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1. Introduction
This chapter present the way in which information/data were collected from
various data sources, reasons for collecting data, also describes about the methods
that were used to collect data and procedures that are required for the successful
completion of the project. These data were collected so as to prove the problem and
help in the design of the proposed system.
Data Collection Methods
Data collection was conducted in various ways involving literature review, site
visiting and questionnaire.
DATA COLLECTION

2. Item Size Quantity Total load Working Voltage Current
Lamps 40W 10 400W lighting 240V 0.17A
11W 6 66W lighting 240V 0.05A
Fan 55W 6 330W cooling 240V 0.23A
 Primary Data
Primary data were taken in a resident, where kind of data taken were about
what are the systems/devices are used, specifications and working of the
devices. A resident has electric lamps and electric fan as shown in table
below

3.  Secondary Data
Literature review from different books, journal, research paper and internet surfing
was done and relevant information extracted. In this I got the data about various
components that can be used for designing the system.
 Control Unit
Control unit is the part of a system that manages all of the actions performed by the
system. This project requires a system that has a control unit with the following
characteristics:
i. Power supply of typically 5V.
ii. Operating frequency: at least 8MHz.
iii. Analog to Digital Converter pins: at least 3 pins
iv. Input/output pins: at least 20 pins

4. Specifications PIC18F452 PIC16F887 ATmega328P
ROM (bytes) 32K 8K 32K
Operating Voltage (V) 2.0-5.5 20-55 2.7-5.5
Cost 20000 15000 15000
Built in ADC Present Present Present
Speed (MHz) 0-40 0-20 0-16
Control units and their specifications which are available
The control unit ATmega328P is preferred because it does not cost a lot and also it
meets the requirements

5.  Liquid Crystal Display
The LCD can be made in different sizes such as 8x1, 8x2,10x2,
16x1,16x2, 16x4, 20x2,20x4, 24x2, 30x2, 32x2, 40x2 etc. For example
take LCD 16X2 which means it can display 16 characters per line and
there are 2 such lines. All these LCD's performs the same functions such as
display characters, numbers, special characters ASCII characters etc.
Hence their programming is also the same since they all comes with 14
pins (0 to 13 Or) or 16 pins (0 to 15).

6. PARAMETER 16×2 DISPLAY 16×4 DISPLAY 20×4 DISPLAY
Characters per Line 16 16 20
Number of Lines 2 4 4
Operating Voltage 3.5V-5 5V 5V 5V
Operating Current 3mA to 12Ma 3mA to 12mA 5mA to 15mA
Dimension 80mm x 36mm 80mm x 68mm 120mm x 86mm
Brightness High High Moderate
Operating
Temperature
0°C to 70°C -20°C to 75°C -20°C to 75°C
Data for Various Displays
Hence 16 x 2 display is chosen

7. Device Output
Voltage(DC)
Output Current Operating
Temperature
LM7805 5V 1A 0 °C - 125 °C
LM7806 6V 1A 0 °C - 125 °C
LM7809 9V 1A 0 °C - 125 °C
LM7810 10V 1A 0 °C - 125 °C
LM7812 12V 1A 0 °C - 125 °C
LM7815 15V 1A 0 °C - 125 °C
LM7824 24V 1A 0 °C - 125 °C
 Voltage Regulator
Voltage regulator is designed automatically to maintain a constant voltage level. It
eliminates all ripples by setting DC output to a fixed voltage They are available
with fixed value typically 5V, 6V, 12V and 15V.
Data for Various Types of Regulator
Hence LM7805 voltage regulator is chosen.

8. Supply voltage 4V-30V
Output voltage 1V-6V
Output current 10mA
Operating Temperature -55 °C 150 °C
 Temperature Sensor
Specification of Temperature Sensor

9. Features of Temperature Sensor (LM35)
o Calibrated Directly in Celsius (Centigrade)
o Linear +10mV/°C Scale Factor
o 0.5°C Ensured Accuracy (at 25°C)
o Rated for Full-55°C to 150°C Range
o Suitable for Remote Applications
o Low-Cost Due to Wafer-Level Trimming
o Operates From 4 V to 30 V
o Less Than 60-μA Current Drain
o Low Self-Heating, 0.08°C in Still Air
o Non-Linearity Only ±1/4°C Typical
o Low-Impedance Output, 0.1 Ω for 1mA Load

10. Input voltage 3.3V-5V
Input current 100μA
Settling time 10sec-60sec
Sensitivity Up to 20 feet
 PIR Sensor
The PIR Sensor detects motion up to 20 feet away by using a Fresnel lens
and infrared- sensitive element to detect changing patterns of passive
infrared emitted by objects in its vicinity. Inexpensive and easy to use
signifies its popularity. The PIR Sensor is compatible with all Parallax
microcontrollers. Passive infrared sensor is a good system because it detects
heat from the body of a person.

11. Parameters Value
Continuous forward current 20Ma
Operating voltage range 1.7V-3.5V
Reverse voltage 5V
operating temperature 40°C-85°C
 Light emitting diode (LED)
Light emitting diode (LED) is a semiconductor device that emits visible light when
an electric current passes through it. The light is not particularly bright, but in most
LEDs it is monochromatic, occurring at a single wavelength. It used as an indicator
lamp.
LED Specification

12.  Power Supply
A typical power supply designed is used to supply power to different
components of the system. A power required to be supplied to the components
is 5V (DC) and this is done with the help of transformer stepping down 240V
(AC) from the authority to 12V (AC) then be rectified and filtered to get pure
DC supply. Then with the help of regulator a constant DC supply of 5V is
obtained.

13. DATA ANALYSIS AND DESIGN
Introduction
Data analysis was very much concerned with all process of relating technical data
and formula applications for obtaining required value and size of components for
design work . Also data from various sources is gathered, reviewed and then
analyzed to form some sort of findings or conclusion Here were the analysis
approaches

14.  Power Supply
Considering a power supply which is available for a standard of single phase
alternating current (AC) is normally fluctuating between 210V-240V with a
frequency supply of 50Hz. The required constant power supply is 5V direct current
(DC) supply that specified by manufactures to initiate the electronic components in
the system. The 240V selected for the design work. It is an alternating current (AC)
power supply in root mean square value (Vrms) .This supply injected to the
primary terminals of a single phase step down transformer of 240V/12V. The
output voltage at secondary terminals stepped down up to 12V AC. This amount of
voltage then linked to a regulator for regulation processes which gives out a desired
steady dc voltage of 5V.

15. Specification of Voltage Levels.
The transformer output is AC stepped down voltage (12V) this known as secondary voltage,
also un-rectified root mean squire voltage (Vrms), its amount is calculated as follows:
From the transformation ratio:
Vp/ Vs = Np/ N
The maximum power supply (Vrms) is 240V AC, it is stepped down by a selected
transformer with turns ratio 20:1
The secondary voltage (AC) voltage (uncertified Vrms) is given by 240/20= 12V.
The peak voltage (Vpu)is given by
VPU =Vrms√2
V PU =12V×1.4142=16.97V)

16. Then, using Diode Bridge rectification unit, the rectified peak voltage (VPR) is given by
VPR=VPU (2 diode's voltage drop)
Where by diode voltage drop (VD) is 0.7V per each (silicon material).
VPR=16.97-2VD
VPR =16.97-2(0.7)
Hence V PR =16.97-1.4=15.57V approx16V. This is the DC output voltage from the
bridge rectifier which is not a pure DC output voltage containing some ripples of AC
components.

17.  Filter
The output of the rectifier circuit contains an AC components called ripples, which
should be
filtered before the voltage goes to the regulator. The simplest method of ripple
filtering is
the use of shunt capacitors.
Vout =Vp –Vripple
Since Vripple from design guide line = 10% of Vp
V ripple = 10 /100 × I6=1.6(Peak)
V R(RMS) = V R(Peak) /√2

18. V R(RMS) = 1.6/ √ 2 =1.1314V
V out =16-1.6=14.4V
VRMS= IDC= 0.5
4√3FC 4√3×50×C
Where,
f =frequency
C= capacitor
Idc=Output DC/full load current which is equal to 500mA
C= I DC/ 4 √ 3× fV R(RMS) =0.5/ 4 √ 3×50×1.1314 =1275.74 µF
Therefore, the value of the capacitor used for filtration is 1275.74µF, but this is not a
standard value, the best choice of capacitor is 1000 µF. This is due to availability and
factor of safety for proper operation

19.  Analysis on Switching System Using Transistor as a Switch
A transistor used as a switch when is operated at its Cut off and Saturation
regions. The transistor is fully OFF when it is at Cut off region and it is fully
ON when it is a Saturation region.
Operating Conditions of Transistor as a Switch At Cut off:
IC = 0V
V CE =V CC
At Saturation:
V CE =0V
IC=IL maximum

20.  Transistor Switch Parameter Calculations
The analysis below intends to determine the base current lB and base resistor RB
(a) Determination of Base Current, IB
Since the maximum coil resistance of the relay extracted from datasheet, RLM=400Ω
At saturation V CE =0V
V CC =V L +V CE
VCC=VL
IL=IC=VCC/RL
IL=IC=VCC/RLMAX
IC= (5V)/(400Ω)
IC= 12.5mA

21. Where, VL=Relay coil voltage
RL=Relay coil resistance
IL=Relay coil current
IC=Collector current
β= Current gain
β= 100(provided in the datasheet)
Also, IC= βIB
IB= IC / β =12.5mA/ 100
IB = 125µA

22. (b) Determination of Base Resistor, RB
The Base Resistor was obtained from the analysis below
Applying KVL in the input loop.
Vin= VB + VBE
Where, IB= Base current and RB=Base resistance
Vin-VB-VBE =0
VB=Base voltage
VB =Vin-VBE
IBRB=Vin –VBE
RB= (VIn – VBE)/IB
RB= (5V - 0.7V)/125µA=34.4KΩ
A standard resistor value of 34 KΩ was chosen since it was the nearest lowered
preferred value.

23.  Driver (L293D) Analysis
In order to interface and control a DC motor with a microcontroller, usually H-bridge
is preferred way of interfacing a DC motor. These days many IC manufacturers have
H-bridge motor driver available in the market like L293D is most used. DC motor do
not have enough torque to drive a machine directly by connecting wheels in it. Gears
are used to increase the torque of DC motor on the expense of its speed.

24. Mathematically,
Pr = T×ω
Thus
T =Pr/ω
Pr is constant for DC motor for a constant input electrical power. Thus T is inversely
proportion to ω.
From the data collected at the site Pr =0.055kW and the speed (ω) is, ω =2∏N
T=O.055KW/ 2∏x1380rpm =0.0063Nm
Where:
Pr=rotational power
T=torque
ω =rotational speed

25.  Resistors Calculation
(a) Resistors Used to Protect LED
In this circuit LED selected is of 20mA and it operates at forward voltage of 2.2V due
to tolerance factor because it can operate at forward voltage of 1.7V to 3.5V.
Since max Vout from micro-controller =5V DC.
Voltage required to drop will be (5V -2.2V) and limiting resistance will be as follows
From V=IR
R = V/I= 2.8/(20mA) = 140Ω
Now 140Ω is not a standard resistor value. The next closest value is 150Ω and will
give 18.67mA at forward voltage 2.2v

26. (b) Pull up Resistors
These resistors are used to limit current flow in a given circuit when switch is
pressed. We want to limit the current to approximately 0.5mA when the reset
switch is pressed in the circuit, where VCC=5v. The resistor value which should be
used is calculated below.
From ohm law V = IR
R= V/I = 5/0.5mA= 10k Ω
Therefore 10k Ω is enough to limit the current entering microcontroller and the
sensors when the reset switch is pressed.
To limit current I = V/R = 5/10k Ω = 0.0005A = 0.5mA

27.  Regulator Analysis
All devices used in this circuit, their current rating is in mill-ampere (mA). This
information obtained from the data sheet of each component. So its total current is less
than 1A. Also it will need voltage of 12V and 5V. There are voltage regulators of 12V
and 5V which supply 0.5A or 1A. 1A it is enough to supply without heating regulator.
From the data sheet for 7812 and 7805 regulator, we must supply minimum voltage of
14.5V for 7812 regulator and minimum voltage of 7.5V for 7805.

28. 7812 Regulator
The minimum input voltage is 14.5V
Voltage range from the supply authority is 210V minimum voltage and 240V
maximum voltage.
210V =14.5 V
230V =X
By crossing multiplication we found that X= 230X14.5/ 210=15.88V.
Therefore 15.88V will be considered as the input voltage to the regulator.

29. Flowchart for automatic control of fans and light depending on human presence, light intensity and room temperature.

30. Image showing simulation of the system when human is detected, fan is on and bulb is on

31. THANK YOU