INTRA DISCIPLINARY PROJECT
ON
LIGHT EMITTING DIODE FLASHER CIRCUIT WITH A 555-TIMER
IC
submitted in partial Fulfilment of the Requirements for the Degree of
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ENGINEERING
BY
M.Namratha
191FA05040
N.Premsai
191FA05045
K.Santhosh
201LA05008
Under the Esteemed Guidance of
K.TIRUPATHAIAH
(ACCREDITED BY NAAC WITH ‘A’ GRADE)
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ENGINEERING
VFSTR, VADLAMUDI
GUNTUR-522213 ANDHRA PRADESH, INDIA
CERTIFICATE
This is to certify that the minor project entitled” Light emitting diode
flasher circuit with a 555-timer chip” that is being submitted by
M.Namratha bearing Regd.No 191FA05040 in partial fulfilment for
the award of 2nd year 1 st semester B. Tech degree in Electronics and
Communication Engineering to Vignan’s Foundation for Science,
Technology and Research, is a record of work carried out by him/her
under the guidance of ECE Department.
Signature of the faculty guide
department
K.Tirupathaiah
Signature of the head of the
DR.T. PitchaiahM.E.Ph.
D.MIEE
CERTIFICATE
This is to certify that the minor project entitled” Light emitting diode
flasher circuit with 555 timer chip” that is being submitted by
N.Premsai bearing Regd.No191FA05045 in partial fulfilment for the
award of 2nd year 1 st semester B. Tech degree in Electronics and
Communication Engineering to Vignan’s Foundation for Science,
Technology and Research, is a record of work carried out by him/her
under the guidance of ECE Department.
Signature of the faculty guide
K.Tirupathaiah
Signature of Head of the department
DR.T.PitchaiahM.E.Ph.D.MIEE
CERTIFICATE
This is to certify that the minor project entitled” Light emitting diode
flasher circuit with a 555 timer chip” that is being submitted by
K.Santhosh bearing Regd.No 201LA05008 in partial fulfilment for the
award of 2nd year 1st semester B. Tech degree in Electronics and
Communication Engineering to Vignan’s Foundation for Science,
Technology and Research, is a record of work carried out by him/her
under the guidance of ECE Department.
Signature of the faculty guide
signature of the head of the departement
K.Tirupathiayya
Dr.T.PitchaiahM.E.Ph.D.MIEE
ABSTRACT
The Light Emitting Diode flasher circuit which flashes the LED meaning turns it
ON-OFF. The 555-timer chip is a very versatile IC, because when connected
correctly, it can create at specific time intervals decided by the resistor-capacitor
(RC)network> when a 555 timer creates pulses in this way. The LED doesn’t stay
constantly on. It only turns on at a pulse and then shuts off after the pulse has
passed.
TABLE OF CONTENT:CHAPTER
NUMBER
CHAPTER 1
CHAPTER 2
CHAPTER 3
CHAPTER 4
CHAPTER 5
CHAPTER 6
CHAPTER NAME
PAGE NUMBER
OBJECTIVE
INTRODUCTION
CIRCUIT DIAGRAM
WORKING
APPLICATIONS AND
LIMITATIONS
CONCLUSION
7
8-13
14
15-16
17-19
20
CHAPTETR 1
OBJECTIVE
 To design a circuit of LED Flasher.
 To develop circuit design that function by using LED.
 To make a basic design that can be continuously show a lighting.
 To produce a variable output.
CHAPTER 2
INTRODUCTION
LED (light emitting diode) is a semiconductor light emitting diode. We know that
diode allows the current in one direction and does not allow the reverse current
which will affect the components in the circuit. LED also do the same function
but will emit a small light when it allowed the current, which will give the sign
or visual indication to normal human that circuit is working. There are lots of
applications using LEDs. They are lots of applications using LEDs. They are
mainly used for visual indication in any electronic devices, measuring and
interacting with the process, displaying the pictures in TV or in any advertisement
hoarding. etc.
Two LED blinking circuits are given. First one is dancing bi- color LEDs (two
different color LEDs) where the two color LED will run in sequence. In the
second circuit, we will blink the LEDs in regular period of time.
COMPONENTS
RESISTOR
A resistor a passive two-terminal electrical-component that
implements electrical resistance as a circuit element. In electronic circuits,
resistors are used to reduce current flow, adjust signal levels, to divide
voltages, bias active elements, and terminate transmission lines, among other
uses. High-power resistors that can dissipate many watts of electrical power as
heat, may be used as part of motor controls, in power distribution systems, or as
test loads for generators. Fixed resistors have resistances that only change slightly
with temperature, time or operating voltage. Variable resistors can be used to
adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing
devices for heat, light, humidity, force, or chemical activity.Resistors are
common
elements of electrical
networks and electronic circuits and
are
ubiquitous in electronic equipment. Practical resistors as discrete components can
be composed of various compounds and forms. Resistors are also implemented
within integrated circuits. The electrical function of a resistor is specified by its
resistance: common commercial resistors are manufactured over a range of more
than nine orders of magnitude. The nominal value of the resistance falls within
the manufacturing tolerance, indicated on the component.
CAPACITOR:
A capacitor is a device that store electrical energy in an electric field. It is
a passive electronic component with two terminals.
The effect of a capacitor is known as capacitance While some capacitance exists
between any two electrical conductors in proximity in a circuit, a capacitor is a
component designed to add capacitance to a circuit. The capacitor was originally
known as a condenser or condensator.This name and its congrates are still
widely used in many languages but rarely in English, one notable exception
being being condenser microphone , also called capacitor microphones.
The physical form and construction of practical capacitors vary widely and
many type of capacitor are in common use. Most capacitors contain at least
two electrical conductors often in the form of metallic plates or surfaces separated
by a dielectric medium. A conductor may be a foil, thin film, sintered bead of
metal, or an electrolyte. The nonconducting dielectric acts to increase the
capacitor's charge capacity. Materials commonly used as dielectrics
include glass,ceramic plastic film,paper,mica, air, and and oxide layers .
Capacitors are widely used as parts of electrical circuits in many common
electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy,
although real-life capacitors do dissipate a small amount (see non ideal
behaviour). When an electrical potential l, a voltage , is applied across the
terminals of a capacitor, for example when a capacitor is connected across a
battery, an electric field
develops across the dielectric, causing a net
positive charge to collect on one plate and net negative charge to collect on the
other plate. No current actually flows through the dielectric. However, there is a
flow of charge through the source circuit. If the condition is maintained
sufficiently long, the current through the source circuit ceases. If a time-varying
voltage is applied across the leads of the capacitor, the source experiences an
ongoing current due to the charging and discharging cycles of the capacitor.
LIGHT EMITTING DIODE(LED):
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 photons. The color of the light
(corresponding to the energy of the photons) is determined by the energy required
for electrons to cross the band gap of the semiconductor.] White light is obtained
by using multiple semiconductors or a layer of light-emitting phosphor on the
semiconductor device.
Appearing as practical electronic components in 1962, the earliest LEDs emitted
low-intensity infrared (IR) light.] Infrared LEDs are used in control circuits, such
as those used with a wide variety of consumer electronics. The first visible-light
LEDs were of low intensity and limited to red. Modern LEDs are available across
the visible,ultraviolet(UV), and infrared wavelengths, with high light output.
Early LEDs were often used as indicator lamps, replacing small incandescent
bulbs, and in in seven segment dispaly. Recent developments have produced
high-output white light LEDs suitable for room and outdoor area lighting. LEDs
have led to new displays and sensors, while their high switching rates are useful
in advanced communications technology.
LEDs have many advantages over incandescent light sources, including lower
energy consumption, longer lifetime, improved physical robustness, smaller size,
and faster.
BATTERY:
A battery is a device consisting of one or more electro chemical cells with
external connections] for powering electrical devices such as flash lights, mobile
phones , and electric cars . When a battery is supplying electric power, its positive
terminal is the cathode and its negative terminal is the anode.The terminal marked
negative is the source of electrons that will flow through an external electric
circuit to the positive terminal. When a battery is connected to an external electric
load, a redox reaction converts high-energy reactants to lower-energy products,
and the free energy difference is delivered to the external circuit as electrical
energy.Historically the term "battery" specifically referred to a device composed
of multiple cells, however the usage has evolved to include devices composed of
a single cell.
Primary (single-use or "disposable") batteries are used once and discarded, as
the elecrode materials are irreversibly changed during discharge; a common
example is the alakaline battery used for flashlights and a multitude of portable
electronic devices. secondary rechargeable batteries can be discharged and
recharged multiple times using an applied electric current; the original
composition of the electrodes can be restored by reverse current. Examples
include the lead-acid batteries used in vehicles and lithium -ion batteries used
for portable electronics such as laptops and mobile phones.
Batteries come in many shapes and sizes, from miniature cells used to
power hearing aids and wristwatches to small, thin cells used in smartphones , to
large lead acid batteries or lithium-ion batteries in vehicles, and at the largest
extreme, huge battery banks the size of rooms that provide standby or emergency
power for telephone exchanges and computer data centres.
555 TIMER IC:
The 555 timer IC is an integrated circuit (chip) used in a variety of timer, delay,
pulse generation, and oscillator applications. Derivatives provide two (556) or
four (558) timing circuits in one package. It was commercialized in 1972
by signetices and it was reported to still be in wide use as of 2013.Numerous
companies have made the original bipolar timers and similar lowpower coms timers too. In 2017, it was said over a billion 555 timers are produced
annually by some estimates, and "probably the most popular integrated circuit
ever made."
DESIGN:
Depending on the manufacturer, the standard 555 package includes 25 transistors
, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin dual in line
package (DIP-8). Variants available include the 556 (a DIP-14 combining two
complete 555s on one chip), and 558 / 559 (both a DIP-16 combining four
reduced-functionality timers on one chip).
The NE555 parts were commercial temperature range, 0 °C to +70 °C, and
the SE555 part number designated the military temperature range, −55 °C to
+125 °C. These were available in both high-reliability metal can (T package) and
inexpensive epoxy plastic (V package) packages. Thus the full part numbers were
NE555V, NE555T, SE555V, and SE555T.
Low-power CMOS versions of the 555 are also available, such as the Intersil
ICM7555 and Texas Instruments LMC555, TLC555, TLC551.CMOS timers use
significantly less power than bipolar timers; CMOS timers also cause less supply
noise than bipolar version when the output switches states.
Circuit of led flasher circuit using 555 timer Ic
CHAPTER 4
WORKING
Here is a 555 timer circuit that flashes dual LED susing a single output. In GCSE,
it is important understand the principle that you can connect devices to the output
pin in this manner. When the output is logic1 ,the output pin will produce a
positive voltage close to the supply rail ,and the current will flow through the
lower resistor to ground lighting LED2.However,when the output is logic0,the
potential at the output pin will be close to ground(0V), and there for e current will
flow from the positive supply rail, through the top resistor lighting LED1.
PIN 1: Ground. The ground pin connects the 555 timer to the negative(0v) supply
rail.
Pin 2: Trigger. The negative input to comparator NO 1. A negative pulse on this
pin “sets” the internal Flip-flop when the voltage drops below 1/3Vcc causing the
output to switch from a “LOW” to a “HIGH” state.
Pin 3: Output. The output pin can drive any TTL.circuit and is capable of sourcing
or sinking up to 200 mA OF current at an output voltage equal to approximately
Vcc-1.5V so small speakers. LEDs or motors can be connected directly to the
output.
Pin 4: Reset. This pin is used to “reset” the internal Flip-flop controlling the state
of the output pin3. This is an active – low input and is generally connected to a
logic “1” level when not used to prevent any unwanted resetting of the output.
Pin 5: Control Voltage. This pin controls the timing of the 555 by overriding the
2/3 Vcc level of the voltage divider network. By applying a voltage to this pin,
the width of the output signal can be varied independently of the RC timing
network. When not used it is connected to ground via a 10nF capacitor to
eliminate any noise.
Pin 6: Threshold. The positive input to comparator no 2. This pin is used to reset
the Flip-flop when the voltage applied to it exceeds 2/3Vcc causing the output to
switch from “HIGH” to” LOW” state. This pin connects directly to the RC timing
circuit.
Pin 7: Discharge. The discharge pin is connected directly to the Collected of an
internal NPN transistor which is used to “discharge” the timing capacitor to
ground when the output at pin 3 switches “LOW”.
Pin 8: Supply +Vcc. This is the power supply pin and for general purpose TTL
555 timer is between 4.5V and 15V.
CHAPTER 5
APPLICATIONS




Safety blinkers for bicycle.
Festival decorations.
Blinkers to locate item in dark.
Functions decorations.
LIMITATIONS:-
 Life time of the LEDs is low.
 It is temperature dependence.
 Light quality
 Voltage sensitivity
OUT PUT OF LED FLASHER ON PCB
SCHEMATIC CAPTURE OF LED FLASHER
PCB ROUTING OF THE LED FLASHER
CONCLUSION
555 timer IC is used to generates a continuous output in the form of square wave
which turns the LED on and off.
REFERENCES
https://youtu.be/hmu5KxuARSQ
http://www.learningaboutelectronics.com/Articles/LED-flasher-circuit.php
https://www.electroschematics.com/tag/led-flasher-circuits/
https://www.build-electronic-circuits.com/blinking-led-circuit/