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10-04-2010, 09:11 PM
Post: #1
LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report

.doc  MInor Project-LASER TORCH-BASED VOICE TRANSMITTER AND RECEIVER.doc (Size: 3.09 MB / Downloads: 1716)

LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER
Using this circuit you can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit (Fig. 1) comprises condenser microphone transistor amplifier BC548 (T1) followed by an pomp stage built around µA741 (IC1). The gain of the op-amp can be controlled with the help of 1-mega-ohm potmeter VR1.The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, in
turn, modulates the laser beam.
The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit”with the body of
The torch connected to the emitter ofBD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit (Fig. 2) uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio
Power amplifier. The receiver does not need any complicated alignment. Just keep
the phototransistor oriented towards the remote transmitterâ„¢s laser point and adjust
The volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs. The reflected sunlight, however, does not cause any problem. But the sensor should not directly face the sun.
A BRIEF SUMMARY OF COMPONENTS USED
When a beginner to electronics first looks at a circuit board full of components
he/she is often overwhelmed by the diversity of do-dads. In these next few sections we will help you to identify some of the simple components and their schematical symbol. Then you should be able to call them resistors and transistors instead of Whatchamacallits.
Electronic component are classed into either being Passive devices
Or Active devices.
A Passive Device is one that contributes no power gain (amplification)
to a circuit or system. It has not control action and does not require any
input other than a signal to perform its function. In other words, A
components with no brains! Examples are Resistors, Capactitors and
Inductors
Active Devices are components that are capable of controlling voltages
or currents and can create a switching action in the circuit. In other
words, Devices with smarts! Examples are Diodes, Transistors and
Integrated circuits. Most active components are semiconductors.
Resistors:
This is the most common component in electronics. It is used mainly to control
current and voltage within the circuit. You can identify a simple resistor
by its simple cigar shape with a wire lead coming out of each end. It uses a
system of color coded bands to identify the value of the component (measured
in Ohms) *A surface mount resistor is in fact mere millimeters in size
but performs the same function as its bigger brother, the simple resistor. A
potentiometer is a variable resistor. It lets you vary the resistance with a dial
or sliding control in order to alter current or voltage on the fly. This is opposed
to the fixed simple resistors.
Condensers/Capacitors:
Capacitors, or "caps", vary in size and shape - from a small surface mount
model up to a huge electric motor cap the size of a paint can. It storages electrical
energy in the form of electrostatic charge. The size of a capacitor generally determines
how much charge it can store. A small surface mount or ceramic cap will
only hold a minuscule charge. A cylindrical electrolytic cap will store a much
larger charge. Some of the large electrolytic caps can store enough charge to kill
a person. Another type, called Tantalum Capacitors, store a larger charge in a
smaller package.
Inductors:
You may remember from science class that adding electrical current to a coil of
wire produces a magnetic field around itself. This is how the inductor works. It is
charged with a magnetic field and when that field collapses it produces current in
the opposite direction. Inductors are used in Alternating Current circuits to
oppose changes in the existing current. Most inductors can be identified by the
"coil" appearance. Others actually look like a resistor but are usually green in
color.
Diodes:
Diodes are basically a one-way valve for electrical current. They let it flow in one
direction (from positive to negative) and not in the other direction. This is used to perform rectification or conversion of AC current to DC by clipping off the negative portion of a AC waveform. The diode terminals are cathode and anode and the arrow inside the diode symbol points towards the cathode, indicating current flow in that direction when the diode is forward biased and conducting current. Most diodes are similar in appearance to a resistor and will have a painted line on one end showing the direction or flow(white side is negative). If the negative side
is on the negative end of the circuit, current will flow. If the negative is on the positive side of the circuit no current will flow.
LEDs (Light Emitting Diodes)
LEDs are simply diodes that emit light of one form or another. They are used as
indicator devices. Example: LED lit equals machine on. The general purpose silicon
diode emits excess energy in the form of heat when conducting current. If a different
semiconductor material such as gallium, arsenide phosphide is used, the excess
energy can be released at a lower wavelength visible to human eye. This is the
composition of LED. They come in several sizes and colors. Some even emit Infrared
Light which cannot be seen by the human eye.
Switch :
This is a mechanical part which when pressed makes the current to flow through
it. If the switch is released the current stops flowing through it. This helps to control a
circuit.
Transistors:
The transistor performs two basic functions:
1) It acts as a switch turning current on and off.
2) It acts as a amplifier.This makes an output signal that is amagnified version of the input signal.Transistors come in several sizes dependingon their application. It can be a
big power transistor such as is used in power applifiers in your stereo, down to
a surface mount (SMT) and even down to .5 microns wide (I.E.: Mucho Small!)
such as in a microprocessor or IntegratedCircuit.
NPN Transistor: Bipolar junction perform the function of amplifications where
a small varying voltage or current applied to the base (the lead on the left
side of the symbol) is proportionately replicated by a much larger voltage or
current between the collector and emitter leads. Bipolar junction refers to sandwich
construction of the semiconductor, where a wedge of "P" material is placed
between two wedges of "N" material. In this NPN construction a small base current
controls the larger current flowing from collector to emitter (the lead withthe arrow).
PNP Transistor: Similar to NPN transistors, PNP's have a wedge of "N" material
between two wedges of "P" material. In this design, a base current
regulates the larger current flowing from emitter to collector, as indicated
by the direction of the arrow on the emitter lead. In CED players, PNP transistors
are used less frequently that the NPN type for amplification functions.
PCBâ„¢s:
PCB stands for printed circuit board which are used for wiring up of the components of a circuit. PCBs are made of paper phenolic FR2 grade (low cost, for low frequency and low power circuit assembly) and glass epoxy FR4 grade (for high frequency, high power circuits) copper clad laminates (available in 1.6mm, 2.4mm and 3.6mm thickness). Singlesided PCBs have copper foil only on one side while double-sided PCBs have copper foil on both side of the laminate. Thickness of copper foil is 35 micrometer minimum on cheaper PCBs and 70 micrometer on slightly costlier PCBs. Tracks (conductive paths) are made by masking (covering) the track part of copper
with etch-resist enamel paint (you can even use nail polish) and later dipping the
laminate in ferric chloride solutions to dissolve all copper except under the masked
part. Holes in PCBs are drilled after etching is over. The tracks on two sides of a PCB are joined using printed through hole (PTH) technique, which is equivalent to using slotted copper rivets for joining tracks on both sides. On cheaper PCBs, PTH are not provided, only Pads (i.e. circular copper land with centre hole) are provided and you have to join the tracks on both sides by soldering a copper wire to the pads with a copper wire. In singlesided PCB components are mounted on the side which has no track (called component side). In a double-sided PCB the component side is defined (marked before hand) or it will show component outline (also called silk screen)
Green masking is the process of applying a layer of green colour insulation varnish on all parts of tracks except near the holes, to protect the tracks from exposure to atmosphere and thus prolong its life and reliability.
Batteries:
Symbol of batteries shows +ve terminal by a longer line than the “ve terminal.
For low power circuit dry batteries are used.
Speakers:
These convert electrical signals to accoustic viberations. It comprises a permanent
magnet and a moving coil (through which electrical signal is passed). This moving coil is fixed to the diaphram which vibrates to produce sound.
ICs (Integrated Circuits):
Integrated Circuits, or ICs, are complex circuits inside one simple package. Silicon
and metals are used to simulate resistors, capacitors, transistors, etc. It is a space
saving miracle. These components come in a wide variety of packages and sizes.
You can tell them by their "monolithic shape" that has a ton of "pins" coming out
of them. Their applications are as varied as their packages. It can be a simple timer, to
a complex logic circuit, or even a microcontroller (microprocessor with a few added functions) with erasable memory built inside.
Microprocessors (MPUs):
Microprocessors and other large scale ICs are very complex ICs. At their core
is the transistor which provides the logic for computers, cars, TVs and just about
everything else electronic. Packages are becoming smaller and smaller as companies
are learning new tricks to make the transistors ever tinier.

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16-07-2010, 01:29 PM
Post: #2
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
I needLASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report.Please send me...
15-09-2010, 06:27 AM
Post: #3
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
hello sir,
please send me the full report of laser torch based voice transmitter and receiver project
i am doing it as my mini project
my mail id is : " yuva1phani[at]gmail.com "
18-09-2010, 05:22 PM
Post: #4
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
http://www.seminarprojects.com/Thread-la...ull-report
28-09-2010, 10:28 AM
Post: #5
Thumbs Up RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report

.ppt  LASERS.ppt (Size: 368.5 KB / Downloads: 359)
Basic Laser Safety Training


Laser Fundamentals

The light emitted from a laser is monochromatic, that is, it is of one color/wavelength. In contrast, ordinary white light is a combination of many colors (or wavelengths) of light.
Lasers emit light that is highly directional, that is, laser light is emitted as a relatively narrow beam in a specific direction. Ordinary light, such as from a light bulb, is emitted in many directions away from the source.
The light from a laser is said to be coherent, which means that the wavelengths of the laser light are in phase in space and time. Ordinary light can be a mixture of many wavelengths.

These three properties of laser light are what can make it more hazardous than ordinary light. Laser light can deposit a lot of energy within a small area.
Common Components of all Lasers

Active Medium
The active medium may be solid crystals such as ruby or Nd:YAG, liquid dyes, gases like CO2 or Helium/Neon, or semiconductors such as GaAs. Active mediums contain atoms whose electrons may be excited to a metastable energy level by an energy source.
Excitation Mechanism
Excitation mechanisms pump energy into the active medium by one or more of three basic methods; optical, electrical or chemical.
High Reflectance Mirror
A mirror which reflects essentially 100% of the laser light.
Partially Transmissive Mirror
A mirror which reflects less than 100% of the laser light and transmits the remainder.

Tongue
06-10-2010, 12:24 PM
Post: #6
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report

.doc  LASER1.doc (Size: 4.42 MB / Downloads: 339)
LASER/LED BASED VOICE COMMUNICATION SYSTEM

INTRODUCTION-:

This project is about laser based communication system, which is one of the form of optical communications system. It is used for inter and intra-building communication, closed circuit TV’s, PC, LAN’ etc. It is suitable for the study of optical communication (more specifically laser based communication). This project helps us for the better understanding of optical communication which has become a primary means of communication in the present world and gives us the view about free optics. It enables communication unto several hundred meters and this technology can be extended in future to enable longer distance communication by using parabolic light reflector.
08-10-2010, 10:45 AM
Post: #7
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report

.pdf  abstract.pdf (Size: 75.75 KB / Downloads: 255)

LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report











Using this circuit you can communicate
with your neighbours
wirelessly. Instead of RF signals,
light from a laser torch is used as the
carrier in the circuit. The laser torch can
transmit light up to a distance of about 500
metres. The phototransistor of the receiver
must be accurately oriented towards the
laser beam from the torch. If there is any
obstruction in the path of the laser beam,
no sound will be heard from the receiver.
The transmitter circuit (Fig. 1) comprises
condenser microphone transistor
amplifier BC548 (T1) followed by an opamp
stage built around μA741 (IC1). The
gain of the op-amp can be controlled with
the help of 1-mega-ohm potmeter VR1.
The AF output from IC1 is coupled to the
base of transistor BD139 (T2), which, in
turn, modulates the laser beam.
The transmitter uses 9V power supply.
However, the 3-volt laser torch (after
removal of its battery) can be directly connected
to the circuit—with the body of
the torch connected to the emitter of
BD139 and the spring-loaded lead protruding
from inside the torch to circuit ground.
The receiver circuit (Fig. 2) uses an
npn phototransistor as the light sensor that
is followed by a two-stage transistor
preamplifier and LM386-based audio
power amplifier. The receiver does not
need any complicated alignment. Just keep
the phototransistor oriented towards the
remote transmitter’s laser point and adjust
the volume control for a clear sound.
To avoid 50Hz hum noise in the
speaker, keep the phototransistor away
08-10-2010, 02:30 PM
Post: #8
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report

.doc  MInor Project-LASER TORCH-BASED VOICE TRANSMITTER AND RECEIVER[1].doc (Size: 3.13 MB / Downloads: 199)
Angel
LASER TORCH-BASED VOICE
TRANSMITTER AND RECEIVER

ABSTRACT
Tongue

Using this circuit you can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit (Fig. 1) comprises condenser microphone transistor amplifier BC548 (T1) followed by an pomp stage built around μA741 (IC1). The gain of the op-amp can be controlled with the help of 1-mega-ohm potmeter VR1.The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, inturn, modulates the laser beam.
The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit—with the body of
The torch connected to the emitter ofBD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit (Fig. 2) uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio
Power amplifier. The receiver does not need any complicated alignment. Just keep
the phototransistor oriented towards the remote transmitter’s laser point and adjust
The volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs. The reflected sunlight, however, does not cause any problem. But the sensor should not directly face the sun.

A BRIEF DISCRIPTION OF LASER TORCH BASED
TRANSMITTER AND RECEIVER

PROJECT DESCRIPTION

(a) A. LASER BASED VOICE TRANSMITTER

 The circuit is based upon the principle of LIGHT MODULATION where instead of radio frequency signals; light from a laser torch is used as the carrier in the circuit.
 Here, the transmitter uses 9V power supply.
 Audio signal or voice is taken as input from the condenser mic, which is, followed transistor amplifier BC548 along with op-amp stage built around UA741.
 The gain of the op-amp can be controlled with the help of 1 mega ohms potmeter.
 The AF output from op-amp UA741 is coupled to the base of the power transistor BD139, which in turn, modulates the laser.
 However, the three volts laser torch can be directly connected to the emitter of BD139 and the spring loaded lead protruding from inside the torch to the ground.
 In the transmitter circuit, audio signal of the non-sinusoidal waveform and having a few mV of amplitude is taken as input from condenser mic.
 Condenser mic is directly followed by the transistor amplifier stage consist of BC548. Transistor BC548 is connected in common emitter configuration.
 Resistor R1 is the source resistor, which is directly connected to the power-supply.
 R2, R3 and capacitor C1 are acting as self-biasing circuits, which is used for the biasing transistor. These circuit arrangements provide or establish a stable operating point. The biasing voltage is obtaining by R2 and R3 resistors network. Self-bias is used for obtaining entire audio signal as input.
 Capacitor C1 is the coupling capacitor, since audio input signal is having a non-sinusoidal waveform of different amplitude and frequency, coupling capacitor is used to reject some of the dc noise/line as well as level from audio input signal.
 The self-biased circuit is connected with the BC548 in CE configuration. It is transistor amplifier stage, where the low amplitude audio signal is amplified to the desired voltage.
 The output is taken from the collector terminal; so inverted audio input signal is obtained.
 Transistor pre-amplifier stage is coupled with op-amp stage built by ua741. C2 is the blocking capacitor while R4 is the op-amp stage resistor. Op-amp ua741 is easily available general-purpose operational amplifier.
 Pin configuration of UA741 is shown in the glossary. Here pin no. 1 and 5 are not connected in order to nullify input-offset voltage. Pin no. 7 and 4 are VCC as well as –VEE supply voltage. Pin no. 3 is non-inverting input while pin no. 2 is inverting input. Between pin no. 2 and 6, 1 mega-ohm potmeter is connected as voltage series negative feedback, which control the infinite gain of the op-amp.
 Resistors R5 and R6 of it value acts as a voltage-divider network, thus it gives a fixed voltage at the non-inverting pin.
 Input inverted audio signal is applied to the inverting pin. Op-amp works on the differences into the applied two input voltage and provide a output at pin no. 6. Since, input is applied to the inverting pin the output is also an inverting one. Thus, again we get in phase high power and high amplitude level audio signal.
 Capacitors C3, C4 and resistor R7 are acting as diffusion capacitors and feedback resistor respectively. These diffusion capacitors stored the carriers like holes and electrons in the base and thus provide self-biasing of the transistor.
 Power dissipation rate of UA741 is very high, which is not practical for driving other electronics devices, so heat sink power transistor BD139 is used.
08-10-2010, 04:01 PM
Post: #9
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
This article is presented by:
DEPARTMENT OF ELECTRONICS AND COMMUNICATIONS
ENGINEERING
KONERU LAKSHMAIAH COLLEGE OF ENGINEERING
Ch.Ravi Kishore


ABSTRACT
Using this circuit you can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit (Fig. 1) comprises condenser microphone transistor amplifier BC548 (T1) followed by an opamp stage built around μA741 (IC1). The gain of the op-amp can be controlled with the help of 1-mega-ohm pot meter VR1. The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, in turn, modulates the laser beam. The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit—with the body of the torch connected to the emitter of BD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit (Fig. 2) uses an NPN phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio power amplifier. The receiver does not need any complicated alignment. Just keep the phototransistor oriented towards the remote transmitter’s laser point and adjust the volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs.
GENERAL
Laser communications systems are wireless connections through the atmosphere. They work similarly to fiber optic links, except the beam is transmitted through free space. While the transmitter and receiver must require line-of-sight conditions, they have the benefit of eliminating the need for broadcast rights and buried cables. Laser communications systems can be easily deployed since they are inexpensive, small, low power and do not require any radio interference studies. The carrier used for the transmission signal is typically generated by a laser diode. Two parallel beams are needed, one for transmission and one for reception. Due to budget restrictions, the system implemented in this project is only one way.
Laser communications have been a hot topic lately, as solutions for how to satisfy ever increasing bandwidth needs are in high demand. Some have suggested that bandwidth could be distributed in neighborhoods by putting laser communication systems on top of homes and pointing them towards a common transceiver with a fast link to the Internet. With possible transmit speeds of up to a gigabit per second, this is an exciting area. Other applications for this technology include temporary connectivity needs (e.g. sporting events, disaster scenes, or conventions), or space based communications.
Using this circuit you can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit (Fig. 1) comprises condenser microphone transistor amplifier BC548 (T1) followed by an opamp stage built around μA741 (IC1). The gain of the op-amp can be controlled with the help of 1-mega-ohm pot meter VR1. The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, in turn, modulates the laser beam. The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit—with the body of the torch connected to the emitter of BD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit (Fig. 2) uses an NPN phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio power amplifier. The receiver does not need any complicated alignment. Just keep the phototransistor oriented towards the remote transmitter’s laser point and adjust the volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs.Sad


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12-10-2010, 09:52 AM
Post: #10
Thumbs Up RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report

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This article is presented by:
G.SRNIVAS
CH.HEMANTH KUMAR
J.N.K.SAGAR
LASER TORCH-BASED VOICE
TRANSMITTER AND RECEIVER


ABSTRACT

Using this circuit you can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit comprises condenser microphone transistor amplifier BC548 followed by an pomp stage built around µA741. The gain of the op-amp can be controlled with the help of 1-mega-ohm potmeter VR1.The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, in turn, modulates the laser beam.
The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit—with the body of The torch connected to the emitter of BD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio Power amplifier. The receiver does not need any complicated alignment. Just keep the phototransistor oriented towards the remote transmitter’s laser point and adjust The volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs. The reflected sunlight, however, does not cause any problem. But the sensor should not directly face the sun.

INTRODUCTION


Laser as a communication medium can provide a good substitute for the present day communication systems as the problem of interference faced in case of electromagnetic waves is not there and high deal of secrecy is available.
Use of laser in communication systems is the future because of the advantages of the full channel speeds, no communication licenses required at present, compatibility with copper or fiber interfaces and no bridge or router requirements . Besides this there are no recurring line costs, portability, transparency to networks or protocols, although range is limited to a few hundred meters. Also the laser transmission is very secure because it has a narrow beam (any potential evesdropping will result in an interruption which will alert the personnel. Also
it cannot be detected with use of spectrum analyzers and RF meters and hence can be used for diverse applications including financial, medical and military. Lasers can also transmit through glass, however the physical properties of the glass have to be considered. Laser transmitter and receiver units ensure easy, straightforward systems alignment and long-term stable, servicefree operation, especially in inaccessible environments, optical wireless systems offer ideal, economical alternative to expensive leased lines for buildings. The laser can also be commissioned in satellites for communication, as laser radar requires small aperture as compared to microwave radar. Also there is high secrecy and no
interference like in EM waves. Further, potential bandwidth of radar using lasers can translate to very precision range measurement. For these reasons, they can be used as an alternative to present modes of communication. laser communication, which is both wide-band and high-speed .

COMPONENT LIST
Transmitter
1. IC 741
2. BC 548
3. BD 139
4. 3 Volts Laser Torch
5.Condenser Mic
6.Resistors- 8.2k,1.8m,15k,1m ,82 Ω,10k
7.Capacitors-1 μF/16v,0.1 μF,470 μF/16v,1000 μF/16v
8. 9v Battery
9.PCB
Reciver:
1.IC741
2.IC 386
3.2n5777 Photo Transistor
4. 0.5w/8ohm Speaker
5.Resisrosr-
6.Capacitors-
7.9v Battery
8.PCB

14-10-2010, 09:25 AM
Post: #11
Smile RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
This article is presented by:
PRADEEP G.
LASER TORCH-BASED VOICE TRANSMITTER AND RECEIVER

INTRODUCTION
Using this circuit you can communicate with your neighbours wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 metres. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit (Fig. 1) comprises condenser microphone transistor amplifier BC548 (T1) followed by an opamp stage built around μA741 (IC1). The gain of the op-amp can be controlled with the help of 1-mega-ohm potmeter VR1. The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, in turn, modulates the laser beam. The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit—with the body of the torch connected to the emitter of BD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit (Fig. 2) uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio power amplifier. The receiver does not need any complicated alignment. Just keep the phototransistor oriented towards the remote transmitter’s laser point and adjust the volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs. The reflected sunlight, however, does not cause any problem. But the sensor should not directly face the sun.
For more information about this article,please follow the link:
http://www.google.com/url?sa=t&source=we...zXi63oAp-w
10-12-2010, 02:24 AM
Post: #12
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
thankss.... i submit dis topic with one of my abstractsss..... further doubts vil ask after daat....
10-12-2010, 08:07 PM
Post: #13
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
1stly i say thanks,

i want to complete circuit digram to construct it.(like where diode, resister, transformer, led, sensor, etc. implemented in general purpose bradbord )

if you can help me then mail me its complete circuit digram on my mail id- raj.rampraweshkumar[at]gmail.com
10-12-2010, 09:20 PM
Post: #14
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
please i need a project topic that i will be able to write program on i am a final list student and need a project to submit.i wan to know if i can be able to write program on this topic and if not kindly get me one that i can be able.

thanks
fasasi
13-12-2010, 02:11 PM
Post: #15
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
hi
please visit the following thread for more details on 'LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER'

http://www.seminarprojects.com/Thread-la...ull-report
26-01-2011, 07:04 PM
Post: #16
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
Hey bro plz give more information on project of "Voice communication through Laser beam".
Thank's
17-02-2011, 12:23 PM
Post: #17
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
sir, can u explain the details of the laser torch that we are going to use in this project. . . . . plz
my mail id is kpsmadhu123786[at]gmail.com
it is must to all of us . . . . . . .
my project report depends on ur reply
Can u explain me about the laser torch that we are going to use in this project and where to find these laser torches of given configuration. If not, which laser we have to use
20-02-2011, 03:47 AM
Post: #18
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
hey i need a report on laser light based voice transmitter and reciever,plz send at my email id:-gss1818[at]gmail.com
20-02-2011, 11:38 AM
Post: #19
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
nice very well
nice ot understanddddddddddddddddddddddd
12-03-2011, 12:22 PM
Post: #20
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
PLZ give me more detail on ckt. Gain and applications & advantages & disadvantages plz help us
17-03-2011, 02:41 PM
Post: #21
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
presented by:
G.srinivas, Ch.hemanthkumar, J.n.k.sagar


.docx  laser torch-based voice transmitter and receiver.docx (Size: 1.17 MB / Downloads: 148)
1.ABSTRACT
Using this circuit we can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit comprises condenser microphone transistor amplifier BC548 followed by an pomp stage built around µA741. The gain of the op-amp can be controlled with the help of 1-mega-ohm potmeter VR1.The AF output from IC1 is coupled to the base of transistor BD139 (T2), which, in turn, modulates the laser beam.
The transmitter uses 9V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit—with the body of The torch connected to the emitter of BD139 and the spring-loaded lead protruding from inside the torch to circuit ground. The receiver circuit uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio Power amplifier. The receiver does not need any complicated alignment. Just keep the phototransistor oriented towards the remote transmitter’s laser point and adjust The volume control for a clear sound. To avoid 50Hz hum noise in the speaker, keep the phototransistor away from AC light sources such as bulbs. The reflected sunlight, however, does not cause any problem. But the sensor should not directly face the sun.
2. INTRODUCTION
Laser as a communication medium can provide a good substitute for the present day communication systems as the problem of interference faced in case of electromagnetic waves is not there and high deal of secrecy is available.
Use of laser in communication systems is the future because of the advantages of the full channel speeds, no communication licenses required at present, compatibility with copper or fiber interfaces and no bridge or router requirements . Besides this there are no recurring line costs, portability, transparency to networks or protocols, although range is limited to a few hundred meters. Also the laser transmission is very secure because it has a narrow beam (any potential evesdropping will result in an interruption which will alert the personnel. Also it cannot be detected with use of spectrum analyzers and RF meters and hence can be used for diverse applications including financial, medical and military. Lasers can also transmit through glass, however the physical properties of the glass have to be considered. Laser transmitter and receiver units ensure easy, straightforward systems alignment and long-term stable, servicefree operation, especially in inaccessible environments, optical wireless systems offer ideal, economical alternative to expensive leased lines for buildings. The laser can also be commissioned in satellites for communication, as laser radar requires small aperture as compared to microwave radar. Also there is high secrecy and no interference like in EM waves. Further, potential bandwidth of radar using lasers can translate to very precision range measurement. For these reasons, they can be used as an alternative to present modes of communication. laser communication, which is both wide-band and high-speed .
3.BLOCK DIAGRAM
4.BLOCK DIAGRAM EXPLANATION
i.CONDENSER MICROPHONE :

It is also called a capacitor or electrostatic microphone. Condenser means capacitor, which stores energy in the form of an electric field. Condenser microphones require power from a battery or external source. Condenser also tends to be more sensitive and responsive than dynamic, making them well suited to capturing subtle nuances in a sound.
The diaphragm vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. Specifically when the plates are closer together capacitance increases and a charge current occurs and this current will be used to trigger the transmitting section.
ii. TRANSMITTING SECTION :
The transmitter section comprises condenser microphone, transistor
amplifier BC548 followed by an op-amp stage built around IC1.
The gain of the op-amp can be controlled with the help of 1-mega ohm pot meter VR1. The AF output from IC1 is coupled to the base of transistor Bd139, which in turn, modulates the laser beam. The transmitter uses 9V power supply. however, the 3-volt laser torch ( after the removal of its battery) can be directly connected to the circuit--with the body of the torch connected to the emitter of BD139 and the spring-loaded lead protruding from inside the torch to circuit ground.
iii. LASER TORCH :
Here we use the light rays coming from laser torch as the medium for transmission. Laser had potential for the transfer of data at extremely high rates, specific advancements were needed in component performance and systems engineering, particularly for space-qualified hardware. Free space laser communications systems are wireless connections through the atmosphere. They work similar to fibre optic cable systems except the beam is transmitted through open space. The laser systems operate in the near infrared region of the spectrum. The laser light across the link is at a wavelength of between 780 - 920 nm. Two parallel beams are used, one for transmission and one for reception.
vi. RECEIVING SECTION :
The receiver circuit uses an NPN phototransistor as the light sensor that is followed by a two stage transistor preamplifier and LM386-based audio power amplifier. The receiver doesn't need any complicated alignment. Just keep the phototransistor
oriented towards the remote transmitter's laser point and adjust the volume control for a clear sound.
v. LOUD SPEAKER
Aloudspeaker (or "speaker") is an electro acoustic transducer that converts an electrical signal into sound. The speaker moves in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water
03-04-2011, 12:06 PM
Post: #22
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
plz give me full report of LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER
05-04-2011, 02:41 PM
Post: #23
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
05-04-2011, 03:33 PM
Post: #24
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
to get information about the topic lazer torch based voice trasmiter and receiver full report ,ppt and related topic please refer link bellow

http://www.seminarprojects.com/Thread-la...ull-report

http://www.seminarprojects.com/Thread-la...rt?page=10

http://www.seminarprojects.com/Thread-la...ort?page=9

Please Use Search http://seminarprojects.com/search.php wisely To Get More Information About A Seminar Or Project Topic
07-04-2011, 12:42 PM
Post: #25
RE: LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER full report
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Marked Categories : lazer microphone, laser communication seminar report using lm386 and laser diode, projects on laser communication audio, laser based voice communication system, laser transmitter and receiver circuit, applications of laser torch based voice transmitter and receiver, laser torch based voice transmitter and receiver advantages, voice transmitter and receiver circuit, voice transmitter and receiver using laser, laser based voice communication, laser based audio communiication, transfer sound on a laser circuit diagram, laser torch based transmitter and receiver, laser torch based voice transmiter and reciver, laser torch based voice transmitter and receiver,

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