Pulse width modulation (PWM) is a method of changing the duration of a pulse with respect to the analog input. The duty cycle of a square wave is modulated to encode a specific analog signal level. This pulse width modulation tutorial gives you the basic principle of generation of a PWM signal. The PWM signal is digital because at any given instant of time, the full DC supply is either ON or OFF completely. PWM method is commonly used for speed controlling of fans, motors, lights in varying intensities, pulse width modulation controller etc. These signals may also be used for approximate time-varying of analogue signals. Below you can see the pulse width modulation generator circuit diagram (pulse width modulator) using op amp. PWM is employed in a wide variety of applications, ranging from measurement and communications to power control and conversion. Pulse width modulation dc motor control is one of the popular circuits in Robotics.

1. Prepared By :
Amar pandey
Pulse width modulation
with using dc fan
&
pulse genertor

2. INTRODUCTION
Pulse width modulation (PWM) is a method of changing the duration of a pulse
with respect to the analog input. The duty cycle of a square wave is modulated to
encode a specific analog signal level. This pulse width modulation tutorial gives
you the basic principle of generation of a PWM signal. The PWM signal is digital
because at any given instant of time, the full DC supply is either ON or OFF
completely. PWM method is commonly used for speed controlling of fans, motors,
lights in varying intensities, pulse width modulation controller etc. These signals
may also be used for approximate time-varying of analogue signals. Below you can
see the pulse width modulation generator circuit diagram (pulse width modulator)
using op amp. PWM is employed in a wide variety of applications, ranging from
measurement and communications to power control and conversion. Pulse width
modulation dc motor control is one of the popular circuits in Robotics.

3. What is modulation ?
OR
What is modulation of a signal
 In electronics and telecommunications, modulation
is the process of varying one or more properties of
a periodic waveform, called the carrier signal, with a
modulating signal that typically contains
information to be transmitted.
Modulation Signal = Original Signal + Carrier Signal

4. What is Carrier Signal ?
How to Generate a Carrier Signal ?
OR
A method of generating a triangle waveform is to first
use a clock oscillator to produce a square wave and
then use an integrator (low pass filter) to integrate
the square wave into a triangle wave it’s called carrier
signal .

5. Types of modulation
 There are three types of modulation.
I. A.M (Amplitude Modulation)
II. F.M (frequency Modulation)
III. P.W.M (Pluse widthmodulation)

6.  A.M (Amplitude Modulation)
In amplitude modulation, the amplitude (signal
strength) of the carrier wave is varied in proportion
to the waveform being transmitted.

7.  F.M (Frequency Modulation)
Frequency modulation (FM) is a modulation
technique used in electronic communication, most
commonly for transmitting information via a radio
carrier wave.

8.  What is PWM (Pulse Width
Modulation)
 Pulse-width modulation (PWM) is a digital modulation
technique in which the width of a pulse carrier is
changed according to the instantaneous value of the
information signal.

9. CIRCUIT DIAGRAM
Fig. CIRCUIT DIAGRAM OF PULSE WIDTH MODULATION

10. Advantages
 Average value proportional to duty cycle, So variation in pulse width
leads change in output which can be easily control.
 P.W.M give output in terms of digital signal which reduction noise.
 Less heat dissipated versus using resistors for intermediate voltage
.values

11. Disadvantages
 Complexity of circuit
 Radio Frequency Interference
 Voltage spikes
 Electromagnetic noise

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