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:
First, we need to get to understand the theory behind the Doorbell mechanism.
What is doorbell?
The doorbell is a device that is used to alert someone.The doorbell are usually placed outside the house beside the door.
when someone pays a visits,the tradition is that he will knock on the door.but the era is new so he would ring a doorbell.
A chime doorbell uses a specialized sort of electromagnet called a Solenoid. A solenoid is just an electromagnet where the coiled wire surrounds a metal piston. The piston contains magnetically conductive metal, so it can be moved backward or forward by the electromagnetic field. Press the button in the diagram below to see how this works.
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 particular note. This is the "ding" sound.
As long as you hold the doorbell button, the current will flow through the electromagnet and the piston will remain in this position. But when you release the button, the current will stop flowing through the electromagnet and the magnetic field will collapse. The spring snaps the piston back to the left, where it hits the tone bar on the other side. The second tone bar produces the "dong" sound.
Electronic doorbells are growing in popularity, but most homes still use conventional electromagnet doorbells. This classic design may not play elaborate songs or messages, but it is so simple and sturdy that it should be around for a long time to come.
Working Principle:
The most important part of a door bell is its magnetic motor. The magnetic motor constitutes a conventional electromagnet. We know that an electromagnet is an arrangement in which a coil of wire is wrapped around magnetic material which produces magnetic field when electricity is passed through the coil. The greater the coiling of the wire, the higher the amplification of magnetic field. This magnetic field produces a substantial effect on any magnetic substance when brought in the vicinity of its magnetic field. This means that when an iron object is placed in this magnetic field, it will be attracted towards the magnetic field due to polar orientation generated by the electromagnetism.
Single Chime with a Push-button Doorbell:
PS-Simulink and Simulink-PS converter, Scopes, Displays, Pulse generator, electrical and mechanical references, solenoid, Battery, switch, ideal Transalation motion sensor, solver configuration. These are the following simscape and Simulink blocks that are going to use in this simulation.
PS-Simulink and Simulink-PS converter: These are basically the converter from Physical systems to Simulink signals and vice versa.
Scopes: Gives the plot of the output
Pulse generator: is an analog input that has amplitude and frequency with which the input is transmitted.
Electrical and Mechanical references: is a reference block with which the system has a ground source as a base.
Solenoid: is an electromagnetic device that is represented as a block 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 manually or automatically depends on the type of switch required.
Ideal Translated motion sensor: It's a type of sensor which provides the position or velocity input for the system to generate output.
Solver Configuration: It's a type of block that acts as a complete equation for where f(x) = 0 where we find the value of x and generate the output which represents the block diagram as an equation.
Before we begin the simulation we need to setup an input parameter here in pulse generator where we delay seconds should be 2 secs with amplitude 1 and Pulse time should be 5 secs to make it in half with 50% pulse width.
Full simulation with all the simscape and Simulink block system of doorbell:
Output:
The input signal of the Pulse generator:
Aim:
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
Thermistor:
thermal resistor is defined as a type of resistor whose electrical resistance varies with changes in temperature. Although all resistor's resistance will fluctuate slightly with temperature, a thermistor is particularly sensitive to temperature changes.Thermistors act as a passive component in a circuit. They are an accurate, cheap, and robust way to measure temperature. While thermistors do not work well in extremely hot or cold temperatures, they are the sensor of choice for many different applications.
Simulink Model:
Output:
