1.Introduction
The 555 IC was designed in 1971 by Hans Camenzind under contract to SigNetics Corporation.
555 timer is a highly stable circuit used to generate time delays, or Oscillations.
A single 555 timer can provide time delay ranging from microseconds to hours.
It operates from a wide range of power supplies ranging from + 5 Volts to + 18 Volts supply voltage.
2.Pin Configuration
3.Working of Pin
4.555 Integral circuit
5.Operating modes of IC
6. Bistable Mode
In bistable (also called Schmitt trigger) mode, the 555 timer acts as a basic flip-flop.
The trigger and reset inputs (pins 2 and 4 respectively on a 555) are held high via pull-up resistors while the threshold input (pin 6) is simply floating.
Thus configured, pulling the trigger momentarily to ground acts as a 'set' and transitions the output pin (pin 3) to Vcc (high state).
Pulling the reset input to ground acts as a 'reset' and transitions the output pin to ground (low state). No timing capacitors
Pin 5 (control voltage) is connected to ground via a small-value capacitor (usually 0.01 to 0.1 μF). Pin 7 (discharge) is left floating
7.Monostable Mode
Pulse generator circuit which the period is calculated from RC network and connected to external of 555 timer
Stable when the output logic LOW (logic = 0)
When a pulse is trigger at pin 2 (normally negative trigger pulse), timer output will change to HIGH (+Vs) for a while and change to LOW (stable condition). The condition will continue LOW until pulse is trigger again.
The timing period is triggered (started) when trigger input (555 pin 2) is less than 1/3 Vs, this makes the output high (+Vs) and the capacitor C1 starts to charge through resistor R1. Once the time period has started further trigger pulses are ignored.
The threshold input (555 pin 6) monitors the voltage across C1 and when this reaches 2/3 Vs the time period over and the output becomes LOW,
At the same time discharge (555 pin 7) is connected to 0V, discharging the capacitor ready for the next trigger.
8.Astable Mode
Astable multivibrators are also known as Free-running Multivibrator.
Astable do not need trigger pulse for external to change the output.
The period for LOW and HIGH can be calculated based on resistor and capacitor value that connected at outside of timer.
9.Applications
Schmitt trigger
PPM
PWM
Linear Ramp generator
Precision Timing
Pulse Generation
Time Delay Generation
Sequential Timing
Used as a quad timer
10. Conclusion
Hence 555 IC timer can produce very accurate and stable time delays, from microseconds to hours. It can be used with supply voltage varying from 5 to 18 V. Timer can be used in monostable mode of operation or astable mode of operation. Its various applications include waveform generator, missing pulse detector, frequency divider, pulse width modulator, burglar alarm, FSK generator, ramp generator, pulse position modulator etc.
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
1.Introduction
The 555 IC was designed in 1971 by Hans Camenzind under contract to SigNetics Corporation.
555 timer is a highly stable circuit used to generate time delays, or Oscillations.
A single 555 timer can provide time delay ranging from microseconds to hours.
It operates from a wide range of power supplies ranging from + 5 Volts to + 18 Volts supply voltage.
2.Pin Configuration
3.Working of Pin
4.555 Integral circuit
5.Operating modes of IC
6. Bistable Mode
In bistable (also called Schmitt trigger) mode, the 555 timer acts as a basic flip-flop.
The trigger and reset inputs (pins 2 and 4 respectively on a 555) are held high via pull-up resistors while the threshold input (pin 6) is simply floating.
Thus configured, pulling the trigger momentarily to ground acts as a 'set' and transitions the output pin (pin 3) to Vcc (high state).
Pulling the reset input to ground acts as a 'reset' and transitions the output pin to ground (low state). No timing capacitors
Pin 5 (control voltage) is connected to ground via a small-value capacitor (usually 0.01 to 0.1 μF). Pin 7 (discharge) is left floating
7.Monostable Mode
Pulse generator circuit which the period is calculated from RC network and connected to external of 555 timer
Stable when the output logic LOW (logic = 0)
When a pulse is trigger at pin 2 (normally negative trigger pulse), timer output will change to HIGH (+Vs) for a while and change to LOW (stable condition). The condition will continue LOW until pulse is trigger again.
The timing period is triggered (started) when trigger input (555 pin 2) is less than 1/3 Vs, this makes the output high (+Vs) and the capacitor C1 starts to charge through resistor R1. Once the time period has started further trigger pulses are ignored.
The threshold input (555 pin 6) monitors the voltage across C1 and when this reaches 2/3 Vs the time period over and the output becomes LOW,
At the same time discharge (555 pin 7) is connected to 0V, discharging the capacitor ready for the next trigger.
8.Astable Mode
Astable multivibrators are also known as Free-running Multivibrator.
Astable do not need trigger pulse for external to change the output.
The period for LOW and HIGH can be calculated based on resistor and capacitor value that connected at outside of timer.
9.Applications
Schmitt trigger
PPM
PWM
Linear Ramp generator
Precision Timing
Pulse Generation
Time Delay Generation
Sequential Timing
Used as a quad timer
10. Conclusion
Hence 555 IC timer can produce very accurate and stable time delays, from microseconds to hours. It can be used with supply voltage varying from 5 to 18 V. Timer can be used in monostable mode of operation or astable mode of operation. Its various applications include waveform generator, missing pulse detector, frequency divider, pulse width modulator, burglar alarm, FSK generator, ramp generator, pulse position modulator etc.
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
PowerPoint Presentation on using IC 555 Timer as an Astable Multi vibrator. Working of the astable multi vibrator, advantages and disadvantages of an Astable Multi-vibrator,Input and Output Pins of 555 IC, Formulae for calculating the charge and discharge time and cycle time of the astable multi vibrator.
Introduction
Band Pass Amplifiers
Series & Parallel Resonant Circuits & their Bandwidth
Analysis of Single Tuned Amplifiers
Analysis of Double Tuned Amplifiers
Primary & Secondary Tuned Amplifiers with BJT & FET
Merits and de-merits of Tuned Amplifiers
A silicon-controlled rectifier or semiconductor-controlled rectifier is a four-layer solid-state current-controlling device. Some sources define silicon-controlled rectifiers and thyristors as synonymous,[5] other sources define silicon-controlled rectifiers as a proper subset of the set of thyristors. SCRs are mainly used in devices where the control of high power, possibly coupled with high voltage, is demanded. Their operation makes them suitable for use in medium- to high-voltage AC power control applications, such as lamp dimming, power regulators and motor control.
Keypad is a common interface with any microcontroller. This presentation gives details of keypad can be interfaced with 8051. The key pressed may be dispalyed on LCD/7 segment/LED displays.
it covers topics Introduction
Classification of Logic Families
Important point
Level of Integration
Specification of Digital ICs
TTL Circuit
TTL NAND Gates
MOS/CMOS Circuits
CMOS NAND Gate
ECL Circuit
Comparison
Numbers of Digital ICs
The Reason Why we use master slave JK flip flop instead of simple level triggered flip flop is Racing condition which can be successfully avoided using two SR latches fed with inverted clocks.
IC 555 TIMER Introduction, Modes & Application.pptxanindyapal288
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 200mA 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, pin 3. 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 2/3Vcc 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 Collector 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 timers is between 4.5V and 15V.
PowerPoint Presentation on using IC 555 Timer as an Astable Multi vibrator. Working of the astable multi vibrator, advantages and disadvantages of an Astable Multi-vibrator,Input and Output Pins of 555 IC, Formulae for calculating the charge and discharge time and cycle time of the astable multi vibrator.
Introduction
Band Pass Amplifiers
Series & Parallel Resonant Circuits & their Bandwidth
Analysis of Single Tuned Amplifiers
Analysis of Double Tuned Amplifiers
Primary & Secondary Tuned Amplifiers with BJT & FET
Merits and de-merits of Tuned Amplifiers
A silicon-controlled rectifier or semiconductor-controlled rectifier is a four-layer solid-state current-controlling device. Some sources define silicon-controlled rectifiers and thyristors as synonymous,[5] other sources define silicon-controlled rectifiers as a proper subset of the set of thyristors. SCRs are mainly used in devices where the control of high power, possibly coupled with high voltage, is demanded. Their operation makes them suitable for use in medium- to high-voltage AC power control applications, such as lamp dimming, power regulators and motor control.
Keypad is a common interface with any microcontroller. This presentation gives details of keypad can be interfaced with 8051. The key pressed may be dispalyed on LCD/7 segment/LED displays.
it covers topics Introduction
Classification of Logic Families
Important point
Level of Integration
Specification of Digital ICs
TTL Circuit
TTL NAND Gates
MOS/CMOS Circuits
CMOS NAND Gate
ECL Circuit
Comparison
Numbers of Digital ICs
The Reason Why we use master slave JK flip flop instead of simple level triggered flip flop is Racing condition which can be successfully avoided using two SR latches fed with inverted clocks.
IC 555 TIMER Introduction, Modes & Application.pptxanindyapal288
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 200mA 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, pin 3. 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 2/3Vcc 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 Collector 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 timers is between 4.5V and 15V.
Functional block, characteristics of 555 Timer and its PWM application – IC-566 voltage controlled oscillator IC; 565-phase locked loop IC, AD633 Analog multiplier ICs.
Simple Automatic Water Level Controller by using ic 555 timer.PRASHANTH RAO
It is a very simple project.present situation all are facing water problems.to over come that water wasteges we are made this project.It is very easy to do and low cost.the cost in between 200 to 300.without human involving it will work.
SIMULATION OF AN ELECTRONIC DICE CIRCUIT USING LEDs IN PROTEUS SOFTWARE VaishaliVaishali14
The following content consists of the brief details about the topic
INTRODUCTION
CONCEPT OF ASTABLE MULTI VIBRATOR
CONCEPT OF DECADE COUNTER IC4017
CIRCUIT EXPLANATION
CIRCUIT DIAGRAM
VIDEO OF CIRCUIT WORKING
WORKING OF CIRCUIT
INFERENCE
REFERENCE
This presentation consist of remote sensing, types of remote sensing and also about the radiometers systems. I have also discussed about the types of radiometers system and how it work. I have also discussed about the principle on which it works. Also I have discussed about the applications .
Transmission system used for optical fibers Jay Baria
In this presentation I have explained various types of transmission system used for optical transmission and also described about the budget method that has to be followed while selecting an source for optical fibers and also about the factors that should be consider while selecting an source.
In this ppt , I have explain everthing about Blu ray disc like about its working then how it came into existence and how data is stored in it . And how its better then our conventional CD player and also why it is known as blu ray disc and its applications in various field and its advantages.
Classification of signals and systems as well as their properties are given in the PPT .Examples related to types of signals and systems are also given .
Construction & E.M.F. eqn. of transformerJay Baria
In this ppt, construction and emf equation of transformer is shown and also the types of transformer and its various losses and its application is given in the presentation.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
#vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore#blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #blackmagicforlove #blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #Amilbabainuk #amilbabainspain #amilbabaindubai #Amilbabainnorway #amilbabainkrachi #amilbabainlahore #amilbabaingujranwalan #amilbabainislamabad
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...
IC 555 timer and its applications
1. DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
PRESENTATION
ON
555 TIMER & ITS APPLICATIONS
Guided by:-
Priyanka Patel
Asst . Prof(ECE)
LIT, Sarigam.
Submitted by:-
Name: Enrollnment No.
Jay Baria 150860111003
Laxmi Institute of Technology, Sarigam
Approved by AICTE, New Delhi; Affiliated to Gujarat Technological University, Ahmedabad
2. WHAT IS THE 555 TIMER?
• The 555 timer is one of the most remarkable integrated circuits ever
developed. It comes in a single or dual package and even low power
cmos versions exist - ICM7555.
• Common part numbers are LM555, NE555, LM556, NE556. The 555
timer consists of two voltage comparators, a bi-stable flip flop, a
discharge transistor, and a resistor divider network.
4. • The voltage divider (blue) has three equal 5K resistors. It divides
the input voltage (Vcc) into three equal parts.
• The two comparators (red) are op-amps that compare the
voltages at their inputs and saturate depending upon which is
greater.
• The Threshold Comparator saturates when the voltage at the
Threshold pin (pin 6) is greater than (2/3)Vcc.
• The Trigger Comparator saturates when the voltage at the Trigger
pin (pin 2) is less than (1/3)Vcc
INSIDE THE 555 TIMER
5. • The flip-flop (green) is a bi-stable device. It generates two
values, a “high” value equal to Vcc and a “low” value equal to 0V.
• When the Threshold comparator saturates, the flip flop is Reset (R)
and it outputs a low signal at pin 3.
• When the Trigger comparator saturates, the flip flop is Set (S) and it
outputs a high signal at pin 3.
• The transistor (purple) is being used as a switch, it connects pin
7 (discharge) to ground when it is closed.
• When Q is low, Qbar is high. This closes the transistor switch and
attaches pin 7 to ground.
• When Q is high, Qbar is low. This open the switch and pin 7 is no
longer grounded
7. • Pin Functions - 8 pin package
• Ground (Pin 1)
• Not surprising this pin is connected directly to ground.
• Trigger (Pin 2)
• This pin is the input to the lower comparator and is used to set the latch, which in
turn causes the output to go high.
• Output (Pin 3)
• Output high is about 1.7V less than supply. Output high is capable of Isource up
to 200mA while output low is capable of Isink up to 200mA.
• Reset (Pin 4)
• This is used to reset the latch and return the output to a low state. The reset is an
overriding function. When not used connect to V+.
8. • Control (Pin 5)
• Allows access to the 2/3V+ voltage divider point when the 555 timer is
used in voltage control mode. When not used connect to ground through
a 0.01 uF capacitor.
• Threshold (Pin 6)
• This is an input to the upper comparator.
• Discharge (Pin 7)
• This is the open collector to Q14 in figure 4 below.
• V+ (Pin 8)
• This connects to Vcc and the Philips databook states the ICM7555 cmos
version operates 3V - 16V DC while the NE555 version is 3V - 16V DC.
Note comments about effective supply filtering and bypassing this pin
below under "General considerations with using a 555 timer"
9. TYPES OF 555-TIMER CIRCUITS
• Astable Multivibrator
puts out a continuous
sequence of pulses
Monostable Multivibrator (or one-
shot) puts out one pulse each time
the switch is connected
10. IC 555 HAS THREE OPERATING MODES:
1. BISTABLE MODE OR SCHMITT TRIGGER – THE 555 CAN OPERATE AS A FLIP-FLOP, IF
THE DIS PIN IS NOT CONNECTED AND NO CAPACITOR IS USED. USES INCLUDE BOUNCE-
FREE LATCHED SWITCHES.
2. MONOSTABLE MODE – IN THIS MODE, THE 555 FUNCTIONS AS A "ONE-SHOT" PULSE
GENERATOR. APPLICATIONS INCLUDE TIMERS, MISSING PULSE DETECTION, BOUNCE-
FREE SWITCHES, TOUCH SWITCHES, FREQUENCY DIVIDER, CAPACITANCE
MEASUREMENT, PULSE-WIDTH MODULATION (PWM) AND SO ON.
3. ASTABLE (FREE-RUNNING) MODE – THE 555 CAN OPERATE AS AN ELECTRONIC
OSCILLATOR. USES INCLUDE LED AND LAMP FLASHERS, PULSE GENERATION, LOGIC
CLOCKS, TONE GENERATION, SECURITY ALARMS, PULSE POSITION MODULATION AND
SO ON.
OPERATING MODES OF IC
11. IN BISTABLE (ALSO CALLED SCHMITT TRIGGER) MODE, THE
555 TIMER ACTS AS A BASIC FLIP-FLOP.
THE TRIGGER AND RESET INPUTS (PINS 2 AND 4
RESPECTIVELY ON A 555) ARE HELD HIGH VIA PULL-UP
RESISTORS WHILE THE THRESHOLD INPUT (PIN 6) IS SIMPLY
FLOATING.
THUS CONFIGURED, PULLING THE TRIGGER MOMENTARILY
TO GROUND ACTS AS A 'SET' AND TRANSITIONS THE OUTPUT
PIN (PIN 3) TO VCC (HIGH STATE).
PULLING THE RESET INPUT TO GROUND ACTS AS A 'RESET'
AND TRANSITIONS THE OUTPUT PIN TO GROUND (LOW
STATE). NO TIMING CAPACITORS
PIN 5 (CONTROL VOLTAGE) IS CONNECTED TO GROUND VIA A
SMALL-VALUE CAPACITOR (USUALLY 0.01 TO 0.1 ΜF). PIN 7
(DISCHARGE) IS LEFT FLOATING
BISTABLE MODE
12. PULSE GENERATOR CIRCUIT WHICH THE PERIOD IS CALCULATED FROM RC
NETWORK AND CONNECTED TO EXTERNAL OF 555 TIMER
STABLE WHEN THE OUTPUT LOGIC LOW (LOGIC = 0)
WHEN A PULSE IS TRIGGER AT PIN 2 (NORMALLY NEGATIVE TRIGGER PULSE),
TIMER OUTPUT WILL CHANGE TO HIGH (+VS) FOR A WHILE AND CHANGE TO
LOW (STABLE CONDITION). THE CONDITION WILL CONTINUE LOW UNTIL PULSE
IS TRIGGER AGAIN.
THE TIMING PERIOD IS TRIGGERED (STARTED) WHEN TRIGGER INPUT (555 PIN
2) IS LESS THAN 1/3 VS, THIS MAKES THE OUTPUT HIGH (+VS) AND THE
CAPACITOR C1 STARTS TO CHARGE THROUGH RESISTOR R1. ONCE THE TIME
PERIOD HAS STARTED FURTHER TRIGGER PULSES ARE IGNORED.
THE THRESHOLD INPUT (555 PIN 6) MONITORS THE VOLTAGE ACROSS C1 AND
WHEN THIS REACHES 2/3 VS THE TIME PERIOD OVER AND THE OUTPUT
BECOMES LOW,
AT THE SAME TIME DISCHARGE (555 PIN 7) IS CONNECTED TO 0V, DISCHARGING
THE CAPACITOR READY FOR THE NEXT TRIGGER.
MONOSTABLE MODE
14. ASTABLE MODE
Astable multivibrators are
also known as Free-
running Multivibrator.
Astable do not need trigger
pulse for external to change
the output.
The period for LOW and
HIGH can be calculated
based on resistor and
capacitor value that
connected at outside of
timer.
C charges through RA+ RB
and discharges through RB.
15. 555 TIMER
• At the beginning of the
cycle, C1 is charged
through resistors R1 and
R2. The charging time
constant is
• The voltage reaches
(2/3)Vcc in a time 1)21(693.01arg CRRTt ech
1)21(arg CRRech
16. 555 TIMER
• When the voltage on the
capacitor reaches
(2/3)Vcc, a switch (the
transistor) is closed
(grounded) at pin 7.
• The capacitor is
discharged to (1/3)Vcc
through R2 to ground, at
which time the switch is
opened and the cycle
starts over.
1)2(arg CRedisch
1)2(693.02arg CRTt edisch
17. 555 TIMER
• The frequency is then given by
f
R R C R R C
1
0 693 1 2 2 1
144
1 2 2 1. ( )
.
( )
18. Output voltage high
turns off upper LED
and turns on lower
LED
Capacitor is charging through Ra and Rb
Output is high for
0.693(Ra+Rb)C
555 Animation
19. SCHMITT TRIGGER
PPM
PWM
LINEAR RAMP GENERATOR
PRECISION TIMING
PULSE GENERATION
TIME DELAY GENERATION
SEQUENTIAL TIMING
USED AS A QUAD TIMER
APPLICATIONS