Week -2

1)

OBJECTIVE:

To create a simulink model of a doorbell which operates for time duration of 2sec.

OPERATION SET-UP:

A battery,a switch ,solenoid is seriesly connected as shown in the model.When switch is closed,solenoid will be energised,as a result electromagnetic force will be developed,as a result of it pluger movement starts.When the plunger moves the doorbell rings.This is the mechanism by which doorbell works.The objective is to operate the doorbell for 2sec duration time,so for that a pulse generator is used to generate a pulse signal whose time period is set to 10sec ,amplutide of signal is 1 and duration of pulse is 20%.This generated pulse signal is given to simulink-ps converter and given to N2 terminal of switch.The switch will closes only if the ampltude of the signal crosses the threshold value of .5V.So signal amplitude applied to VT terminal must be greater than .5V.As a result switch remain closed for 2sec in the timeperiod of 10sec.The plunger movement is sensed using a ideal force sensor and this signal is given to ps-simulink converter and ultimately given to a scope.The generated pulse signal can be seen in the attachment named pulse.PNG.The whole model is given in attachment named bell.slx

RESULTS:

The results of simulation are given in attachemnt bell12V and bell20V for battery volatge of 12V and 20V.It is observed from the result as we increase battery voltage force developed on the plunger also increases from -.045 to -.12.Here simulation is run for a time of 10sec.

2)

AIM:

Modelling of heater using a thermistor and turn it ON when temprature exceeds 25degree celcius.

OPERATION SET-UP:

Here the required source temprature signal should produce a temprature of 293K for 0-10sec,300K for 10-30sec and 296K for 30-50sec.For this signal generation pulse generator is used whose time period is set to 50sec and pulse width are given as 20%,40% and 40%.Delay is given as 0,10 and 30.The summation of these three signal from pulse generator gives the required temprature signal as given in the attachment tempsignal.PNG.This signal is given to a simulink-PS converter and thereby given to a the thermistor.Thermistor is a device whose resistance change as the temprature change occur.The thermistor is connected in series witha battery having 12V and a resistor whose resistance is 1ohm.The voltage across the resistor is measured by a voltage sensor and observed in a scope.From the scope its evident that when temprature is 25degree celcius the corresponding voltage is .0112V.From the voltage sensor signal is given to ps-simulink converter and given to a switch whose threshold value is set to .0112,which means that if voltage signal exceeds .0112V,the output is 1 or else its 0,which inirectly means that if temprature exceeds 25degree celcius the heater gets ON otherwise its OFF.The voltage signal and the final output can be seen in the attachement named voltagesignal.PNG and output.PNG.

RESULT:

Here from the output its observed that when temprature exceeds 25 ie 298K heater will become ON or else it remain in OFF condition.