Week -2

1. Solenoid block doorbell:

Solenoid: A solenoid can be an electromagnet which consists of a coil of wire and a plunger. When electric current is induced a magnetic field is formed around the coil and the plunger moves in.

Here we are construct a solenoid doorbell using simulink blocks to study the plunger movement with respect to the given conditions.

Figure 1:

Simulink block diagram:

Simulink blocks used in the model:

1. Pulse generator: This block generates square waves at specified regular intervals
2. Switch: It helps in keeping the circuit either open or closed
3. Battery: This block acts as the power source and generates a required voltage
4. Solenoid: This is an electromagnetic device where a force is generated by electromagnetic interference.
5. Electrical reference: This block acts as the reference or electrical ground.
6. Mechanical translation reference: Its acts as a reference or base for equipment
7. Display: Displays the generated signal during the simulation
8. Scope: It displays the value of the input signal

Working:

When the switch is turned on, the current generated by the source moves along the circuit as the signal generated by the pulse generator. While passing the solenoid it generates a magnetic field and moves the plunger which in turn clings to the bell to produce the sound.

The pulse generator is calibrated as follows:

Input signal from pulse generator with a delay of 2 seconds:

The plunger movement with respect to time:

From the plot we can observe that the signal is generated with a delay of 2 seconds and the plunger movement can be tracked with same delay. The spring constant is set as 200 N/m.

2. Thermistor:

A thermistor is a sensor or a resistance thermometer whose resistance is altered with respect to temperature conditions.

Design conditions:

Temperature:

20 degree C : 0 TO 10 seconds

27 degree C : 10 to 30 seconds

23 degree C : 30 TO 50 seconds

Fan:

ON if temperature rises above 25 degree C.

Simulink model:

Simulink blocks used:

1. Signal builder
2. Controlled temperature source
3. Thermal referance
4. Voltage sensor
5. Thermistor
6. Resistor
7. Battery
8. Solver configuration
9. Constant
10. Switch
11. DC motor
12. Controlled voltage source
13. Electrical reference
14. Mechanical translational reference
15. Ideal rotational motion sensor
16. Scope