Week -2

1. AIM : Construct a model for doorbell using Solenoid Block

CONDITION : Circuit/Switch to be closed for 2 seconds.

DOREBELL USING SOLENOID :

Solenoid is a device comprising of a coal and a wire and a movable plunger. When electric current is applied magnetic field is created which draws the plunger to move in. Thus the phenomenon is used in bell as when the circuit is closed and current is supplied magnetic field is genrated which results in plunger and metalic dome like surface to interact to produce ringing sound.

Blocks used in constructing the circuit is shown above.

• Above image shows the pulse generator signal for 10 seconds with the time interval of 2 seconds.
• When the circuit is closed for 2 seconds i.e when the value of input signal is greater then the threshold value of switch.
• The switch is connected to a solenoid which consists of a plunger which consists of two possible movements i.e when R moves away from C & when it moves towards C. Depending on the direction we get the corrosponding output.

• Above shows the parametrization of solenoid block in which movement can be selected.
• Here the position of plunger is obtained by using ideal translational motion sensor.
• Further the output of the scope can be controlled by varying the Damping & Spring Constant.
• Here is the final graphical representation of the above sequence, Which shows the closed circuit at every 2 seconds.

2. Aim : Turn on a Fan using a Thermistor

Condition Given :

1. 20 deg(293 K) from 0-10 secs

2. 27 deg(300 K) from 10-30 secs

3. 23 deg(296) from 30-50 secs

Fan on if temp > 25 deg(298 K)

Required Simulink model can be designed as :-

• Blocks used are shown in above arrangement.
• For input signal Signal builder block is used using the given temperature conditions and we can see the temperature unit has been converted to Kelvin for the convenience of model.
• Here the different temperature is given by signal builder at different time intervals as per given conditions.
• Thermistor hereis a device whose resistance depends on the temperature, and as an input we have used temperature controlled source. Resistor is used to control the flow of current across the circuit.
• Voltage sensor is used to measure the voltage across the circuit and to use its measured value as a threshold to the switch. The switch here acts as an if else block when the value is above the threshold it will close the circuit and the fan will be turned on during that time period.
• The final output's graphical representation can be shown as :-

As a result fan is on during the duration between 10 to 30 seconds as the temperature is greater then 25 deg C during that time period.