Monthly Archives: August 2013

Variation of Capacitance of Ceramic Capacitors with Voltage and Temperature

The ceramic capacitors that you work with in the lab have two or more alternating layers of a metal acting as the electrodes and a ceramic acting as the dielectric. The capacitance measured in farad represents the charge stored in a capacitor at a particular applied voltage. The quantity should be a constant for a particular capacitor at all values of applied voltages and temperatures.

Capacitor Categories

While working with Class I capacitors, you may find that their capacitances do not deviate from the expected values. However, Class II and Class III capacitors do show a marked deviation from the rated values. These capacitors have greater volumetric efficiencies, however. This means that they offer higher capacitances compared to the volume occupied by the capacitors.

Identifying Codes

An alphanumeric code of three characters designates the type of a class II capacitor. The first and second characters of the code indicate the lower and upper limits of temperature and the third character specifies the change of capacitance within the range.

Take the case of X7R, which is a popular Class II capacitor. The letter X indicates a lower limit of temperature of -55°C and the number 7 indicates an upper limit of +125°C. The third character R points to a change in the actual capacitance by +/- 15% from the rated value while the device is working within the temperature range defined above.

Deviation of Capacitances

In other words, you can expect that an X7R capacitor of a rated value of 4.7 microfarad might show a capacitance of 3.9 microfarad, while working under these temperature limits. However, it is a common occurrence to find that capacitors in certain circuits show a much more remarkable drop from their rated values. An X7R capacitor can exhibit a drop of 20%. Certain other Class II capacitors may show a drop as significant as 80% of their rated values of capacitances.

The real fact is that the rated capacitance value of a capacitor holds for a particular value of the applied voltage, also called the DC bias voltage. If the bias voltage is different from the specified value, the capacitor will offer a capacitance that is different from the rated value.

For instance, if you choose a capacitor of 4.7 microfarad designed to operate at 16 V, it may offer a capacitance as low as 1.5 microfarad while working at 12 V.

The code used to identify the capacitors does not indicate the exact variation of capacitance with the applied DC bias voltage. However, it is a known fact that Class II capacitors designated by the letter X are the most stable. The capacitors designated by the letter Y are less stable under adverse environmental conditions while the Z capacitors are the least stable.

Material Used

To understand the problem, you need to study the data sheet for capacitors, which indicates the variation of capacitance with the applied bias voltage. The data sheet illustrates another interesting fact regarding capacitor sizes. A larger capacitor offers a greater capacitance at a particular DC bias voltage than a smaller one identified by the same alphanumeric code. Hence, you can expect a better performance with a larger capacitor than with a smaller capacitor of the same code. A possible reason for the fact could be that manufacturers have to compromise on the material while making smaller capacitors of the same code.

Raspberry Pi and Laika

Raspberry Pi and Laika – A Powerful Combination for Robotics

Some of you may recall Laika, the first dog in space, and the first animal to orbit the Earth. In 1957, Laika gave up her life to prove that living beings can survive being launched into orbit.

This platform, aptly named the Laika Explorer, presents a powerful robotics control for your Raspberry Pi (Raspberry Pi). With Laika Explorer and using C, Python or Scratch programming, you can control switches, lamps, motors, robots and more from your Raspberry Pi.

The Laika Explorer is a simple platform, and you can start with the Scratch programming language for controlling the hardware in a matter of minutes. You only need to download the drivers, plug in the USB cable and you are ready to go, building up your hardware and software skills.

The Laika Explorer provides you with:

— Inputs to connect sensors, switches and other input devices – 2x analog and 4x digital;
— Outputs for controlling LEDs, motors, sounders and other output devices – 7x digital;
— Control for motors, drive forward, reverse and brake – 2x H-bridge motor drivers;
— Interaction between hardware and software – 4x switches;
— Diagnostics for digital outputs – 7x indicator LEDs

All the above are available on one PCB. You connect this PCB to your Raspberry Pi using a USB lead, and start the control by using one of the three programming languages – C, Python or Scratch. If you buy the Inventor’s kit, you get a laser cut, custom designed Perspex base to mount the Explorer board and the Raspberry Pi (the Pi is not included with the kit). Some motors, LEDs, potentiometers, wiring, etc., are thrown in. The USB connection will give you access to all the hardware control on the Laika Explorer board.

By sending a Scratch Broadcast, you transfer data to the Explorer board and to the seven digital outputs. Each output is capable of handling 500mA, although not at the same time. Each output is also protected by a back-emf diode, which means you can connect small motors, relays and solenoids, without having to worry about blasting the output driver transistors.

The dual h-bridge motor driver on the Explorer board is very useful in driving two motors individually. The two motors can be independently driven either in backwards, forwards or in braked condition. Both channels can each handle 1.5A continuously, or 3A if you want to drive one bigger motor with the outputs tied together.

The two analog inputs on the Explorer board provide 10-bit resolution. This makes it possible to use variable resistors or potentiometers to give precise control.

In practice, you do not need Scratch running on your Raspberry Pi to control the connected Laika Explorer. You can run a special Python script on your Raspberry Pi, allowing use of Scratch to communicate with the Laika Explorer over a network connection. Therefore, now you can control your Raspberry Pi robot through your Wi-Fi connection.

What does the future look like for Laika? Well, it is quite exciting as of now, with other modules in development. One such module is the multiple radio transceivers (868MHz for EU and 915MHz for US) forming a mesh network extension option, an exciting option for home automation to control lights, music and more through Raspberry Pi and Laika.

Publishing Photos with the Raspberry Pi and Pygmyfoto

You have tons of photos, which you would like to share with your acquaintances, loved ones and so on. Well, there are several sites on the web that will allow you to do so, but doing it through your own server has a separate charm. Additionally, if that server can be put up with the new Raspberry Pi you just bought, then the project takes on a whole different hue altogether.

Although your Raspberry Pi (RBPi) is completely capable of doubling up as a web-server and sharing photos on the web, most of the popular photo publishing applications, such as Piwigo, Gallery, etc., are heavyweights meant for the PC. For publishing your photos online through RBPi, a lightweight entity such as Pygmyfoto is a better choice. Not only can you publish your photos in a continuous roll, Pygmyfoto allows you to add a brief description and assign tags to your photos. In addition, Pygmyfoto displays key EXIF data after automatically processing the photos.

Now the viewer has all information of the exposure, aperture and ISO you used when you clicked the photo. Not only this, Pygmyfoto also adds a link to the photo’s full size version, along with a map URL. Now, if your photo was geotagged, the URL will allow the viewer to use OpenStreetMap service to view the exact place where you had clicked the photo.

When you need simple photo sharing without the unnecessary extras, bells and whistles of more advanced blogging platforms, Pygmyfoto may be more suited to your needs. Since it is open-source, you can tweak it to meet the requirements of even the simplest of hardware. Pygmyphoto is meant to be simple, and if you find something you need is missing, well, you can program it in.

So, how do you install Pygmyfoto on an RBPi? First, you need some required packages to be installed. For this, set up your RBPi to run the following command:

sudo apt-get install apache2 php5 sqlite3 php5-sqlite imagemagick libimage-exiftool-perl git

Now you must switch to the directory /var/www and clone the repository of the Pygmyfoto GitHub:

sudo git clone https://github.com/dmpop/pygmyfoto.git

Now change the directory’s owner and group with:

sudo chown www-data:www-data -R pygmyfoto

Switch to the Pygmyphoto directory and use a text editor to open phpliteadmin.config.php. Replace the default password by editing the line –

$password = “admin”

Modify the default values in the file config.php, if necessary.

Now you can add photos to the directory pygmyphoto/photos. Run the ./pygmyphoto.sh command in a terminal, and provide the required into.

The viewer must point their browser to http://127.0.0.1/pygmyphoto to view your photos. Of course, they must replace the 127.0.0.1 with the IP address or the domain name of your server.

For accessing and managing your database at pygmyphoto.sqlite, you must make it writable. Use the command:

sudo chmod 600 pygmyphoto.sqlite

Now, you can point your browser to http://127.0.0.1/pygmyfoto/phpliteadmin.php and log in. you must use the password you specified in the file phpliteadmin.config.php earlier. Do not forget to replace the 127.0.0.1 with the IP address or the domain name of your server.

How does a smartphone camera autofocus?

How does the camera of a super slim smartphone autofocus?

As long as cell phones were over 10 mm thick, manufacturers had no problem of getting the camera to autofocus. Of the 2 billion cameras manufactured for the phone and tablet market, nearly half of them autofocus. Usually, one of more of the lenses in the camera are moved in or out using a linear actuator, while an algorithm calculates a figure of merit for the sharpness of image for that location of the lens. The best focus for the scene is achieved by repeating this procedure.

This was going fine, until form factors started to get thinner. Manufacturers made thinner phones, and people took this as a paramount design consideration. As the 5 mm form factor was approached, compressing an 8-13 M Pixel auto focus camera that would still produce high fidelity images became a challenge. In addition, the requirement of speed, power and performance also changed, and altogether, forced manufacturers to abandon the old method of Voice Coil Motor in favor of a MEMS linear actuator.

The Voice Coil Motor (VCM) operated using the principle of electromagnetism. This is the same technology used in loudspeakers to produce sound from electricity. When electricity passes through a coil, it produces a magnetic field that reacts with a permanent magnet to either repel or attract the coil. The movement of the coil is restricted such that it can only move along its axis. Springs attached to the coil help to bring it back to its rest position once the electricity in the coil stops flowing.

The main disadvantage of the VCM is the hysteresis of its stroke. Usually, the coil does not return to its original position after a displacement and this prevents rapid tracking of focal distances in a VCM controlled camera lens. Other disadvantages are the high requirement of power for operating the VCM and de-centering and lens-tilting while operating. All these problems became increasingly acute with increasing image sensor resolution, decreasing pixel dimensions and f-numbers. Moreover, with the VCM technology now over 100 years old, the opportunities for further cost reduction are virtually nil.

This paved the way for a competing technology with a commercial opportunity that can deliver improved performance at a reasonable cost. This is the MEMS or Micro-Electro-Mechanical-System that uses components from one to 100 micrometers in size.

The MEMS technology for autofocus integrates the three functions of a linear actuator. It provides a linear vertical movement, has a spring to provide the restoring force and uses an electrostatic comb as a drive to displace the lens. The MEMS technology saves on power since it does not use electromagnetism.

The comb drive is more like interlocking fingers, only the fingers never touch. The electrostatic charge developed when a DC voltage is applied, develops an attractive force causing the combs to be drawn to each other. The lens, which is attached in the center, completes the silicon MEMS autofocus actuator.

The MEMS technology allows only one lens to move very precisely, while the other lenses are locked in the most optimal position. This approach offers an excellent image quality over the entire focal range within the 5 mm allowed in a thin smartphone.

All about Fritzing

Fritzing is a software program to help designers translate their prototypes into real products. Created at the University of Applied Sciences, Potsdam, the software is an open source software tool. It runs on Linux, Mac OS X and MS Windows.

The Open Source Idea

The term open source in software development indicates an approach that provides any individual access to the design of a product or improvements made to it. The Internet has made the concept of open source more viable.
In an open source program, any individual may open or unlock the source code. An innovative programmer may even make modifications to the code in an attempt to improve upon it.

Concepts behind Fritzing

To understand Fritzing, it is important to know something about Breadboard View, Schematics View, and Printed Circuit Boards View.

Breadboard View – Fritzing can present your circuit in breadboard view, making it easy to visualize how components will fit together and be wired together. Fritzing has a vast library of parts to represent all major components in the Breadboard view.

Schematic View – This is the traditional view of the circuit as represented in books. Frtizing has a large library of schematic parts to build up the Schematic View.

Printed Circuit Board View – A printed circuit board (PCB) consists of electronic components connected electrically on copper tracks laminated on a non-conducting substrate. This view is necessary to fabricate the PCB for the circuit.

Purpose of Fritzing

The software program allows designers and other professionals to record their prototypes created for various circuits and design corresponding PCBs. You can use the company website to communicate your ideas and drafts with other individuals. Others may create electronic items based on your prototypes. This concept of sharing helps reduce production costs.

One of the great advantages of Fritzing is amateur electronics enthusiasts can design circuits and build PCBs suited to their needs. All the gear needed is available from the Fritzing store.

You can even play with the Raspberry Pi using Fritzing. The rapidly growing Fritzing library now features the Raspberry Pi Model B!

Making your own PCB

You can design and create a printed circuit board using the Fritzing software.
Print your circuit diagram onto a sheet of glossy photographic paper using a laser printer. Place the sheet on a copper board with the printed side facing the board. Run a hot clothes iron over the sheet. If you have done the job well, you should get a clear etching of the circuit on the board. You may need to clear away the excess copper with a Ferric Chloride solution.

Be careful with the Ferric Chloride solution as this is a very corrosive liquid and will eat through most clothing and skin. Wearing a PVC apron, gloves and PVC shoes is recommended when working with Ferric Chloride.

The Fritzing software company provides a service called the Fritzing Fab. You will have to upload your file, place your order and make the payment. At the time of placing your order, you can request extra services like punching holes for mounting the board. The company will deliver your printed circuit board in about two weeks.

How Professional Grade Capacitors Are Used In the Automotive Industry

The challenging conditions faced by automobiles have compelled component manufacturers in the automotive industry to come up with superior capacitors. Two of these advanced capacitors are professional grade capacitors of tantalum and niobium oxide.

A capacitor is comprised of two conducting plates separated by a dielectric (insulating) medium. One plate maintains a positive charge while the other maintains a negative charge.

Benefits of Professional Grade Tantalum Capacitors

A tantalum capacitor has a pellet of tantalum as the positive end separated from the negative conductor by a dielectric, which in this case is a thin layer of tantalum oxide formed on the tantalum pellet surface.

Professional grade variety of tantalum capacitors has several advantages over standard tantalum capacitors. Manufacturers adopt strict design specifications to construct the capacitors and use thicker and better dielectrics. In addition, the manufactures check the devices for high surge current and burn-in procedures.

The use of these capacitors results in a low failure rate of 0.5% in 1000 hours. In addition, the leakage current is almost 75% less than that in conventional tantalum capacitors. Manufacturers make professional grade capacitors available with low and standard equivalent series resistances (ESR). This makes these components suitable for several types of control circuits in automobiles.

The low ESR capacitors are particularly useful in airbag modules, engine control modules and power supply modules.

Functioning at High Temperatures

Automotive engineering requires placing electronic components close to sources of heat like engines, gearboxes, AC circuits and headlights. The temperatures in these regions may be in the region of 175°C. Since tantalum capacitors can function over a wide temperature range from -55°C to +175°C, they are suitable for use in these regions.

Niobium Capacitors

How The Automotive Industry Uses Capacitors

Before deciding on a tantalum or niobium oxide capacitor in a particular automotive circuit, the industry thinks about the nature of the circuit and the device using it. The first factor, which is the maximum voltage drop across the load in the circuit, determines the voltage rating of the capacitor. The second factor is the applied DC voltage. The applied voltage must be 50% of the rated voltage for the capacitors. This takes care of an unexpected surge in voltage. The third factor is the maximum value of the operating temperature. The capacitor selected must be able to withstand the temperature of the operating device.

A circuit operating under high temperature conditions (up to 125°C) can expect to see additional voltage surges. It is crucial that capacitors employed can endure these issues.

4 Accessories to Turn your Raspberry Pi into a Workhorse!

Gert Board To Pair Up Your Raspberry Pi With The ATmega Microcontroller

You can now expand the General Purpose Input Output (GPIO) pins of your Raspberry Pi with a Gert Board. Gert Board is the brainchild of Gert Van Loo, one of the developers of the alpha version of the Raspberry Pi. With the addition of the 28-pin ATmega microcontroller, you have the entire Arduino Integrated Development Environment (IDE) at your disposal. Moreover, it is possible to add any of the following ATmega controller models to the Raspberry Pi – ATmega 48A/PA, ATmega 88A/PA, ATmega 168A/PA or the ATmega 328A/PA.

So, what does this mean for your Raspberry Pi? By adding the Gert Board, you get an 18V @ 2A port for your motor projects. You also get a 2-channel, 8-, 10- or 12-bit Digital to Analog converter along with a 2-channel 10-bit Analog to Digital converter. Additionally, you get 6-Open Collector drivers capable of 50V @ 0.5A, 12-Buffered I/O’s and three push buttons.

PiFace Digital Controller

If you intend to control external hardware via the Raspberry Pi’s GPIO header, the easiest way is to use the PiFace Digital developed by Andrew Robinson of the University of Manchester. The PiFace Digital has two onboard changeover relays, and this is the central feature of the add-on board. The changeover relays have open-and-close positions, which are accessible to the user. Each open-and-close position of the relay can handle 5V @ 10A maximum. You can program the board through Python, C or Scratch. Scratch has also developed an emulator, called the PiFace Emulator. This gives you a graphical control over the features of PiFace. Not only this, PiFace has additional onboard features such as eight digital inputs., eight open-collector outputs on connectors, eight LED indicator lights on the outputs and four tactile switches.

Pi Camera

The Raspberry Pi has an onboard CSI port, which you can connect using a ribbon cable to the Camera Module. The Raspberry Pi camera module measures only 25mm x 20mm x 9mm. The tiny module has an Omnivision 5647 fixed-focus module that can handle 5MP still images, while weighing only 3 gm. You must use a 4GB or larger SD Card on your Raspberry Pi, as this is where the images from the camera are stored. The camera can handle resolutions of 1080p30 (1080 pixels at 30 frames per second), 720p60, and 480p60/90. The CSI bus on the Raspberry Pi is capable of handling high data rates streamed directly to the processor on board (BCM2835 ARM 11).

A Slice of Pi

This breakout board, called the Slice of Pi, is the least expensive of all the expansion boards for the Raspberry Pi. The board has a serial peripheral IO port expander, MCP23017, which adds 16-input/output channels to your Raspberry Pi. Apart from this unique feature, you can also use the board as a custom development area. One key feature of this Slice of Pi is the Xbee style connector mounts. Since this can support the XRF, Xbee and the RN-XV wireless modules, the functionality definitely expands the popularity of the board. Apart from this, you have easy access to the on-board GPIO, the 3V3, 5V; GND and the TX/RX solder points.

Do Even More with your Raspberry Pi

When you own a Raspberry Pi, there is so much you can do with it. However, combine the bare Raspberry Pi with some attachments, and you have a gadget that could far exceed your expectations. Presented here are some of the more useful attachments, which will increase your expectations from the Raspberry Pi.

LCD Option from 4D

When you want to exploit the full HD capabilities of the Raspberry Pi, give it the color LCD options from 4D Systems. The company’s EVE (Extensible Virtual Engine) that is featured by the “Picasso Processor” drives the 480×272 pixels on the TFT Screen of the 4.3-inch “uLCD-43-PT-Pi”. This gives you 65,000 true to live colors on a 4.3-inch diagonal screen. The 4.3-inch screen is notable for its resistive touch layer, which can sense both finger as well as stylus interaction.

When you are going portable with your Raspberry Pi, this screen will be absolutely essential. To connect with the Raspberry Pi, this series of LCD screens from 4D has a “4D Serial Pi Adapter” that connects to the GPIO port of the Raspberry Pi board, through a 5-way cable adapter. The best feature of this adapter is it does not hog all the GPIO port, but allows for duplication of the GPIO lines, so that you can stack another board on top.

AlaMode

A team of like-minded students and engineers has made the AlaMode board that has some special features. Working off the Raspberry Pi GPIO port, AlaMode is a stackable board compatible with Arduino. The goal of the Wyolem Team was to provide the Raspberry Pi and its user’s access to the vast library, devices and “Shield” expansion boards available for the Arduino and its community. This allows you the complete freedom to program the Raspberry Pi in any language you prefer and control the Arduino or the AlaMode directly.

The AlaMode takes its power directly from the Raspberry Pi, or you can power it separately from USB, wall-mart or external batteries. For application memory support or for data logging, a micro-SD card slot is added. You also have a real-time clock (DS3234), which reports its time back to the Raspberry Pi, thus removing the necessity to program two clocks.

You can even connect a Fastrax UP501 GPS receiver module on the AlaMode. This opens up the Raspberry Pi to the expanding stackable shields of the Arduino.

LCD & Keypad Kit

Digital Isolators vs Optocouplers

Industrial equipment may need to operate in a region of strong electromagnetic fields. There can be a sudden surge in the voltage applied to the equipment, which may be hazardous to the user and the gear. It is crucial that you incorporate a reliable isolation system to take of these issues.

Until very recently, the optocoupler was the only practical choice in providing safety isolation for manufacturers of medical and industrial isolated systems. The arrival of digital isolator has however, changed the situation greatly.

Digital isolators offer several advantages over optocouplers. They are more reliable, cheaper and have greater power efficiency compared to the optocouplers.

It is important that you understand the three vital aspects of an isolation system. These are the insulation material, the structure and the method of transfer of data.

Insulation Material

Typical insulation materials are silicon dioxide wafers and thin film of polymers. Optocouplers use polymer films. Digital isolators make use of a particular form of polymer called polyimide. This material serves to increase the efficiency of isolation systems.

Silicon Dioxide is not a very suitable material as an isolator. While you may increase the thickness of polyimide to increase the insulation, you cannot adopt the same method for silicon dioxide. Wafers thicker than 15 micrometers may crack during processing.

Structure

Digital isolators use either transformers or capacitors to transfer data across the isolation barrier. A transformer system has two coils placed side by side. Current flowing through a coil (called the primary coil) gives rise to a magnetic field in the space surrounding the coil. This induces a current to flow in the other coil (called the secondary coil).

A capacitor consists of two metal plates with the space between the plates filled with a non-conductor.

Optocouplers use light emitting diodes (LED) for data transmission.

Transfer of Data

The LED in an optocoupler turns on for logic high state and turns off for logic low state. The device consumes a significant amount of power when the LED is on. Digital isolators do away with this undesirable aspect. The sophisticated circuitry in the system encodes and decodes data at a rapid pace so that the transmission of data involves less power consumption.

A digital isolator using a transformer for data transmission transfers the data from the primary coil to the secondary coil during the pulses of current driving the transformer.

A digital isolator may use radio frequency signals as well, in a fashion similar to the way an optocoupler uses light from an LED. However, since a logic high state causes a continuous transmission of radio frequency signals, this method uses more power.

Digital isolators with capacitors have an advantage in that they consume lower currents for creating coupling electric fields for data transmission.

Ensuring the Correct Combination

It is important to use the right insulating material and the apt method for data transfer depending upon the application.

Since polymers provide more than adequate insulation, they are suitable in most applications. Polyimide insulation is particularly suitable for equipment used in healthcare and heavy industries.

Concerning data transfer, capacitor isolation is adequate for situations requiring just functional and not safety isolation. Isolation systems making use of transformers will serve the purpose of safety as well as functional isolation.

Some Frequently Asked Questions about Raspberry Pi

Q. What is a Raspberry Pi?

A. The Raspberry Pi is a low cost, tiny computer, about the size of a credit card. You can plug your keyboard, mouse and your TV into it, and use it just as you would use a PC. It is capable of playing games, word-processing and working with spreadsheets. You can even watch high-definition video. The composite and HDMI out allows you to connect to any old analog TV, a digital TV or to a DVI Monitor. It is a wonderful device for kids to learn programming.

Q. What are the different models of Raspberry Pi available?

A. As of today (August, 2013) there are two: Model A and model B. Model A has 256MB RAM and one USB port. Model B has 512MB RAM, 2 USB ports and one Ethernet port. When you buy the Raspberry Pi, you get only the board. No SD card or power supply is included, but you can buy them separately. Pre-loaded SD cards are also available.

Q. What are the physical dimensions of the Raspberry Pi?

A. The Raspberry Pi dimensions are 85.6x56x21 (mm) or 3.37×2.21×0.827 (in.), with a small overlap as the connectors and the SD Card project over the edges. The Raspberry Pi weighs about 45 gm.

Q. What is the SoC used for the Raspberry Pi?

A. The SoC or System on Chip is a Broadcom BCM2835. This contains an ARM1176JZFS processor running at 700 MHz, with floating point and a Videocore 4 GPU. The GPU is capable of Blu-ray quality playback and uses H.264 at 40MBits/s. The fast 3D core is accessed using the supplied OpenVG and OpenGL ES2.0 libraries.

Q. How powerful is the Raspberry Pi?

A. The GPU or the Graphical Processing Unit operates with OpenGL ES2.0 and the hardware-accelerated OpenVG libraries, providing 1080p30 H.264 high-profile decode.
The GPU can provide 1Gpixel/s, 1.5Gtexel/s or 24GFLOPS of general-purpose compute along with several texture filtering and DMA infrastructure.
In real world terms, the performance is similar to a 300MHz Pentium 2; however, Raspberry Pi provides much swankier graphics. Overall, the graphical capabilities can be equated to an Xbox 1 level of performance.

Q. Will the Raspberry Pi blend?

A. Yes, extensive virtual simulations have been carried out, there were no failures.

Q. Is it possible to overclock the Raspberry Pi?

A. Most of the devices run comfortably at 800MHz. The latest operating system has options of changing the options for overclocking on the first boot. If you run “raspi-config” you can change the options again at any time, and your warranty stays intact. However, these settings are experimental and not every board can be expected to run stably at the highest setting. To restore stability, try reducing the settings for overclocking.

Q. How do you boot the Raspberry Pi?

A. You need a pre-loaded SD card to boot. After the initial boot, a USB HD can “take over”. The root partition on the SD card must contain the operating system. Currently Debian Linux is the default distribution, but you can use any other ARM Linux distro available on the downloads pages.

Q. What are the power requirements of the Raspberry Pi?

A. The device is powered by 5V from the micro USB. To switch on, simply plug in the USB, to switch off, remove the power.