Week -2

1) Simulink model of Door bell using solenoid block

Steps to prepare the model:

Obtain the Solenoid block, a battery or a DC voltage source,an electrical switch, ideal translational motion sensor, pulse generator, solver configuration block, electrical reference and translational reference.

Solenoid block: This block contains a coil and mechanical connecting ports C and R where R is moving contact and C is the fixed contact.In order for the contact R to move, the solenoid coil should be excited.

Battery: In order to energize the coil which inturn is responsible for the movement of R, battery is used.

Electrical switch: In order to control the opening and closing of the circuit as per the requirement (here in this case, it is to be operated for a period of 2sec)

Ideal translational motion sensor: In order to observe the movement of the plunger, this block is used.

Pulse Generator: To operate the switch for a period of 2sec, this block is used.

Scope: The movement of the plunger can be observed in the scope.

Run the below model of doorbell and observe the result

The graph of the model is as shown below

2) Thermistor model for sensing the temperature of the heater

A Thermistor is a resistor whose resistance depends on the temperature.

For implementing the above condition, following are the requirements:

• Thermistor block, Battery, Resistor, Voltage sensor, Signal Builder, Switch, Scope, Solver Configuration,

Run the below Simulink model of thermistor and observe the graph.

Explanation of the model:

1) Constant Block: Use a constant block and set it to the value for which the fan is to be operated (in this case it is above 298.15 kelvin) and give this as input to the physical port of Thermistor.

2) Battery: Connect the Battery to the circuit which will cause a current to flow, and the voltage will drop across Thermistor and Resistor.

3)Switch : Set the threshold value same as the value across the resistor. When different temperature range occurs (with change in temperature, the voltage across thermistor and resistor will vary) the switch will operate accordingly based on the threshold value.

4)Signal Builder: Use this block to build a signal with temperature values in kelvin.

Graph:

From the graph it can be observed that the position of the switch is at ZERO for a period of 10seconds as the temperature is below 25 degree celcius and it becomes ONE for a period of 20 seconds as the temperature rises more than 25 degree celcius.