Week -2

Ans 1) Simulink model of door bell using solenoid block. In the below block model when the switch is closed the electromagnet receives electrical signal which in turn pulls the metal arm which hits the bell producing sound.

Using pulse generator a signal is generated which gives a value of 1 for every 2 seconds and 0 for other 2 seconds. The Signal is passed through the PS-switch, a PS-switch is controlled by external signal if the input signal is greater than the threshold value then the switch is closed or else it is open. In this case the threshold value is 0.98 and as the signal hits the value 1 the switch is closed and the circuit is completed and thus the bell rings due to the movement of plunger.

Block Used

1. Pulse Generator.
2. Simulink to physical signal converter.
3. PS-switch.
4. Battery.
5. Solenoid.
6. Solver configuration.
7. Electrical referance.
8. Ideal translation motion sensor.
9. Physical system to simulink converter.
10. Mechanical translational reference.
11. Scope.

BLOCK DIAGRAM

RESULTS

• The upper part of the graph represents signal from Pulse generator.
• The lower part of the graph represents signal from the ideal motion sensor which proves that when the current passes through the solenoid the plunger is pulled up which in turn hits the bell producing sound.

Ans 2) A thermistor is used to sense the temperature in the heater and turn on or ff the fan for cooling purpose. The condition for turning on the fan is temperature> 25 degree celcius.

Below is the block model for the same a DC motor is used to represent the fan when ever the above condition is met the fan is turned on which will be clearly understandable from below results.

A signal builder block is used to build the required signal that is 20 degree celcius for 0 to 10 seconds , 27 degree celcius for 10 to 30 seconds and 23 degree celcius for 30 to 50 seconds. Then this signal goes to controlled heat source from there it is further transfer to PTC Thermistor connected to resistance in series and and a voltage senor in parallel to resistant. The PTC Thermistor block represents a switching type Positive Temperature Coefficient (PTC) thermistor. This type of thermistor has a decreasing resistance with temperature increasing up to the Curie temperature. A thermisor is a resitance thermometer whose resistance increases with increase in temperature and decrease with decrease in temperature.

The volatge senor sense the voltage in the circuit and the scope is use to see a plot between voltage and time from where we can find the voltage at 25 degree celcius which can be further be used as threshold value for switch to be in ON condition. The threshold voltage is 0.0012 V. The signal from the switch is send to scope where we get an plot for signal builder and switch which clearly shows that that the switch is ON only for 10 to 30 seconds when the temperature is 27 degree celcius which is above 25 degree celcius. A signal from switch is aslo feeded to DC motor via simulink-ps converter to run DC motor Via ideal angular velocity source. When the switch is ON the the DC Motor rotates whic can be sensed from Ideal rotational sensor which is feede to scope via ps-simulink converter. From the plot it is very clear that the fan runs from 10 to 30 seconds as the temperature is 27 degree celcius.

Below is the Block model along with all the results.

RESULTS

• Signal Builder the temperature is in Kelvin.

• Voltage sensor result.

• Results from switch and signal builder.

• Result from DC Motor.

From the above plots it is proved that the fan is On for 10 to 30 seconds when the temperature is 27 degree celcius which is above 25 degree celcius. The threshold voltage is 0.0012.