be. It operates from a wide range of power ranging from +5 Volts to +18 Volts supply voltage. Sinking or sourcing 200 mA of load current. The external components should be selected properly so that the timing intervals can be made into several minutes along with the frequencies exceeding several hundred kilohertz. The output pin of a 555 timer can drive a transistor-transistor logic (TTL) due to its high current output. It has a temperature stability of 50 parts per million (ppm) per degree Celsius change in temperature which is equivalent to 0.005 %/ °C Also, the maximum power dissipation per package is 600 mW and its trigger pulse and reset inputs has logic compatablity ..

DISPLAY TO IC CONNECTION. Display to Connection 02 - IC2 03 - IC3 04 - IC4 Electronics—p Seconds Blinking LEO Min ALL 220 GND 10K x 2 oject—hub-corn TO Clock Input (1 pulse / rnin).

CIRCUIT DIAGRAM OF IC 555.

SPECIFICATIONS. Part number NE555 IC Process Bipolar Supply voltage ( V CC )4.5 to 16 V Supply current ( V CC = +5 V)3 to 6 mA Supply current ( V CC = +15 V)10 to 15 mA Output current (maximum)200 mA Maximum Power dissipation600 mW Power consumption (minimum operating)30 mW @ 5 V,225 mW @ 15 V Operating temperature0 to 70 degrees..

ASTABLE MODE AND ITS WORKING. Pin 2 – Trigger: Turns on the output when the voltage supplied to it drops below 1/3 of Vcc Pin 6 – Threshold: Turns off the output when the voltage supplied to it reaches above 2/3 Vcc . Pin 7 – Discharge: When the output voltage is low, it discharges C1 to ground. In astable mode, the output cycles on and off continuously. In the schematic above, notice that the threshold pin and the trigger pin are connected to C1. This makes the voltage the same at the trigger pin, threshold pin, and C1. At the beginning of an on/off cycle, the voltage is low at C1, the trigger pin, and the threshold pin. Whenever the trigger pin voltage is low, the output is on, and the discharge pin is off. Since the discharge pin is off, current can flow through resistors R1 and R2, charging capacitor C1. Once C1 charges to 2/3 Vcc , the output is switched off by the threshold pin. When the output goes off, the discharge pin switches on. This allows the charge accumulated on capacitor C1 to drain to ground. Once the voltage across C1 drops to 1/3 Vcc , the trigger pin turns off the discharge pin, so C1 can start charging again..

MONOSTABLE MODE AND ITS WORKING. Monostable mode is sometimes called one-shot mode, which seems a little more descriptive. Oneshot mode conveys the idea that when triggered, the 555 gives one and only one output pulse . When the time interval is reached, the output pulse stops, and the circuit goes quiet until another trigger pulse is detected. A Monostable 555 Timer is required to produce a time delay within a circuit . If a 10uF timing capacitor is used, calculate the value of the resistor required to produce a minimum output time delay of 500ms..

WORKING. The output of the monostable multivibrator using 555 timer remains in its stable state until it gets a trigger. In monostable 555 multivibrator , when both the transistor and capacitor are shorted then this state is called as a stable state. When the voltage goes below at the second pin of the 555 IC, the o/p becomes high. This high state is called quasi stable state. When the circuit activates then the transition from a stable state to quasi stable state. Then the discharge transistor is cut off and capacitor starts charging to VCC. Charging of the capacitor is done via the resistor R1 with a time constant R1C1 Hence, the voltage of the capacitor increases and finally exceeds 2/3 Vcc , it will change the internal control flip flop, thereby turning off the 555 timer IC Thus the o/p goes back to its stable state from an unstable state. Finally we can conclude that, in the monostable multivibrator using 555 timer, the o/p stays in a low state until it gets a trigger i /p. This type of operation is used in push to operate systems. When the input is triggered, then the o/p will go to high state & comes back to its original state..

SPECIFICATIONS. The design should use 7-segment LED displays to display AM/PM, hours, minutes, and seconds. The board and the Arduino should be powered from a 5V wall mounted power supply. All components used in the design need to be mounted to a separate printed circuit board designed using CAD software. The PCB design should be compatible with the Arduino pin headers, so that the PCB can plug directly into the Arduino..

Software required. Multisim 12.0 version Tinkercad.

Result and Discussion. Our project divided into four modules. They are as follows: 155 IC Timer Section The 555 timer IC is an integrated chip (IC) used in a variety of timer, pulse generator and oscillator application. The 555 timer which give one Hz frequency to JK FILP FLOP Second section We used total four JK FLIP FLOP (74107) and one single IC contains two flip flops. We use three flip flop which give 0 to 7 outputs and remaining other 4 flip flop give 0 to 15.But we know digital clock always displays 5 & 9 in second. Instead of it we required 0 to 5 outputs in single seven segment display so we connect the NAND gate which gives low logic to flip flop and not allow it to exceeding from 5 digits number which is our requirement on single seven segment display. On the other hand, the remaining four flip flop which give 0 to 15 but our requirement that it should only display 0 to 9 count not to exceeding from it so we also here need NAND gate to stop it and give us our perquisite which is 0 to 9 counting on single seven segment display. When the circuit will display successfully 5 & 9 in each seven segment display with the help of driver IC 7447 then it gives pulse to minutes section. Minute Section Repeating the same circuit operation which we had previously used for the second section but this portion activates when section more than from 5 & 9 second displays. We used total four JK FLIP FLOP IC (74107) and one single IC contains two flip flops. We use three flip flop which give 0 to 7 count output and remaining after other 4 flip flop give 0 to15. But we know digital clock always displays 5 & 9 in minute but instead of it we required 0 to 5 count output in single seven segment displays so we connect the NAND gate which give low logic to flip flop and not allow it to exceeding from 5 digit number which is our requirement on single seven segment display. On the other hand the remaining four flip flop and not allow it to exceeding from 5 digit number which is our requirement on single seven segment display. On the other hand the requirement on single seven segment display. On the requirement that it should display 0 to 9 count not to exceeding from it so we also here need NAND gate to stop it gives us our prerequisite which is 0 to 9 count. When the circuits will displays successfully 5 & 9 in each seven segments display with the help of driver IC 7447 then it gives pulse to hour section. Hour Section Designing the circuit in such a way so that the output resets to 0 0 0 automatically displaying11.59.59. The counting proceeds with a frequency of one pulse per hour coming from minute section. We used three J-K flip flop IC (74107) and in a single J-K flip flop IC it contain two flip flop. We know that hour would show 2 & 4 in each seven segment displays not greater than that number. So we need 0 to 2 displays count on first segment and 0 to 4 counts on other segment. In hour section same as previous section we used J-K flip flop to connect all needed component we need 0 to 2 display on single seven segment due to prevent it from exceeding we need 0 to 2 display on single NAND gate to clear the two flip flop which they want to show 0 to 4 count but our requirement is to only want to display 0 to 2. On the other hand remaining flip flop contain which is four out of six which would like to show 0 to 15 but our requirement is to display only 0 to 9 count on single seven segment clear when it want to increase but our target display only 0 to 2 and 0 to 4 on each seven segment only not above than that..

REFERENCES. https://en.wikipedia.org/wiki/Digitalclock http://www.mathematik.unimarburg.de/~thormae/lectures/ti1/code/karnaughmap/ Thomas L. Floyd, ”Digital Fundamentals”, Seventh Edition, Prentice-Hall International, Inc.,2000. Donald D. Givone , “Digital Principles and Designs”, McGraw-Hill 2003. Victor P. Nelson, H. Try Nagle, Bill D . Carroll, and J. David Irwin, “Digital Logic Circuit Analysis & Design”, Prentice-Hall Englewood Cliffs. NJ, 1995. HCF4027B datasheet. 74LS47 datasheet..

CONCLUSION. The circuit was purely designed with the basic knowledge on sequential circuit designed And with the components provided by the authority.The clock is excepted to operate normally With desired accuracy.Unfortunately our clock did not operate like it suppose to. The circuit from second section does not functioning well.Automatically the minutes and hours circuits cannot be function since our clock use asynchronous counter which mean, the minute input is from second section while the hour input is from minute section.Once one circuit not functioning ,the rest circuit will be not functioning too.Therefore,we have made some analysis of why our clock did not functioning. Jumper wires are dirty and have kinked end-it is because the metal wire inside the jumper Wire is multiple wire which is diffult to use. Lines of tinned\copper of the strip board running up and down the board. Lekage circuit which lead to more heating issues can easily affect other components. Incorrectly wired to Ic . The timer doesnot work because the 555 timer may be damage. Soldering problems; The surface of the joint did not melt completely. The surface of the joint may be appear frosted, crystalline or rough. The solder has not yet flowed well which cause the residue of burnt flux will make fixing this joint difficult..

DIGITAL CLOCK CIRCUIT DIAGRAM.

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