Week -2

1)Doorbell model:

To generate a door bell model first we need to choose all components required. First component we required is a pulse generator through which we give our input, like the duration of a switch to be turned on. By using the battery we give electrical input(current) to the solenoid. when an electric current is introduced, a magnetic field forms around the coil of solenoid which in turn attracts the plunger or door bell in. By giving the neccessary time period through switch we can control the motion of door bell.

In the above plot we can see that as the switch is turning ON and OFF the mechanical movement or vibrations are changing.In the pulse generator we gave the phase delay of 2 sec, that is the reason why the switch is turning ON after 2 sec. As we can see that the total pulse duration of a cycle is 4 seconds. The switch turns off for 2 seconds and turns on for 2 seconds and the output changes accordingly.

2)Themister Challenge:

Thermister is a variable resisitor in which the value of its resistance changes with respect to the temperature. There are two types of thermisters NTC and PTC. In NTC(Negative Temparature Coefficient) thermister value of resistance decreses as the temperature increases. In PTC(Positive Temperature Coefficient) thermister value of resistance increses with increse in temperature value.

In the above shown model we are observing the change in voltage across resistor with respect to the change in temperature given from signal builder to the thermister through controlled temperature source.

As per our requirement the Fan has to turn ON whenever temperature exceeds 25 degree centigrade. So here 25 degree is our threshold value. So set this value(correspoding plot value) at the place of switch threshold condition. The switch has three ports out of which one is input port and other two are conditional output ports. Value of voltage across resistor is given to input port. If the temparature is above 25 degrees then the switch turns ON otherwise it turns OFF.