Week -2
- Make a Simulink model of Doorbell using solenoid block with the following details:
In the above arrangement, when the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing sound.
Create a situation where the switch is closed for 2 seconds and then released. Observe the physical movement of the plunger.
Assume remaining parameters.
2. Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions:
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.
Simulink model for the above given arrangement is as shown bellow.
And the bellow graph showing position of the plunger in response with the switch operation (ON/OFF), (simulink file is attached)
2. Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions:
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
Ans.
Block diagram for the given system requirements is as bellow.
- Controlling the Switch to On/Off position using voltage drop across the 1000 ohms resistor in series with a thermistor and a DC voltage source of 100V DC .
- In this case for an input temarature of 25degC resulting in a voltage drop of 50 across the resisotr, which is used to control the switch.
- The switch output is set to constatnt 100 which is activating the controlled voltage source to run the DC motor.
- An Ideal motion sensor is connected to the motor to sense the angular velocity and displacement.
- Gain blocks are used to convert rad/s to RPM and rad to Rev.
- Finally the scope observing the provided input is bellow.
From the above graph its visible that
- The fan is started to run at 10Sec and taken 2-3 sec to accelerate to full speed,
- then continuously run till temarature fall bellow 25degC (i.e 30sec) then at 30sec ,
- when the temparature falling bellow 25degC, the switch cut iff the supply and fan deceleraed in 2-3 sec to zero velocity.