2. INTRODUCTION
Human motion detection is one of the key challenges in most of the security
applications. Radar is an object-detection system which uses radio waves to determine the range,
altitude, direction, or speed of objects. It can be used to detect aircraft ships, spacecraft, guided
missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits
pulses of radio waves or microwaves which bounce off any object in their path. The object
returns a tiny part of the wave's energy to a dish or antenna which is usually located at the same
site as the transmitter.
A fire-control radar is a radar which is designed specifically to provide information
to a fire-control system in order to calculate a firing solution (i.e. information on how to direct
weapons such that they hit the target(s)). Such radars typically emit a narrow, intense beam of
radio waves to ensure accurate tracking information and to minimize the chance of losing track
of the target. Some modern radars have a track-while-scan capability enabling it to function
simultaneously as a fire-control radar and a search radar.
A fire-control system is a number of components working together, usually a gun data computer,
a director, and radar, which is designed to assist a weapon system in hitting its target. It performs
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3. the same task as a human gunner firing a weapon, but attempts to do so faster and more
accurately.
Although you may be involved in the operation of search radar, the majority of your work
will be with radar systems used to control the direction and fire of gun and missile systems.
These radar systems are normally part of a larger system. They are called Gun Fire Control
Systems (GFCS) or Missile Fire Control Systems (MFCS). Some systems may be able
to control the fire of either guns or missiles.
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5. WORKING
These principles can basically be implemented in a radar system, and allow the determination of
the distance, the direction and the height of the reflecting object.
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6. All targets produce a diffuse reflection i.e. it is reflected in a wide number of directions. The
reflected signal is also called scattering. Backscatter is the term given to reflections in the
opposite direction to the incident rays.
Radar signals can be displayed on the traditional plan position indicator (PPI) or other more
advanced radar display systems. A PPI has a rotating vector with the radar at the origin, which
indicates the pointing direction of the antenna and hence the bearing of targets.
The electronic principle on which radar operates is very similar to the principle of sound-wave
reflection. If you shout in the direction of a sound-reflecting object (like a rocky canyon or cave),
you will hear an echo. If you know the speed of sound in air, you can then estimate the distance
and general direction of the object. The time required for an echo to return can be roughly
converted to distance if the speed of sound is known.
Radar uses electromagnetic energy pulses in much the same way, as shown in Figure 1. The
radio-frequency (rf) energy is transmitted to and reflected from the reflecting object. A small
portion of the reflected energy returns to the radar set. This returned energy is called an ECHO,
just as it is in sound terminology. Radar sets use the echo to determine the direction and distance
of the reflecting object.
The distance is determined from the running time of the high-frequency transmitted signal and
the propagation c0. The actual range of a target from the radar is known as slant range. Slant
range is the line of sight distance between the radar and the object illuminated. While ground
range is the horizontal distance between the emitter and its target and its calculation requires
knowledge of the target's elevation. Since the waves travel to a target and back, the round trip
time is divide by two in order to obtain the time the wave took to reach the target.
FLOW CHART
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7. POWER SUPPLY
Power supply is the first and most important part of our project. In the proposed project the
power supply circuit is used to provide the regulated supply to the IC`s used in the project.
Power supply circuit consists of step down transformer, rectifier circuit, filter circuit and
regulator IC.
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8. BLOCK DIAGRAM OF POWER SUPPLY
CIRCUIT DIAGRAM OF THE POWER SUPPLY
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INPUT
AC
SUPPLY
REGULATED
IC
STEP DOWN
TRANSFORMER
RECTIFIER
CIRCUIT
FILTER
CIRCUIT
9. Step Down Transformer
Transformers are static device which convert the electrical energy from one
circuit to another circuit without any change in frequency and power. Step down transformer
means the transformer which reduces the supply voltage to the desired value. In our project we
need 12 volt DC supply, therefore in this project 12-0-12, 500mA transformer is used.
Rectifier Circuit
Rectifier is a circuit which converts the AC electrical energy into Dc electrical
energy. For operating of semiconductor devices used in this project we need regulated DC
supply. In this project we use centre tap full wave rectifier. Full wave rectifier circuit is capable
of converting sinusoidal input into a unidirectional output. The circuit diagram is as shown in the
figure.
Filter Circuit
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10. It is seen that the output of the rectifier is not pure DC, because it contain
some amount of AC component which is called as ripple factor which gives the fluctuation and
hence to minimize the ripple in the output the filter circuit is used. This circuit is connected after
the rectifier circuit. In our project capacitor input filter is used. The circuit is as shown in the
figure. The capacitor is connected in parallel to minimize the ripple factor.
Regulator Circuit
In our project for the operation of IC we need +5 volt regulated supply is
necessary therefore a voltage regulator circuit is used. A voltage regulator is a circuit that
supplies constant voltages regardless of change in the load current. IC voltage regulators are
versatile and generally used. The 78xx series consist of three terminal positive voltage
regulators. These ICs are designed as fixed voltage regulator and adequate
heat sink. It can be deliver output current in access of 1A. These devices do not required external
component. These ICs has internal terminal overload protection
and internal short circuit and current limiting protection.
ULTRASONIC PROXIMITY DETECTOR
TRANSMITTER :-
This ultrasonic proximity detector comprising independent, battery-
powered transmitter and receiver sections makes use of a pair of matched ultrasonic
piezoceramic transducers operating at around 40 kHz each. This circuit can be used in
exhibitions to switch on prerecorded audio/video messages automatically when a visitor evincing
in- wide bandwidth and very low bias current apart from being capable of single-supply
operation. Quad op-amp LM324 is used here due to its low terest in a product comes near an
exhibited product.
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Fig. Regulator IC (IC 7805)
11. The transmitter circuit comprises CMOS timer IC 7555 (IC1) configured as an
astable multivibrator, which may be tuned to the frequency of the ultrasonic piezoceramic
transmitter’s resonant frequency of around 40 kHz using preset VR1. A complementary
pair of transistors T1 and T2 is used for driving and buffering the transducer while it
draws cost. For higher efficiency, you may use single op-amps such as CA3130 or
CA3140. When a visitor pauses before a spikes of current from IC1 circuit to sustain
oscillations and thereby avoids any damage.
RECEIVER :-
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Fig. Ultrasonic Transmitter
12. The receiver front-end (refer Fig. 2) is designed to provide a very high gain for the
reflected faint ultrasonic frequency signals detected by the ultrasonic transducer. The amplifiers
built around N1 and N2 respectively provide AC voltage gain of around 80 each. These two
stages should have a high open-circuit gain, product, it signifies his interest. Switching diode D1
followed by a filter comprising capacitor C5 and resistor R10 is used to meet this requirement.
The filter also helps to bypass brief bursts of ambient noise in the ultrasonic range. The third
stage comprising N3 works as a comparator to provide a triggering pulse when a visitor stops by.
This pulse can be used to trigger a timer or a monostable, whose output may then be used to
switch on the audio/video message concerning the product for a predetermined period. When
somebody comes in front of the ultrasonic piezoceramic transducer pair, the status LED (LED1)
glows because of the signal reflected from the body of the visitor.
The circuit can be assembled on any general-purpose PCB. The transmitter and the
receiver should be aligned such that the transmitted ultrasonic signal is optimally received by the
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Fig. Ultrasonic Receiver
Fig. OP-AMP IC (LM324)
13. receiver after reflection. Fig. 3 shows the pin configuration of transistors T1 and T2, while Fig. 4
shows installation of the ultrasonic piezoceramic transducer pair operating at around 40 kHz.
RADAR AND GUN STEPPER MOTOR CONTROL
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16. RADAR AND GUN CIRCUIT DESCRIPTION
In electronics, an opto-isolator (or optical isolator, optical coupling device, optocoupler,
photocoupler, or photoMOS) is a device that uses a short optical transmission path to transfer an
electronic signal between elements of a circuit, typically a transmitter and a receiver, while
keeping them electrically isolated—since the electrical signal is converted to a light beam,
transferred, then converted back to an electrical signal, there is no need for electrical connection
between the source and destination circuits.
A common implementation is a LED and a phototransistor in a light-tight housing to exclude
ambient light and without common electrical connection, positioned so that light from the LED
will impinge on the photodetector. When an electrical signal is applied to the input of the opto-
isolator, its LED lights and illuminates the photodetector, producing a corresponding electrical
signal in the output circuit. Unlike a transformer the opto-isolator allows DC coupling and can
provide any desired degree of electrical isolation and protection from serious overvoltage
conditions in one circuit affecting the other.
Uln2803 Featuring continuous load current ratings to 500 mA for each of the drivers, the Series
ULN28xxA/LW and ULQ28xxA/LW highvoltage, high-current Darlington arrays are ideally
suited for interfacing between low-level logic circuitry and multiple peripheral power loads.
Typical power loads totaling over 260 W (350 mA x 8, 95 V) can be controlled at an appropriate
duty cycle depending on ambient temperature and number of drivers turned ON simultaneously.
Typical loads include relays, solenoids, stepping motors, magnetic print hammers, multiplexed
LED and incandescent displays, and heaters. All devices feature open-collector outputs with
integral clamp diodes.
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17. RADAR AND GUN POSITIONING
What is Serial port in computer
In computing, a serial port is a serial communication physical interface through which
information transfers in or out one bit at a time (contrast parallel port).[1]
Throughout most of the
history of personal computers, data transfer through serial ports connected the computer to
devices such as terminals and various peripherals.
While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term
"serial port" usually identifies hardware more or less compliant to the RS-232 standard, intended
to interface with a modem or with a similar communication device.
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18. What is Parallel port in computer
A parallel port is a type of interface found on computers (personal and otherwise) for connecting
various peripherals. In computing, a parallel port is a parallel communication physical interface.
It is also known as a printer port or Centronics port. The IEEE 1284 standard defines the bi-
directional version of the port, which allows the transmission and reception of data bits at the
same time.
USING THE SERIAL PORT
8051 provides a transmit channel and a receive channel of serial communication. The transmit
data pin (TXD) is specified at P3.1, and the receive data pin (RXD) is at P3.0. The serial signals
provided on these pins are TTL signal levels and must be boosted and inverted through a suitable
converter(MAX232) to comply with RS232standard.
All modes are controlled through SCON, the Serial CONtrol register. The SCON bits are defined
as SM0, SM1, SM2, REN, TB8, RB8, TI, RI from MSB to LSB. The timers are controlled using
TMOD, the Timer MODe register, and TCON, the Timer CONtrol register.
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of
Flash programmable and erasable read only memory (PEROM). The device is manufactured
using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-
standard MCS-51 instruction set and pinout. The on-chip Flash allows the program memory to
be reprogrammed in-system or by a conventional nonvolatile memory programmer. By
combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a
powerful microcomputer which provides a highly-flexible and cost-effective solution to many
embedded control applications.
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20. HARDWARE & SOFTWARE
REQUIREMENTS
Component List
1. Stepper motor
2. 100 k
3. 11 Khz
4. Microcontroller (89c51)
5. Resistance array
6. Rectifying diode
7. BC547
8. 470 uf
9. 100uf
10. Laser
11. Copper plate
12. Fecl3
13. Isopropyl
14. Fexli wire
15. Body
16. Parallel port
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21. 17. Serial port
18. 10 core she lied wire
19. Transformer
20. Ultra sonic
21. Filter capacitor
22. LM234
HARDWARE DEScRIpTION
1.MIcROcONTROllER AT89c51
AT89C51 is a low-power, high-performance CMOS 8-bit microcontroller and
belongs to Atmel's 8051 family. AT89C51 has 4KB of Flash programmable and erasable read
only memory (PEROM) and 128 bytes of RAM. It can be erased and program to a maximum of
1000 times. The device is manufactured using Atmel’s high density nonvolatile memory
technology and is compatible with the industry standard MCS-51 instruction set and pinout.
In 40 pin AT89C51, there are four ports designated as P 1, P2, P3 and P0. All
these ports are 8-bit bi-directional ports, i.e., they can be used as both input and output ports.
Except P0 which needs external pull-ups, rest of the ports have internal pull-ups. When 1s are
written to these port pins, they are pulled high by the internal pull-ups and can be used as inputs.
These ports are also bit addressable and so their bits can also be accessed individually.
Port P0 and P2 are also used to provide low byte and high byte addresses,
respectively, when connected to an external memory. Port 3 has multiplexed pins for special
functions like serial communication, hardware interrupts, timer inputs and read/write operation
from external memory. AT89C51 has an inbuilt UART for serial communication. It can be
programmed to operate at different baud rates. Including two timers & hardware interrupts, it has
a total of six interrupts.
Features
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22. Ø Compatible with MCS-51 Products
Ø 4 Kbytes of In-System Reprogrammable Flash Memory. Endurance 1,000 Write/Erase.
Ø Fully Static Operation: 0 Hz to 24 MHz
Ø Three-Level Program Memory Lock
Ø 128 x 8-Bit Internal RAM
Ø 32 Programmable I/O Lines
Ø Two 16-Bit Timer/Counters
Ø Six Interrupt Sources
Ø Programmable Serial Channel
Ø Low Power Idle and Power Down Modes
Table showing the pin description of AT89C51
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23. S
Pin No Function Name
1
8 bit input/output port (P1) pins
P1.0
2 P1.1
3 P1.2
4 P1.3
5 P1.4
6 P1.5
7 P1.6
8 P1.7
9 Reset pin; Active high Reset
10 Input (receiver) for serial communication RxD
8 bit input/output
port (P3) pins
P3.0
11
Output (transmitter) for serial
communication
TxD P3.1
12 External interrupt 1 Int0 P3.2
13 External interrupt 2 Int1 P3.3
14 Timer1 external input T0 P3.4
15 Timer2 external input T1 P3.5
16 Write to external data memory Write P3.6
17 Read from external data memory Read P3.7
18
Quartz crystal oscillator (up to 24 MHz)
Crystal 2
19 Crystal 1
20 Ground (0V) Ground
21
8 bit input/output port (P2) pins
/
High-order address bits when interfacing with external memory
P2.0/ A8
22 P2.1/ A9
23 P2.2/ A10
24 P2.3/ A11
25 P2.4/ A12
26 P2.5/ A13
27 P2.6/ A14
28 P2.7/ A15
29 Program store enable; Read from external program memory PSEN
30
Address Latch Enable ALE
Program pulse input during Flash programming Prog
31
External Access Enable; Vcc for internal program executions EA
Programming enable voltage; 12V (during Flash programming) Vpp
32
8 bit input/output port (P0) pins
Low-order address bits when interfacing with external memory
P0.7/ AD7
33 P0.6/ AD6
34 P0.5/ AD5
35 P0.4/ AD4
36 P0.3/ AD3
37 P0.2/ AD2
38 P0.1/ AD1
39 P0.0/ AD0
40 Supply voltage; 5V (up to 6.6V) Vcc
24. Fig. 1 Pin Diagram of AT89C51 Fig. 2 Package of AT89C51
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26. 2. STEppER MOTOR
What is a stepper motor?
A Stepper Motor or a step motor is a brushless, synchronous motor which divides a full rotation into a
number of steps. Unlike a brushless DC motor which rotates continuously when a fixed DC voltage is
applied to it, a step motor rotates in discrete step angles. The Stepper Motors therefore are
manufactured with steps per revolution of 12, 24, 72, 144, 180, and 200, resulting in stepping angles of
30, 15, 5, 2.5, 2, and 1.8 degrees per step. The stepper motor can be controlled with or without feedback.
How a stepper motor works?
Stepper motors work on the principle of electromagnetism. There is a soft iron or magnetic rotor shaft
surrounded by the electromagnetic stators. The rotor and stator have poles which may be teethed or not
depending upon the type of stepper. When the stators are energized the rotor moves to align itself along
with the stator (in case of a permanent magnet type stepper) or moves to have a minimum gap with the
stator (in case of a variable reluctance stepper). This way the stators are energized in a sequence to
rotate the stepper motor.
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27. Applications
Robotics
Motion Control and Industrial Equipment
Techno-Art
Technical Specifications
Rated Voltage 12 vdc
Rated Current/Phase 259 mA
No. of Phase 4
DC Coil Resistance 50 / phase ±7% (100 / coil)
Step Angle 7.5° / phase
Excitation Method 2-2 phase (unipolar)
Mechanical Specifications
Types of Stepper Motor
By construction the step motors come into three broad classes:
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28. 1. Permanent magnet stepper
2.VariableReluctancestepper
3. Hybrid Stepper Motor
1. Permanent Magnet Stepper :
The rotor and stator poles of a permanent magnet stepper are not teethed. Instead the rotor have
alternative north and south poles parallel to the axis of the rotor shaft.
When a stator is energized, it develops electromagnetic poles. The magnetic rotor aligns along the
magnetic field of the stator. The other stator is then energized in the sequence so that the rotor moves
and aligns itself to the new magnetic field. This way energizing the stators in a fixed sequence rotates the
stepper motor by fixed angles.
The resolution of a permanent magnet stepper can be increased by increasing number of poles in the
rotor or increasing the number of phases.
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29. 2. Variable reluctance stepper :
The variable reluctance stepper has a toothed non-magnetic soft iron rotor. When the stator coil is
energized the rotor moves to have a minimum gap between the stator and its teeth.
The teeth of the rotor are designed so that when they are aligned with one stator they get misaligned with
the next stator. Now when the next stator is energized, the rotor moves to align its teeth with the next
stator. This way energizing stators in a fixed sequence completes the rotation of the step motor.
The resolution of a variable reluctance stepper can be increased by increasing the number of teeth in the
rotor and by increasing the number of phases.
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30. 3. Hybrid stepper :
A hybrid stepper is a combination of both permanent magnet and the variable reluctance. It has a
magnetic teethed rotor which better guides magnetic flux to preferred location in the air gap.
The magnetic rotor has two cups. One for north poles and second for the south poles. The rotor cups are
designed so that that the north and south poles arrange in alternative manner. Check out the inside of
Hybrid Stepper Motor.
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31. The Hybrid motor rotates on same principle of energizing the stator coils in a sequence.
Types of Winding and Lead-out
The step motors are mostly two phase motors. These can be unipolar or bipolar. In unipolar step motor
there are two winding per phase. The two winding to a pole may have one lead common i.e. centre
tapped. The unipolar motor so, have five, six or eight leads. In the designs where the common of two
poles are separate but centre tapped, motor have six leads. If the centre taps of the two poles are
internally short, the motor has five leads. Eight lead unipolar facilitates both series and parallel connection
whereas five lead and six lead motors have series connection of stator coils. The unipolar motor simplifies
the operation because in operating them there is no need to reverse the current in the driving circuit.
These are also called bifilar motors.
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32. In bipolar stepper there is single winding per pole. The direction of current need to be changed by the
driving circuit so the driving circuit of the bipolar stepper becomes complex. These are also called unifilar
motors.
Stepping Modes
There are three stepping modes of a stepper motor. The stepping mode refers to the pattern of sequence
in which stator coils are energized.
1. Wave drive (One phase ON at a time)
2. Full drive (Two phase ON at a time)
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33. 3. Half drive (One and two phase ON at a time)
1. Wave drive :
In wave drive stepping mode only one phase is energized at a time.
2. Full Drive :
In full drive, two phases are energized at a time.
3. Half Drive :
In half drive, alternately one and two phases are energized. This increases the resolution of the motor.
Circuit Connections
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34. Use the circuit below to connect a 4-phase unipolar stepper motor to a BASIC Stamp or Javelin Stamp.
The ULN2803 may also be used and has enough driver circuits to control two stepper motors (be sure to
verify motor current requirement versus ULN2x03 sink capability for multiple outputs).
3. SERIAl pORT:
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35. Serial communication is a popular means of transmitting data between a computer and a
peripheral device such as a programmable instrument or even another computer. Serial
communication uses a transmitter to send data, one bit at a time, over a single communication
line to a receiver. You can use this method when data transfer rates are low or you must transfer
data over long distances. Serial communication is popular because most computers have one or
more serial ports, so no extra hardware is needed other than a cable to connect the instrument to
the computer or two computers together.
Serial communication requires that you specify the following four parameters:
• The baud rate of the transmission
• The number of data bits encoding a character
• The sense of the optional parity bit
• The number of stop bits
Each transmitted character is packaged in a character frame that consists of a single start bit
followed by the data bits, the optional parity bit, and the stop bit or bits. Figure shows a typical
character frame encoding the letter m.
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36. RS 232
Devices that use serial cables for their communication are
split into two categories. These are DCE and DTE. DCE are
devices such as a modem, TA adapter, plotter, and so on,
while DTE is a computer or terminal. RS-232 serial ports
come in two sizes, the D-Type 25-pin connector and the D-
Type 9-pin connector. Both of these connectors are male on
the back of the PC. Thus, you require a female connector on the device. While the RS-232 standard
originally specified a 25-pin D-type connector, many designers of
personal computers chose to implement only a subset of the full
standard: they traded off compatibility with the standard against the use of less costly and more compact
connectors (in particular the DE-9 version used by the original IBM PC-AT). The desire to supply serial
interface cards with two ports required that
IBM reduce the size of the connector to fit
onto a single card back panel. A DE-9
connector also fits onto a card with a second
DB-25 connector that was similarly changed
from the original Centronics-style connector.
Starting around the time of the introduction of
the IBM PC-AT, serial ports were commonly
built with a 9-pin connector to save cost and
space. However, presence of a 9-pin D-subminiature connector is neither necessary nor sufficient to
indicate use of a serial port, since this connector was also used for video, joysticks, and other purposes.
4. pARAllEl pORT:
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Fig. Pin diagram of Serial Port
Fig. Serial Port
37. A parallel port is a type of interface
found on computers (personal and otherwise) for connecting
various peripherals. In computing, a parallel port is a parallel
communication physical interface. It is also known as a
printer port or Centronics port. The IEEE 1284 standard
defines the bi-directional version of the port, which allows
the transmission and reception of data bits at the same time.
The Centronics Model 101 printer was introduced in 1970 and included the first parallel interface
for printers.[1]
The interface was developed by Robert Howard and Prentice Robinson
at Centronics.
5. UlN2803:
A ULN2803 is an Integrated Circuit (IC) chip with a High Voltage/High Current
Darlington Transistor Array. It allows you to interface TTL signals with higher voltage/current
loads. In English, the chip takes low level signals (TLL, CMOS, PMOS, NMOS - which operate
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Fig. Pin Diagram of Serial Port
Fig. Parellel Port
38. at low voltages and low currents) and acts as a relay of sorts itself, switching on or off a higher
level signal on the opposite side.
A TTL signal operates from 0-5V, with everything between 0.0 and 0.8V
considered "low" or off, and 2.2 to 5.0V being considered "high" or on. The maximum power
available on a TTL signal depends on the type, but generally does not exceed 25mW (~5mA @
5V), so it is not useful for providing power to something like a relay coil. Computers and other
electronic devices frequently generate TTL signals. On the output side the ULN2803 is generally
rated at 50V/500mA, so it can operate small loads directly. Alternatively, it is frequently used to
power the coil of one or more relays, which in turn allow even higher voltages/currents to be
controlled by the low level signal. In electrical terms, the ULN2803 uses the low level (TTL)
signal to switch on/turn off the higher voltage/current signal on the output side.
Typical power loads totaling over 260 W (350 mA x 8, 95 V) can be
controlled at an appropriate duty cycle depending on ambient temperature and number of drivers
turned ON simultaneously. Typical loads include relays, solenoids, stepping motors, magnetic
print hammers, multiplexed LED and incandescent displays, and heaters. All devices feature
open-collector outputs with integral clamp diodes.
1.The ULN2803 comes in an 18-pin IC configuration and includes eight (8) transistors.
2.Pins 1-8 receive the low level signals, pin 9 is grounded (for the low level signal reference).
3.Pin 10 is the common on the high side and would generally be connected to the positive of the
voltage you are applying to the relay coil.
4.Pins 11-18 are the outputs (Pin 1 drives Pin 18, Pin 2 drives 17, etc.).
Fig. Pin Diagram of ULN 2803
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40. Fig. Interfacing of ULN 2803 with Stepper Motor
6. DIODE:
Rectifier diodes are two-terminal electronic components that allow current to flow
in only one direction, from an anode (+) to a cathode (-), and that convert AC to DC. These
simple semiconductors are PN junctions with a positive or P-region with positive ions and a
negative or N-region with negative electrons. Applying voltage to the PN junction causes current
to flow in only one direction as electrons from the N-region fill “holes” in the P-region.
Typically, rectifier diodes are made of semiconductor materials such as silicon, germanium or
selenium. Half-wave rectifier diodes deliver DC output during alternate half-waves of AC
input. Full-wave rectifier diodes produce a unidirectional DC current by rectifying both the
positive and negative half-cycles of the AC input. Several rectifier configurations are available,
including bridge, center-tap, Schottky, and fast recovery.
Performance specifications for rectifier diodes include average rectified current, reverse current,
forward voltage, peak forward surge current, reverse recovery time, and junction operating
temperature. Average rectified current (Io) is the maximum allowable continuous average current
in the forward direction under specified conditions. Reverse current or leakage current (IR), the
current at which the specified reverse voltage is applied, measures the current that flows when
reverse bias is applied to a semiconductor junction. Forward voltage (VF) is the voltage across
the diode terminals resulting from the flow of current in the forward direction. Peak forward
surge current (IFSM) is the maximum allowable surge value of forward current without repetition.
Reverse recovery time (trr) is the time taken for the reverse current (IR) to reach a specified level
when the reverse voltage is applied while the device is conducting in the forward direction.
Junction operating temperature (Tj) is the range of temperatures at which diode are designed to
operate.
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41. IC package types for rectifier diodes include transistor outline (TO), diode
outline (DO), small outline transistor (SOT), and small outline diode (SOD). Other rectifier
diodes are available in a discrete package (DPAK) or in D2PAK, a large surface-mounted
package that includes a heat sink. SC-59, SC-74, and SC-76 are plastic, surface-mounted IC
packages with three leads. Metal electrode leadless face (MELF) diodes have metallized
terminals at each end of a cylindrical body and are designed to fit the same footprints as flat
components. QuadroMELF diodes have a square cross section to provide better on board
stability and greater "pick and place" accuracy. MiniMELF is a miniature version of MELF and
MicroMELF has the same footprint as the SOD110 and SOD323 packages.
Rectifier diodes follow product life style stages that are defined by the Electronic Industries
Alliance (EIA) in EIA-724. Numbered stages range from zero to eight and cover product
introduction, growth, maturity, market saturation, phase out, last shipment, and removal. The
first stage, Life Cycle Stage Code 0, describes rectifier diodes that are in the planning or early
design stages. The last stage, Life Cycle Stage Code 8, describes rectifier diodes that are no
longer stocked in inventory or available for sale.
Fig. Symbol Fig. Diode
Function
Diodes allow electricity to flow in only one direction.
The arrow of the circuit symbol shows the direction in
which the current can flow. Diodes are the electrical
version of a valve and early diodes were actually called
valves.
Forward Voltage Drop
Electricity uses up a little energy pushing its way
through the diode, rather like a person pushing through
a door with a spring. This means that there is a small
voltage across a conducting diode, it is called
the forward voltage drop and is about 0.7V for all
normal diodes which are made from silicon. The
forward voltage drop of a diode is almost constant whatever the current passing through the
diode so they have a very steep characteristic (current-voltage graph).
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42. Reverse Voltage
When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a
very tiny current of a few µA or less. This can be ignored in most circuits because it will be very
much smaller than the current flowing in the forward direction. However, all diodes have
a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and
pass a large current in the reverse direction, this is called breakdown.
Ordinary diodes can be split into two types: Signal diodes which pass small currents of 100mA
or less and Rectifier diodes which can pass large currents. In addition there are LEDs (which
have their own page) and Zener diodes (at the bottom of this page).
Rectifier diodes (large current)
Rectifier diodes are used in power supplies to convert alternating current (AC) to direct current
(DC), a process called rectification. They are also used elsewhere in circuits where a large
current must pass through the diode.
All rectifier diodes are made from silicon and therefore have a forward voltage drop of 0.7V. The
table shows maximum current and maximum reverse voltage for some popular rectifier diodes.
The 1N4001 is suitable for most low voltage circuits with a current of less than 1A.
Bridge rectifiers:
There are several ways of connecting diodes to make a rectifier to convert AC to DC. The bridge
rectifier is one of them and it is available in special packages containing the four diodes required.
Bridge rectifiers are rated by their maximum current and maximum reverse voltage. They have
four leads or terminals: the two DC outputs are labelled + and -, the two AC inputs are
labelled .
The diagram shows the operation of a bridge rectifier as it converts AC to DC. Notice how
alternate pairs of diodes conduct.
Fig. Circuit Diagram of Bridge Rectifier
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43. Fig. Various types of Bridge Rectifiers
7. π - FILTER
The capacitor-input filter, also called pi filter due to its shape that looks like
the Greek letter pi, is a type of electronic filter. Filter circuits are used to remove unwanted or
undesired frequencies from a signal.
A typical capacitor input filter consists of a filter capacitor C1, connected
across the rectifier output, an inductor L, in series and another filter capacitor, C2, connected
across the load, RL. A filter of this sort is designed for use at a particular frequency, generally
fixed by the AC line frequency and rectifier configuration. When used in this service, filter
performance is often characterized by
itsregulation and ripple.
1. The capacitor C1 offers
low reactance to the AC
component of the rectifier
output while it offers infinite
resistance to the DC component. As a result the capacitor shunts an appreciable amount
of the AC component while the DC component continues its journey to the inductor
The inductor L offers high reactance to the AC component but it offers almost zero resistance to
the DC component. As a result the DC component flows through the inductor while the AC
component is blocked.
2. The capacitor C2 bypasses the AC component which the inductor had failed to block. As
a result only the DC component appears across the load RL.
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Fig. Circuit diagram of π Filter
Fig. Circuit Diagram of π Filter
44. 8. IC 7555:
The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse
generation and oscillator applications. The 555 can be used to provide time delays, as
an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one
package.
Introduced in 1971 by Signetics, the 555 is still in widespread use, thanks to its
ease of use, low price and good stability, and is now made by many companies in the original
bipolar and also in low-power CMOS types. As of 2003, it was estimated that 1 billion units are
manufactured every year.[1]
The IC was designed in 1971 by Hans R. Camenzind under contract to Signetics,
which was later acquired by Philips.
Fig. Pin Diagram of IC 7555 Fig. IC Package
MODES
The 555 has three operating modes:
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45. Monostable mode: in this mode, the 555 functions as a "one-
shot" pulse generator. Applications include timers, missing
pulse detection, bouncefree switches, touch switches,
frequency divider, capacitance measurement, pulse-width
modulation (PWM) and so on.
Astable: free running mode: the 555 can operate as
an oscillator. Uses include LED and lamp flashers, pulse
generation, logic clocks, tone generation, security
alarms, pulse position modulationand so on. Selecting
a thermistor as timing resistor allows the use of the 555 in a
temperature sensor: the period of the output pulse is determined by the temperature. The use
of a microprocessor based circuit can then convert the pulse period to temperature, linearize
it and even provide calibration means.
Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not
connected and no capacitor is used. Uses include bounce-free latched switches
9. LED:
A light-emitting diode (LED) is a semiconductor light source.[3]
LEDs are used as
indicator lamps in many devices and are increasingly used for otherlighting. Introduced as a
practical electronic component in 1962,[4]
early LEDs emitted low-intensity red light, but modern
versions are available across thevisible, ultraviolet,
and infrared wavelengths, with very high brightness.
When a light-emitting diode is forward-biased (switched on), electrons are able
to recombine with electron holes within the device, releasing energy in the form of photons. This
effect is called electroluminescence and the color of the light (corresponding to the energy of the
photon) is determined by the energy gap of the semiconductor. LEDs are often small in area (less
than 1 mm2
), and integrated optical components may be used to shape its radiation pattern.
[5]
LEDs present many advantages over incandescent light sources including lower energy
consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs
powerful enough for room lighting are relatively expensive and require more precise current
and heat management than compactfluorescent lamp sources of comparable output.
Fig. Symbol of LED
Light-emitting diodes are used in applications as diverse as replacements for aviation
lighting, automotive lighting (in particular brake lamps, turn signals, and indicators) as well as
in traffic signals. LEDs have allowed new text, video displays, and sensors to be developed,
while their high switching rates are also useful in advanced communications technology. Infrared
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Fig. LED
46. LEDs are also used in the remote control units of many commercial products including
televisions, DVD players, and other domestic
appliances.
10. LASER:
A laser is a device that
emits light (electromagnetic radiation) through a process of optical amplification based on
the stimulated emission of photons. The term "laser" originated as an acronym for Light
Amplification by Stimulated Emission of Radiation. The emitted laser light is notable for its high
degree of spatial and temporal coherence, unattainable using other technologies.
Spatial coherence typically is expressed through the output being a narrow beam
which is diffraction-limited, often a so-called "pencil
beam." Laser beams can be focused to very tiny spots,
achieving a very high irradiance. Or they can be
launched into a beam of very low divergence in order
to concentrate their power at a large distance.
Temporal (or longitudinal) coherence
implies a polarized wave at a single frequency whose
phase is correlated over a relatively large distance
(the coherence length) along the beam.[3]
A beam produced by a thermal or other incoherent light
source has an instantaneous amplitude and phase which vary randomly with respect to time and
position, and thus a very short coherence length.
Most so-called "single wavelength" lasers actually produce radiation in
several modes having slightly different frequencies (wavelengths), often not in a single
polarization. And although temporal coherence implies monochromaticity, there are even lasers
that emit a broad spectrum of light, or emit different wavelengths of light simultaneously. There
are some lasers which are not single spatial mode and consequently their light
beams diverge more than required by the diffraction limit. However all such devices are
classified as "lasers" based on their method of producing that light: stimulated emission. Lasers
are employed in applications where light of the required spatial or temporal coherence could not
be produced using simpler technologies.
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Fig. Different colors of LEDs
47. APPLICATION OF LASER
1. Military
2. Medical field
3. Nuclear fusion
4. Photochemistry etc
11. LM324:
The LM324 series are low−cost, quad operational amplifiers with true differential inputs. They
have several distinct advantages over standard operational amplifier types in single supply
applications. The quad amplifier can operate at supply voltages as low as 3.0 V or as high as 32
V with quiescent currents about one−fifth of those associated with the MC1741 (on a per
amplifier basis). The common mode input range includes the negative supply, thereby
eliminating the necessity for external biasing components in many applications. The output
voltage range also includes the negative power supply
voltage.
Features
• Short Circuited Protected Outputs
• True Differential Input Stage
• Single Supply Operation: 3.0 V to 32 V
• Low Input Bias Currents: 100 nA Maximum (LM324A)
• Four Amplifiers Per Package
• Internally Compensated
• Common Mode Range Extends to Negative Supply
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Fig. LASER Beam
48. • Industry Standard Pin outs
• ESD Clamps on the Inputs Increase Ruggedness without Affecting
Device Operation
• NCV Prefix for Automotive and Other Applications Requiring Site
and Control Changes
• These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
PIN DIAGRAM
12. SPDT:
In electronics, a switch is an electrical component that can break an electrical
circuit, interrupting the current or diverting it from one
conductor to another.
Fig. Symbol of SPDT
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Fig. Pin Diagram of LM 324
49. A simple on-off switch: The two terminals are either
connected together or disconnected from each other. An example is a light
switch.
SPDT Relay : (Single Pole Double Throw Relay) an electromagnetic switch, consist of a
coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one
normally open terminal (87) (Figure 1).
When the coil of an SPDT relay (Figure 1) is at rest (not energized), the
common terminal (30) and the normally closed terminal (87a) have continuity. When the coil
is energized, the common terminal (30) and the normally open terminal (87) have continuity.
The diagram below center (Figure 2) shows an SPDT relay at rest,
with the coil not energized. The diagram below right (Figure 3) shows the relay
with the coil energized. As you can see, the coil is an electromagnet that causes
the arm that is always connected to the common (30) to pivot when energized
whereby contact is broken from the normally closed terminal (87a) and made
with the normally open terminal (87).
When energizing the coil of a relay, polarity of the coil does not
matter unless there is a diode across the coil. If a diode is not present, you may
attach positive voltage to either terminal of the coil and negative voltage to the other, otherwise
you must connect positive to the side of the coil that the cathode side (side with stripe) of the
diode is connected and negative to side of the coil that the anode side of the diode is connected.
13. POTENTIOMETER:
Potentiometer (Pot) is another class of
variable resistors and is used as an adjustable voltage divider. It consists of
a fixed resistance track having connections at both ends and a sliding contact, called wiper,
which moves along this track by turning the spindle. If only one of the connections and wiper are
used, it behaves as a variable resistor or rheostat. In case wiper is not used, it will offer fixed
resistance across the two connections. They are specified by their fixed value resistance.
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Fig. SPDT
Fig. Potentiometer
50. 14. BC 547:
BC547 is an NPN bi-polar junction transistor. A
transistor, stands for transfer of resistance, is commonly used to
amplify current. A small current at its base controls a larger current at
collector & emitter terminals.
BC547 is mainly used for amplification and switching purposes. It has a maximum current
gain of 800. Its equivalent transistors are BC548 and BC549.
The transistor terminals require a fixed DC voltage to operate
in the desired region of its characteristic curves. This is known as the biasing.
For amplification applications, the transistor is biased such that it is partly on for all input conditions. The
input signal at base is amplified and taken at the emitter. BC547 is used in common emitter configuration
for amplifiers. The voltage divider is the commonly used biasing mode. For switching applications,
transistor is biased so that it remains fully on if there is a signal at its base. In
the absence of base signal, it gets completely off.
15. TRANSFORMER :
A transformer is a device that transfers electrical energy from one circuit to
another through inductively coupled conductors—the transformer's coils. A varying current in the first
or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic
field through thesecondary winding. This varying magnetic
field induces a varying electromotive force (EMF), or "voltage", in the
secondary winding. This effect is called inductive coupling.
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Fig. Pin Diagram of BC
547
Fig. Transformer
51. If a load is connected to the secondary, current will flow in the secondary winding, and electrical energy
will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the
induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp) and is given by
the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows:
By appropriate selection of the ratio of turns, a transformer thus enables an alternating current
(AC) voltage to be "stepped up" by making Ns greater thanNp, or "stepped down" by making Ns less
than Np.
In the vast majority of transformers, the windings are coils wound around a ferromagnetic core, air-
core transformers being a notable exception.
Fig. Equivalent Circuit of Transformer
Transformers range in size from a thumbnail-sized coupling
transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to
interconnect portions of power grids. All operate on the same basic principles, although the range of
designs is wide. While new technologies have eliminated the need for transformers in some
electronic circuits, transformers are still found in nearly all electronic devices designed for household
("mains") voltage.
The conducting material used for the windings depends upon the
application, but in all cases the individual turns must be electrically insulated from each other to
ensure that the current travels throughout every turn.[39]
For small power and signal transformers, in
which currents are low and the potential difference between adjacent turns is small, the coils are
often wound from enamelled magnet wire, such as Formvar wire. Larger power transformers
operating at high voltages may be wound with copper rectangular strip conductors insulated by oil-
impregnated paper and blocks ofpressboard.[65]
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52. 16 .CAPACITOR :
A capacitor (formerly known as condenser) is a passive two-terminal electrical
component used to store energy in an electric field. The forms of practical capacitors vary widely, but all
contain at least two electrical conductors separated by a dielectric (insulator); for example, one common
construction consists of metal foils separated by a thin layer of insulating film. Capacitors are widely used
as parts of electrical circuits in many common electrical devices.
When there is a potential difference (voltage) across the conductors, a
static electric field develops across the dielectric, causing positive charge to collect on one plate and
negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is
characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric
charge on each conductor to the potential difference between them.
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Fig . Capacitor
53. The capacitance is greatest when
there is a narrow separation between large areas of
conductor, hence capacitor conductors are often called
"plates," referring to an early means of construction. In
practice, the dielectric between the plates passes a small
amount of leakage current and also has an electric field
strength limit, resulting in a breakdown voltage, while the
conductors and leads introduce an
undesired inductance andresistance.
Fig . Ceramic Capacitor
Capacitors are widely used in electronic circuits for blocking direct current while
allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in
the resonant circuits that tune radios to particular frequencies and for many other purposes.
17. uLTRASONIC SENSORS :
How Ultrasonic Sensors work?
Ultrasonic sensors are devices that use electrical–mechanical energy transformation, the
mechanical energy being in the form of ultrasonic waves, to measure distance from the sensor to
the target object. Ultrasonic waves are longitudinal mechanical waves which travel as a
succession of compressions and rarefactions along the direction of wave propagation through the
medium. Any sound wave above the human auditory range of 20,000 Hz is called ultrasound.
Depending on the type of application, the range of frequencies has been broadly categorized as
shown in the figure below:
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54. When ultrasonic waves are incident on an object, diffused reflection of the energy takes place
over a wide solid angle which might be as high as 180 degrees. Thus some fraction of the
incident energy is reflected back to the transducer in the form of echoes and is detected. The
distance to the object (L) can then be calculated through the speed of ultrasonic waves (v) in the
medium by the relation
Where ‘t’ is the time taken by the wave to reach back to the sensor and is the angle between the
horizontal and the path taken as shown in the figure. If the object is in motion, instruments based
on Doppler shift are used.
Applications
The applications of ultrasonic sensors can be classified on the basis of the
property that they exploit. These can be summarized as:
Domain Parameter Applications
Time Tile-of-Flight, Velocity Density, Thickness, Flaw Detection,
Anisotropy, Robotics, Remote
Sensing etc.
Attenuation Fluctuations in reflected and
Transmitted Signals
Defect characterization,
microstructures, interface analysis
Frequency Ultrasonic Spectroscopy Microstructure, grain size, porosity,
phase analysis.
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Fig . Ultra Sonic
Sensors
55. Image Time-of-Flight, velocity,
attenuation mapping in
Raster C-Scan or SARs
Surface and internal Defect
imaging, density, velocity,
2D and 3D imaging.
Research has been going on to overcome the problems of ultrasonic sensors,
particularly in medical imaging where it is known as ultrasound. The artifacts of
ultrasonic sensors like Acoustic shadowing and Acoustic Enhancement are being exploited to
characterize tissues which allow the differentiation between solid and cystic tissues. The industry too has
reaped the benefits from ultrasonic sensors in applications like plastic welding, jewelry cleaning, remote
sensing and telemetry, assisted parking systems etc. Robotics has been known to use ultrasonic
rangefinders as a favorite tool for distance ranging and mapping. Even the fashion industry is using
ultrasonic sensors in hair styling like hair extension implants.
Flaw Detection Using Ultrasonic Sensors
18 . CRySTAL OSCILLATOR :
A crystal oscillator is an electronic oscillator circuit that uses
the mechanical resonance of a vibrating crystal of piezoelectric material to
create an electrical signal with a very precise frequency. This frequency is
commonly used to keep track of time (as in quartz wristwatches), to provide a stableclock
signal for digital integrated circuits, and to stabilize frequencies for radio
transmitters and receivers. The most common type of piezoelectric resonator used is the quartz
crystal, so oscillator circuits designed around them became known as "crystal oscillators."
Quartz crystals are manufactured for frequencies from a
few tens of kilohertz to tens of megahertz. More than two billion (2×109
) crystals are
manufactured annually. Most are used for consumer devices such
as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside
test and measurement equipment, such as counters, signal generators, and oscilloscopes.
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Fig. crystal
oscillator
56. A crystal is a solid in which the
constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern
extending in all three spatial dimensions.
Almost any object made of an elastic material could be
used like a crystal, with appropriate transducers, since all objects have
natural resonant frequencies ofvibration. For example, steel is very elastic and has a high speed
of sound. It was often used in mechanical filters before quartz. The resonant frequency depends
on size, shape, elasticity, and the speed of sound in the material. High-frequency crystals are
typically cut in the shape of a simple, rectangular plate. Low-frequency crystals, such as those
used in digital watches, are typically cut in the shape of a tuning fork. For applications not
needing very precise timing, a low-cost ceramic resonator is often used in place of a quartz
crystal.
When a crystal of quartz is properly cut and mounted, it
can be made to distort an electric field by applying a voltage to an electrode near or on the
crystal. This property is known as piezoelectricity. When the field is removed, the quartz will
generate an electric field as it returns to its previous shape, and this can generate a voltage. The
result is that a quartz crystal behaves like a circuit composed of
an inductor, capacitor and resistor, with a precise resonant frequency. (See RLC circuit.)
Quartz has the further advantage that its elastic constants
and its size change in such a way that the frequency dependence on temperature can be very low.
The specific characteristics will depend on the mode of vibration and the angle at which the
quartz is cut (relative to its crystallographic axes).[8]
Therefore, the resonant frequency of the
plate, which depends on its size, will not change much, either. This means that a quartz clock,
filter or oscillator will remain accurate. For critical applications the quartz oscillator is mounted
in a temperature-controlled container, called a crystal oven, and can also be mounted on shock
absorbers to prevent perturbation by external mechanical vibrations.
A nine-volt battery, the most common of which (and the one referred to here unless otherwise stated) is
designated a PP3 battery, is shaped as a rounded rectangular prism. 9-volt batteries are commonly used
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57. in pocket transistor radios, smoke detectors, carbon monoxide alarms, guitar effect units, and radio-
controlled vehicle controllers. They are also used as backup power to keep the time in digital
clocks and alarm clocks.
Nine-volt alkaline batteries are constructed of six individual 1.5V LR61 cells enclosed in a
wrapper. [1]
These cells are slightly smaller than standard LR8D425AAAA cells and can be used in their
place for some devices, even though they are 3.5 mm shorter.
As of 2007, 9-volt batteries accounted for 4% of alkaline primary battery sales in the US. In Switzerland
as of 2008, 9-volt batteries totalled 2% of primary battery sales and 2% of secondary battery sales.
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59. VISUAL BASICS
History
Microsoft released Visual Basic in 1987. It was the first visual development tool
from Microsoft, and it was to compete with C, C++, Pascal and other well-known programming
languages. From the start, Visual Basic wasn't a hit. It wasn't until release 2.0 in 1991 that people
really discovered the potential of the language, and with release 3.0 it had become the fastest-
growing programming language on the market.
What Is Visual Basic?
Programmers have undergone a major change in many years of programming
various machines. For example what could be created in minutes with Visual Basic could take
days in other languages such: as "C" or "Pascal". Visual Basic provides many interesting sets of
tools to aid you in building exciting applications. Visual Basic provides these tools to make your
life far more easier because all the real hard code is already written for you.
With controls like these you can create many applications which use certain parts of windows.
For example, one of the controls could be a button, which we have demonstrated in the "Hello
World" program below. First create the control on the screen, then write the code which would
be executed once the control button is pressed. With this sort of operation in mind, simple
programs would take very little code. Why do it like the poor old "C" programmer who would
have to write code to even display a window on the screen, when Visual Basic already has this
part written for you.
Even though people tend to say Visual Basic's compiler is far behind the
compilers of Pascal and C, it has earned itself the status of a professional programming language,
and has almost freed BASIC of the reputation of a children's language. Overall you would class
Visual Basic as a Graphics User Interface(GUI). Because as you draw, you write for the
program. This must always be remembered in any kind of creation of a Visual Basic program.
All in all, VB is the preferred language of many future programmers. If you want to start
programming Windows, and don't know how to start, give Visual Basic a shot.
Significant Language Features
Visual Basic is not only a programming language, but also a complete graphical
development environment. This environment allows users with little programming experience
to quickly develop useful Microsoft Windows applications which have the ability to use OLE
( Object Linking and Embedding ) objects, such as an Excel spreadsheet. Visual Basic also has
the ability to develop programs that can be used as a front end application to a database system,
serving as the user interface which collects user input and displays formatted output in a more
appealing and useful form than many SQL versions are capable of.
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60. Visual Basic's main selling point is the ease with which it allows
the user to create nice looking, graphical programs with little
coding by the programmer, unlike many other languages that may
take hundreds of lines of programmer keyed code. As the
programmer works in the graphical environment, much of the
program code is automatically generated by the Visual Basic
program. In order to understand how this happens it is necessary to
understand the major concepts, objects and tools used by Visual
Basic. The main object in Visual Basic is called a form. When you
open a new project, you will start with a clear form that looks
similar to this :
This form will eventually be incorporated into your
program as a window. To this form you add controls. Controls
are things like text boxes, check boxes and command buttons.
Controls are added to your form by choosing them from the
Visual Basic "tool box" with the mouse and inserting them in
the form. Yours may look different, but the basic Visual Basic
Tool Box looks like this :
Once forms/controls are created, you can change the
properties ( appearance, structure etc.) related to those objects in that particular
objects properties window. From this window, you choose the property you want to
change from the list and change its corresponding setting. Here is an example of a
properties window :
Finally, you can add events to your controls. Events are responses to actions
performed on controls. For example, in the "Hello world" program sample on this
page, when you click on the command button on our form the event that is triggered
is the output of the message "Hello world" to the screen. Code must be written to
create an event. You can do this in Visual Basic's code window. Yours will look
similar to this ( except of course, the body of the sub-procedure where the actions are
specified) :
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61. Once the code box is open, you select the object to create an event for and
the triggering action ( such as a
certain mouse action ) from the
drop down menus in the code
box. You can open a code box for
a particular form by choosing it
from the project window and
selecting the View Code button.
The project window contains a
list of objects associated with that project. Below is an example of a project window :
Once all your objects are created, you can combine them to form a single
executable program that can be run outside of the Visual Basic environment, in Microsoft
Windows.
Areas of Application:-
The term "Personal Programming" refers to the idea that, wherever you
work, whatever you do, you can expand your computer's usefulness by writing applications to
use in your own job. Personal Programming is what Visual Basic is all about.
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62. Using Visual Basic's tools, you quickly translate an abstract idea into a program design you can
actually see on the screen. VB encourages you to experiment, revise, correct, and network your
design until the new project meets your requirements. However , most of all, it inspires your
imagination and creativity.
Visual Basic is ideal for developing applications that run in the new Windows 95 operating
system. VB presents a 3-step approach for creating programs:
1. Design the appearance of your application.
2. Assign property settings to the objects of your program.
3. Write the code to direct specific tasks at runtime.
Visual Basic (VB) is the third-generation event-driven programming language
and integrated development environment (IDE) from Microsoft for its COM programming
model. Visual Basic is relatively easy to learn and use.[1][2]
Visual Basic was derived from BASIC and enables the rapid application development (RAD) of
graphical user interface (GUI) applications, access to databases using Data Access Objects,
Remote Data Objects, or ActiveX Data Objects, and creation of ActiveX controls and objects.
Scripting languages such as VBA and VBScript are syntactically similar to Visual Basic, but
perform differently.[3]
A programmer can put together an application using the components provided with Visual Basic
itself. Programs written in Visual Basic can also use the Windows API, but doing so requires
external function declarations.
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63. The final release was version 6 in 1998. Microsoft's extended support ended in March 2008 and
the designated successor was Visual Basic .NET (now known simply as Visual Basic).
VISUAL BASIC is the super set of BASIC LANGUAGE. BASIC is
windows, it provides graphical user interface (GUI). Since it is GUI application build in VB are
more attractive. VB was launched in 1997 in which local database and remote data base
connectivity is possible. VISUAL BASIC is the fastest and easiest way to create applications for
Microsoft windows programming VISUAL BASIC provides with a complete set of tools to
simplify rapid application development.
“VISUAL” part return to the method to create the graphical user
interface (GUI). Instead of writing various lines of code for creating the appearance and location,
we can directly place the object and the screen and set its different properties such as shape,
colour etc. “BASIC” part refers to the BASIC (Beginners All Purpose Symbolic Instruction
Code) language VISUAL BASIC has evolved from the original BASIC language and now
contains several hundred statements, functions and keyboards, may of which relate directly to the
windows GUI. Any beginner can create the application by just learning a few of the keywords.
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66. IMPLEMENTATION
PLANNING
We all know “the best planning leads to the best results”. So when we
finalized our project it was a question from where to start? There are many directions but we had
to choose the right one. This was starting the step of our project.
The first event we did was to go through many books, discussion, meeting,
consultations & suggestions, satisfying the basic needs of client. After hard working we designed
our circuit.
Now next task was procurement of material for that we listed first the
required parts & divided our team in four parts. The work was equally divided. As our project is
hardware & software based so two of us were worked for software & other two were worked for
hardware.
We had divided our project in following parts: -
a. Designing of actual material.
b. Procurement of material.
c. Layout of PCB.
d. Preparation of PCB.
e. Assembling of components & their maintaining.
f. Software Implementation.
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67. g. Interfacing hardware with software.
h. Testing.
PCB DESIGNING
The name printed circuit board suggests that printing processes involved in
drawing the artwork on the board. And printing processes are often used to transfer an image to a
PCB.
History of the PCB:-
In 1930’s the technology for making a PC board was invented and name into
use during 1945. Before that time circuits were constructed with point to point soldering
component on an insulating board. But this is time consuming and bard to troubleshoot. Printed
circuit board is a piece of art. The performance of an electronics circuit depends upon layout and
sensing PCB.
PCB are used to route electrical urgent and signal through copper track while
are firmly bonded to an insulating base. The base material used for PCB is paper phenolic, glass
epoxy, polyester etc. paper phenolic is less costly and used to consumer electronic circuit. Paper
phenolic is more resistance to moisture, but difficult to machine and drills compared to glass
epoxy.
Rules for Layout:-
PCB interconnects various electronics component by an interconnectivity pattern.
The general considerations are:
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68. 1. Mechanical consideration: size, shape, mounting of PCB, etc.
2. User system consideration: that is whether for consumes or laboratory or industry etc.
3. Electrical and electronics parameter such as impedance gain, and electromagnetic
coupling.
4. Easy of maintenance.
Art Work:-
For photographic reduction process the artwork should provide maximum contact between the
portion to be each away and those to be left. Thus the art work should be generated on white
sheet with black ink.
A polyester foil can also be used with sticking tape and prepare artwork but it is costly. Tracking
paper may be used but it is not stable with temperature.
Basic Methods of Preparing Artwork
• Ink the drawing. The method is cheap. High quality water proof ink base is to be used.
• Using black tape and sticking pattern.
• Using red and blue transparent tape.
Advantages of PCB:-
Advantages of PCB over normal wiring are as follows.
• PCB is necessary for interconnection a large number of electronics component in a very
small area with minimum parasitic wiring affects.
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69. • PCB is stable for mass production with less chances of wiring error.
• Small component can be easily mounted on PCB.
• Wiring micro phony is avoided.
• Construction is neat, small and truly a work or art.
• By using PCB, the electronic equipment becomes more reliable in size and less costly.
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70. Disadvantages of PCB:-
• Art work is a time consuming activity.
• Art work requires skill and without designing a new board is not possible to make
connection.
Etching of PCB:-
Etching is the process of chemically attacking and removing the unprotected copper from the
copper plate to yield the desired conductor pattern. The most common enchant used in the
industry is ferric chloride. The erotically anyone of the following solution can be used to make
PCB.
1. ammonium per sulphate
2. chromic acid
3. cupric acid
4. ferric chloride
Method of etching includes tray rocking tank etching and spray etching. Out of there May
rocking is the simplest one. This consist of the tray of Pyrex glass, attached to a powered rocking
table is not available , rocking of the tray with etching solution and the plate can be done
manually also.
Ferric chloride crystal of 500 gms are mix in water to make a total solution of 1 liter. During the
etching process the connection weakens because the soluble cupric acid ferric ions precipitate
out of the solution in the form of sludge that rends to settle on the bottom on the etching vat.
Ideal etching condition required that the enchant be related to the temperature of between 60 to
70.
The copper plate is immersed in enchant solution with copper side up in the tray. Only one board
should be etched at one time. As the table is rocked the unprotected copper is dissolves.
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71. When etching is completed the resist material is remove by using lacquer thinner or acetic acid
or petrol. After the board is infected and proved. It is ready for whole drilling, component
mounting and soldering.
Drilling:-
Drilling is performed with the help of drilling machine. While doing drilling needles was change
according to the required diameter of the hole is to be made.
Mounting:-
After drilling mounting of the component is done. On PCB respective component was placed
imperfective holes and finally soldered.
After soldering the PCB was ready to be connected to the respective relays and supply. Before
than wiring diagram areas draw which decide the external wire connection to the PCB
Testing:-
Testing is the main event, which has its own importance in the electronics field. Testing is the
process to find the output performance and fault of the circuit in the various forms. The main
objective of the testing is to check the output performance as per our assumption.
The least carelessness may lead to the major fault in case of electronics circuit and it is depend
upon the layout and design of the PCB. Printed circuit board are used to route electrical current
and signal through the copper tracks which are primarily bounded to an insulating core.
For the testing of any electronics circuit some common steps are performed. These steps are as
follows.
• To check the main power source.
• To tress out the circuit. In which following steps are followed.
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72. 1). The tracks are not open.
2).The distances between two tracks are sufficient to avoid capacitance.
3).The track linked with the other related tracks is proper or not.
4).The jumper which goes from one track to another track should not short with the tracks which
are in between required two.
• Thus by testing the tracks of the printed circuit board it helps the project for making
successful. After testing copper tracks the component were tested with the help of instrument
like multimeter, CRO, signal generator etc.
• After mounting the component on the PCB the possibility of the dry soldering was
checked to avoid the possibility of shorting those tracks as well as the tracks were checked
individually to avoid the possibility of opening those tracks. This testing was carried out with the
help of multimeter keeping in range of Ohm.
• After all check the power was supplied and the operation of the circuit it was observed.
• Check the supply voltage and voltages at the points where it is known or expected to be
of certain value.
• Check the output voltage and waveform of the circuit by the equipment such as CRO,
signal generator.
Thus by checking the above aspects, it helps the project to become successful.
Testing of Power supply circuit:-
The entire components are tested with the help of multimeter. After testing of component we fix
the component on the wet board. Now we give the supply to the transformer and input waveform
is to be checked. This procedure is simultaneously carried out for Rectifier, Filter and Regulator
circuit. We check the waveform but it is not according to our assumption, because the waveform
is started and then it goes to decreasing. Due to this the output voltage is also decreases.
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73. WAVEFORM OF FULL WAVE CENTER TAP RECTIFIER
For such a fault we test the power supply circuit step by step and found that the regulator IC is
not work as per our assumption (that means it is faulty). Hence we replace the regulator IC and
check the output waveform and voltage that it is as per our assumption. At that condition we stop
the testing of power supply.
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74. Testing of Switching Circuit:-
For switching circuit firstly we check the tracks that there should be no defect. Then we mount
the component and give the supply to the circuit and input from PC and check the output
performance of the circuit. The circuit is work as per our assumption.
Testing of speed controller circuit:-
The procedure of the testing of speed controller circuit is same as the switching circuit at the
point of potentiometer for required assumption we set the preset and again test is carried out after
that we give the supply to the circuit and check the waveform of the astable multivibrator which
is as per our assumption as that it is square wave. And then we give input from the computer and
check the speed control as per our assumption.
OUTPUT WAVEFORM OF IC 555 AT PIN 3
ASSEMBLING AND TESTING OF THE TOTAL PROJECT:-
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75. After testing and confirm the output of the individual circuit we connect all this circuit is as
shown in the figure. When we make the circuit carefully connect all the connecting wire and to
avoid loose connection soldered and check the continuity of the wires and tracks by the
multimeter. And then give the supply to the input side of the circuit and checks all modes on
output side of the circuit. After completing all modes and operation are works as per our
assumption.
Hence it is said that proper assembling and testing plays an important role for success of the
project.
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76. CONCLUSION AND SCOPE OF FUTURE WORK
In the designing of our projects, we have kept in mind the user in the
implementation part which interacting with the user we had given lot of guideline to user
with various messages. Visual basics very good programming languages for
implementation of any data base projects because it has powerful control with which you
can easily implement various facilities in our projects .the screen are very user friendly.
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