Week -2
1. 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.
Ans:- In this challenge, we make a simulink model of doorbell using solenoid block.Doorbell is an electrical device with a button near the outside door of house or apartment that makes a noise when pressed to let the people inside know someone is there.
In this simulation we used following simscape and simulink blocks:
1. Pulse generator :- The pulse generator block used for generating pulse signal which is depend upon following parameter like amplitude, time period of one cycle,pulse width, phase delay. The following parameters determine the shape of input as well as output waveform shapes.
2. Simulink-PS Converter :- This block convert simulink signal into a physical signal.
3.Switch :- Switch is used for ON / OFF condition which is controlled by external physical signal.
4.Voltage source :- Voltage source block gives DC voltage of our electical ckt.
5. Electrical reference and mechanical translational references :- It shows connection to electrical ground and mechanical ground source as a base.
6. solenoid :- Solenoid is an electromagnetic device and that is the main block of our simulink model.
7.Ideal translation motion sensor :- It is a type of sensor which provides the position and velocity as an output of our simulink model.
8.PS-simulink convertor:- It convert physical signal into simulink output signal.
9. scope :- This block is used as a display of our input and output signals during simulation.
This is the input signal which is generated by pulse generator
This is the output signal graph
OBSERVATION :-
From the above output graph, we can observe plunger is moved from its original position to some amplitude with a time delay of 2 sec. that means it hit the bell and pause for 2 sec and come to its initial position.
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:- The term thermistor comes from thermal and resistor . A thermistor is a type of resistor whose resistance is strongly dependent on temperature.Thermistors are used as temperature sensors. They can be found in every day appliances such as fire alarms, ovens and refrigerators. They are also used in digital thermometers and in many automotive applications to measure temperature.
Explanation :- As per above condition of time and temperature we build a signal using signal builder block.
we observed in above graph y- axis represent temperature in kelvin and x axis represent time in second.
A. 0 - 10 secs temperature 293 (20 degree)
B. 10 - 30 secs temperature 300 (27 degree)
C. 30 - 50 secs temperature 296 (23 degree)
These A, B, C, are our input signals. This input signal is given to controlled temperature source block through a simulink - PS converter that convert simulink signal to physical signal. Then this signal is passes to thermister which is connected to our electrical circuit. The voltage sensor is connected in parallel with resistor used to measure voltage as a threshould value for the condition of our simulink model. As per our condition Fan is ON if temperature is above or equal to 25 degree othervise OFF. We used the switch and give the threshold value of 298 kelvin (25 degree)=9.140 which is shown in scope 1 when signal 2 is given as an input to the controlled temperature source.
This is the threshould value of our simulink model.
Result :- In below output graph we observed that
A. At 20 degree Fan is OFF
B. At 27 degree Fan is ON
C. At 23 degree Fan is OFF
As per our condition Fan is ON if temperature is above or equal to 25 degree othervise OFF.