Door bell and heater

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.

MAIN BLOCKS USED :

Pulse Generator

This block is used to create a pulse signal of values 0 and 1.

Solenoid

A solenoid is an in-built block in Simulink to represent a solenoid. A solenoid is an electromagnet which acts as a magnet when an electric current is passed through the coils of the solenoid. We can configure the magnetic and mechanical quantities of the solenoid in this block.

Ideal Translational Motion Sensor

It is used to determine the position and velocity in translational motion. We can configure the initial position of the plunger in this block.

remaining blocks are explained in the previous challenge.

PROCEDURE :

1. First, the pulse signal is created using the Pulse Generator block. The required signal is of time period 4 sec and pulse width 2 sec.
2. The switch is controlled by the pulse signal and a battery is provided inside the electrical circuit. When the switch is in a closed position, current flows through the circuit and the solenoid becomes active.
3. The initial position of the solenoid plunger is given as 5 mm. When the solenoid becomes active, the rod position changes and comes to zero position and hits the bell.
4. The position is sensed by Ideal Translational Motion Sensor which is connected to the scope.
5. Vibrations of large amplitudes after hitting the bell and reaching its initial position are reduced by adjusting the damping coefficient of the solenoid.

Initially, the plunger is at position is 0 . When the solenoid becomes active, the plunger comes to zero position and hit the bell (2.25*10^-4 m). It remains at this position for 2 sec and returns to the initial position when the circuit turns off. This process continues according to the pulsating input.

2. Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per 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

AIM :

To model a thermistor to sense the temperature of a heater & turn on or turn off the fan as per 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.

MAIN BLOCKS USED :

Repeating Sequence Stair

This block is used to create a discrete-time sequence of different values and the sequence gets repeated.

Controlled Temperature Source

This block is used as a temperature source that is controlled by a physical signal. It controls the heat flow according to the value of temperature in the input signal.

Thermistor

A thermistor is a device of which the resistance changes according to the temperature. The thermistor used here is a negative thermal coefficient thermistor,i.e., the resistance decreases with an increase in temperature.

SIMULINK MODEL:-

PROCEDURE :

1. First, the input signal for the controlled temperature source is created by using the Repeating Sequence Stair block.
2. The controlled temperature source provides the input to the thermistor which is connected to a battery and a resistor. A voltage sensor is connected across the resistance.
3. The output voltage from the voltage sensor is fed as an input condition for the Switch block.
4. A threshold value of voltage is found corresponding to the given condition of temperature 25 °C. This voltage value is given as a threshold value (0.5671 V in this case) for switch condition.
5. If the voltage is greater than a threshold value, constant '1' is given as output, else, constant 0.
6. Lamp block is created to represent the condition of a fan. If the output is 1, green color lights up which means the fan is ON. If the output is 0, the red color will light up which indicates the fan is OFF.