LASER Transmitter and Receiver

LASER Transmitter and Receiver




This set of two circuits from the basis for a very simple light wave transmitter. A LASER beam is

modulated and then aimed at a receiver that demodulates the signal and then presents the information voice, data, etc.. The whole thing is very easy tobuild and requires no specialized parts execpt for the LASER itself.

Part Total Qty. Description Substitutions C1, C2 2 0.1uf Ceramic Disc Capacitor
C3 1 100uf 25V Electrolytic Capacitor
R1 1 100K Ohm 1/4W Resistor
R2 1 1M Ohm 1/4W Resistor
R3 1 10K Pot
Q1 1 NPN Phototransistor
U1 1 741 Op Amp
U2 1 LM386 Audio Amp
SPKR1 1 8 Ohm Speaker
T1 1 8 Ohm:2K Audio Transformer
MISC 1 Wire, Board, Knob For R3, LASER Tube and Power Supply

Simple lie detector

Simple lie detector

  

PcSpice Student Version (Free Edition)

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Description :

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Download: http://www.filesonic.com/file/1902446571

SOLID STATE RELAY REQUIRES ONLY 50uA DRIVE CURRENT

This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays. It is ideal for battery-powered systems. Using a combination of a high current TRIAC and a very sensitive low current SCR, the circuit can control about 600 watts of power to load while providing full isolation and transient protection.

Audio monitoring system

Description.
Here is the circuit schematic of a simple audio surveillance system in which the transmitter will pickup sound from one location and the receiver at other location will reproduce it. The receiver and transmitter are connected by only one set of wire. Here both power supply and transmitted signal share the same wire.

The audio signals picked up by the microphone will be amplified by the double stage amplifier build around transistors Q1 and Q2.The POT R2 controls gain of the amplifier. The power supply for this circuit is drawn from the interconnection lines itself. The capacitor C4 bypasses all audio frequencies & noise from the line and ensures pure DC for the circuit. The output of the amplifier (audio signal) is coupled to the line via the capacitor C6.

At the receiver end the capacitor C7 extracts the audio signal from the line and feds it to the inverting input of IC1 (TL071) which is wired as a voltage amplifier. Output of IC1 is given to the input of IC2 (LM386) which is a integrated power amplifier.IC2 provided necessary current gain to drive the speaker. The POT R14 can be used control the gain of receiver. Capacitor C11 isolates audio frequencies and noise from the power supply of both the ICs.

Circuit diagram with Parts list.

Receiver:

Transmitter :

Notes.

• Assemble the circuit on a general purpose PCB.
• Terminal A must be connected to A’ using the wire of required length. Do the same with B, B’.
• The microphone M1 can be a general purpose one.
• The speaker k1 can be 8 Ohm/2 Watt.
• POT R2 can be used to control gain of the transmitter.
• POT R14 can be used to control gain of the receiver.
• The circuit can be powered from a 12V battery or 12V DC power supply.
• IC1 and IC2 must be mounted on holders.

Digital volume control circuit

A two channel digital volume control circuit based on IC MAX5486 is shown here. MAX5486 is a 40K dual digital volume / balance controller that has a pushbutton interface. The IC has a built in bias voltage source that eliminated the need of an external circuitry for the same purpose and thereby by reduces external parts count. The IC also has an LED status indicator driver circuit which can be used for driving the status indicator LEDs which indicates the volume level and balance level. The IC can be operated from a single or dual power supply and is available in 24 pin TSSOP package. The volume control circuit based on MAX5486 can be applied in a lot applications like personal audio systems, hand held audio devices, home theatre systems, car audio systems, computer audio systems etc.

Circuit description.

The right channel input is applied to the pin8 (high terminal (HR) of first internal digital potentiometer of the IC) and left channel input is applied to the pin17 (high terminal (HL) of the second internal digital potentiometer of the IC). Low terminals (pin 9 and 6) of the internal potentiometers are shorted and connected to the mid bias voltage output (pin11) of the IC. The right channel output is available at the buffered wiper terminal (pin10) of the first internal potentiometer and left channel output is available at the buffered wiper terminal of the second internal potentiometer of the IC. A 1uF capacitor is connected from the bias generator bypass (pin12) to ground. The purpose of this capacitor is noise bypassing. The purpose of capacitors C4 and C5 are to bypass noise from the VDD and VLOGIC sources. This improves the overall stability and performance of the circuit.

LEDs D1 to D5 are the status indicator LEDs which indicates the current volume and balance levels. R1 to R5 limits current through the corresponding LEDs. 1M resistor R6 is meant for activating the status indicator LED drivers. LED D6 represents the current operation mode of IC. When it glows, the IC is in balance control mode and when it is off, the IC will be in volume control mode. Resistor R7 limits the current through LED D6. In the volume control mode the status LEDs work just like a bar graph display indicating the current volume. In the balance control mode, the centremost LED alone glows when there is a centred balance. In the mute mode, all status indicator LEDs remain OFF.

Push button switches S1 to S4 are used for controlling the circuit. Pressing S1 will push the IC into mute mode. Push button S4 can be used for selecting between volume control mode and balance control mode and LED D6 indicated it. Push button S2 and S3 are used for increasing and decreasing the volume in the volume control mode and shifting the balance to left and right in the balance control mode. The Vss pin of the IC is grounded because single supply operation is employed in this circuit. Shutdown pin (pin6) is tied to the VLOGIC source for disabling the shutdown function. Connecting the shutdown pin to the ground will drive the IC to the shutdown mode.

The output of the MAX5486 is sufficient enough to drive standard high impedance headphones. For driving low impedance headphones or speakers an amplifier stage must be added to the output. The maximum power dissipation of MAX5486 is 675mW and consider this point while selecting the loads.

Notes.

• The circuit must be assembled on a good quality PCB.
• Use 5V DC for powering the circuit (both VLOGIC and VDD).
• The power supply must be well regulated and free from noise.
• Switches S1 to S4 are used for controlling the circuit.
• LED D1 to D5 are status indicators.
• An additional amplifier stage is required for driving low impedance loads.

Nanotechnology

There's an unprecedented multidisciplinary convergence of scientists dedicated to the study of a world so small, we can't see it -- even with a light microscope. That world is the field of nanotechnology, the realm of atoms and nanostructures. Nanotechnology i­s so new, no one is really sure what will come of it. Even so, predictions range from the ability to reproduce things like diamonds and food to the world being devoured by self-replicating nanorobots.
In order to understand the unusual world of nanotechnology, we need to get an idea of the units of measure involved. A centimeter is one-hundredth of a meter, a millimeter is one-thousandth of a meter, and a micrometer is one-millionth of a meter, but all of these are still huge compared to the nanoscale. A nanometer (nm) is one-billionth of a meter, smaller than the wavelength of visible light and a hundred-thousandth the width of a human hair [source: Berkeley Lab].

As small as a nanometer is, it's still large compared to the atomic scale. An atom has a diameter of about 0.1 nm. An atom's nucleus is much smaller -- about 0.00001 nm. Atoms are the building blocks for all matter in our universe. You and everything around you are made of atoms. Nature has perfected the science of manufacturing matter molecularly. For instance, our bodies are assembled in a specific manner from millions of living cells. Cells are nature's nanomachines. At the atomic scale, elements are at their most basic level. On the nanoscale, we can potentially put these atoms together to make almost anything.
In a lecture called "Small Wonders:The World of Nanoscience," Nobel Prize winner Dr. Horst Störmer said that the nanoscale is more interesting than the atomic scale because the nanoscale is the first point where we can assemble something -- it's not until we start putting atoms together that we can make anything useful.
In this article, we'll learn about what nanotechnology means today and what the future of nanotechnology may hold. We'll also look at the potential risks that come with working at the nanoscale.