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    Digital Techniques Micro-Project

    Uploaded by

    Ronit Patil
    1. This document describes a student micro-project to build an LED flasher circuit using a 555 timer chip. 2. The circuit works by using the 555 timer chip in astable mode to generate square wave pulses that turn the LED on and off. The timing of the on and off cycles is determined by resistor and capacitor values in the circuit. 3. The students successfully built the circuit, explaining the theory and components needed. Applications of the LED flasher circuit include use as a flashing beacon, in signaling devices, and to indicate vehicle breakdowns. The total cost of the project was approximately 66.5 Indian rupees.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Digital Techniques Micro-Project

    Uploaded by

    Ronit Patil
    41 views11 pages
    1. This document describes a student micro-project to build an LED flasher circuit using a 555 timer chip. 2. The circuit works by using the 555 timer chip in astable mode to generate square wave pulses that turn the LED on and off. The timing of the on and off cycles is determined by resistor and capacitor values in the circuit. 3. The students successfully built the circuit, explaining the theory and components needed. Applications of the LED flasher circuit include use as a flashing beacon, in signaling devices, and to indicate vehicle breakdowns. The total cost of the project was approximately 66.5 Indian rupees.

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    1. This document describes a student micro-project to build an LED flasher circuit using a 555 timer chip. 2. The circuit works by using the 555 timer chip in astable mode to generate square wave pulses that turn the LED on and off. The timing of the on and off cycles is determined by resistor and capacitor values in the circuit. 3. The students successfully built the circuit, explaining the theory and components needed. Applications of the LED flasher circuit include use as a flashing beacon, in signaling devices, and to indicate vehicle breakdowns. The total cost of the project was approximately 66.5 Indian rupees.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    41 views11 pages

    Digital Techniques Micro-Project

    Uploaded by

    Ronit Patil
    1. This document describes a student micro-project to build an LED flasher circuit using a 555 timer chip. 2. The circuit works by using the 555 timer chip in astable mode to generate square wave pulses that turn the LED on and off. The timing of the on and off cycles is determined by resistor and capacitor values in the circuit. 3. The students successfully built the circuit, explaining the theory and components needed. Applications of the LED flasher circuit include use as a flashing beacon, in signaling devices, and to indicate vehicle breakdowns. The total cost of the project was approximately 66.5 Indian rupees.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 11

    DIGITAL

    TECHNIQUES
    MICRO-PROJECT
    YADAVRAO TASGAONKAR
    POLYTECHNIC
    Bhivpuri Road (karjat)
    Computer Engineering
    Academic Year
    2023-24
    TITLE OF PROJECT
    LED Flasher Circuit With a 555 Timer Chip

    DEPARTMENT: Computer Engineering (III semester)


    SUBJECT: Digital Techniques.
    SUBJECT CODE: 22320

    SUBMITTED BY:

    1. Jayesh Rane
    2. Hardik Hase
    3. Sakshi Kapadi
    4. Krish Girdhar
    5. Arin Godse
    • Aims/Benefits of the micro project: -
    In the present scenario, most of the electronic equipment like
    computers, mobiles, music systems, ATMs, automation and control
    circuits, and systems are based on digital circuits which the diploma
    electronic engineering pass-outs (also called technologists) must test.
    The knowledge of basic logic gates, combinational and sequential logic
    circuits using discrete gates as well as digital ICs will enable the students
    to interpret the working of the equipment and maintain them. After
    completion of the course, students will be able to develop digital circuit-
    based applications.

    • INTRODUCTION: -
    An LED flasher circuit is a circuit that flashes the LED- meaning turns it
    ON-OFF, ON-OFF. The 555-timer chip is a very adaptable IC because
    when connected perfectly, it can produce pulses of current at a specific
    time breaks chosen by the resistor-capacitor (RC) network. When a 555
    timer creates pulses in this way, the LED doesn't stay frequently on. It
    only turns on at a pulse and then shuts off after the pulse has passed.
    And it does this in a never-ending cycle, which makes flashes of light. To
    produce the 555-timer chip to create pulses, it must be placed in a
    stable mode. Astable mode thoroughly means that the 555 timer has no
    stable state. It switches constantly between high and low, or on and off.
    This why this mode is also called oscillator mode because it utilizes the
    555 timers as an oscillator, which makes square wave signals.

    • THEORY: -
    This circuit will flash the LED on and off, on and off. The speed that the
    LED flashes are specified by the resistors R1 and R2 and the electrolytic
    capacitor C1. Also, the output of a 555 timer is square waves. There are 3
    essential time measurements for a square wave. There is the total length
    of the square wave (the time it is on and off or high and low), there is the
    length of time it is high (T-high), and the length of time it is low (T-low).
    The total time of a square wave is equal to the sum of T-low and T-high.
    The quantity of time that the square wave is high is its duty cycle. So, for
    example, if the total time of a square wave is 1 second and it's high for
    0.2s, it has a duty cycle of 20%, because it's on for only 20% of the cycle.

    The duty cycle is very necessary for an application like this LED flasher
    circuit. The duty cycle we select determines how long the LED will stay on
    compared to how long it is off for. Again, as an example, if we set our duty
    cycle to be 20%, this means the LED will flash on for 20% of the cycle and
    be off for 80% of the cycle. If we select a duty cycle of 80%, the LED will
    be on for 80% of the cycle and off for 20% of the cycle. Thus, our duty
    cycle is very essential.

    • The formulas to calculate values in circuit: -


    T= 0.7 * (R1 + 2R2) * C1
    T-high= 0.7 * (R1 + R2) * C1
    T-low= 0.7 * R2 * C1

    C1 charges via both R1 and R2 but discharges only via R2. That's why we
    must add the 2 resistor values for the T-high calculation, but only utilize
    R2 for the T-low calculation. It's also why you must double R2 but not R1
    for the total time (T) calculation.

    According to the overhead formulas, the bigger value we utilize for the
    resistors and the capacitor, the longer the cycle will be. If we utilize very
    large values such as 100KΩ or 100µF, we will have very large cycles. For
    example, let's say we make R1 and R2 resistors both 1MΩ resistors and
    C1 100µF. This would create a total time period of 210 seconds for the
    cycle. Of these 210s, the LED would be on for 140s and off for the 70s.
    This is not what we want at all. This is way too long. This would not create
    a LED flasher. We must choose much lower resistor and capacitor values
    in order to see a flashing or flickering effect.

    However, on the other extreme, we do not want to choose values that are
    too small as well. If we do, the human eye won't be able to detect that it
    has even turned on. For example, if we choose 1KΩ resistors and a 0.1µF
    capacitor, the time cycle and the on-off cycle would be too short. It will
    be as if the LED is constantly on. Therefore, we must choose a precise
    range of values to see the flashing effect. Each cycle would last just a few
    millionths of a second with these values.

    For the values, we must in our circuit, our duty cycle is just about 50%.
    With a 50% duty cycle, the LEDs are on for about the same time that they
    are off.

    With R1= 1KΩ and R2=10KΩ and C1= 10µF, our calculations will be:

    T= 0.7 * (1KΩ + 2(10KΩ)) * 10µF= 0.147s


    T-high= 0.7 * (1KΩ + 10KΩ) * 10µF= 0.077s
    T-low= 0.7 * 10KΩ * 10µF= 0.07s

    • Components Needed
    1. 555 timer IC: -The 555 Timer is designed using 25 transistors, 2
    diodes and 15 resistors. The functional parts of the 555 timer IC include
    a flip-flop, voltage divider & a comparator altogether. The main function
    of this IC is to generate an accurate timing pulse for operating various
    devices and electronic components.

    2. 9-volt Battery: - A power supply is an electrical device that supplies


    electric power to an electrical load. The primary function of a power
    supply is to convert electric current from a source to the correct voltage,
    current, and frequency to power the load.

    3. LED (Light-emitting diode): - -A light-emitting diode (LED) is a


    semiconductor light source that emits light when current flows through
    it. Electrons in the semiconductor recombine. with electron holes,
    releasing energy in the form of photon. When a bright light shines on the
    circuit, such we will make it so that a LED turns on.

    4. jumper wires: - Jumper wires are electrical wires with connector


    pins at each end. They are used to connect two points in a circuit
    without soldering. You can use jumper wires to modify a circuit or
    diagnose problems in a circuit.
    5. 10µF electrolytic capacitor: -This 10uF 50V capacitor is a good
    quality radial polarized Electrolytic capacitor. Electrolytic capacitors are
    widely used in switched-mode power supplies, DC-DC converters, and
    power supplies. This capacitor has a long life, low leakage current, and
    wide operating range.

    6. 0.01µF ceramic capacitor: -0.01µF Ceramic Capacitor Use this


    capacitor for power decoupling, having a smooth power in your circuit,
    timing circuits etc. It is always a good idea to put one of these next to the
    power pins of a microcontroller.

    7. Two1KΩ Resistors: - 1k ohm 4 band resistors with the colour


    code of brown-black-red-gold. resistance value: 1,000 ohms,
    tolerance:5%, Approximate Maximum Current: 5mA
    8. 10KΩ Resistor: -10k ohm 4 band resistors with the colour code of
    brown – black – orange – gold. resistance value: 10,000 Ohms,
    tolerance: 5%, Approximate Maximum Current: 5mA

    • PROCEDURE: -

    1. Collect all the required components and place the 555 timer IC on the
    breadboard.
    2. Connect pin 1 of a 555 timer IC to the ground. You can find the pin
    structure of a 555 timer IC in the circuit diagram shown above.
    3. The longer lead of a polarized capacitor is the positive and the shorter
    lead is negative. Connect pin 2 to the positive end of a capacitor.
    Connect the negative lead of the capacitor to the ground of the battery.
    4. Now short the pin 2 to pin 6 of the 555 timer IC.
    5. Connect the pin 3 which is the output pin with the positive lead of LED
    using 1kΩ resistor. Negative lead of LED needs to be connected with the
    ground.
    6. Connect pin 4 with the positive end of battery.
    7. Pin 5 doesn’t connect with anything.
    8. Connect pin 6 with pin 7 using a 10kΩ resistor.
    9. Connect pin 7 with the positive end of battery using 1kΩ resistor.
    10.Connect pin 8 with the positive end of battery.
    11.Finally connect the battery leads with the breadboard to start the power
    supply in the circuit.

    • Applications: -

    1. LED blinking circuit can be used as flashing beacon.


    2. LED blinking circuit can be used in signalling purpose (It can be used as
    signal for help, if you are in danger)
    3. LED blinking circuit can be used as vehicle indicator when it is broke
    down in the middle of the road

    • The schematic diagram of the LED flasher


    circuit
    • Total cost of project

    • 555 timer IC=10/-RS


    • 9-volt Battery=20/-RS
    • LED=4/-RS
    • Jumper wires=24/-RS
    • 10µF electrolytic capacitor=1.5/-RS
    • Two 1KΩ Resistors=4/-RS
    • 10KΩ Resistor=2/-RS
    • 0.01µF ceramic capacitor=1/-RS
    --------------------------------------------------------------------------------
    TOTAL=66.5/-RS

    • FINAL LOOK OF PROJECT: -


    CONCLUSION

    The 555 timer chip is an incredibly robust and stable 8-pin device
    that can be worked either as a very precise Monostable, Bistable, or
    Astable Multivibrator to create a variety of applications such as one-
    shot or delay timers, pulse generation, LED and lamp flashers, alarms
    and tone generation, logic clocks

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