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.
The situation for switch action is created using signal builder and thereby it controls the switch which momentary gives power to solenoid and gives the mechanical motion..
consider the mechanical motion created here is the cause for the door bell to ring.
here we can observe that after turning on the solenoid, the spring action of solenoid is came into picture by causing to-fro motion in the end, due to damping effect we can see ringwave in the output of scope.
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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
The circuit is designed based on real time application
In this condition we can use op amp in comparator mode for switching on fan supply.
in real time relay or solid state switch is used withrespect to output of opamp to turn on the devices, but here i connected op amp directly fan load because as it is simulation, So we can see the fan is getting turned as per the requirement. As thermistor changes the resistance with respect to temperature for that we need to calibrate the voltage for set temperature value by placing another resistor in series to create voltage divider for sensing.
Procedure:
first the value of thermistor in voltage divder is calculated using voltage sensor at 25 deg set value. There after notedown the value of voltage, then set the opamp non inverter pin withthe same level of voltage. so whenver temperature crosess more than 25 deg, the opamp becomes high and vice-versa
