Week -2

Ans 1) Whenever the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing sound.

The blocks are used in simulink to make this projects are :-

1) Pulse Generator :-

The pulse generator block generates the square wave pulses at regular intervals.

2) Battery :-

In battery positive terminal is connected with "switch" and negative terminal is connected to "solenoid".

3) Switch :-

The block represents a switch controlled by an external physical signal. If the external signal PS is greater than the threshold, then the switch is closed, otherwise the switch is open.

4) Solenoid block:-

The solenoid block represents the electrical characteristcs and generated force for the solenoid. A solenoid is a device comp[rised of a coil of wire, the housing and movable plunger. whenever an electric current is introduced a magnetic field forms around the coil which draws the plunger in. A solenoid is a type of electromagnet that converts electrical energy to mechanical work.

5) Ideal Translation Motion Sensor:-

This block measures velocity or displacement in a mechanical translational network. The Sensor is ideal since it does not account for inertia , Friction , delays , energy consumption and so on.

6) Solver configuration:-

The Solver configuration block specifies the solver parameters that your model needs before you can be a simulation.

7)PS - simulink convertor:-

It converts the input physical signal to a simulink output signal.

SIMULINK MODEL:-

In the simulink model i have used a pulse generator block as an input.The pluse is such that, every 2 sec its ON.

The above image shows the pulse given as a input.This cycle repeats for 20 sec.

In the output plot, we can see a step function with up and down in the curve.when looking at the time x-axis, we see a difference of 2 sec for every peak.This indicates opening and closing of the switch for every 2 sec.

Ans 2) Temperature source:20 degree C from 0 to10 seconds,27 degree C from10 to 30 seconds,23 degree C from 30 to 50 seconds.

Fan Condition: ON if the temperature above 25 degree C , OFF otherwise.

The main blocks are used in simulink to make this projects are :-

1) Signal builder block:-

The Signal builder block is used to generate the signal according to the inputs provided. This could be used to build signals on own.

2) Control Temperature source:-

The control temperature block represents an ideal source of thermal energy that is powerful enough to maintain specified temperature difference across the source regardless of the heat flow consume by the system.

3) Thermistor:-

A thermistor is a resistance thermometer or a type of resisitor those resistor is strongly depends on temperature.

4) Voltage Sensor:-

The block represents an ideal voltage sensor, a device that convert voltage measured between an electrical connection into physical signal proportional to voltage.

5) Battery:-

In battery positive terminal is connected with "Thermistor" and negative terminal is connected to "Resistor".

SIMULINK MODEL:-

In this model the Fan should be turn ON when the temperature is greater than 25 degree C . For this we use a voltmeter to find thge voltage of the circuit at different temperature.It is found that voltage is 25 degree C is approx 0.23 volt.So this voltage signal is pass through the switch and switch is open when voltage across the voltmeter is less than 0.23 volt and close when voltage across voltmeter is greater than 0.23 volt.The threshold of switch is set to 0.23 volt.

Above figure shows how the signals are set in the "Signal builder block" as given in question that is 20 degree C from 0 to10 seconds,27 degree C from10 to 30 seconds,23 degree C from 30 to 50 seconds. and we want to convert degree celsius into kelvin because the thermistor reference temperature is in kelvin. so for that 293 kelvin from 0 to10 seconds, 300 kelvin from 10 to 30 seconds, 296 kelvin from 30 to 50 seconds and in 300 kelvin our ouput that is fan get operated.

From the switch output we can see that output is ON in between 10- 30 sec as a temperature is greater than 25 degree C and that output is given to Fan.