This practical temperature controller controls the temperature of any device according to its requirement for any industrial application. It also displays the temperature on an LCD displays in the range of –55°C to +125°C. At the heart of the circuit is the microcontroller from 8051 family which controls all its functions. It is important to control the speed of DC motor where precision and protection are essence. Here we will use a technique called PWM (pulse width modulation) to control the speed of DC motor.

1. Industrial Temperature
Controller

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Introduction
Industrial Temperature Controller
 We can achieve speed control of DC motor using mechanical or electrical
techniques but they require large size hardware to implement but
Microcontroller based system provides easy way to control the speed of
DC motor. The speed of DC motor is directly proportional to the voltage
applied across its terminals. Hence, if voltage across motor terminal is
varied, then speed can also be varied. PWM (Pulse Width Modulation)
wave can be used to control the speed of the motor

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Industrial Temperature Controller
Block Diagram

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Industrial Temperature Controller
Hardware Requirements
o 8051 series Microcontroller
o 7-Segment Displays
o Temperature Sensor
o Transformer
o Crystal
o Diodes
o Voltage Regulator
o LED
o Resistors
o Capacitors
o Push Buttons
o Relay
o Lamp

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Industrial Temperature Controller
Software Requirements
 Keil compiler
 Language: Embedded C or Assembly

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Industrial Temperature Controller
Micro Controller
 Compatible with MCS®-51 Products
 8K Bytes of In-System Programmable (ISP) Flash Memory
 4.0V to 5.5V Operating Range
 Crystal Frequency 11.0592MHZ
 Three-level Program Memory Lock
 256 x 8-bit Internal RAM
 32 Programmable I/O Lines
 Three 16-bit Timer/Counters
 Eight Interrupt Sources
 Full Duplex UART Serial Channel
 Watchdog Timer

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Industrial Temperature Controller
PWM – Plus Width Modulation
 The PWM switching frequency has to be much faster than what would
affect the load, which is to say the device that uses the power.
 The term duty cycle describes the proportion of on time to the regular
interval or period of time.
 A low duty cycle corresponds to low power, because the power is off for
most of the time. Duty cycle is expressed in percent, 100% being fully on.

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Industrial Temperature Controller
PWM Application
 Telecommunications
 Power delivery
 Voltage regulation
 Audio effects and amplification.

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Industrial Temperature Controller
DC- MOTOR
 A DC motor is an electric motor that runs on
direct current (DC) electricity. In any electric
motor, operation is based on simple
electromagnetism.
 A simple 2-pole DC electric motor (here red
represents a magnet or winding with a "North"
polarization, while green represents a magnet or
winding with a "South" polarization).
 Every DC motor has six basic parts -- axle, rotor
(a.k.a., armature), stator, commutator, field
magnet(s), and brushes.

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Industrial Temperature Controller
How to Operate PWM based DC Motor Speed Control
Circuit using Microcontroller?
 Connect 12V battery or adaptor to the development board.
 Switch on the supply.
 Keep the programming switch in prgm mode.
 Burn hex file to the atmega8 controller with the help of serial cable.
 Now switch off the supply.
 Connect PC0, PC1 pins of controller to the switches.

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Industrial Temperature Controller
How to Operate PWM based DC Motor Speed Control
Circuit using Microcontroller?
 Connect PB3 pin to the DC motor.
 Now switch on the supply and press switch sw1 and observe motor. It
runs with full speed.
 If you press switch sw2 motor runs with half speed.
 Switch off the supply.

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Industrial Temperature Controller
PWM Based DC Motor Speed Control using
Microcontroller Circuit Principle:
 The Principle to control the speed of the motor by varying the duty cycle
of the pulse applied to it (popularly known as PWM control).
 It uses two input buttons interfaced to the microcontroller, which are
used to control the speed of motor.
 PWM (Pulse Width Modulation) is generated at the output by the
microcontroller as per the program.

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Industrial Temperature Controller
PWM Based DC Motor Speed Control using
Microcontroller Circuit Principle:
 The average voltage given or the average current flowing through the motor
will change depending on the duty cycle (ON and OFF time of the pulses).
 So the speed of the motor will change.
 A motor driver IC is interfaced to the microcontroller for receiving PWM
signals.
 It delivers desired output for speed control system of a small DC motor.

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Industrial Temperature Controller
Advantages
 Using this PWM method, we can save the power.

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Industrial Temperature Controller
Applications
 Used in industries to control the speed of motors.
 Used in shopping malls.
 We can use this concept to control the light intensity.

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Industrial Temperature Controller
Conclusion
 This practical temperature controller controls the temperature of any
device according to its requirement for any industrial application. It also
displays the temperature on an LCD displays in the range of –55°C to
+125°C. At the heart of the circuit is the microcontroller from 8051
family which controls all its functions.

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