Week -2

Aim : To make a simulink model of doorbell using solenoid block.

To sense the temperature of a heater & turn on or turn off the fan using thermistor.

Objective :

• Make a simulink model of doorbellusing solenoid block.
• Sense the temperature of a heater & turn on or turn off the fan using thermistor.

Theory:

# part 1

Doorbell :

• The doorbell is a device having both mechanical and electrical component produce sound on pressing them.
• When you press a doorbell button, you complete an electrical circuit that allows household electricity to flow through the doorbell's internal electromagnet.

Solenoid :

• A solenoid is a type of electromagnet formed by a helical coil of wire whose length is substantially greater than its diameter, which generates a controlled magnetic field. It is a device comprised of a coil of wire, the housing and a movable plunger, a solenoid convverts electrical energy into mechanical work.

Simulink model of doorbell using solenoid

Explanation :

Pulse generator: The pulse generator block generates square wave pulses at regular intervals . The block waveform parameters, amplitude, pulse width, period and phase delay, determine the shape of the output wave form.

Simulink-PS converter: It converts the simulink input signal into physical signal.

Switch: Switch controlled by an external physical signal.

Battery: It gives the power to the closed loop.

Electrical reference: It shows connection to electrical ground.

Solenoid: Electrical characteristics and generated force of solenoid.

Ideal translational motion sensor: It is a motion sensor for mechanical translational system.

PS- Simulink converter: It coverts physical signal into simulink output signal.

Mechanical translational reference: Reference connection for mechanical translational ports.

Scope:It dispalys siganls generated during simulation.

Output:

• From the above two graphs, we can observe that plunger is moved from its original position to some amplitude with a time delay of 2 sec.
• Then it hit the bell and pause there for 2sec and come to its initial position.

# Part 2:

Thermistor: A thermistor is a resistence thermometer or a resistor whose resistence is dependent on temperature.

Simulink block :

Explanation :

• The signal builder blocks allows you to create inter changeable groups of piecewise linear signal source and use them in a model. In the signal builder window, create signals and define the output waveforms.
• Input parameters are given in signal builder. Here it is required to input three temperatures and those in kelvin, as the temperature requirements are in kelvin within the code.
• The signal builder generates the time interval with various temperature as a source of heater.

Conditions of heat source,

T =20 degree celcius for (0-10sec)

T =27 degree celcius for (10-30sec)

T =23 degree celcius for (30-50sec)

Condition for FAN,

T = Above 25 degree celcius - ON

T = Above 25 degree celcius -OFF

Threshold value:

Output:

• The angular velocity graph shows that if the temperature is 20deg celcius(293k) the fan is off for the first 10sec when the temperature reaches 25 deg celcius (300k) then the fan is for the next 20 sec and wwhen the temperature comes to 23 deg celcius(296k) fan gets off.

Conclusion:

• In this way, in the first part, we use solenoidto convert electrical energy into mechanical energy and made a simulink model into a doorbell.
• In the second part, we use the thermistor to sense the temperature, and according to the given condition, we put the threshold value to the switch for turn on or turn off the fan.