Week -2

Aim:

• Create a Simulink model of a doorbell using a solenoid block.
• To use a thermistor to sense the temperature of a heater & turn on or turn off the fan.

1. Door Bell
Simulink Model:

Simulink Model Explanation:
The pulse generator is used to create square wave pulses at regular intervals. The block waveform parameters Amplitude, pulse
width, period, and phase delay determine the shape of the output waveform.

• The switch block used is controlled by an external physical signal. If the external signal is greater than the threshold parameter then
  the switch is closed, otherwise, the switch is open.
• The Solenoid block is connected to the switch and battery and we will get a complete electrical circuit. The port c is connected
  with mechanical reference.
• The ideal translational sensor is connected with solenoid to observe the movement of the plunger.
• The scope is connected with the ideal translational sensor to get the output.
• PS-Simulink converter is used to convert the physical signal to a Simulink signal.
• Solver Configuration: Each physical network represented by a connected simscape block requires solver for simulation

Output:

The period given is 2 seconds for the Pulse generator to open and close the switch. When the switch is closed the solenoid blocks
receive electrical power from the battery and the plunger moves from port R to c to hit the bell and produce sound.

2. Thermistor

Given Inputs:
Temperature source:

• 20 °C from 0 to 10 seconds,
• 27 °C from 10 to 30 seconds,
• 23 °C from 30 to 50 seconds
• Fan conditions: ON if the temperature is above 25 °C, OFF otherwise

Simulink Model:

Simulink Model Explanation:

• Signal Builder block is used to input the values as per given conditions:
  Temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50 seconds

• A controlled Temperature source represents an ideal source of thermal energy, that can maintain a controlled temperature
  difference regardless of the heat flow rate. The temperature difference is set by the physical signal port S. A positive temperature difference causes the temperature at port B to be greater than the temperature at part A.

• A thermistor is a type of resistor whose resistance is based on temperature.
• A linear resistor is used to control the amount of current from the battery.
• The voltage sensor is used to convert the voltage measured between two points into a physical signal.
• Voltage source which represents dc or ac electrical reference block is given
• Solver Configuration: Each physical network represented by a connected simscape block requires a solver for
  simulation.

Thermistor output:

For 0 to 10 s fan is OFF condition because the temperature is 20 deg which is below the threshold of 25deg K. After 10 s temperature goes to 27deg

the switch will be in ON condition as the temperature exceeds 25deg.

After the 30s the fan will turn OFF as the temperature comes down to 23deg From the above conditions, all the values are evaluated.