Week -2

Model of a Doorbell:-

The model of the door bell used for the simulation is given below.

The details of the components are as follows

1. Pulse Generator:- This block generates a pulse of amplitude 1 for a duration of 2 seconds. This signal is converted to a physical signal using a converter block

2. Physical Signal controls the switch. Switch remains cloased if physical signal greater than threshold.

3. Battery. Details of the parameters used for Battery is given below.

4. Solenoid:-

F1 and F2 are forces corresponding to X1 and X2. Rated voltage is the voltage required to power up the solenoid.

5. Ideal Translational Motion Sensor

It is a motion sensor which senses p;unger motion to plot plunger motion versus time

Results

1) Pulse vs Position Signal:

Plot for Pulse vs Time

For 1st 2 seconds switch is closed which activates the electrical circuit thereby causing the door bell to ring. At time 2sec, the circuit breaks and the spring pulls the Plunger back to its original position. Some oscillations are observed for about half a secons due to damping effect.

- Velocity Signal

Plunger velocity is 0 except for minor oscillations when pulled back by the spring. This occurs when circuit deactivates

Modelling a Thermistor

Temperature is to be maintained at 20 degrees from 0-10 seconds. 27 degrees from 10-30 seconds and 23 degrees from 30 to 50 degrees. To achieve this temperature variation with time, the following waveform was input into the signal generator. Temperature waas converted into Kelvin for compatibility with Controlled Temperature Source and Thermistor Block.

Output

From the graph we can infer that when temperature is 20 degree celsius the fan was off fot 10 seconds, when temperature reached 25 degree the fan turns on for next 20 second and when temperature again reaches 23 degree celsius the fan turns off.