Week -2

1. Making simulink model for of doorbell using solenoid block with the help following given details.

A. When the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing sound.

B. A situation where the switch is closed for 2 seconds and then released. Observe the physical movement of the plunger.

To begin the simulation we need to setup an input parameter here in pulse generator.

Where delay timing of 2 seconds with amplitude 1 and Pulse time should be 4 secs to make it in half with 50% pulse width.

SCOPE

Input signal of the Pulse generator:

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

Thermistor: thermal resistor is defined as a type of resistor whose electrical resistance varies with changes in temperature.

Although all resistor's resistance will fluctuate slightly with temperature, a thermistor is particularly sensitive to temperature changes.

Thermistors act as a passive component in a circuit. They are an accurate, cheap, and robust way to measure temperature.

While thermistors do not work well in extremely hot or cold temperatures, they are the sensor of choice for many different applications.

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 of thermistor

Simulink Model Explanation

Signal Builder block is used to input the values as per given conditions:

At point 1,Time=0 seconds,Temperature=293 K

At point 2,Time=10 seconds,Temperature=293 K

At point 3,Time=10 seconds,Temperature=300 K

At point 4,Time=30 seconds,Temperature=300 K

At point 5,Time=30 seconds,Temperature=296 K

At point 6,Time=50 seconds,Temperature=296 K

For 0 to 10 s fan is OFF condition because temperature is 293K which is below the thresold 298K.

After 10 s t6emperature goes to 300K then the switch will be in ON condition as the temperature exceeds 298K.

After 30s fan will turn OFF as the temperature comes down to 296K which is below the thresold temperature of 298K.

From the all above condition and observation the values are evaluated.