Week -2
1. Make a Simulink model of Doorbell using solenoid block with the following details:
In the above arrangement, when the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing sound.
Create a situation where the switch is closed for 2 seconds and then released. Observe the physical movement of the plunger.
In the above arrangement, when the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing sound. Create a situation where the switch is closed for 2 seconds and then released. Observe the physical movement of the plunger.
Theory of Doorbell:
A chime doorbell uses a specialized sort of electromagnet called a Solenoid. A solenoid is just an electromagnet where the coiled wire surrounds a metal piston. The piston contains magnetically conductive metal, so it can be moved backward or forward by the electromagnetic field. Press the button in the diagram below to see how this works.
In this design, the solenoid piston consists of an iron core mounted to a non-magnetic metal bar. When there is no power to the electromagnet, a spring pushes the piston to the left, and the iron core extends outside of the wire coil. When you turn the electromagnet on (by pressing the doorbell button), the iron core is drawn to the magnetic field, so it slides into the center of the coiled wire.
As the iron core slides to the right, the end of the piston strikes the right-hand tone bar. The tone bar vibrates, producing a particular note. This is the "ding" sound.
As long as you hold the doorbell button, the current will flow through the electromagnet and the piston will remain in this position. But when you release the button, the current will stop flowing through the electromagnet and the magnetic field will collapse. The spring snaps the piston back to the left, where it hits the tone bar on the other side. The second tone bar produces the "dong" sound.
You can make more elaborate tone sequences by adding more solenoids and tone bars. Some variations on this design produce a different tone pattern when someone rings the back doorbell than when someone rings the front doorbell. Each doorbell button closes a separate circuit, connected to separate solenoids in the doorbell mechanism. In the simplest design, one of the solenoids hits a bumper instead of the second tone bar. In this way, one doorbell button will trigger a "ding-dong" tone and the other button will trigger only a "ding" tone.
In recent years, more and more people have been installing electronic doorbells in their homes. An electronic doorbell doesn't have any electromagnets or tone bars. Instead, it has an integrated circuit (IC) that registers when the button has been pressed. The IC triggers a digitally recorded song or message. A lot of electronic doorbells have a wireless control system so the doorbell mechanism doesn't have to be specially wired.
Electronic doorbells are growing in popularity, but most homes still use conventional electromagnet doorbells. This classic design may not play elaborate songs or messages, but it is so simple and sturdy that it should be around for a long time to come.
The Principle behind Doorbell:
The solenoid is an electromagnet with wire winding and a small metal piston inside it. ... When electric current flows through the wire, an electromagnetic field is generated which pulls the metal piston towards it. The metal piston hits the tone bar located on both sides of the arrangement.
Simulink Model Explanation:
The pulse generator is used to create square wave pulses at regular intervals.The block waveform parameters Amplitude,pulsewidth,period and phase delay,determine the shape of the output waveform
The switch block used is controlled by external physical signal.If the external signal is greater than the threshold parameter then the switch is closed, otherwise switch is open.
The positive terminal of the switch is connected to switch and the negative terminal is connected to the electrical reference.
The Solenoid block is connected with switch and battery and we will get a complete electrical circuit. The port c is connected with mechanical reference.
The ideal translational sensor is connected with solenoid block R to observe the movement of the plunger.
Scope is connected with the ideal translational sensor to get the output.
PS-Simulink converter is used to convert the physical signal to simulink signal.
Solver Configuration: Each physical network represented by a connected simscape blocks requires solver setting information for simulation
Ideal Translated motion sensor: It's a type of sensor which provides the position or velocity input for the system to generate output.
Solver Configuration: It's a type of block that acts as a complete equation for where f(x) = 0 where we find the value of x and generate the output which represents the block diagram as an equation.
Before we begin the simulation we need to setup an input parameter here in pulse generator where we delay seconds should be 2 secs with amplitude 1 and Pulse time should be 4 secs to make it in half with 50% pulse width.
Output:
The switch block used is controlled by external physical signal.If the external signal is greater than the thresold parameter then the switch is closed, otherwise switch is open.
The positive terminal of the switch is connected to switch and the negative terminal is connected to the electrical reference.
The Solenoid block is connected with switch and battery and we will get a complete electrical circuit.The port c is connected with mechanical reference.
The ideal translational sensor is connected with solenoid block R to observe the movement of the plunger.
Scope is connected with the ideal translational sensor to get the output.
PS-Simulink converter is used to convert the physical signal to simulink signal.
Solver Configuration:Each physical network represented by a connected simscape blocks requires solver setting information for simulation.
2.Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions:temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50 seconds.
Answer:
Fan conditions: ON if the temperature above 25 °C, OFF otherwise
Thermistor: thermal resistor is defined as a type of resistor whose electrical resistance varies with changes in temperature. Although all resistor's resistance will fluctuate slightly with temperature, a thermistor is particularly sensitive to temperature changes.
Thermistors act as a passive component in a circuit. They are an accurate, cheap, and robust way to measure temperature. While thermistors do not work well in extremely hot or cold temperatures, they are the sensor of choice for many different applications. Following is the Simulink block assembly for Thermistor based heater. And with condition follows here as :
- 0-10 sec temperature 293
- 0-30 secs temperature 300
- 30-50 secs temperature 296
and you can see these details in plot basis in signal builder block where the input is inserted with these signals.
Simulink Model Explanation:
Signal Builder block is uded to input the values as per given conditions:
At point 1,Time=0 seconds,Temperature=293 K
At point 2,Time=10 seconds,Temperature=293 K
At point 3,Time=10 seconds,Temperature=300 K
At point 4,Time=30 seconds,Temperature=300 K
At point 5,Time=30 seconds,Temperature=296 K
At point 6,Time=50 seconds,Temperature=296 K
Controlled Temperature source represents an ideal source of thermal energy,that can maintain a controlled temperature difference regardless of the heat flow rate. The temperature difference is set by the physical signal port S. A positive temperature difference causes the temperature at port B to be greater than the temperature at port A.
Thermistor is a type resistor whose resistanceis based upon temperature.
A linear resistor is used is used inorder to control the amount of current from thebattery.
The voltage sensor is used to convert the voltage measured between two points into a physical signal.
Voltage source which represenrs dc or ac
electrical reference block is given
Solver Configuration:Each physical network represented by a connected simscape blocks requires solver setting information for simulation.
RESULTS :
DOORBELL
Time period given is 2 seconds to the Pulse generator to open and close the switch.When the switch is closed the solenoid blocks receives electrical power from the battery and the plunger move from port R to c to hit the bell and produce sound.
Thermistor:
For 0 to 10 s fan is OFF condition because temperature is 293K which is below the thresold 298K.After 10 s t6emperature goes to 300K then the switch will be in ON condition as the temperature exceeds 298K.After 30s fan will turn OFF as the temperature comes down to 296K which is below the thresold temperature of 298K.