Week -2

THE ABOVE FIGURE SHOWS CIRCUIT DIAGRAM REPRESENTATION OF AN ELECTRIC DOOR BELL.

ABOVE FIGURE CONTAINS FOLLOWING COMPONENTS:-

1. BELL PUSH
2. SWITCH
3. SOLENOID
4. GONG

NOW THE TASK IS TO SIMULATE THE SAME IN MATLAB.

OBJECTIVES:-

1. TO GENERATE A SIMULINK MODEL OF A DOORBELL USING SOLENOID.
2. TO GENERATE A SIMULINK MODEL OF A THERMISTOR TO SENSE THE TEMPERATURE OF A HEATER TO CONTROL THE FAN FOR COOLING.

SIMULINK MODEL OF A DOORBELL

CONSTRUCTION:-

• PULSE GENERATOR:- TO GENERATE TIME SIGNALS WHICH WILL CONTROL THE SWITCHING OPERATION.
• SIMULINK PS CONVERTER:- TO CONVERT SIMULINK TO REAL TIME.
• SCOPE:- IN ABOVE 3 SCOPES ARE BEEN USED

1. SCOPE1:- FIRST SCOPE, WHICH IS CONNECTED TO PULSE GENERATOR AND SIMULINK PS CONVERTER SHOWS THE GRAPH OF SIGNAL GENERATED.
2. SCOPE2:- SECOND SCOPE IS CONNECTED TO IDEAL TRANSATIONAL MOTION SENSOR TO PLOT VELOCITY.
3. SCOPE3:- THIRD SCOPE IS ALSO CONNECTED FROM IDEAL TRANSATIONAL MOTION SENSOR TO PLOT POSITION.

• PS-SIMULINK CONVERTER:- IT AGAIN CONVERTS REALTIME TO SIMULINK ENVIRONMENT. AND IT IS CONNECTED IN BETWEEN BOTH SCOPE 2 AND 3.
• BATTERY:- IT GIVES THE POWER SOURCE TO THE BELL.
• SPST SWITCH:- IT COMPLETES THE CIRCUIT WHENEVER BELL IS BEING PRESSED.
• ELECTRICAL REFERENCE:- IT IS BASICALLY A GROUND CIRCUIT WHICH IS USED AS SAFETY MEASURE.
• SOLENOID:- IT IS USED TO GENERATE ELECTROMAGNETIC PATH WHICH WILL ATTRACT THE HAMMER AND STRIKE THE BELL.

• IDEAL TRANSATIONAL MOTION SENSOR:- THE BLOCKS MEASURES VELOCITY AND DISPLACEMENT.

• MECHANICAL TRANSATIONAL REFERRENCE:- IT IS ALSO USED AS A SAFETY MEASURES BUT TO THE MECHNICAL COMPONENTS,PROVIDES GROUND TO THE CIRCUIT.
• SOLVER CONFIGURATION:- IT DEFINES SOLVER SETTING TO USE SIMULATION. IT IS USED IN SUCH PLACES WHERE SOME BACKGROUND SIMULATION IS GOING ON.

WORKING:-

1. FIRST THE PULSE GENERATOR SIGNALS ARE GENERATED IN INTERVAL OF EVERY 2SECS BY CONTROLLING THE SWITCH AND RING THE BELL.
2. THE GENERATED PULSE IS RECORDED IN SCOPE1 AND THEN IS CONVERTED TO REAL TIME ENVIRONMENT WITH THE HELP OF SIMULINK PS CONVERTER.
3. THEN ACCORDING TO SIGNAL, SPST SWITCH ACTS TO CONTROL THE FLOW OF CURRENT TO SOLENOID.
4. WHEN THE CURRENT PASSED THROUGH SOLENOID,IT GENERATES MAGNETIC FIELD WHICH RESULTS TO ATTRACT THE HAMMER AND STRIKE THE BELL.
5. THEN IDEAL MOTION SENSOR SENSES THE MOTION THROUGH SOLENOID AND THAT SIGNALS ARE AGAIN CONVERTED TO SIMULINK AND BEEN PLOTTED TO SCOPE2 AND 3.

RESULTS:-

GENERATED TIME GRAPH (TIME vs AMPLITUDE)

THE ABOVE GRAPH SHOWS THE PLOTTING OF PULSE GENERATED IN ACCORDANCE TO TIME, IN X-AXIS SHOWS TIME AND IN Y-AXIS SHOWS AMPLITUDE. THE SHOWS THE EXACT TIME GIVEN ACCORDING TO QUESTION i.e 2SECS WITH A PERFECT INTERVAL OF 50SECS.

VELOCITY PLOT(TIME vs VELOCITY):-

THE ABOVE GRAPH SHOWS THE PLOTTING OF VELOCITY TO TIME OF STRIKING OF HAMMER TO THE BELL.

IT SHOWS THE VELOCITY TO STRIKE THE BELL IN SAME INTERVAL OF TIME. HERE X-AXIS REPRESENTS TIME AND Y-AXIS VELOCITY.

POSITION PLOT(TIMEvs POSITION):-

THE ABOVE GRAPH SHOWS THE PLOTTING OF POSITIONING OF BELL AFTER A CERTAIN INTERVAL OF TIME.

IT CLEARLY SHOWS THAT BELL IS BEEN RUNG IN EVERY 50SECS FOR 2 SECS.

HERE X-AXIS REPRESENTS TIME AND Y-AXIS AS POSITION.

USE A THERMISTER TO SENSE THE TEMPERATURE OF A HEATER & TURN ON OR OFF THE FAN AS PER FOLLOWING CONDITIONS:-

TEMPERATURE SOURCE: 20 °C FROM 0-10 sec, 27 °C FROM 10 - 30sec, 23 °C FROM 30 -50sec.

FAN CONDITION: ABOVE 25 °C (ON), ELSE (OFF).

THEORY:-

WHAT IS A THERMISTOR?

A THERMISTER IS A TYPE OF RESISTOR WHOSE RESISTANCE IS STRONGLY DEPENDENT ON TEMPERATURE, MORE SO THAN IN STANDARD RESISTOR. HERE THE SETUP COMPLETELY DEPENDS UPON THERMISTOR WHERE THE RESISTANCE CHANGES W.R.T TEMPERATURE.

IT IS BASICALLY A TWO-TERMINAL SOLID STATE THERMALLY SENSITIVE TRANSDUCER CONSTRUCTED FOR USING SENSITIVE SEMICONDUCTOR-BASED METAL OXIDES WITH METALLISED OR SINTERED CONNECTING LEADS FORMED INTO A CERAMIC DISC OR BED. THIS ALLOWS THE THERMISTOR TO CHANGE ITS RESISTIVE VALUE IN PROPORTION TO SMALL CHANGES IN AMBIENT TEMPERATURE. THEY CAN BE OPERATED UPTO BY PRODUCING GOOD RESISTANCE Vs TEMPERATURE.AND THE SENSED RESISTANCE IS USED TO GENERATE VOLTAGE RESPECTIVELY TO CONTROL A CIRCUIT.

SIMULINK MODEL:-

CONSTRUCTION:-

• SIGNAL BUILDER:- IT IS USED FOR INPUTTING TEMPERATURE AT DIFFERENT TIME INTERVALS.
• SCOPE:- USED FOR GRAPHYICAL REPRESENTATION.
• SIMULINK-PS:- TO CONVERT SIMULINK TO REAL TIME.
• PS-SIMULINK:- TO DO VICE-VERSA.
• THERMISTOR:- USED TO SENSE THE TEMPERATURE FOR PRODUCING RESISTANCE.
• BATTERY:- FOR POWER SOURCE.
• VOLTAGE SENSOR:- TO SENSE THE VOLTAGE ACROSS THE CIRCUIT.
• DISPLAY:- TO VIEW THE THRESHOLD VOLTAGE VALUE.
• SWITCH:-TO CONTROL THE VOLTAGE OUTPUT AT PARTICULAR THREDHOLD VALUE.
• CONTROL VOLTAGE SOURCE:- TO SEPARATE THE VOLTAGE IN +ve & -ve IONS.
• DC MOTOR:- TO RUN AT CONTROLLED VOLTAGE.
• IDEAL ROTATIONAL MOTION SENSOR:- IT SENSE THE WORING OF DC MOTOR.
• ELECTRICAL,MECHANICAL & THERMAL REFERENCES:- IT PROVIDES SAFETEY FOR DESIRED CIRCUIT COMPONENTS.

WORKING:-

1. THE SIGNAL BUILDER GENERATES THE TIME INTERVAL WITH VARIOUS TEMPERATURE AS A SOURCE OF HEATER.

CONDITIONS OF HEATING,

T=20 °C FOR (0-10s)

T=27 °C FOR (10-30s)

T=23 °C FOR (30-50s)

CONDITION FOR FAN,

T=25 °C > ON

T=25 °C < OFF

2.NOW, THE TEMPERATURE IS PASSED TO THE THERMISTOR, TO SENSE AND GENERATE THE RESISTANCE VALUE ACCORDINGLY.

3. AS THE RESISTANCE R VARIES ACCORDINGLY TO THE CURRENT I, VOLTAGE ACROSS IT BEING SENSED USING VOLTAGE SENSOR.

4. THE SAME VOLTAGE IS INPUTED TO (THRESHOLD CONTROLLED)SWITCH FOR TURNING ON THE MOTOR(FAN) WITH THRESHOLD VALUE.

5. THEN THE PARTICULAR VALUE(T=27 °C) THE DC MOTOR TURNS ON.

6. THEREFORE, USING THE IDEAL ROTATIONAL MOTION SENSOR, ACTIVITIES OF DC MOTOR IS OBTAINED FOR PLOTTING THE VELOCITY AND ANGULAR DISPLACEMENT PLOTS.

RESULTS:-(TIME vs TEMPERATURE)

THE ABOVE GRAPH REPRESENTS TIME VS TEMPERATURE RELATION.

i.e, 20°C LASTS FOR 10 SECONDS, WHICH IS 293.15K.

27°C FOR 20 SECONDS, WHICH WILL BE 300.15K.

AND, 23°C AGAIN FOR 20 SECONDS, WHICH WILL BE296.15K.

TIME vs VOLTAGE:-

FROM THE ABOVE GRAPH WE CAN SEE THAT VOLTAGE IS GENERATED ACCORDING TO TEMPERATURE INPUT.

SO THE MAXIMUM VOLTAGE AT 27°C IS 0.01V.

TIME vs CONTROLLED VOLTAGE:-

FROM THE ABOVE GRAPH WE UNDERSTOOD THAT THE VOLTAGE OBTAINED FOR (10-30s) AT T=27°C

TO TURN ON THE MOTOR. THE THRESHOLD VALUE USED IS 0.009.

TIME vs VELOCITY:-

TIME vs ANGULAR VELOCITY:-

FROM THE ABOVE TWO GRAPHS WE CAN SAY THAT FAN(DC MOTOR) TURNED ON EXCEEDING 25°C FOR(10-30S).

CONCLUSION:-

THUS FROM THE ABOVE TWO SIMULATION, FIRST WE LEARNED HOW SOLENOID IS USED TO CONSTRUCT AN ELECTRIC BELL. AND IN THE SECOND SIMULATION WE SAW HOW SIGNAL BUILDER IS USED TO MANAGE AND HANDLE TIME WITH RESPECT TO TEMPERATURE AND WE ALSO SAW THE GRAPHYCAL REPRESENTAIONS OF ALL THE RESULTS.