Week -2
- 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.
Assume remaining parameters.
The model consists of following blocks:
- Pulse Generator
As per given condition that the switch switch to be closed for 2 sec and then to be released, a pulse generator is used with a time based pulse. The parameter to produce the required pulse are given as follows and the pulse obtained is :
- Switch
- Battery
- Solenoid
- Ideal Translational Motion Sensor
Pulse given by pulse generator is given to the switch through a Simulink-PS converter. For the period of 2 sec switch is pressed and circuit is completed. Battery voltage will be applied across the solenoid coil creating magnetic field. Due to which the plunger will experience a force and is designed to move away from C terminal, towards R terminal.
This movement will be measured by a Ideal Translational Motion Sensor. To observe this output, it is connected to a Scope via PS-Simulink converter.
So by means of pulse generator, for every 2 sec bell is ringing by producing sound vibrations according to the plunger movement.
2. Use 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.
Thermister is a type of resister whose resistance is highly dependent upon the temperature. With increase in temperature, value of resistance increases or decreases depending upon the type.
In the above model, with signal builder, the signal reflecting as temperature is created as per the given conditions,
t= 0-10 sec, Temp.= 20'c = 293 k
t= 10-30 sec, Temp.= 27'c = 300 k
t= 30-50 sec, Temp.= 23'c = 296 k
further, Thermister circuit is supplied by a battery and change in the resistance value is measured by adding an extra resistance in series with the thermister and voltage drop is measured acoss it. This Voltage drop will reflect as the change in the temperature and with this output fan circuit will be operated by means of a switch.
Hence, we can observe the for 0-10 sec, as temperature is 20 degree i.e 293 k which below 25 degree i.e. 298 k fan is OFF. For 10-30 sec, temperature becomes 27 degree i.e. 300 k so fan is ON. Again for next 30-50 sec, temperature drops below 25 degree, fan turns OFF.