Working stimulation of a bell & Thermistor

SIMULINK WEEK 2 CHALLENGE:-

Objective :-

1) To create the working stimulation of a bell

2) With the help of 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

Software used :-

Matlab- Simulink R2022a

1) To create the working stimulation of a bell: -

Construction of a bell:-

One end of armature winding is connected to terminal T₁ and the other to a spring, which is mounted on a soft iron strip. A rod is attached to the armature and the free end of the rod carries a small hammer, which strikes a bell. A very light spring is attached to a screw, which is joined to terminal T₂.

Working process of a bell:-

The electric circuit is completed through a battery and push switch button connected to the terminal T₁ and T₂. When the push button is pressed the electric circuit is completed and the armature is attracted towards the electromagnet as a result, the small spring gets detached from the screw due to which the electric circuit is broken and the electromagnet is demagnetized. Hence, the attraction disappears and the armature is brought back by the spring to its original position. Contact of the spring with the screw is now remade, which completes the electric circuit. The action is repeated over and over again consequently. The armature vibrates and hammer attached to it strikes the gong and the bell rings and sound is produced.

Creating Block diagram:-

Step 1:- The first step is to create the block of a 'battery', 'switch' and a 'solenoid'

Step 2:- The three blocks are connected , by just dragging the arrow marks to the respective end.

Step 3:- To give the input for a bell, a 'Pulse generator' is connected with the switch through 'Simulink to PS conerter' block and a 'scope' block is connected with the pulse generator to see the pulse waves.

Step 4:- Then for the complete electrical circuit, 'Electrical reference' block is connected with the entire electrical circuit block

Step 5:- The next step is to connect the solenoid with the respective mechanical systems

Step 7:- Now, the R end of the solenoid is connected through a 'Ideal translational motion sensor' block, since the bell is going to produce translational mechanical vibrations.

Step 8:- Again both the Solenoid and ideal translational motion sensor block is connected with a 'Mechanical reference' block, indicating the mechanical sort of cicuits.

Step 9:- The output signal of the translational motion sensor is again connected to a 'scope' block through 'PS - Simulink converter' signal converter and the output signals are obtained in the form of a graph through the scope block.

Step 10:- Finally, the 'solver configration' block is connected inorder to solve all the physical prebuild blocks which are already connected to out block diagram.

Step 11:- By double clicking the pulse generator block, we can defined the input parameters which were mentioned in the objective. And then we can run our stimulation.

Circuit block diagram:-

Input Signal provided:-

Output graph:-

2) To create a simulink block using thermistor and to sense the given temperature limits : -

Thermistor: -

A thermistor is a resistance thermometer, or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”. It is made of metallic oxides, pressed into a bead, disk, or cylindrical shape and then encapsulated with an impermeable material such as epoxy or glass.

There are two types of thermistors: Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC). With an NTC thermistor, when the temperature increases, resistance decreases. Conversely, when temperature decreases, resistance increases. This type of thermistor is used the most.

A PTC thermistor works a little differently. When temperature increases, the resistance increases, and when temperature decreases, resistance decreases. This type of thermistor is generally used as a fuse.

Typically, a thermistor achieves high precision within a limited temperature range of about 50ºC around the target temperature. This range is dependent on the base resistance.

Simulink Model:-

Steps to create the model:-

Step 1:- Creating thermistor circuit:- Choose 'Thermistor' block from the library then choose 'Battery' block to provide the power source for the thermistor and both the battery and thermistor block are connected to the 'Current sensor' block.

Step 2:- Creating inputs:- Now a 'Controlled temperature source' block is created and it is connected with a 'Signal Builder' block to provide the input signals according to our requirements.

Step 3:- To convert the physical signal inputs, 'Simulink-PS converter' block is provided. And a 'Scope' block is provided to witness the form of input signals.

Step 4:- Creating blocks for output: A 'switch' block is connected to the output signal from the current sensor, through a 'PS-simulink conerter' block

Step 5:- Two 'constant' blocks, 1 & 0 are connected to the switch block which represents the on and off conditions.

Step 6:- The output signal from the switch block, is then connected with a scope block to see the output results graph.

Step 7:- 'Display' block is also connected to get the output values.

Step 8:- Finally , 'solver configuration' block is connected with the electrical block circuits to solve the simulink blocks connected.

Step 9:- Check with some constant values, and give the treshold value to the switch block

Step 10:- After connecting the blocks, double click the 'signal builder' block and give the given temperature conditions.

Step 9:- Set the stop time for about, 20s and run the simulink code created.

The following output will be obtained after the compilation .

Output:-