Week -2

Aim:

To make a simulink model of doorbell using solenoid block and Observe the physical movement of the plunger.

To Use a thermistor to sense the temperature of a heater & turn on or turn off the fan

Simulink model:

1.Door Bell

The below model represents the block diagram of door bell

• The pulse generator is used as an input to create square wave pulses at regular intervals. The block waveform parameters amplitude, period, pulse width and phase delay determine the shape of the waveform.

• The scope are used to check the input pulse generated by the pulse generator.
• PS-Simulink converter is used to convert the physical signal into simulink signal.
• The switch block is used for open and close operation which is externally controlled by physical signal. if the external signal is greater than the threshold parameter then the switch is closed.
• The solenoid block is connected with switch and battery. The positive terminal is connected with switch and the negative terminal is connected with battery.
• The ideal translational sensor is connected with solenoid block to observe the movement of the plunger.
• Scope is connected with ideal translational sensor to get the output.
• Each physical network represented by a connected simscape blocks requires solver setting information for simulation.
• The electrical and mechanical reference are connected respectively.
• The output shows how the plunger moves and hits the bell.

2. Thermistor

Given Inputs:

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 Block:

Signal builder block is used as an input values as per given conditions:

• At point 1, Time=0 seconds, Temperature= 293 K
• At point 2, Time=10 seconds, Temperature= 293 K
• At point 3, Time=10 seconds, Temperature= 300 K
• At point 4, Time=30 seconds, Temperature= 300 K
• At point 5, Time=30 seconds, Temperature= 296 K
• At point 6, Time=50 seconds, Temperature= 296 K

The Scope named as Temperature input shows the graph of Input

• Controlled temperature source represents an ideal source of thermal energy, that can maintain a controlled temperature difference regardless of the heat flow rate. The temperature difference is set by the physical signal port S. A positive temperature difference causes the temperature at port B to be greater than the temperature at port A.
• Thermistor is a type of resistor whose resistance is based upon a temperature.
• The battery source is connected with the thermistor and resistor.
• A linear resistor is used to control the amount of current from the battery.
• The voltage sensor is used to convert the voltage measured between two points into a physical signal.
• The Voltage scope shows the value of voltage through which threshold value can be calculated.

• The calculated threshold value will be assigned to the switch.
• The Controlled voltage source is used to maintain the specified voltage at its output regardless of the current passing through it. The output voltage is V = Vs, where Vs is the numerical value presented at the physical signal port.
• An Ideal rotational motion sensor is connected with an DC motor to measures angular velocity or angle in a mechanical rotational network. The physical signal ports W and A report the angular velocity and angle, respectively, of port R relative to port C. The measured angular velocity is positive when the angular velocity at port R is greater than the angular velocity at port C.
• The Scope shows the graphical representation of the output.

Results:

Door Bell:

• The above graphical system represents the physical movement of the plunger in a door bell.
• Time period given as 2 seconds to the pulse generator for the on and off operations of switch.
• When the switch is closed the solenoid blocks receives electrical power from the battery and the plunger move from port R to C to hit the bell and produce the sound.

2.Thermistor

The above graph shows the fan condition during the change of temperature

• For 0 to 10 seconds, Fan is in Off condition because temperature is in 293K which is below the threshold temperature 298K.
• After the 10 seconds, Fan is in On condition because temperature is in 300K which is above the threshold temperature 298K.
• After completion of 30 seconds from the beginning time, Fan goes to Off condition because temperature is in 296K which is below the threshold temperature 298K.

From the given conditions, the results are evaluated.