Week -2

Aim:

1. To make a Simulink model of Doorbell using a solenoid block.
2. To use a thermistor to sense the temperature of a heater & turn on or turn off the fan.

Objective: 1. To make a Simulink model of Doorbell using a 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. Temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50s

Fan conditions: ON if the temperature above 25 °C, OFF otherwise

Doorbell using solenoid:

When the doorbell switch is pressed, the switch completes the electrical circuit that allows the current to pass through the doorbell's internal electromagnet. The electromagnet is powered and generates a magnetic field that attracts the iron strips which strike the bell. When the iron strip returns to its initial position, the electromagnet loses its magnetic field, and the current stops flowing in the circuit.

Model:

Result:

Input signal-

Input to the switch is given by pulse generator such that the switch is switched ON every 2s.

Output-

From the output signal, we can see that the switch is switched ON on every 2s wherein spikes are seen when the switch is closed and open due to the electromagnetic interference.

2. To use a thermistor to sense the temperature of a heater & turn on or turn off the fan.

Conditions : 1. Temperature - 0 °C from 0 to 10 seconds

27 °C from 10 to 30 seconds

23 °C from 30 to 50 seconds

2. Fan conditions: ON if the temperature is above 25 °C, OFF otherwise

Model:

Input:

Input to the temperature-controlled sensor is given from the signal builder. From the given temperature conditions input signal is generated.

The requirement is that the fan should be turned ON when the temperature is greater than 25 degrees celsius. To fulfill this requirement, a voltage sensor is used to sense the voltage at different temperatures. The voltage at 25 degrees celsius is sensed and displayed in the display block and the same has been given to the switch where the switch is configured in such a way that the threshold is set to the voltage at 25 degrees so that temperature is switched ON if the temperature is greater than 25 degree, Off otherwise.

Output:

From the output, it is seen that the switch is On between 10 to 30 s where the temperature is greater than 25degree celcius.