Week -2

1) To mimic the operation of a bell I have connected a solenoid to a DC source through a switch which is controlled by an eternal signal. The solenoid plunger is connected to a ideal force sensor by which plunger movement can be visualised using scope. To create the sound a bell's internal mechanism hits the target n number of times till switch is kept on. This feature is created using pulse generator and a signal builder(which is used to keep the signal ON only for 2 sec as required). The product of these two gave rise to a pulse signal which lasts for 2 sec. This signal is fed to switch which in turn operates solenoid. The generated signal and plunger operation can be viewed in scope. Electrical, mechanical translational references, PS- Simulink converters and Simulink-PS converters used whereever necessary.

2) A heater is created using an ideal temperature source. The required temperatures 20°C(293.15K), 27°C(300.15K) and 23°C(296.15K) at the given intervals are created by using signal builder block. Three signals are created for three different temperatures and added using sum block. Output summation is fed to ideal temperature source. The output temperature is fed to a thermistor, thermal mass and also connected to a temperature sensor with scope for cross reference. The thermistor is connected in series with a DC voltage source and a resistor to create a potential divider circuit. The voltage drop across the resistor is continuosly measured, for a given voltage and at various temperatures are as follows 20°C - 3.756V, 27°C - 4.844V, 23°C - 4.198V, 25°C - 4.513V (voltage drop to satisfy or condition). The voltage sensor output signal is used as a trigger for the SPST relay with threshold voltage set to 4.513V. This SPST relay is connected in series with a DC voltage source and a motor(to mimic the operation of a fan). The state of switch and the voltage drop is connected to scope for viewing. Electrical, mechanical rotational references, PS- Simulink converters and Simulink-PS converters used whereever necessary.