MULITIPURPOSE ELECTONICS DEVICE AND VISITOR COUNTING SYSTEM
Mini Project done by:
Bibin Mohanan
Basha KM
Ijas

S6 ECE, College Of Engineering Trivandrum


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1.INTRODUCTION
With the growing need to conserve energy, more people are becoming conscious of energy consumption and are looking for ways to reduce costly waste associated with electricity.
Though most consumers do not think about lighting until the light bulb fails or
the power goes out, expenses incurred due to lighting have been found to be a large part of overall energy consumption and lighting has now become the focus of efforts aimed at reducing the high cost of electricity. The purpose of our project is to design an Automatic Light Control
Device to help curb the high cost of internal lighting while creating a convenient effortlessly lighted environment for the consumer.
Today, energy saving devices, such as occupancy or motion sensors, is used by a multiple of people for the conservation of power. Motion detectors cause lights to turn on after entering the room and off after no movement is detected for a certain amount of time. This unit is efficient; however, energy is loss due to the presence and absence of movement in a
particular room by the sensor continuously activating on or off. Unneeded cycling uses more power and defeats the intended purpose of saving energy. The ALCD will save energy by eliminating false conditions, thereby minimizing light cycles. The ALCD will use two infrared beams, a digital counter as part of the control unit, and a controllable switch/relay for lighting. The infrared beams will be used as an indication that someone has entered or left the room. This will send a signal to the controlling unit,depending on which beam was activated first, letting the counter know how many people
have entered or left the room at any given time. It will also consist of a timer, which signals the electronic control unit after the counter has reached zero and a given amount of time has elapsed, depending on the type of lights being used. The ALCD will incorporate a manual override switch to allow for unlighted occupancy. There will be various design conditions that must be met in order to implement this. The first condition is power consumption. The power consumption of the device will coincide with the present voltage and frequency used for the lighting system of today. The lighting must be adaptable to the device. The cost efficiency of the lighting equipment must be
accurate; otherwise, the device is not profitable. The size should be compatible to the size of a typical light switch for convenience.
The Automatic Light Control Device will use the current technology of light
control devices, but with a few implementations. The design component of our project will be the control unit. The main components of the control unit will be a PIC microcontroller,a relay, a transformer, an AC/DC converter, and a voltage regulator. Implementing this control unit
properly will provide the convenience of the light remaining on and not going off after any
detection of motion, while also conserving energy.



2.BLOCK DIAGRAM
It contains:
IR TRANSMITTER
MICROCONTROLLER
PIC16F877AA
BCD TO SEVEN SEGMENT
DECODER
SEVEN SEGMENT
DISPLAY
RELAY UNIT
IR RECEIVER
ELECTRICAL
APPLIANCES

3.BLOCK DIAGRAM DESCRIPTION
IR TRANSMITTER:
It is an astable multivibrator which is designed for producing
38Khz.Astable multivibrator consist of 555IC.The ouput of this multivibrator is switched by
using a transistor BC548.Two IR emitting leds are connected in series at the output.
IR RECEIVER:
It consist of a IR receiving circuit,ie a TSOP 1738. It is designed for
receiving 38 Khz IR rays.It is an active low device. When IR rays are received by the tsop, the
output goes low. Otherwise it is normally high.
MICROCONTROLLER:
Microcontroller used is PIC 16F877A. It is the controlling unit which can
be programmed as per requirements. Based on the input from the receiver, the output of the
micro controller decides the number of persons inside the room and controls the appliances.
BCD TO SEVEN SEGMENT DECODER:
The decoder used is 7447. it converts BCD output from the micro
controller into its equivalent 7-segment code.
RELAY UNIT:
A relay is an electrically operated switch. Relays find applications where it
is necessary to control a circuit by a low-power signal, or where several circuits must be
controlled by one signal. The relay unit consists of a relay, diode(1N4148) and
transistor(BC548).
SEVEN SEGMENT DISPLAY:
The Seven Segment Display used is LTS542 which is a common anode
display. It displays number of persons in the room.
ELECTRICAL APPLIANCES:


5.CIRCUIT DESCRIPTION
It consists of the following sections:
5.1 Transmitter section
5.2 Receiver section
5.3 Counter section
5.4 Appliance section
5.1 TRANSMITTER SECTION
This section sends out pulses of frequency 38 kHz. It consists of a 555IC, 2 IR LEDs, a
diode 1N4148 and a transistor BC548.
The 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and
multivibrator applications. The 555IC is used as an astable multivibrator whose frequency can
be varied by the potentiometer. It sends out continuous rectangular pulses of frequency 38KHz.
The output of 555IC is connected to the base terminal of the transistor(BC548)
1N4148 is a fast switching diode. It is connected parallel to the resistor R1 to bypass it
during the charging of the capacitor C1 in order to get 50% duty cycle.
The BC548 is a general purpose silicon, NPN, bipolar junction transistor. It is used for
current amplification. In this circuit it acts as a switch.
Two IR LEDs are connected in series at the collector terminal of BC548. These LEDs
emit IR radiations whose frequency is same as the astable multivibrator.

5.2 RECEIVER SECTION
This section receives IR signals from the transmitter. It consists of TSOP1738. Its
Output is active low. Continuous data transmission is possible. It is TTL and CMOS
compatible. It is designed in that way that unexpected output pulses due to noise or disturbance
signals are avoided. A band pass filter, an integrator stage and an automatic gain control are
used to suppress such disturbances. The output of TSOP is low when it detects IR of frequency
38Khz. Its output pin is connected to the microcontroller.


5.3 COUNTER SECTION
This section displays the number of persons inside the room. This section consists of
micro controller PIC16F877A, BCD to 7-segment decoder (7447 IC) and 7-segment display.
PIC16F877A is a 40 pin package. Its operating frequency range is 0-20 MHz. It has got
5 I/O ports(A,B,C,D&E) and 15 interrupts. It has got 8k flash program memory, 368 bytes of
data memory and 256 bytes of EEPROM data memory. A crystal oscillator of frequency 4MHz
is externally connected.
Port C is used as input port and Port B&D is used as output port. The output from TSOP
is connected to input port. The Port B is connected to BCD to 7-segment decoder and Port D is
connected to appliance section.
It is a decoder driver IC used to drive a common anode seven segment display. Logic
circuits inside the 7447 convert 4-bit BCD input to the 7-bit output which are active low. It
converts BCD code from the Port B to its equivalent 7-segment code and it is fed to 7-segment
display.
The Seven Segment Display used is LTS542 which is a common anode display. It
consists of seven LEDs labeled 'a' through 'g' arranged in a shape of '8'. When an LED is
forward biased, that segment glows. Display of 0 through 9 is possible by selectively forward
biasing these LEDs.


5.4 APPLIANCE SECTION
This section switches on/off the appliances based on the number of persons inside the
room. This section consists of a relay, transistor and appliances.
A relay is an electrically operated switch. Relays find applications where it is necessary
to control a circuit by a low-power signal, or where several circuits must be controlled by one
signal. The relay unit consists of a relay, diode(1N4148) and transistor(BC548). When the
output from the micro controller is high, the transistor is switched on. This in turn switches on
the appliances.

6. WORKING
The 555IC in the transmitter section produces pulses of 38 KHz frequency. These pulses
causes the IR LEDs to emit IR radiations of the same frequency. These IR LEDs are kept at a
distance of 1m apart. Let them be IR1 and IR2.
The IR rays from the two IR LEDs are received by two TSOP receivers. The output of
the TSOP is low when it detects IR radiations and high otherwise. The outputs of these two
TSOPs are connected to micro controller input.
When a person enters the room, he first cuts the IR rays from IR1 and then from IR2.
This is sensed by the TSOP and micro controller increments the counter by one. When a person
leaves the room, he first cuts IR rays from IR2 and then from IR1. This is sensed by TSOP and
micro controller decrements counter by one.
When the counter value is greater than zero the micro controller outputs a high on one of
its output. It is fed to relay circuit and it turns on the appliances.
When the counter value is greater than five, one more output of microcontroller becomes
high. These outputs are connected to the transistor. This turns on the transistor causing the
supply to flow through the inductor of the relay. The electromagnetic field thus produced
causes the switch in the relay to connect the light to the supply. When more than five persons
enter the room one more light is turned on causing the light intensity to rise. When all persons
leave the room the light is turned off.
The BCD code which indicates the count value is converted to its equivalent sevensegment
code by the decoder. Thus the count value is displayed on the 7-segment led.

8.FABRICATION OF PCB
The printed circuit board (PCB) provides the electrical interconnections various
components and as well as provides mechanical support to the components. The components
are soldered to the PCB. The quality of soldering directly affects the reliability of the circuit.
The procedure for fabricating the PCB for any general project is described below.
8.1 PCB MAKING
The making of PCB essentially involves two steps.
1.Preparing PCB drawing
2.Fabricating PCB from the drawing.
8.2 PCB Drawing
Making of PCB drawing involves placement of components, locating holes, optimum
area each component should occupy shape and size of pads for the components, track size and
spacing and prevention of overcrowding of components at a particular area. With these details
the sketch of the PCB is made.
8.3 PCB FABRICATION
The fabrication of the PCB starts by transferring the PCB drawing onto a copper clad
sheet. For a small number of PCB, a direct photographic transfer of the PCB drawing from a
negative image of the drawing to a photo sensitized copper clad sheet is carried out. The copper
from the unexposed area is later etched away. For large quantity production, screen printing
method is used to transfer the PCB drawing image to the copper clad sheet.
For etching the copper clad sheet 20-30grms of ferric chloride 75ml of water heated to
about 60degree Celsius may be used . The copper clad sheet is placed in the solution with its
copper side upwards in a plastic tray. Stirring the solution helps in speedy etching. The
dissolution of unwanted copper would take about 45min. If etching takes longer, the solution
may be heated again and the process is repeated. The paint on the pattern can be removed by
rubbing with a rag soaked in thinner, turpentine or acetone. The PCB can then be washed and
dried.
The pads are drilled with proper drill sizes of 0.9mm,1mm,3mm etc for the leads and
mounting holes.

9. ASSEMBLY AND TESTING
Assembly consists of soldering of components and wires on the PCB and mechanical of
wired PCB and other assemblies. Testing is carried out even at design phase itself in
breadboard level to verify the design, so that little circuit changes are required after designing
the PCB.
9.1 SOLDERING:
Before soldering, all the discrete components are tested. The leads of the components are
cleaned with a fine abrasive paper. The PCB also thoroughly cleaned by scratching the areas to
be soldered. The leads of the components are bend properly, inserted into the holes and placed
correctly. A small quantity of flux is applied to the component leads and pads to remove the
oxide coating. The leads are soldered with good quality solder with sufficient heat from the
soldering iron. Excess heat will result in improper soldering and may damage the component.
9.2 TESTING
After soldering the components on to the PCB, the board is thoroughly cleaned for any All the
joints are checked after the soldering. Residual flux and wire leads. All the components are
checked for their value and for the proper orientation if applicable. Before ICs are inserted into
the sockets, power applied to the board and voltages are measured at the IC power point. Power
is switched off before the ICs are inserted. Press the required switch and check whether the
corresponding code is available at various stages. If all these requirements are satisfied connect
the required appliance in the circuit.
9.3 ASSEMBLY
The tested PCB is placed inside a wooden box in a compact manner. Four holes are
drilled on the box and bulb holders are fitted in it. A small hole is made in the box to connect
the necessary wires to the AC supply.

10. BILL OF MATERIALS
No Designation Item Qty Rate Cost
RESISTORS
1 R1 33 1 0.25 0.25
2 R2 100 3 0.25 0.75
3 R3 1K 3 0.25 0.75
4 R4 2.2K 4 0.25 1
5 R5 4.7k 1 0.25 0.25
6 R6 100K 2 0.25 0.50
CAPACITORS
7 C1 0.01uf 2
8 C2 22pf 2
9 C3 22uf 1
SEMICONDUCTORS
10 U1 PIC16F877A 1 175 175
11 U2 555 1
12 U3 7447 2
13 U4 7805 1
14 U5 TSOP38 2
15 U6 CRYSTAL OSCILLATOR 1
16 U7 BC548 1
17 U8 BC547 2
18 U9 1N4148 3
19 U10 IR LED 2
20 U11 LED 2
21 U12 DISPLAY 2
MULITIPURPOSE ELECTONICS DEVICE CUM VISITOR COUNTING SYSTEM 10
MISCELLANEOUS
22 B1 BULB 2
23 L1 RELAY 2
24 S1 SWITCH 2
25 BULB HOLDER 2
26 PLUG 1
27 WIRES 4m
28 PVC FORM SHEET 1sq.m
29 INSULATION TAPE 1
30 WOODEN BOX 1
31 NUTS&BOLTS 2
32 SCREW 2
33 FEVIQUICK 2
34 BATTERY 3

11. CONCLUSION
The multipurpose electronic device cum visitor counting system is designed and
fabricated.
The PCB is designed and fabricated as per standard procedure as described in forgoing
chapter. The assembled circuit board is encased in a neat plastic cabinet with sufficient
mechanical support.
The unit is thoroughly tested and performance is verified.
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