Week -2

AIM: To Make a Simulink model of Doorbell using solenoid block.

To Use a thermistor to sense the temperature of a heater & turn on or turn off the fan.

SIMULATION MODEL OF DOOR BELL USING SOLENOID BLOCK

EXPLANATION OF SIMULINK MODEL OF DOOR BELL BLOCKS

PULSE GENERATOR: Pulse Generator is a electronic circuit equipment used to generate the Rectangular pulses at regular intervals.

SIMULINK – PS CONVERTER: As the name itself suggests that it is a converting device. It converts the Simulink input signal to physical signal. The unit expression in 'Input signal unit' parameter is linked with the Simulink input signal and determines the unit assigned to the Physical Signal.

SWITCH: A switch is any device used to interrupt the flow of electrons in a circuit. If the external physical signal PS is greater than the threshold, then the switch is closed, otherwise the switch is open.

BATTERY: The flow of electrons provides an electric current that can be used to do work.

SOLENOID: Solenoid is an electromagnetic device. Whenever the current flows through the circuit the magnetic field can be generated and when the magnetic field is created the solenoid starts moving.

When the Battery is ON and the switch is in ON position solenoid generates a magnetic field around it. When the switch of the bell is ON the current passes through the circuit, exciting the magnetic field pulls the plunger towards the metal body which produces the sound signal.

RESULTS

The time period of 2sec is given to the pulse generator and the amplitude of 1 is given. When the switch is ON current passes through the solenoid produces the magnetic field and the plunger starts to move and hits the bell gives the sound/audio signals. The process is repeated for every 2 seconds.

THERMISTOR TO SENSE THE TEMPERATURE OF A HEATER & TURN ON OR TURN OFF THE FAN

Given Conditions are

Temperature (Degrees) Time (sec) Fan Temp (Degree)

20⁰c 0-10sec ON <25⁰c

27⁰c 10-30sec OFF >25⁰c

23⁰c 30-50sec

SIMULINK BLOCK DIAGRAM

THERMISTOR SENSOR: This block represents a Negative Temperature Coefficient thermistor is self resetting over current protectors. Measures the temperature around by comparing it with the known temperature and resistance values.

SIGNAL BUILDER: Signal builder block helps actually create a own signals. The conditions are given to the signal builder block to generate the signals.

The fan should be in ON position when the threshold value >25⁰c & in OFF position when the threshold value <25⁰c. To obtain this condition the voltage sensor is connected to common between the thermistor and the resistance. The voltage sensor that converts voltage measured between any electrical connections into a physical signal proportional to the voltage other end of the voltage sensor is connected to PS-Simulink converter which converts from physical signals to Simulink signals. The switch is connected in such way that if it is open the voltage across the voltmeter is less than 25kv and the switch is close the voltage across the voltmeter is greater than 25kv. The threshold value of the switch should be 0.9.

RESULTS

From the above results we can observed that from 0 to 10seconds the temperature is at 293k and 10 to 30seconds the temperature raises to 300k and 30 to 50seconds the temperature comes at 296k.

From the results of PS-Simulink converter we can observed that from 0 to 10seconds the temperature is at 20⁰c and 10 to 30seconds the temperature raises to 27⁰c and 30 to 50seconds the temperature comes at 23⁰c.

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