Week -2

AIM-

1) To make a simulink model of the door bell of the using solenoid.

2) To make a simulink model use a thermistor to sense the temperature of a heater & turn on or turn off the fan.

OBJECTIVES-

for doorbell-

1) create a situation where the switch is closed for 2 seconds and then released.observe the physical movement of the plunger.

for fan-

2) Temperature source should be 20c from 0 to 10 seconds,27 c from 10 to 30 seconds,23 c from 30 to 50 seconds.fan continous should be ON if the temperature is belowe 25 c OFF otherwise

GOVERNING DIAGRAM-

FOR SOLENOID-

Basic componets of used to genarate the simple doorbell circuit.

1) battery

2) switch

3) solenoid

4) A bell with plunger

FOR THERMISTOR-

Basic compontens are used to genarate the simple cooling fan circuit are:

1)battery

2) fan

3)thermistor

4)transistor

5)resistor

THEORY-

SOLENOID-

A solenoid is a type electromagnet the purpose of which is to generate a controlled magnetic field through a call wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field a volume of space When an electric current is passed through it. THe term solenoid was coined in 1823 by Andre marie Ampere to deignate a helical coil. In engineering the term may also refer to a variety of transdure device that convert energy into linear motion.The term is also refer to a solenoid valve an integrated device containing an electromechanical solenoid which actuates either a pneumatic or hydrauluic value,or a solenoid switch,which is a specific type of a relay that interbnally uses an electromechanicl solenoid to operate an electricval switch of example,an automobikle starter solenoid or linear solenoid.solenoid bolts,a type of electromagenetic technology,a solenoid is an actuator assembely with a silding ferromagenetic plunger inside the coil.without power,the plunger extends for part of its length outside the coil; applying power pulls the plunger into the coil.Electromagnets with fixed cores are not considered solenoides.

THRMISTOR-

a thermistor is resistor whose resistance is depends on tempereture more so that standard resistors.The word is the combination of thermal and resistor.Thermistors are widely used as inrush current limiters.temperature sensors (negative tempera0ture coefficient or NTC type typically),self-resetting overcurrent protectors,and self-regulating heating with elements(positive temperature coefficient or PTC type typically).

thermistors are of two types opposite fundamental types:

1.with NTC thermistors, resistence decreased as temperature rises.An NTC is commonly used as a temperature sensor,or in series with a circuit as an incrush current limiters.

2.With PTC thermistors,resistance increases as temperature rises.PTC thermistors are commonly installed in series with a circuit, and used to protect against overcurrent conditions ,as resettable fuses.

thermistors are generally produced using powdered metal oxides.With vastly improved formulus and techniques over the past 20 years,NTC thermistors can now achieve accuracies over wide temperature ranges such as=0.1C or =0.2c from 0c to 70c with excellent long term stability.NTC thermistor elements come in many styles such as axial-leaded glass-encapsulated(DO-35,DO-34 and DO-41 diodes),glass coated chips,epoxy-coated with bare or insulated lead wire and surface-mount,as well as rods and discs.The typically operating temperature range of a thermistors is -55c,though some glass-body thermistors have a maximal operating temperature of+300c

thermistors differ from resistance temperature detectors (RTDs) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals.The temperature response is also different RTDs are useful over larger temperature renges,while thermistors typically acheive a greater precision within a limited temperature range, typically-90c to 130c

SIMULINK MODEL:

DOOR BELL:-

EXPLANATION:

1.From the above governing circuit of a door bell we know that we need a switch,solenoid,battery and a plunger.

2.so,in order to get all these componets into a simulink model we have to taken blocks that perform same action what the above devices perform.

3.NOw first a 'solinoid block' is taken into a represent a solinoid in the model,then to represent the battery we have taken battery block,from the library browser.

4.then these 'solinoid block' and battery block are connected to each other via positive negative terminal.

5.A switch block is placed in between 'solinoid block' and the battery block and its connected into both the blocks.

6.Now from the switch to operator we need to provide physical siganals to PS blocks in the switch block.they provide physical signal should be greater than in threshold of the switch,for switch begain closed or else it open.

7.Now these whole battery switch and solinoid for is connected to an electrical reference blockwhich represent earthing of this circuit.these electrical reference block should be connected with negative port of the battery block.

8.Then in the 'Solinoid block' ,'R' and 'C' are to two variables which represent pluger and fixed point respectively.

9.Now this 'R' is connected to a 'R' of ' Ideal Translation Motion Sensor Block', which senses the position of the pluger in the 'Solinoid block' and gives the output.

10.Now in 'Ideal Transection Motion Sensor Block' the outputs are given as 'V' and 'P' which represent the velocity and the position of the pluger .Since we are only intrested in knowing the change in position of the pluger,so we need only result from 'P' output.

11.Now 'C' in the 'Ideal Transection Motion Sensor Block' is a machanical transection converting port ,which means that the mechanical process start from 'R' and 'C' and again its start at 'R' and cycle goes on.

12.So 'C' in the 'Ideal Transectin Motion Sensor Block' is connected to a 'Mechanical Transection Reference' as foxed poin where it ius rigidly clamped in real time.

13.Similarly 'C' of 'Solinoid Block' is also connected to the same 'Mechanical Transectins Reference' as fixed point for the solinoid.

14.Since we position of the pluger as output from 'Ideal Transection Motion Sensor Block' we have connected port 'P' to a 'PS'-Simulink Convertor' is connected to 'Scope Block' which will generate a graph for change in position of pluger from port 'P' of 'Ideal Transection Motion Sensor Block'.

15.Now to provide a physical siganal for operating the switch, we have used a 'Plus Generator Block',which generates a continuous square pulse.

16. From the above figure we can observe that we have taken we have given o to 4 sec and width are 10 sec phase delay as 2 sec

17. To this 'signal builder'is connected the switch by simulink ps_ convertor.

FOR FAN OPERATIONS USING THERMISTOR:-

EXPLANATION-

1. To create a simple cooling fan model using thermistor we need a thermistor we need thermistor,battery,resistor,,voltmeter,

a logical switch which are basic components of the circuit we need in the simulink model.

2.Frist to represent a thermistor. a 'thermistor block' is taken and placed in the model.now to represent a battery, a 'battery block'is taken and the positive port of this block is connected to positive port of the 'thermistor block'

3.now to represent a 'resistor block' is taken from the library browser and its positive port is connected to negative port of the 'thermistor block'.the negative port of 'resistor block' is connected to the negative port of the 'battery block'.Now a "Electrical referance block' is connected near the negative terimanal of the battery block which represents the earthing of the real time circuit.

4.Now to represent a voltmeter a 'voltage sensor block'is connected parallel to the 'resistor bl;ock',became to measure to voltage across a components,voltmeter should be always connected paerallel to that component.

5.Thus,we have completed our simple circuit model, but we need some physical quqntities to as signal for thermistor to work.

6.In this case we need the fan to ON and OFF at diffferent tempereture.so,to provide temperature we have used controlled tempereture source block which only given a specified temperature as output even though heat flow is more.

7.Now to give dofferent temperature to this 'controlled tempereture source block' we need to send tempereture signals.To send these signals we have3 used a signal builder block which allows use to send any type of signals as inputs.

8.we have to double click on the signal bilider block to set the signal according to our requiremen

9. Above figure shows how the signal are set in the 'signal builder block'.As this dialogue box opens,frist we have to click on the 'signal' at the top and then select 'custom' option.Now it will ask to give the values of y-axis and x-axis.since we know that at which time we need which tempereture as mentionesd in the starting we can give those values in an array in this box and then the above figure signal are generated.

10. we can see in the figure that how different temperture are given at different time.so thus,we have created our signals and before connected tempereture source block we have to convert these signal into a physical value.so,to do this we hwve used a simulink-ps converter block.

11.so now the port 'B'of 'controlled temperature source block' is connected to port 'A' of the thermistor block and port 'A' of controlled temperature source block is connected to the a thermal referance block'. In controlled tempereture source block a positive temperature difference causes the tempereture at port B to be greater than the tempereture at port A.

12. now the outputs of the voltage sensor block is connected to scope block frist and before and before connecting to the 'scope block' a 'ps-simulink converter' is used to convert physical value to simulink vales.

13.now when we run the simulation and double click on the 'scope block' we will get the following the graph.

14.From the above figure we can see that how voltage is changing with change in temperature.Using this information ,we can set conditions for fan to ONN and OFF.

15.If we observe the graph, we notice that from time 0 to 10 seconds when temerature is 293k,voltage is between 0.0095 nad 0.01 and from time 10 to 30 seconds when temerature is 300k,voltage is between 0.0125 and 0.013 and from time 30 to 50 seconds when temperature is 296k,voltage is nearly 11.888e-3

16.As mentioned in the objective fan should be ONN when temperature is more than 25 degree celsius,from the above graph when voltage is more than 11.888e-3 the fan should ONN and when voltage is below 11.888e-3 and the fan should be OFF.

17.This above logic used to ONN and OFF the fan to do this we have used a switched block that routes the signals according to conditions provide.

18.The center port of 'Switch Block' is the connected to output of the PS simulink converter ' which gives the voltage volume.The top port of the 'Switch Block' is connected to 'Constant Block' of value 1 and bottom port of the 'Switch Block' is connected to another 'Constant Block' of value 0.

19.The center port of 'Switch Block' is the condition input which means that when the value from 'Voltage Sensors Block' is more than the thershold value in the 'Switch Block'.If the voltage from 'Voltage Sensor Block' is less than the thershold val;ue in the 'Switch Block' then it pass the value 0 which we have specified in the bottom port of the 'Switch Block'.Here it acts like a transistor in a real time circuit.

20.To set the thershold value of a switch block we have double click on switch block and then we change the value of thershold.Since we have to be switch to be ONN only when temperature is 300k so the thershold is given 11.888e-3 when voltage get more than 11.888e-3 the switch will give value 1 as output which means fan will be ONN when the voltage is less than 11.888e-3 the switch will value 0 as output which means fan will be OFF.

21.Now the output of the switch block is connected to the another scope block to get the result .

CONCLUSION:

1.Thus both the objectives were achived successfully.

2.Similarly aproched can be used for simulating other physical devices using simulink.