Week -2
1. OBJECTIVE: Make a Simulink model of Doorbell using solenoid block where the switch is closed for 2 seconds and then released.
EXPLANATION: Pulse generator is used to create square wave pulse at regular intervals with time period of 4sec , time delay of 2sec of amplitude 1 . This pulse generated signal is converted into physical signal using PS-converter block.The 12V battery (internal resistance 2 ohm) is connected to energise the solenoid when the switch is CLOSED .The solenoid is a simple electronic device that convert electrical energy into mechanical energy.The positive terminal of battery is connected to switch and negative is connected to electrical reference.The ideal translational sensor is connected to solenoidal block for the movement of the plunger as the current flows in the solenoid.When an electrical current is introduced , a magnetic field forms around the coil which draws the plunger in.The coil is made up of many turns of tightly wound copper wire and This plunger movement due to induced field causes the doorbell to ring.
BLOCK DIAGRAM: File attached as UNTITLED4 
This is the screenshot of Doorbell simulink model
RESULT AND JUSTIFICATION:
Input signal is given to pulse generator of square wave pulse at regular intervals with time period of 4sec , time delay of 2sec of amplitude 1unit .Waveshape is shown below:
Output result is shown when plunger moves as a curent in the solenoid passes when switch is closed.The plunger movement causes the doorbell to ring.The plunger motion is measured by a translation motion sensor which is plotted by the scope block.Waveshape is shown below:
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2.OBJECTIVE: Use a thermistor to sense the temperature of a heater & turn on or turn off the fan
GIVEN CONDITION:
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 above 25 °C, OFF otherwise
EXPLANATION: In this model we require thermister, signal builder ,resister,dc motor and some switches,and voltage regulator. From signal builder we have created temperature profile signal according to the time duration given conditions which converted into physical signal through converter block and send it to the controlled temperature source block which is an ideal energy source in thermal network that can maintain a controlled temperature difference regardless of the heat flow rate.Now this generated temperature is sensed by Temperature sensor block or either by thermistor ,it senses equivalent temperatuere as resistanace changes, along with the voltage sensor is connected parallel to the resistorwhich measures the change in voltage across the resistor for the time cycle.The output of th switch is provided to the DC motor via a controlled voltage source which provide voltage in response to the load.The motor asing and rotor ports are connected with the ideal rotational motion sensor along with mechanical rotational reference.This motion sensor output ports connected to the scope for measuring the angular velocity and angle.
BLOCK DIAGRAM: this is the block model of thermistor for the required conditon of temperature
RESULT AND JUSTIFICATION:
Input signal given to signal builder in which x-axis is time and the y-axis is the temperature .for the first 10 second,the heater temperature will be 20 deg celsius and then to 27 deg for the next 20 sec later which falls to 23 deg celsius for 30-50 sec.
output : graph1 shows the voltage produced across the resistance according to thermistor in scope1 (voltage vs temperature)
graph2 shows the temperatures in kelvin for the different time period in scope (temp vs time)
