1.Dorr bell System using Solenoid switch & 2. Automated Cooling system using thermistor.

Task 1.

Aim: Design a Door bell using an Electromagnetic Solenoid switch.

Input: Pulse Generator.

Output: Linear displacement of the plunger in an Electromagnetic Solenoid switch.

System Block Diagram:

• Battery: DC Voltage source for an electric circuit
• Controllable Mechanical switch: To on/ off the circuit as per input signal
• Solenoid actuator: Which converts the electric energy in to mechanical output using Plunger. Plunger is the piece of iron rod which repeals and attracts towards generated electromagnetic field poles.
• Translational motion sensor: It is system output which observes the linear displacement of plunger.

Result analysis:

• From the graph it can be seen that plunger has movement every 2 sec as per given input.
• From 0 to 2sec:Current is passing through the electric circuit so the output graph shows plunger displacement in the negative direction. (parameter given port” R” moves towards port “C”).
• From 2 to 4sec:In this duration the output graph shows the positive displacement of plunger which shows the spring has stored potential energy which releases through positive displacement of plunger.
• From 4 to 6 sec & 8 to 10sec: the switch is on and the same output is shown in the graph as it is in 0 to 2sec.
• From 6 to 8 sec: the switch is off but the plunger displacement is due to potential energy of spring as it is in 2 to 4sec.

Task 2.

Aim: Design a cooling system which operates automatically over 25^° C system temperature with the reference from Thermistor.

Input: Signal builder (Builds the signal according system requirement)

Output: Rotational Angular velocity of DC Motor.

System Block Diagram:

• Controlled Temperature Source: which is temperature source of the thermistor and controlled by input signal.
• Thermistor: It is working as an actuator of the electrical circuit it has fixed reference temperature and resistor given by system default however its functionality is that at curtain temperature value or else greater than the reference temperature value. Its internal resistor is decrease and it passes the electric current in the circuit.
• Voltage sensor: Which observes the voltage across the circuit.
• DC Motor: Basically, it is a controlled output of the system which is being observed in rotational motion sensor.
• HDL coder switch: It is a conditional switch where reference threshold value can be set and then it will be compared with the input value given to the switch and on that condition, it will be switched off/ on.

Result Analysis:

• From 0 to 10 sec:
• In this duration not any rotational movement of the motor is being observed due to input signal through switch is zero.
• As switched is conditioned it will be switched on only if the input voltage value is higher than the 28mV (set reference value).
• The input voltage value is 25.33mV which is lower than the set reference value.
• During this time period input temperature is 319 K at this temperature value of thermistor resistor is much higher

• From 10 to 30 sec:
• In this duration angular velocity of motor is being observed because of the input signal of switch is one at this time.
• The input value of the voltage is 39.33mV. It is greater than the set reference value of the switch so, switched is on during this time period and current will be passing through the switch to the DC motor circuit.
• At 10 to 30sec the value of the input constant temperature is 332 K in thermistor so the resistance of thermistor will decrease and the voltage across circuit is also increased.

• From 30 to 60sec:
• Again, rotational movement of the motor is zero.
• Switched is off during this time period as it is unable to satisfy the condition of switch.
• As the shaft of motor rotates the fan will be rotate and so the system temperature again drops to the 321 K and at this temperature the value of resistor is much higher in thermistor due to this input voltage in the switch also drops to 27.67mV.