Simulation for Doorbell using solenoid block and Use of thermistor to switch ON or OFF the fan

Simulation for the Doorbell using Solenoid block and Use of a Thermistor to switch ON or OFF the fan for a particular temperature.

- 1. Aim:

- To make a simulink model of Dorebell using solenoid block.

- Use a thermistor to sense the temperature of a heater and turn on or off the fan.

- 2. Objective:

- To create a block diagram for the simulation of a dorebell using a solenoid and try to simulate the model.

- Understand the working of thermistor, switches and try to find the threshold value at which the fan get turned on and to keep it turn off and any other condition.

- 3. Method:

- 3.1 Simulation for the Dorebell using Solenoid block:

- Dorebell is a singanling device which get activated i.e produces sound when an electric current pass through it and voltage is applied. 

- In this particular simulation, it is required to produce the bell sound when switch is closed.

- When the switch is closed the electromagnet receives electric power from the battery and pulls the metal arm to hit the bell and produce the sound.

- Here we need to create a simulation, where then switch is closed for 2 seconds and then released. However, it is not possible to produce a simulation of a moving arm, an output is taken in the form of a plot using the ' scope ' block which shows the output for every 2 second.

- As per the requirements the inputs are given in the pulse generator and output is taken. Before giving any inputs the basic like amplitude, period, pulse width and phase delay are need to be understood.

- Here a Solenoid is used, which is a electro magnetic devise, which consist of a coild of wire, a housing and a movable plunger. When an electric current is intorduced, magnetic field forms around the coil which causes the plunger to move. In simple way it converts the electric energy into mechanical energy.

- A battery is used in order to generate the current and allow the working of the simulation. Here the negative terminal is grounded in order to maintain the positive terminal potential at the rated voltage. If we connect negative terminal to ground the positive terminal now is at the potencial differnece. Otherwise, if the positive terminal is grounded the negative terminal will be at negative potencial difference. 

- In this simulation inputs are given properly. For example, the initial displacement of the bell must not be 0 because this means that the plunger is already in contact with the metal part and further displacement will cause the bell to either move away from the bell or will cause a negative displacement which is not the real case.

- 3.2 Thermistor to sense the temperature of a heater & turn ON or OFF the fan

- We are providing 3 inputs which are in the form of temperature. However the thermistor does not know what inputs we are giving, if we give the input as voltage it will take it as it is. In order to let the thermistor know whatever the input we are giving is a Temperature values, we are providing a Controlled Temperature Source.

-  The output from the Controlled temperature source is given to the temperature input of the thermistor. Thermistor itself is a resistor whose resistance changes as per the input temperature.

- The positive terminal is connected to the positive of thermistor as it will create a potential differnece and the negatice terminal is grounded, so that the current will from which is necessary to run the thermistor.

- A voltage sensor is used which is a a device that converts voltage measured between any electrical connections into a physical signal proportional to the voltage. It is a physical signal port that gives voltage value. Here in this case this value is a volate threshold value, which is used to activate the swithc as per the requirement. 

- Our need is to activate the fan when the temperature is greater than 25 degree C and for all the other inputs which are 20 and 23 degree C it will be off i.e the output value must be 0 and for temperature input greater than 25 the output value must be 1 in the scope.

- The display block shows the output value at the end and the display block just near the PS- Simulink convertor shows the threshold voltage value. 

- As the Voltage sensor produces a physical signal it is need to be converted into the signal for the switch. Switch is the block which allows the fan to either ON or OFF depending upon the threshold voltage. Here the threshold value is measured and a display block is given to show the threshold value and this same value is given in the switch block to activate the switch and turn on the fan.

- The signal builder is a block where we are giving the inputs and from there it is given to the controlled temperature source.

- 4. Learning Outcome:

- To do the simlation of a doorbell and understand the working and basic principle of a solenoid.

- To do the simulation of a Fan for the input conditions and start and stop the fan depending upon the temperature.

- Understanding the working of a thermistor, its properties, how to switch on or off a fan depending upon the inputs.

- 5. Conclusion:

- In order to obtain the simulation of the doorbell a solenoid is used which convert the electrical energy into mechanical energy and form a simulation accordingly. However, while simulating there is a small delay which is causing a delay in response of the plunger while disconnecting from the bell.

- In the second simulation, it is clear that the fan gets ON when the temperature in above 25 degree c, when the temperature reaches 27 for 10 to 30 sec time gap, and turns OFF when the temperature again comes below 25.