Week -2

Question 1) Make a Simulink model of Doorbell using solenoid block.

Here through the pulse generator pulses has been generated for 2sec on and 2 sec off. for that pulse period is given as 4sec and the pulse period is for 50%. The switch is used from the foundational library which has one conditionary input port and according to these pulses or condition, it automatically gets on and off. Solenoid is an electromechanical switch so on left side it has an electrical connection and on another say on right side, it has mechanical connections. To sense its traveling Ideal translational motion sensor is placed and through its velocity and position port output is given to the scope.

The below image shows the result of Question 1

Third window shows generated pulse and accordingly solenoid is getting closed and opened in the second window. As it is the mechanical system it has some damping at the starting of each pulse but gets settled within some time.

Question 2) Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions.

Given conditions are -

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

So first signal builder block is used in which the temperature signals are fixed(which are given above) in kelvin. A controlled Temperature source block is used as input to the thermister thermal port and thermal reference is also used. A thermistor is a device whose resistance gets affected by varying surrounding temperatures in this case NTC thermistor is used in this case resistance is inversely proportional to the temperature. To providing sufficient power to the circuit a DC voltage source is used. The voltage sensor is used to sense the voltage across the resistor and its conditional port is given to the switch in this switch threshold is kept to the 0.015 accordances with the 23oC temp. So if the temperature is above or equal to 23oC then on motor or fan will turn on otherwise it will be off. The output of the switch is given to a controlled voltage source which provides power to the motor. DC motor block is used on the left side electrical connections and on the right side mechanical connections are there it is a rotational device so further Ideal rotational motion sensor is used whose input is given from DC motor R port and both C is connected to Mechanical rotational referance. output is taken from omega port with help of scope.

The below graph shows when the temperature is above 23oC motor is starting with 1450rad/sec.

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