Tamper Proof and Self Destructing USB Memory Stick

Victorinox, the family company behind the famed Swiss Army Knife, has launched a pioneering memory stick design at an event held at its European flagship store on London’s

New Bond Street

.

The device is, says the company, the most secure of its kind available to the public. It uses several layers of security including fingerprint identification and a thermal sensor — so that the finger alone, detached from the body, will still not give access to the memory stick’s contents. The Victorinox Secure has also been made tamper-proof. Any attempt to forcibly open it triggers a self-destruct mechanism that irrevocably burns its CPU and memory chip.

Victorinox says it is so confident of its new product’s elite security standards that it offered a £100,000 prize to a team of professional hackers if they could break into it during the two hours the launch event lasted. The money went uncollected.

A new version of the device, which will employ e-paper to give users a read-out of its contents, is already in the pipeline. Victorinox say they wanted to create not only a product for today’s modern lifestyle but a new generation of memory stick that had all the values of functionality and reliability that the iconic Swiss Army Knife has come to represent.

3-D Shapes Covered in Solar Cells Beat Flat Panels

Flat solar photovoltaic panels are becoming more widespread, but the power they produce varies over the course of the day as the sun’s position changes — unless the panels are mounted on tracking systems to keep them pointed sunward, which adds complexity and expense.

Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering at MIT’s Department of Materials Science and Engineering, was inspired by the way trees spread their leaves to capture sunlight and wondered if a three-dimensional shape covered in solar cells would be more efficient than a flat panel. He worked with a UROP student, Marco Bernardi, to create a computer program that starts with basic shapes and lets them evolve, changing slightly each time and selecting those that perform best to start the next generation, he found that such systems could produce relatively constant power throughout the day without the need for tracking, and produce significantly more power overall — up to two and a half times as much as a flat array. He is continuing to work on finding the best shapes and building a prototype system, and figures that solar panels based on this concept could be shipped flat and then unfolded at the site to their complex shapes.

The images in the slide show produced by Jeffry Crossman and Bryan Myers for MIT visualize some of the varied shapes with improved efficiency that emerged from the evolving simulation.

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50-MHz Function Generator Sets New Price/Performance milestone

The TG5011 function generatorfrom TTi is a combined function, arbitrary waveform and pulse generator with a frequency range of 1 µHz to 50 MHz. Priced at around £900, it is claimed to offer a better price/performance ratio than competitive products with bandwidths of only 20 or 25 MHz. The TG5011 produces high-purity sine waves with low harmonic distortion and low phase noise over the full frequency range. Square-wave rise time is less than 8 ns with low overshoot for good waveform shape right up to 50 MHz.

The output frequency can be set with up to 14 digit resolution and is derived from a TCXO timebase oscillator with a stability of 1 ppm. The high resolution of the direct digital synthesizer (DDS) also allows the instrument to generate very low frequencies. For example, a frequency of 1 mHz can be set with a resolution of 0.1% and a stability of 1 ppm. The TG5011 also has a pulse generator mode with the pulse width adjustable over a wide range and pulse delay independent of period. The pulse period setting range is 2000 seconds to 80 ns (0.5 mHz to 12.5 MHz), and the duty cycle can be as low as 1 in 2 billion. The rise and fall times (edge speeds) are also independently variable over a wide range.

Arbitrary waveforms of up to 128k words can be generated with 14-bit vertical resolution and a sampling rate of 125 MS/s. A front-panel USB port enables external flash memory storage of up to 1000 waveforms. This also provides a quick and convenient method for transferring waveform files to and from a PC. Commonly used complex waveforms are provided, including sin(x)/x, exponential rise and fall, logarithmic rise and fall, Gaussian, Lorentz, haversine and cardiac waveforms. The generator comes with Waveform Manager Plus for Windows to allow complex waveform files to be created on a PC.

The TG5011 provides a comprehensive set of digital modulation modes including AM, FM, PM, PWM and FSK. The modulation source can be any standard or arbitrary waveform, or any external signal applied to the modulation input. A wideband noise generator produces Gaussian white noise with a high crest factor and a bandwidth of 20 MHz. Noise can be added to any waveform or used as a modulating source.

Six Rotors -- Happy Landings with the HexaKopter!

Quadrokopters — 4-rotor remote controlled helicopter drones may be familiar to many Elektor readers. Typically, the direction of these aircraft is controlled by slight tilt as a result of individual rotor blade speed variations, the principle just begging to be implemented in state of the art electronics. That’s not a trivial matter though and you’ll soon find that communication with people having “been there and done that” is extremely useful if not an absolute necessity to get anything off the ground.

Holger Buss and Ingo Busker are experts in the field. On their mikrokopter.de website they provide construction guides, many links to existing quadrocopter projects, tips and tricks and tonnes more. Mechanical and electronic parts as well as kits are available through an online store.

The latest gizmo on the mikrokopter.de website is a hexacopter with six rotors. The agility of this drone is demonstrated in a number of impressive videos.

3-D Shapes Covered in Solar Cells Beat Flat Panels

Flat solar photovoltaic panels are becoming more widespread, but the power they produce varies over the course of the day as the sun’s position changes — unless the panels are mounted on tracking systems to keep them pointed sunward, which adds complexity and expense.

Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering at MIT’s Department of Materials Science and Engineering, was inspired by the way trees spread their leaves to capture sunlight and wondered if a three-dimensional shape covered in solar cells would be more efficient than a flat panel. He worked with a UROP student, Marco Bernardi, to create a computer program that starts with basic shapes and lets them evolve, changing slightly each time and selecting those that perform best to start the next generation, he found that such systems could produce relatively constant power throughout the day without the need for tracking, and produce significantly more power overall — up to two and a half times as much as a flat array. He is continuing to work on finding the best shapes and building a prototype system, and figures that solar panels based on this concept could be shipped flat and then unfolded at the site to their complex shapes.

Modified Virus Splits Water

A team of MIT researchers has found a novel way to mimic the process by which plants use the power of sunlight to split water and make chemical fuel to power their growth. In this case, the team used a modified virus as a kind of biological scaffold that can assemble the nanoscale components needed to split a water molecule into hydrogen and oxygen atoms.

Splitting water is one way to solve the basic problem of solar energy: It’s only available when the sun shines. By using sunlight to make hydrogen from water, the hydrogen can then be stored and used at any time to generate electricity using a fuel cell, or to make liquid fuels (or be used directly) for cars and trucks.

Other researchers have made systems that use electricity, which can be provided by solar panels, to split water molecules, but the new biologically based system skips the intermediate steps and uses sunlight to power the reaction directly. The advance is described in a paper published on April 11 in Nature Nanotechnology.

The team, led by Angela Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering, engineered a common, harmless bacterial virus called M13 so that it would attract and bind with molecules of a catalyst (the team used iridium oxide) and a biological pigment (zinc porphyrins). The viruses became wire-like devices that could very efficiently split the oxygen from water molecules.

Over time, however, the virus-wires would clump together and lose their effectiveness, so the researchers added an extra step: encapsulating them in a microgel matrix, so they maintained their uniform arrangement and kept their stability and efficiency.

While hydrogen obtained from water is the gas that would be used as a fuel, the splitting of oxygen from water is the more technically challenging “half-reaction” in the process, Belcher explains, so her team focused on this part. Plants and cyanobacteria (also called blue-green algae), she says, “have evolved highly organized photosynthetic systems for the efficient oxidation of water.” Other researchers have tried to use the photosynthetic parts of plants directly for harnessing sunlight, but these materials can have structural stability issues.

Using the virus to make the system assemble itself is claimed to improve the efficiency of the oxygen production fourfold. The researchers hope to find a similar biologically based system to perform the other half of the process, the production of hydrogen. Currently, the hydrogen atoms from the water get split into their component protons and electrons; a second part of the system, now being developed, would combine these back into hydrogen atoms and molecules. The team is also working to find a more commonplace, less-expensive material for the catalyst, to replace the relatively rare and costly iridium used in this proof-of-concept study.


Source: “Biologically templated photocatalytic nanostructures for sustained light-driven water oxidation” Yoon Sung Nam, Andrew P. Magyar, Daeyeon Lee, Jin-Woong Kim, Dong Soo Yun, Heechul Park, Thomas S. Pollom Jr, David A. Weitz and Angela M. Belcher. Nature Nanotechnology, April 11, 2010.

Motion detector

A motion detector is a device that contains a physical mechanism or electronic sensor that quantifies motionthat can be either integrated with or connected to other devices that alert the user of the presence of a moving object within the field of view. They form a vital component of comprehensive security systems, for both homes and businesses.

Overview

An electronic motion detector contains a motion sensor that transforms the detection of motion into an electric signal. This can be achieved by measuring optical or acoustical changes in the field of view. Most motion detectors can detect up to50-80 feet.

A motion detector may be connected to a burglar alarm that is used to alert the home owner or security service after it detects motion. Such a detector may also trigger a red light camera.

An occupancy sensor is a motion detector that is integrated with a timing device. It senses when motion has stopped for a specified time period in order to trigger a light extinguishing signal. These devices prevent illumination of unoccupied spaces like public toilets.

There are basically three types of sensors used in motion detectors spectrum:

Passive infrared sensors (PIR)

Looks for body heat. No energy is emitted from the sensor.

Ultrasonic (active)

Sensor sends out pulses and measures the reflection off a moving object.

Microwave (active)

Sensor sends out microwave pulses and measures the reflection off a moving object. Similar to a police radar gun.

How a Photocopier Works

A Photocopier

A photocopier (or copier) is a machine that makes paper copies of documents and other visual images quickly and cheaply. Most current photocopiers use a technology called xerography, a dry process using heat. (Copiers can also use other output technologies such as ink jet, but xerography is standard for office copying.)

Xerographic office photocopying was introduced by Xerox in 1949,^[1] and it gradually replaced copies made by Verifax, Photostat, carbon paper, mimeograph machines, and other duplicating machines. The prevalence of its use is one of the factors that prevented the development of the paperless office heralded early in the digital revolution.

Photocopying is widely used in business, education, and government. There have been many predictions that photocopiers will eventually become obsolete as information workers continue to increase their digital document creation and distribution, and rely less on distributing actual pieces of paper.

How a photocopier works

1. Charging: cylindrical drum is electrostatically charged by a high voltage wire called a corona wire or a charge roller. The drum has a coating of a photoconductive material. A photoconductor is a semiconductor that becomes conductive when exposed to light.^[2]
2. Exposure: A bright lamp illuminates the original document, and the white areas of the original document reflect the light onto the surface of the photoconductive drum. The areas of the drum that are exposed to light become conductive and therefore discharge to ground. The area of the drum not exposed to light (those areas that correspond to black portions of the original document) remain negatively charged. The result is a latent electrical image on the surface of the drum.
3. Developing: The toner is positively charged. When it is applied to the drum to develop the image, it is attracted and sticks to the areas that are negatively charged (black areas), just as paper sticks to a toy balloon with a static charge.
4. Transfer: The resulting toner image on the surface of the drum is transferred from the drum onto a piece of paper with a higher negative charge than the drum.
5. Fusing: The toner is melted and bonded to the paper by heat and pressure rollers.

This example is of a negatively charged drum and paper, and positively charged toner as is common in today's digital copiers. Some copiers, mostly older analog copiers, employ a positively charged drum and paper, and negatively charged toner.

How OLEDs Work

Imagine having a high-definition TV that is 80 inches wide and less than a quarter-inch thick, consumes less power than most TVs on the market today and can be rolled up when you're not using it. What if you could have a "heads up" display in your car? How about a display monitor built into your clothing? These devices may be possible in the near future with the help of a technology called organic light-emitting diodes (OLEDs).

OLEDs are solid-state devices composed of thin films of organic molecules that create light with the application of electricity. OLEDs can provide brighter, crisper displays on electronic devices and use less power than conventional light-emitting diodes (LEDs) or liquid crystal displays (LCDs) used today.

What is the Difference Between Two- and Three-Pronged Plugs?

Let's start with what the holes in an outlet do. When you look at a normal 120-volt outlet in the United States, there are two vertical slots and then a round hole centered below them. The left slot is slightly larger than the right. The left slot is called "neutral," the right slot is called "hot" and the hole below them is called "ground." The prongs on a plug fit into these slots in the outlet.

If you have read How Batteries Work, you know that electricity must flow in a circuit. In a battery, electricity flows from one terminal of the battery to the other. In a house outlet, power flows from hot to neutral. The appliance you plug into an outlet completes the circuit from the hot slot to the neutral slot, and electricity flows through the appliance to run a motor, heat some coils or whatever. Let's say you plug a light bulb into the outlet. The power will flow from the hot prong, through the filament and back to the neutral prong, creating light in the process.

What if you were to plug a thick strand of wire straight from the hot slot to the neutral slot of an outlet? Unlike an appliance, which limits the amount of electricity that can flow to 60 watts (for a light bulb) or 500 watts (for a toaster), the wire would let an incredible amount of electricity flow through it. Back in the fuse box, the fuse or circuit breaker for the outlet would detect this huge surge and it would cut off the flow of electricity. The fuse prevents the wires in the wall or the outlet itself from overheating and starting a fire.

The ground slot and the neutral slot of an outlet are identical. That is, if you go back to the fuse box, you will find that the neutral and ground wires from all of the outlets go to the same place. They all connect to ground (see How Power Distribution Grids Work for details on grounding). Since they both go to the same place, why do you need both?

If you look around your house, what you will find is that just about every appliance with a metal case has a three-prong outlet. This may also include some things, like your computer, that have a metal-encased power supply inside even if the device itself comes in a plastic case. The idea behind grounding is to protect the people who use metal-encased appliances from electric shock. The casing is connected directly to the ground prong.

Let's say that a wire comes loose inside an ungrounded metal case, and the loose wire touches the metal case. If the loose wire is hot, then the metal case is now hot, and anyone who touches it will get a potentially fatal shock. With the case grounded, the electricity from the hot wire flows straight to ground, and this trips the fuse in the fuse box. Now the appliance won't work, but it won't kill you either.

What happens if you cut off the ground prong or use a cheater plug so you can plug a three-prong appliance into a two-prong outlet? Nothing really -- the appliance will still operate. What you have done, however, is disable an important safety feature that protects you from electric shock if a wire comes loose.

How Transistors Work

If cells are the building blocks of life, transistors are the building blocks of the digital revolution. Without transistors, the technological wonders you use every day -- cell phones, computers, cars -- would be vastly different, if they existed at all.

Before transistors, product engineers used vacuum tubes and electromechanical switches to complete electrical circuits. Tubes were far from ideal. They had to warm up before they worked (and sometimes overheated when they did), they were unreliable and bulky and they used too much energy. Everything from televisions, to telephone systems, to early computers used these components, but in the years after World War II, scientists were looking for alternatives to vacuum tubes. They'd soon find their answer from work done decades earlier.

In the late 1920's, Polish American physicist Julius Lilienfeld filed patents for a three-electrode device made from copper sulfide. There's no evidence that he actually created the component, but his research helped develop what today is a field effect transistor, the building block of silicon chips.

Twenty years after Lilienfeld filed his patents, scientists were trying to put his ideas to practical use. The Bell Telephone System, in particular, needed something better than vacuum tubes to keep its communications systems working. The company assembled what amounted to an all-star team of scientific minds, including John Bardeen, Walter Brattain and William Shockley, and put them to work researching vacuum tube substitutes.

In 1947, Shockley was director of transistor research at Bell Telephone Labs. Brattain was an authority on solid-state physics as well as expert on nature of atomic structure of solids and Bardeen was an electrical engineer and physicist. Within a year, Bardeen and Brittain used the element germanium to create an amplifying circuit, also called a point-contact transistor. Soon afterward, Shockley improved on their idea by developing a junction transistor.

The next year, Bell Labs announced to the world that it had invented working transistors. The original patent name for the first transistor went by this description: Semiconductor amplifier; three-electrode circuit element utilizing semi conductive materials. It was an innocuous-sounding phrase. But this invention netted the Bell team the 1956 Nobel Prize for Physics, and allowed scientists and product engineers far greater control over the flow of electricity.

It's no exaggeration that transistors have enabled some of humankind's biggest leaps in technology. Keep reading to see exactly how transistors work, how they altered the course of technology, and in the process, human history, too.

How Semiconductors Work

Semiconductors have had a monumental impact on our society. You find semiconductors at the heart of microprocessor chips as well as transistors. Anything that's computerized or uses radio waves depends on semiconductors.

Today, most semiconductor chips and transistors are created with silicon. You may have heard expressions like "Silicon Valley" and the "silicon economy," and that's why -- silicon is the heart of any electronic device.

A diode is the simplest possible semiconductor device, and is therefore an excellent beginning point if you want to understand how semiconductors work. In this article, you'll learn what a semiconductor is, how doping works and how a diode can be created using semiconductors. But first, let's take a close look at silicon.

Silicon is a very common element -- for example, it is the main element in sand and quartz. If you look "silicon" up in the periodic table, you will find that it sits next to aluminum, below carbon and above germanium.

Silicon sits next to aluminum and below carbon in the periodic table.

Carbon, silicon and germanium (germanium, like silicon, is also a semiconductor) have a unique property in their electron structure -- each has four electrons in its outer orbital. This allows them to form nice crystals. The four electrons form perfect covalent bonds with four neighboring atoms, creating a lattice. In carbon, we know the crystalline form as diamond. In silicon, the crystalline form is a silvery, metallic-looking substance.

In a silicon lattice, all silicon atoms bond perfectly to four neighbors, leaving no free electrons to conduct electric current. This makes a silicon crystal an insulator rather than a conductor.

Metals tend to be good conductors of electricity because they usually have "free electrons" that can move easily between atoms, and electricity involves the flow of electrons. While silicon crystals look metallic, they are not, in fact, metals. All of the outer electrons in a silicon crystal are involved in perfect covalent bonds, so they can't move around. A pure silicon crystal is nearly an insulator -- very little electricity will flow through it. But you can change all this through a process called doping.

How Circuit Breakers Work

The circuit breaker is an absolutely essential device in the modern world, and one of the most important safety mechanisms in your home. Whenever electrical wiring in a building has too much current flowing through it, these simple machines cut the power until somebody can fix the problem. Without circuit breakers (or the alternative, fuses), household electricity would be impractical because of the potential for fires and other mayhem resulting from simple wiring problems and equipment failures.

In this article, we'll find out how circuit breakers and fuses monitor electrical current and how they cut off the power when current levels get too high. As we'll see, the circuit breaker is an incredibly simple solution to a potentially deadly problem.

To understand circuit breakers, it helps to know how household electricity works.

Electricity is defined by three major attributes:

• Voltage
• Current
• Resistance

Voltage is the "pressure" that makes an electric charge move. Current is the charge's "flow" -- the rate at which the charge moves through the conductor, measured at any particular point. The conductor offers a certain amount of resistance to this flow, which varies depending on the conductor's composition and size.

­Voltage, current and resistance are all interrelated -- you can't change one without changing another. Current is equal to voltage divided by resistance (commonly written as I = v / r). This makes intuitive sense: If you increase the pressure working on electric charge or decrease the resistance, more charge will flow. If you decrease pressure or increase resistance, less charge will flow.

How Electric Motors Work

Electric motors are everywhere! In your house, almost every mechanical movement that you see around you is caused by an AC (alternating current) or DC (direct current) electric motor.

A simple motor has six parts:

• Armature or rotor
• Commutator
• Brushes
• Axle
• Field magnet
• DC power supply of some sort

The armature of a typical DC motor

The armature contains an electromagnet. When you run electricity into this electromagnet, it creates a magnetic field in the armature that attracts and repels the magnets in the stator. So the armature spins through 180 degrees. To keep it spinning, you have to change the poles of the electromagnet. The brushes handle this change in polarity. They make contact with two spinning electrodes attached to the armature and flip the magnetic polarity of the electromagnet as it spins.

This setup works and is simple and cheap to manufacture, but it has a lot of problems:

• The brushes eventually wear out.
• Because the brushes are making/breaking connections, you get sparking and electrical noise.
• The brushes limit the maximum speed of the motor.
• Having the electromagnet in the center of the motor makes it harder to cool.
• The use of brushes puts a limit on how many poles the armature can have.

With the advent of cheap computers and power transistors, it became possible to "turn the motor inside out" and eliminate the brushes. In a brushless DC motor (BLDC), you put the permanent magnets on the rotor and you move the electromagnets to the stator. Then you use a computer (connected to high-power transistors) to charge up the electromagnets as the shaft turns. This system has all sorts of advantages:

Inside a Cell Phone

If you ever take a cell phone apart you will find that it contains just a few individual parts:

• A microscopic microphone
  
  Read Cell Phone Reviews and compare prices at Consumer Guide Products before you buy.­
• A speaker
• An LCD or plasma display
• A keyboard not unlike the one we saw in a TV remote control
• An antenna
• A battery
• An amazing circuit board containing the guts of the phone

The circuit board is the heart of the system. Here is one from a typical Ericsson cell phone:

In this picture several of the components are identified. Starting from the left you the see the Analog-to-Digital and Digital-to-Analog conversion chips. You can learn more about A-to-D and D-to-A conversion and its importance to digital audio in How CDs Work. The DSP is a "Digital Signal Processor" -- a highly customized processor designed to perform signal manipulation calculations at high speed. This DSP is rated at about 40 MIPS (Millions of Instructions per Second) and handles all the signal compression and decompression. The microprocessor (Ericsson phones use an ASIC version of the Z-80) and memory handle all of the housekeeping chores for the keyboard and display, deal with command and control signaling with the base station and also coordinate the rest of the functions on the board. The RF and power section handles power management and recharging and also deals with the hundreds of FM channels. Finally the RF (Radio Frequency) amplifiers handle signals in and out of the antenna.

What is amazing is that all of that functionality -- which only 30 years ago would have filled the entire floor of an office building -- now fits into a package that sits comfortably in the palm of your hand.

Light Emitting Diodes

commonly called LEDs, are real unsung heroes in the electronics world. They do dozens of different jobs and are found in all kinds of devices. Among other things, they form the numbers on digital clocks, transmit information from remote controls, light up watches and tell you when your appliances are turned on. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.

Basically, LEDs are just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor.

CAR ENGINE

Have you ever opened the hood of your car and wondered what was going on in there? A car engine can look like a big confusing jumble of metal, tubes and wires to the uninitiated.

You might want to know what's going on simply out of curiosity. Or perhaps you are buying a new car, and you hear things like "3.0 liter V-6" and "dual overhead cams" and "tuned port fuel injection." What does all ­of that mean?

­­In this article, we'll discuss the basic idea behind an engine a­nd then go into detail about how all the pieces fit together, what can go wrong and how to increase performance.

The purpose of a gasoline car engine is to convert gasoline into motion so that your car can move. Currently the easiest way to create motion from gasoline is to burn the gasoline inside an engine. Therefore, a car engine is an internal combustion engine -- combustion takes place internally.

Two things to note:

• There are different kinds of internal combustion engines. Diesel engines are one form and gas turbine engines are another. See also the articles on HEMI engines, rotary engines and two-stroke engines. Each has its own advantages and disadvantages.

• There is such a thing as an external combustion engine. A steam engine in old-fashioned trains and steam boats is the best example of an external combustion engine. The fuel (coal, wood, oil, whatever) in a steam engine burns outside the engine to create steam, and the steam creates motion inside the engine. Internal combustion is a lot more efficient (takes less fuel per mile) than external combustion, plus an internal combustion engine is a lot smaller than an equivalent external combustion engine. This explains why we don't see any cars from Ford and GM using steam engines.

Ultrasonic Parking Sonar

This circuit electronic is an ultrasonic parking sonar. Based on an ultrasonic amplifier from an article seen on a 1982 magazine, it was once installed on the rear bumper of my Volvo Station Wagon. It served very well for many years. Connecting it to the reverse gear lights, it switches on automatically and shows you the distance to the nearest obstacle (according to his beam) on a led scale. When the last led lights, a buzzer is also activated telling you to stop

Feautures:

* automatic switch on on rear gear

* led-bargraph display

* audible bleep on last led

* "good old" design style, no microcontrollers!









It works on the sonar principle, sending an ultrasound burst and listening for first echo. The burst generated by the oscillator built around U4D (you must set the frequency using TR2 to have 40 kHz or the maximum sensitivity), U4E buffers the output and U4F boost the signal doubling the voltage span across the TX piezo transducer .

Infrared Gate Sensor

Circuit is Infrared gate sensor. It's an infrared gate with two sensors planned to use in the wall in the way behind a door. It can be applied in a toilet to keep track of that someone is inside exceeding a certain amount of time. After that time elapsed, the circuit triggers the digital output wich can turn on a ventillator. The time period the output is turned on can be separately controlled by a second timer.

If you plan to build this gate sensor circuit, beware that you may have lots of difficulties though the schematic may seem simple. The construction of the circuit requires some amount of equipment like an oscilloscope and a DVM, too. Without them, the device will do weird things you wouldn't expect, and even if it is correctly put together, you must adjust it with care both mechanically in its final place and electronically with the help of an oscilloscope. Only if you want to span about less than 20-30 inches with the infra diodes can forget about this calibration. Alternatively you can take ideas from this construction.

Rain Alarm Using Water Sensor

Rain alarm is a simple circuit using water sensor (transducer) that produces an audible alarm whenever rain falls. The circuit can be based on two transistors and or a NE555 IC.

The two transistors are wired as a switch which goes on when the base of Q1 is shorted to the positive of the supply by the rainwater falling on the sensor. When the transistors are ON power supply is available to the IC1 which is wired as an astable multivibrator .The out put of IC1 drives the speaker to produce a alarm.
A 555 astable multivibrator is used here which gives a tone of about 1 KHz upon detecting water. The sensor when wetted by water completes the circuit and makes the 555 oscillate at about 1kHz.
Water Sensor (Transducer)-Rain Sensing Grid Schematic

It has to placed making an angle of about 30 - 45 degrees to the ground. This makes the rain water to flow through it to the ground and prevents the alarm from going on due to the stored water on the sensor.

The metal used to make the sensor has to be aluminium and not copper. This is because copper forms a blue oxide on its layer on prolonged exposure to moisture and has to be cleaned regularly.

The aluminium foils may be secured to the wooden / plastic board via epoxy adhesive or small screws.
The contact X and Y from the sensor may be obtained by small crocodile clips or you may use screws.

Fire Alarm Using NE555

Here's a fire alarm circuit using LDR (Light Depending Resistor) as light sensor. It warns the user against fire accidents. It relies on the smoke that is produced in the event of a fire. When this smoke passes between a LED and an LDR, the amount of light falling on the LDR decreases. This causes the resistance of LDR to increase and the voltage at the base of the transistor is pulled high due to which the supply to NE555 then activated the alarm.

The thermistor offers a low resistance at high temperature and high resistance at low temperature. This phenomenon is employed here for sensing the fire.

The IC1 (NE555) is configured as a free running oscillator at audio frequency. The transistors T1 and T2 drive IC1. The output (pin 3) of IC1 is couples to base of transistor T3 (SL100), which drives the speaker to generate alarm sound. The frequency of NE555 depends on the values of resistances R5 and R6 and capacitance C2.When thermistor becomes hot, it gives a low-resistance path for the positive voltage to the base of transistor T1 through diode D1 and resistance R2.

Capacitor C1 charges up to the positive supply voltage and increases the the time for which the alarm is ON. The larger the value of C1, the larger the positive bias applied to the base of transistor T1 (BC548). As the collector of T1 is coupled to the base of transistor T2, the transistor T2 provides a positive voltage to pin 4 (reset) of IC1 (NE555). Resistor R4 is selected s0 that NE555 keeps inactive in the absence of the positive voltage. Diode D1 stops discharging of capacitor C1 when the thermistor is in connection with the positive supply voltage cools out and provides a high resistance path. It also inhibits the forward biasing of transistor T1.

Mutual Inductance

If two coils of wire are brought into close proximity with each other so the magnetic field from one links with the other, a voltage will be generated in the second coil as a result. This is called mutual inductance: when voltage impressed upon one coil induces a voltage in another.

A device specifically designed to produce the effect of mutual inductance between two or more coils is called a transformer.
The device shown in the above photograph is a kind of transformer, with two concentric wire coils. It is actually intended as a precision standard unit for mutual inductance, but for the purposes of illustrating what the essence of a transformer is, it will suffice. The two wire coils can be distinguished from each other by color: the bulk of the tube's length is wrapped in green-insulated wire (the first coil) while the second coil (wire with bronze-colored insulation) stands in the middle of the tube's length. The wire ends run down to connection terminals at the bottom of the unit. Most transformer units are not built with their wire coils exposed like this.

Because magnetically-induced voltage only happens when the magnetic field flux is changing in strength relative to the wire, mutual inductance between two coils can only happen with alternating (changing -- AC) voltage, and not with direct (steady -- DC) voltage. The only applications for mutual inductance in a DC system is where some means is available to switch power on and off to the coil (thus creating a pulsing DC voltage), the induced voltage peaking at every pulse.

A very useful property of transformers is the ability to transform voltage and current levels according to a simple ratio, determined by the ratio of input and output coil turns. If the energized coil of a transformer is energized by an AC voltage, the amount of AC voltage induced in the unpowered coil will be equal to the input voltage multiplied by the ratio of output to input wire turns in the coils. Conversely, the current through the windings of the output coil compared to the input coil will follow the opposite ratio: if the voltage is increased from input coil to output coil, the current will be decreased by the same proportion. This action of the transformer is analogous to that of mechanical gear, belt sheave, or chain sprocket ratios:

A transformer designed to output more voltage than it takes in across the input coil is called a "step-up" transformer, while one designed to do the opposite is called a "step-down," in reference to the transformation of voltage that takes place. The current through each respective coil, of course, follows the exact opposite proportion.

Compact Fluorescent Light Bulbs

If you want to change the world, start by changing a few light bulbs. It is one of the best things you can do for the environment—and your budget.

According to the Union of Concerned Scientists, if every U.S. household replaced just one regular incandescent light bulb with a compact fluorescent light bulb, it would prevent 90 billion pounds of greenhouse gas emissions from power plants, the equivalent of taking 7.5 million cars off the road. And the U.S. Environmental Protection Agency says that by replacing regular light bulbs with compact fluorescent light bulbs at the same minimal rate, Americans would save enough energy to light more than 2.5 million homes for a year.

How Much Can You Save by Using Compact Fluorescent Light Bulbs?

For most people, switching from incandescent to compact fluorescent bulbs offers a lot of opportunity for energy and cost savings. Lighting accounts for 20 percent of the electric bill in the average U.S. home, and the average home has approximately 30 light fixtures. (Calculate your personal energy and cost savings with this handy online calculator, and find out how much you will be helping the environment.)

To save the most energy and money by using compact fluorescent light bulbs, the U.S. Environmental Protection Agency recommends replacing standard bulbs in areas where lights are used frequently and left on for a long time, such as family rooms, living rooms, kitchens, dining rooms, and porches.

Solid State Tesla Coil Circuit

An advantage of the primary feed method is that it provides the necessary voltage transformation required to match the output impedance of the inverter to the resonator. This negates the need to employ a separate high frequency matching transformer or the use of elevated supply rails to get the required drive voltage.

A significant disadvantage of the primary feed method is that very tight coupling is required (k>0.35) in order to get good power transfer. This makes insulating the primary from the secondary somewhat challenging as the power level is increased.
The drive electronics is based around the TL494 PWM controller IC made by Texas Instruments. This IC is fairly "long in the tooth" but it is well behaved and is also easy to obtain. The IC contains an internal sawtooth generator and the necessary comparators and latches to produce the drive signals required for each MOSFET in the half bridge. The IC generates two complementary drive signals with a short dead time between transitions to ensure that one MOSFET has had time to turn off before the opposing device is turned on. Without this precaution the conduction times of both devices can overlap shorting the mains supply with interesting (read expensive,) consequences.
Full wave rectification,
This was achieved by using a full wave bridge rectifier between the mains line and the MOSFET bridge. This ensures that there is current flowing through the inverter during the entire supply cycle. The power drawn from the mains line roughly doubled as expected and the RF envelope assumed the classic full-wave rectified shape. This implies a considerable increase in the average RF energy applied to the TC.

Spark appearance:

Sparks became noticeably fatter and more bushy, but there was no increase in length. The picture opposite clearly shows the greater "fullness" of the discharge including wispy branches leading off from the main feature.

The tone of the sound changed to twice the pitch (100Hz) and became distinctly more "full-throated" and hissy.
Power is estimated to be around 300 watts.
These two pictures show the ability of the coil to produce a lot of corona from points. Notice how the discharge often divides into two jets of corona right at the breakout points.

Average RF power

Unlike a conventional damped-wave Tesla Coil, the solid state Tesla coil is capable of producing considerable amounts of sustained RF power. This leads to a few unusual things:

Firstly, the base of the secondary became very hot due to the high RMS current flowing through the fine wire. Maybe skin effect plays some part in this also. This is particularly noticeable if the system is run in CW mode for any length of time.
There is visibly more current in ground strikes than found with my spark gap TC.

Sparks to ground appear like pale ghostly white flames and arch upwards with the heat like the arc from a Jacobs Ladder. Anything flammable catches fire instantly in the arc.
I noticed that I got tiny RF burns if I touched anything metallic in the vicinity of the running coil even at fairly low power levels.

At one time I forgot to put the breakout point on the solid state coil, and an unused resonator about 2 feet from the solid state coil, (but quite close to me,) sprang to life with a firey crown of corona. Boy did that surprise me !!!

The 1381-based solar engine

The 1381 solar engine uses a 1381* voltage detector (a.k.a., a voltage supervisor) IC to drive a voltage-based (type 1) solar engine. The 1381 is normally used to reset CPUs and Micros when the power supply drops too low for reliable operation. So 1381s detect and switch when the input voltage crosses the rated upper and lower threshold voltages. The upper- and lower-switching voltages are slightly overlapped so that the turn-on voltage is a few hundred mV above the turn-off voltage. This hysteresis keeps input noise (around the switching threshold) from resulting in multiple output cycles as the transition occurs.

The 1381 SE is designed to increase the 1381 hysteresis from 0.2 - 0.3 V to a much larger value (2 - 4.6 V). This is done by essentially dropping the turn-off voltage to zero, while allowing SE to "fire" at the 1381's rated turn-on voltage.


How it Works

As the solar cell charges the (4700 uF) storage capacitor, the voltage across the capacitor increases with time. Eventually it reaches the 1381's trip point, and the 1381 applies voltage to the base of the 2N3904. Since this is an NPN transistor, it "trips" and applies current to the motor. Meanwhile, it has brought the base of the 2N3906 "low," which causes it to conduct to the 2N3904's base as well (so at this point, the 1381 is essentially out of the circuit). This state of affairs will continue until the capacitor is fully drained, at which point the 2N3906 and 2N3904 both go "quiescent," and the solar cell resumes charging the capacitor

LG-KP4000 pushes Qualcomm chip for advanced features

While Semiconductor Insights is currently analyzing the MSM6800, it's important to look at devices that have successfully been adopted in consumer products. The Qualcomm MSM6100 is an efficient, feature-rich part that's driven by several powerful processing cores ((Fig. 2). An ARM926EJ-S and two QDSP4000 DSPs provide considerable processing ability and are supported by a large amount SRAM and ROM. By using a stacked-die approach, Qualcomm elected to use the smaller secondary die for analog circuitry while concentrating on the efficient placement of digital circuitry on the larger main die. In the KP4000 specifically, the MSM6100 connects to Elpida TY8000B410BMGF mobile RAM and a 1-Gbit Toshiba NAND flash memory.

To operate both the transmit and receive portions of the handset, LG chose to continue the use of Qualcomm devices with the RFT6100 and RFR6000. It's typically not a difficult decision to remain with the same vendor for various inter-related components for a few reasons. First, it's often possible to get better pricing when you're purchasing multiple components. Second, the parts are all designed to work together, so reference designs will be available, reducing the handset's time to market. As well, the components can be optimized, typically resulting in a smaller form factor. This also includes enhancing the functionality without difficulty, such as GPS location. Finally, support will be easier, as one call should be sufficient to find an applications engineer familiar with all of the associated components.

Wireless IMU - transmits sensor data via Bluetooth

The Wireless Inertial Measurement Unit transmits sensor data via the Bluetooth protocol. It also features a 2.5 hour battery life on one 9V battery, 100+ foot range, temperature compensation for bias and sensitivity, and alignment correction. The Wireless IMU Series of products provide untethered serial digital outputs of 3D acceleration, 3D angular rate of rotation, and 3D magnetic field via the Bluetooth protocol in a miniature 1.685 x 2.135 x 0.437 in. package. Powered by an external 9V battery, custom algorithms provide temperature, alignment, and cross-axis sensitivity (alignment) compensation. With wireless Bluetooth capability the IMU can communicate with a wide variety of hosts from standard PC’s to handheld PDAs to embedded systems.

Each unit ships with a 9V battery and data acquisition software (IMU Data Console) for easy setup and data collection. Rechargeable battery and charger are also available separately. Please select from the following 'Standard' device ranges:

The Wireless IMU incorporates a wireless serial port module with a unique Bluetooth address. The address can be found by a host system thru a discovery. Pairing with the Wireless IMU is not required, however if desired, the passkey(PIN) is ‘1111’.

uIMU - High performance 3D digital output sensor

High performance 3D digital output sensor featuring RS422 protocol with a minimal weight of 95 grams. Temperature compensated IMU with a robust housing ideal for rugged and military environments. Also available with an additional High G triaxial accelerometer. The rugged 6DOF Micro IMU (µIMU) provides serial digital outputs of 3D acceleration, 3D angular rate (rotational), and 3D magnetic field data in a ruggedized aluminum housing. Digital outputs are factory configured to the RS422 protocols and custom algorithms provide 3D real-time data corrected for both cross-axis sensitivity and temperature. The µIMU is available in both military (-40 to +85C) and commercial (0 to +70C) temperature ranges, and is also available with optional triaxial hi-g accelerometer in 35g and 50g ranges.

The uIMU ships with a USB data acquisition (DAQ) module and open-source software (IMU Data Console) for easy setup and data collection.