Week -2

OBJECTIVE:-

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. 

Assume remaining parameters. 

     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

SOLUTION:-

Here first we are going to study the simulink model of the doorbell using a solenoid block.We need to access the simulink with the block parameters to run the simulation.First we need to get understand the theory behind the doorbell mechanism.

THEORY OF DOORBELL:-

A chime doorbell uses a specialized sort of electomagnet called a soenoid.A solenoid is just an electromagnet where the coiled wire surrounds a metal piston.The piston contains magnetically conductive metal,so it can be mooved backward or forward by the electromagnetic fileld 

In this design,the solenoid piston consists of an iron core mounted  to a non-magnetic metal bar.When there is no power to the electromagnet,a spring pushes the piston to the left and the iron core extends outside the wire coil.When you turn the electromagnet on,the iron core is drawn to the magnetic field so it slides into the center of the coiled wire.

As the iron core slides to the right the end of the piston strikes the right-hand tone bar.The tone bar vibrates,producing a perticular note.This is the "ding"sound.

As long as you hold the doorbell button,the current will flow through the electomagnet and the pston will remain in this position.But when you release the buttion,the current will stop flowing through the electromagnet and the magnetic field will collapse.The spring snap the piston back to the left,where it hits the tone bar on the other side.The second tone bar produces the "dong"sound.

You can make more elaborate tone sequences by adding more solenoids and tone bars.Some variations on this design produce a different tone pattern when someone rings the back doorbell than when someone rings the front doorbell.Each doorbell button closes a seperate circuit connected to seperate solenoids in the doorbell mechanism.In the simplest design,one of the solenoids hit a bumper insted of the second tone bar.In this way one doorbell button will trigger a "ding-ding" tone and the other button will trigger only a "ding" tone.

In recent years,more and more people have been installing electronic doorbells in their homes. An electronic doorbell doesn't have any electromagnets or tone bars. insted,it has an integrated circuit(ic) the registers when the button has been passed.The iC triggers a digitally recorded song or messege.A lot of electronic doorbells have a wireless control system so the doorbell mechanism doesn't have to be specially wired.

PS-Simulink & Simulink-PS converter:-These are basically the converter from physical system to simulink signal and vice versa.

SCOPE:-Give the plot of the output.

PLUSE GENERATOR:-is an along input that has amplitude and freequency with which the input is trasnsmitted.

ELECTRICAL AND MECHANICAL REFFERNCE:-is the refference block with which the system has a ground source as a base

SOLENID:-is an electromagnetic device that is represented as ablock here.

BATTERY:-is a device that has a negative and positive terminal for the electric circuit to be completed for an electric flow

THE SWITCH:-is a device the completes the electric circuit for current flow and can be controlled manially or automatically depends on type of switch required.

IDEAL TRANSLATED MOTION SENSOR:-its a type of sensor which provides the position or velocity input for the system to generate output.

SOLVER CONFIGURATION:- its a type of block that acts as acomplete equation for where f(x) = 0 where we find the value of x and generate the out which represents the block diagram as an equation.

BLOCK PARAMETER:-

SIMULINK MODEL:-

SCOPE VALUE OF PULSE GENERATOR:-

DOORBELL FINAL SCPE VALUE:-

There are some spikes in the graph when switch is closed due to electromagnetic interference.

THERMISTOR:-

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

SIGNAL BUILDER OUTPUT:-

SIMULINK MODEL:-

The requirement is such that the fan should be turned on when the temperature sensed is greater than 25 degree celsius.To fullfill this objective we use a voltmeter to find the voltage of the circuit at different temperatures.It is found that voltage at 25 degree celcius is approximately 0.23v.now this voltage signal is passed through switch.The switch is configured in such a way that it is open if the voltage across the voltmeter is less than 0.23v and close if the voltage across the voltmeter is greater than 0.23.The threshold of the switch is set to 0.23 V.

FINAL SCOPE OUTPUT:-

CONCLUSION:-

• I was able to make the model of door bell using solenoid block.
• I was able to make  a block on thermistor to sense the temperature of a heater and turn on or turn off the fan.
• This task helped me a lot in understanding the blocks and working of it.

GOOGLE DRIVE LINK:-

https://drive.google.com/drive/folders/1fax96CIFVVbX8L7PKr-UZkFft8TarhhP?usp=sharing