Week -2

1. Make a Simulink model of Doorbell using solenoid block with the following details:

AIM: To make a Simulink model of doorbell using solenoid block and to make a Simulink model of a thermistor to sense the temperature of heater and turn on or turn off the fan as per the temperature conditions.

DOORBELL USING SOLENOID:

The Solenoid is a electromagnet. On passing current through the conducting wires a magnetic field is generated around it which attracts magnetic materials. This phenomenon is used in the bell. When the switch of the bell is pressed the current passes through the circuit, exciting the electromagnet and pulling the plunger towards the metal portion. This produces a ringing sound.

SIMULINK MODEL:

In the Simulink model I have used a pulse generator block as an input. The pulse is such that, every 2 seconds its ON.

The above image shows the pulse pattern given as input. This cycle repeats for 20 seconds.

As we want the circuit to be close only in the interval of 2 seconds a switch block is used. The switch block has a threshold value of 0.8. The threshold of the pulse generator is 1. The switch will only close if the value of threshold is more than 0.8. This then connected to Solenoid block which contains the plunger arrangement. Initially when the plunger is away from C the value of X is 5 mm and when the plunger is near C the value of X is 0 mm. This can be seen from the output graph of plunger distance vs time. The position of the plunger is obtained by using the Ideal Translational Motion Sensor.

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

Model-

In this model I used following blocks with their function.

1. thermistor:temperature sensing element, Negative temperature coefficient thermistor using B-parameter equate.
2. controlled temperature: This block represents an ideal energy source in a thermal network that can maintain a controlled temperature difference regardless of the heat flow rate.
3. 3. signal builder: function to create and access Signal.
4. DC voltage source: The DC Voltage Source block maintains a time-invariant (constant) voltage across its output terminals, independent of the current through the source.
5. voltage sensor:The block represents an ideal voltage sensor, that is, a device that converts voltage measured between any electrical connections into a physical signal proportional to the voltage.
6. switch: The Switchblock passes through the first input or the third input signal based on the value of the second input. The first and third inputs are data input. The second input is a control input. Specify the condition under which the block passes the first input by using the Criteria for passing first input and Threshold parameters.
7. fundamental block for output and electrical and mechanical reference.

Output-