Search Here

Importance of PWM

Pulse Width Modulation (PWM):

It is modulation technique in which the width of pulse or digital control signals changes with respect to time keeping frequency and amplitude constant. It is used to control the power delivered to any load. It is mainly used to control analog devices.

PWM has low power loss and high efficiency therefore it is used in wide range of operation.


Fig.1
Fig.2

  • Fig.2 shows brightness control of LED using PWM technique.

  • The electronic switch is connected between source and LED circuit and the electronic switch is controlled by external control signal.

  • When switch is closed then entire voltage appear across the LED circuit.

  • When switch is in open condition then no voltage across the LED circuit.

  • If we apply control voltage over switch then LED turn ON/OFF rapidly. If the source is of 9v then only 4.5v (average value) appears across the LED circuit.

  • If switch is on only for 25% then the average value or voltage appears across the LED circuit is 2.25v.

  • So like this by changing the width of pulse we can control brightness of LED circuit. And same technique is used to control the speed of DC motor. By using PWM technique we can control the brightness linearly.


Generation of PWM Signal:

By using comparator we can generate the PWM signal. By applying triangular wave to the non-inverting terminal and control voltage to the inverting terminal we get PWM signal at the output of comparator. When triangular wave voltage is less than the control voltage then output of comparator gets low, and when the triangular voltage is greater than the control voltage then output of comparator become high. The width of pulse depends on value of control voltage.

As control voltage reduces the width of pulse increases and vice versa.


Switching frequency:

Switching frequency defines as how fast switching takes place. If the switching frequency is higher, then the greater number of times switches changes per second.


Duty cycle:

The Duty cycle defines ON time of pulse. It is ratio of ON time of pulse to total time period. It is expressed in %.

Duty Cycle= Ton/T*100%

If the duty cycle is 25% that means the pulse ON for 25% of the time.

If the duty cycle is 50% that means the pulse ON for 50% of the time.

If the duty cycle is 75% that means the pulse ON for 75% of the time.


Application of PWM:

  1. Dimming the LED lights

  2. Controlling the fan speed of CPU

  3. Controlling the brightness of display in laptops

  4. DC-DC Converters and SMPS etc.


Dimming LED lights:



CPU fan:



Laptop Display:



SMPS:


More Posts

Image

Compact Fluorescent Lamp Circuit (CFL)

All about Compact Fluorescent Lamp circuit (CFL): The CFL is also known as compact fluorescent light, energy saving light, and compact fluorescent tube. Fig 1 shows the CFL lamp. Why CFL? CFL is compact and energy efficient lamp. It requires less amount of power i.e. 13 to 14 watts than Incandescent light so it is widely used to save energy. Lifespan of CFL lamps is 7 to 9 years. Working of CFL: Fig 2 shows the diagram of CFL lamp circuit and the parts of CFL. The main three parts of CFL lamp is Base, circuit, and tube. We apply actual AC supply to the base. A CFL uses vacuum pipe which is same as tube light. Tube has two electrodes on both ends and they are treated with Barium. Cathode is having temperature of 900 0 C. When we apply AC supply to the cathode it generates a beam of electrode. The beam is further accelerated by potential difference between electrodes. From fig 3 we can see that, accelerated electrons strike mercury and organ atoms, and as a result it prod...
Image

Arduino UNO

Basics of Arduino UNO: Arduino UNO is nothing but microcontroller board based on ATmega328. The ATmega328 is single-chip microcontroller with Atmel. And the family is megaAVR. This board includes digital input/output pins, a power jack, analog input pins, a USB connection, an RST button, and an ICSP header. We can provide power to board using AC to DC adaptor, USB or a battery. The important features of Arduino UNO: The operating voltage is 5v. The input voltage ranges from 6v to 20v. Digital input/output pins are 14. Analog input pins are 6. DC current for each input/output pins is 40mA. DC current for 3.3v pin is 50mA. Flash memory is 32kb. SRAM is 2kb. EEPROM is 1kb. Clock speed is 16MHz. Hardware of Arduino UNO: Fig.1 shows the basic hardware structure of Arduino. The microcontroller is important part of Arduino i.e. ATmega328. There are 14 digital input output pins which are mostly used to connect output devices like LED, LCD...
Image

SMD Register coding

SMD Register coding SMD register are most widely used register and this types of register used in various electronics equipment like TV mobile and different research and development .If we observe the printed circuit board (PCB) we observe the this SMD components with different codes basically this codes define the value of this components in this article we learn that how to fine value of this resisters There are three types of coding teachnics used for these resistors 1.          3 Digit coding scheme 2.          4 Digit coding scheme 3.        EIA 96 SMD Resistor coding scheme Let see the one by one 1.      three Digit coding   scheme In this method three digits   are use   for define the value   of this resistors . The first two digits define the two most significant digits the resister values while the   third value define t...
Image

Thermoelectric Generators AKA Peltier Modules

All about Peltier Module: Peltier modules are electronic devices designed for cooling object below ambient temperature. It can be used as temperature controller.  Fig 1 shows the peltier module. From fig 1 we can see that the “TEC1-12057” shows on module which means 12V and 7amp. Principle and structure: Fig 2 shows the internal structure of peltier module. The internal structure of peltier module comprises semiconductor from P-type and N-type Bismuth Telluride Material. After applying current the thermoelectric effect takes place due to peltier effect. Applying a dc voltage causes the positive and negative charge carriers to absorb heat from one side and transfer and release it on other side. Therefore, the surface which absorbs energy become cool and the surface which releases energy become hot. Working of peltier module: The peltier module has two terminals i.e. positive and negative. While applying voltage remember that the connection must be positive to positi...
Image

Capacitors

Capacitors: Before knowing how does a capacitor works, it is essential to know basics of capacitor and what exactly a capacitor is     • Capacitor is component which is used for storing energy in electric charge.     • The capacitance is measured is the unit Farads.     • It is a passive component, so it does not need any electrical power to operate.     • Capacitor can be fixed capacitor, variable capacitor, polarised capacitor. CONSTRUCTION OF CAPACITOR The capacitor is made up of two conducting plates, between these two conducting plates dielectric material is used such as paper, glass mica etc. Dielectric simply means insulator which can be polarised  if electric field is applied to it. FUNCTION OF CAPACITOR How the capacitor gets charged ??? When a capacitor is connected in a circuit upper terminal or top terminal of the capacitor is connected to the positive terminal of the battery and the bottom terminal of the capacitor is con...

PN Junction Diode

PN Junction Diode Basically, PN junction diode is two-terminal semiconductor device that control flow of electric current in a circuit. In case P-type semiconductor holes are majority carriers and electrons are minority carrier and in n-type of semiconductor electrons are majority carries & holes are minority carriers. They individually act like resistor. But when they joined together by the method of doping the junction is form between them. When a p-n junction is formed, some of the electrons which are present in n-region diffuse across the junction and combine with holes to form negative ions. Similarly, the positive charges or holes from the p-side are diffused to the n region and they form a layer of positive charge on the n-side. The region between these two layers is the depletion region . About unbiased p-n junction , due to presence of immobile positive and negative ions on opposite side of junction, an electric field is created across the junction this is nothing but bar...
Image

Introduction To Raspberry Pi

RASPBERRY PI The raspberry pi is a small computer which is used in the IOT Devices. It is powerful small computer. Raspberry pi was invented by raspberry pi foundation in UK. There are numbers of Raspberry pi versions available to use. Raspberry pi comes with a SOC system on chip with a ARM processors with a GPU Raspberry processor have 700 to 1.2 ghz speed and have a ram size from 256 mb to 1 gb. Raspberry pi make uses of sd card to store the os of raspberry pi. Raspberry pi have a operating system name Raspbian os .it have suggested by the raspberry pi foundation.it is a linux based operating system . In raspberry pi others various operating system can be installed to perform various task. Raspberry pi support s python language well. Its also have a support for a sensors and other devices. It also have usb port , Ethernet ports ,HDMI ports , gpio pins , audio support, Display serial interface , camera interface, sd card slot . Raspberry pi is a small com...
Image

Gas sensor

Gas sensor Hello geeks in this article I am going to share information about the various gas sensors and also their working principle. There is a very intresting phenomena in working of gas sensor I will share that information with some illustrations in this article. First of all we get a doubt what is a gas sensor, why we need it? What is working principle behind it ? What are the different gas sensor and where do we use them ? Dont worry, I am going to answer all these questions in this article. Our first question is very simple to answer a gas sensor is a device that senses the gas around it and gives us the output either in a digital signal for a continuous discrete values as a analog signal. When when we come to the next question why we need it then the reason is to identify the gas leakage in the home, industries, hotels and they are also used for detecting the alcoholic people. It is used to detect the flammable,   toxic gases in petroleum and some other indu...
Image

What Are Resistors?

Resistor It is the passive circuit linear element which opposes the flow of current or electricity. As the name indicate linear element it means that as the voltage applied to the resister is changes(increase/decrease),the current flowing through this resister is also changes. So the relation between the voltage, current and resistance is given by I=V/R (Ohms Law) Resistance is a property of a material which changes according to the resistivity of the material. The relation between the length, area and resistivity is given by R = ρ ℓ / A Power rating is a maximu m power which is handled by the resistor. Mathematically it is written as P=V*I Power rating ranges from 1/16W to 300W. While selecting the resistor apart from power rating the ambient temperature is also consider. Tolerance is a deviation in the resistance from the normal value. Tolerance ranges from 0.1% to 20%. As the temperature changes the amount of resistance is changes this amount of ...
Image

INTERFACING OF ARDUINO WITH ULTRASONIC SENSOR

INTERFACING OF ARDUINO WITH ULTRASONIC SENSOR In this session, ARDUINO interfacing with Ultrasonic Sensor is discussed. Ultrasonic Sensor is used to calculate the distances of the obstacle. It works on the principle of SONAR. Ultrasonic Sensor senses the distance of an object by sending the ultrasonic sound at 40,000 Hz, which travels through the air and if there is an object or obstacle on its path it will reflect or bounce back to the receiver of the module.         The common name of Ultrasonic Sensor is HC-SR04.         Operating Voltage of this sensor is +5V.         It can measure distance from 2cm to 80cm.         It contains 4 pins – VCC, Ground, Echo, Trigger. Trigger pin is the input pin and it sends the ultrasonic waves. Echo pin is the output pin and it receives the bounced or reflected waves FORMULA TO CALCULATE DISTANCE...

Archived