Week -2

AIM:

this challenge aims to make a simulik modal of a door bell using a solenoid and block and make enother similink model where a thermistor will be used to sense the temperature of heater &turn it on off the fan.

OBJECTIVE:

1.make a simulink model of door bell using a solenoid block with the following details:

in this above arrangment ,ehen the switch is closed the electro-magnet recieves electrical power from the battery and pulls the metal arms to hot the bell producing sound .create a situation where the switch iss closed for 2'' second and then released observe the physical movement of the plunger .assume remaining parameters.

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

tempearture: 20' from 0to 10 seconds ,

27,c from 10 to 30 seconds,

23,c from 30 to 50 seconds.

fan condition : ON if the temperature above 25,c , off oherwise.

solution of objective -1:

theory:

Door bell:

A door bell is a signaling device typically placed near a door to building entrance.when a visitor presses a button the bell ring inside the building , alternating the occupant to the presence of the visitor. the heart of door bell is an electro-magnet arecolls of wire wrapped a small piece of magnetic mental.when electricity passes through the wire it creat a magnetic filed arond a small piece of magnetic mental . when electricity passes through the wire , it creat a magnetic field around wire .when you press a door bell button , you complete an electicitry circuit .that allows household electricity to flow through the door bell internat electro-magnet .the magneic field generated by the electro-magnet is then used to power a mechanismthst creates the door bell sound.

door bell are low -voltage devices .this means they requir relatively little energy to operate.an important part of a door bell mechanism is tghe transfomer .the transformer converts regular 120-volt household current to lower voltage (usally somewhere between6-16volt) required by the door bell.

Solenoid:

a solenold is a 3-dimensional structure of wire.when this wire is wrapped around a metallic block in a coil and electricity passed through it , it has special magnetic properties .electro-magnetic induction makes it electro-magnet that can be switched on or off .the side in which thte current appears to be passing clockwise is the south pole ,and the side in which the seconds seems to be passing anticlockwise is the north pole

fig-1. A simple diagram of door bell

fig-2 traditional door bell.

SIMULINK MODEL OF OBJECTIVE-1:

fig-3- simulink model of objective-1

The figure above is the representaion of '' A door bell operated on solenold '' in this model ,some blcks are used to make the working model of the door bell. these blocks are:

1.pulse generator : the purpose geneartor block genewartes square wave pulses at regular intervals the wave from parameter, amplitude , pulse width ,peroid and phase delay ,determine the shape of the output wavefrom .

2.scope: display signals genearated during simulation .

3.switch: switch controller by an external physical signal.

4. simulink-ps converter: converts the unitless simulinkinput signal to physical signal.

5.battery :the battery block represent a simple battery model:

6.solenoid: model battery electrical characteristics and generated force of solenoid :

7.ideal translation motion sensor: the ideal translational motion sensor block represents a device that convert an across vaiable measured between two mechanical translation nodes ints a control signal proportional to velocity or position you can friction delay ,energy consumption and so on

8. mechanical translational refererence: the ideal translational motion sensor block represent a device that convert an across

all translational ports that are rigidly clamped to the frame ground must be connected to a mechanical translational reference block .

9. electrical references : the electrical referencs block represent an electrical ground . electrical conserving port of all the block that are directly connected to the ground must be connected to an eletrical referencs block . a model electrical must contain at least one electrical block .

10. solver configuration : the solver configuration block specifies the parametters that your model needs before you can begin the simulation.

11. ps-simulink converter: convert physical signal ino simulation output signal:

MODEL EXPLANATION :

the purpose generator is used to give the signal input where ,amplitude =1,period =4sec,pilse width=50%,and phase delay =2sec(see fig -4)

after that ,the input signals is converted in to physical from with the use of ''simulink -ps converter '' and further send to the switch off the electrical circuit.

the electrcal circuit consist of a solenoid ,a battery ,and a switch ,one end of the solenoid is connected to the battery and its other end is connected to the switch ,and electrical referencs is provided in the electrical circuit.

a solver configuration is connected to an electrical circuit to solve all parameters before the geginning of the simulation

fig-4 pulse geneartor.

fig-5 signal input in door bell:

OUTPUT:

here we can see thst the switch is closed for '2' seconds and after that switch is open . amplitude =0 means the switch is closed .it can also be seen that the plunger strikes after every 2 seconds the motion of the plunger was simulated and recorded plotted in scope.

solution of objective-2:

theory:

A thermistor (or thermal resistor) is defined sa a types of resistor whose electrical resistances varies with tempearture changer . although all resistor resistance wii fluctuate sightly with temperature,a thermistor is particulary sensitive to temperature changes.

themistor acts as a passive component in a circuit they arte an accurate cheap and robust way to measure temperature while thermistore do not work well in extremely hott or cold temperature , they are the sensor of choice for may different applications

fig -7 different types of thermistor.

simulink model of objective-2:

fig-8 simulink model of objective -2:

the figure show the representattion of thermistor connection which senses the temperature of heater and passes the signal to a switch where a threhold limtit is already set. if the temperaturels above or equal to the threhold limits ,then it gives ''1'' as output which is switch on, if the tempearture is below the threshold limits then it will give '0' as output which meancs switch off 'the input signal is generated with the help of a signal bullder block (see flg .9) this signal is created according tobthe condition give in this challenge .

the condition are as following :20'c from 0to10seconds ,

27' c from 10to 30seconds '

23' c from 30to 50 seconds .

fan condiion : on if the temperature above 25'c, off otherwise .

here the temperature is converted in kelvin from degree calcus because the signal converter does not take o c value a than input also have to see set thge signal unit as ''kelvin'' in simlink -ps converter.

the from for conversion :1' c=273.15k

the signal 1 is:

from 0-10 sec -emperature is 293.15k.

from 10-30 sec -temperature is 300.15k.

from 30-50 sec -temperature is 296.15k.

thermistor -model /signal builder :ground-1

fig-9 input signal creates on signal bullder block.

fig-10 enable zero -crossing detection.

model explanations:

1.at frist ,the signal is created in ''signal buillder'' and further passes ''simulink -ps converter the input signal into the physical signal.

2. this physical signal is connected to a block '' controlled to block ''contrilled temperature source'' this block is connected to thermistir and ''thermistor voltage sensor an electrical referencs are connected to make a complete circuit .a solver all parameter before the begining of the similink .

4. the voltage sensor senses the temperature in the from of voltage and send the data to its port''v''.

5.from this port,we get output and send it two different ''ps -simulink converter.

6. from converter -1 ,the signal is sent to the threshold switch,in the threshold limits to 1.10555e-0.2.if the temperature is above or equal to the threshold limits then it give ''1'' as which is ON'' if the temperature is below the threshold limts ,the it will give ''0'' as outputs which means ''switch off'' the input signal is generated with the help of a '' signal builder '' block (see fig .9)

7.the swich is connected to the scope ,where we can see our output plot.

8.from converter2, it converter the physical the signal into a simulink signal and sends the voltage data from the voltage sensor to display .

8. from converter2, it converter the physical signal into a simulink signal and sends the voltage sensor to display

this display give us the threshold value of voltage . this value set in the switch,

OUTPUT:

it can be seen that the value of the signal is ''0'' from 0-10sec because in this time temperature was 20c' which is below 25 'c meancs'' switch off the fan'' after that, the signal value gives ''1'' as output from 10-30 because in this time ,the temperatureewas 27'c which is above 25'c meancs ''switch on the fan '' the value of the signal agian goes to ''0'' from 30-50 sec . because in this time the temperature was 23'c which is above 25'c ,eancs '' switch off the fan'''

now it is clear that our model is correct and fullfills all the inputs conditions

fig-11 output signal of objective-2