Week -2

AIM:-

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.

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.

1) Door Bell

Theory:-

When the door bell button is present ,on electrical circuit is closed .Which teads to the following of electric current thruogh the electromagnet . the current then passes through the electromagnetic wire winding A magnetic field is generate as aresult ,which is used to drive a saound making mechanism.differend types of sound making mechanism are used to generate different sorts of noise.

Procedure:-

* First the input given with the help of pulse generator and its connected to the electrical switch with the help of a simulink - ps converter and the input is abserved by connecting scope .

* Then the solver configration block is connect to the switch .

* Battary block is defined for voltage source.

* The battary is connected to an electrical switch and the switch is connected to the solenoid to complete the circuit.

* Then we give the blockfor solenoid and connected it to an ideal translational motion sensor to measure the translation motion of the solenoid the translation motion of the bell is obsorved by connecting it to a scope with the help for ps -simulink converter.

* Electrical reference and mechanical translation reference connected as earthing .

* Stop time is given as 20 sec.

* initial position of the ideal translation motion sensor is given as 5.

Parameters:-

pulse type:-Time based

Time (t):- Use simulation time

Amplitute:-1

period (sec):-4

pulse width(%of period):-50

phase delay(sec):-1

Solenoid mechanicl parameter:-

Magnetic Force:-

spring constant: 200 N/m

Stroke for zero spring force :-5 mm

Damping :- 5 N/(m/s)

plunger mass:- 0.05 kg

Maximum stroke:- inf mm

contact stfiness:- 1e6 N/m

contant damping :-500N/(m/s)

Simulink Model :-

figure:- door bell 1.

output scope:-

figure:- door bell.

2) Thermiste

Theory:-

A thermister is a translation thermister ,or a resistance is dependent on temperature .The term is a combination of "thermal "and "resistor ". It is made of metallic oxider ,pressed into a bead, disk or vcylindrical shape and then encapsulated with an impermeable material such as epoxy or glass.

There are two types of thermistors negative temperature cofficient (NTC)and pastivetemperature cofficient (PTC) with an NTC thermister ,when the temperature increase ,resistance decrease Conversely , when temperature decreases ,resistance increase .this type of thermister is used the most .

A PTC thermister works alittile differently. when temperature increase ,the resistance increase ,and when temperature decreases resistance decreases this type of thermistor is generally used as a fuse .

Typicall,a thermistor achieves high precision within a limited temperature range of about 50 degree sellcious arround the target tempeature .this range is dependent on the basic resistance.

Preoceure:-

• First we give the input signal with the help of repeating sequnce stair block.
• Ascope is connected to the input signal of absorver the input .
• Then we make a thermistor block and connected a battary to it as a voltage source .
• Then we connected a resistor block and connected it to a voltage block in series to measure the voltage flowing through the resistor .
• Display block is connected to"v"of the voltage sensor with the help of a ps -simulink convertor to display the output .
• Aconditional switch block with 2 constant blocks value "0" and "1" is connected to the "v" port of the voltage sensor .
• T1 is the first temperature point in kelvin .
• T2is the second temperature point in kelvin .
• R1 is the thermistor resistance at temperature T1in ohms.
• R2 is the thermistor resistance at temperature T2 in ohms .
• Thermal reference and electrical refernce is connected to provide earthing .

Simulink model :-

The fan is off when the temperature is less than 25 degree celsius and the fan is on when the temperature is gearter than 25 degree celsius .

input digram:- thermistor 1

output scope:-

figure :-thermistor 2,3 .

Parameter:-

repeating sequence stair :

vector of output value :-[292 300 296 296 296 ].

sample time :10 sec.