European Commission has reached a voluntary agreement with some of the biggest names in the electronics industry to introduce a common charger for cell phones that fits all models. New phones configured to use the standardized chargers use a micro-USB connector for charging. Information on this USB charging connector is available at USB Approved Class Specification Documents documents. Read Battery Charging v1.1 Spec and Adopters Agreement document for more information (NOTE: Document is inside .zip file you get). The new technology could mean chargers would eventually be sold separately from new phones. Ten major mobile phone producers representing the vast majority of the E.U. market have pledged to participate in the agreement. USB As A Power Source has some interesting facts on using USB power for charging and operating electronic devices.
Archive for June, 2009
Agreement on Cell Phone Chargers in E.U.
Tuesday, June 30th, 2009Lack of safety ground
Tuesday, June 30th, 2009Besides short circuit surge currents flowing on safety ground wire there are also other situations where you can see 60-115 V AC between the equipment cases. In the age of switch mode power supplies the safety ground has a new job, ie EMC line filter ground. When the power supply EMC filter is not connected to electrical ground, the the line filter y-capacitor often ends up connected to the output ground putting the output at half the line voltage that is 60V or 115v depending the country you live in. The low capaciance of y-capacitor limits the available current to some low value (fraction of milliampere normally but can be up to few milliamperes), so the system is kind of hi-Z output. If the unit powered by this ps has no other ground, balanced IO requires common mode mode rejection that that can handle 60V or 115v rms voltage. The techniques that can do this are rare, this is far more than normal op-amps or RS-422/485 drivers can handle. Beware “universal” switch mode adapters!
Safety ground is not reliable ground reference
Friday, June 26th, 2009I have written quite a bot of material on Ground loop problems and how to get rid of them. The ground loop related problems are often caused by small ground potential differences between different electrical outlets. Typically those ground potential differences are few volts or less.
Not your fault article by Howard Johnson published in EDN magazine describes situations where those ground potential differences can raise to much higher voltages, up to tens of volts.
The green safety wire, or “third wire,” merely connects the metallic chassis of each product to earth at the ac power entrance. Under ideal, no-fault conditions, the green safety wire carries no current. Based on this an inexperienced designer might therefore conclude that the green wires form a single-point-ground reference system that provides a consistent voltage reference between different ac-powered products.
If live wire during some fault situation touches the metallic chassis, a large fault current back to the power source through the ground wire. The fault current trips the circuit breaker, shutting off power and possibly saving the life. The power shutoff normally takes from a small fraction of second up to few seconds depending on the way the circuit is protected. As the huge fault current surges (up to hundreds of amperes) through the green wire, other devices connected to adjacent outlets can experience voltage differences as large as 60V rms in 120V AC system used in USA. The voltages can be even higher on 230V AC system used in Europe (in theory up to 115V AC, in practice normally less than 70V).
This kind of huge voltage differences between equipment can fry the communications interface on interconnected devices because it is normally outside the operating voltage range most normal interconnection systems can sustain (RS-232, RS-422, RS-485). The thin ground connection on the interconnection cable does not much to reduce the surge those devices get. If you want to design reliably working electronics, it would be better if you design gear that can sustain such extraordinary voltages without damage. If your devices can’t sustain those voltages, it would be better if the equipment would be permanently connected to a common outlet or power strip.
Suitable technologies that can easily sustain 60V or more voltage between devices are Ethernet on UTP wiring (transformer isolated), fiber-based optical links, free space optical communications and wireless RF communications. Traditional RS-232 or RS-485 or RS-422 can be made to withstand this voltage if you take case that the equipment on one of the ends of the communications link or both of them have the communications port electrically isolated (usually uses optioisolators) from the equipment case.
PHP gets goto command
Thursday, June 25th, 2009PHP is a widely-used general-purpose scripting language that is especially suited for Web development. The PHP language is very widely used on web sites. Many parts of ePanorama.net site are built using PHP programming language.
PHP programming language finally gets goto command. The goto operator is available as of PHP 5.3. I am not really sure if adding the goto command was a good or bad thing for PHP language. Many programmers think that goto command is potentially dangerous and there is a funny xkcd comic strip warning of the potential dangers of goto command included in official PHP goto command manual page.
How big shows are built: American Idol Experience
Wednesday, June 24th, 2009Youtube has a Timelapse video of the set construction for the American Idol Experience at Disney’s Hollywood Studios: AI Timelapse vid. The attraction opened is February 2009. You can see in this vidoe how much construction work takes to make a big show like this.
Digital cameras are phasing out analog
Tuesday, June 23rd, 2009Digital cameras are slowly phasing out analog. In still cameras the situation seems to be so that the manufacturers of the films are stopping to manufacture well known film types. For example Polaroid has phased out Polaroid film years ago and Kodak is retiring iconic Kodachrome film. Digital photography winds the once-iconic color films into obscurity. To celebrate the Kodachrome film’s retirement, Kodak has created an online gallery of some of Kodachrome’s best shots. Before the film has fully retired it might be also a good idea to take a look at the Chemistry of Photography.
Hard disk vs. solid-state drive
Thursday, June 18th, 2009Solid-state disk (SSD) drives are all the rage among techies. The drives use non-volatile NAND flash memory, meaning that there are no moving parts and they are faster in reading and, in most cases, writing data. Computerworld magazine has published a worth to read article Review: Hard disk vs. solid-state drive — is an SSD worth the money?
The conclusion in the article is: For most users, this a good time to consider buying a higher-end HDD that should deliver more-than-enough performance while you wait for SSD prices to drop further. That could be a long wait.
Typical notebook or desktop users probably won’t notice a big difference between an SSD drive and a traditional hard disk drive other than a faster boot-up and quicker application-launch times. For laptops and desktops, where consumers will continue to seek as much capacity as money can buy, SSD adoption will likely suffer for years to come.
SSDs make sense for small handheld devices and special applications. SSD will continue to dominate in small handheld devices because the cost to produce flash memory-based drives is significantly cheaper than hard disk drives when drive capacity does not need to be very big.
Samsung LED TV is not an entirely new category of TV
Wednesday, June 17th, 2009I’ve been hearing and seeing a lot about these new LED TV models from Samsung. They are advertising them as entirely new type of TV that changes everything. After some checking round what is this new technology is I found out that it is nothing spectacular new in it. Samsung’s so-called “LED TV” is pretty much like a normal LCD TV. The only difference is that the backlights technology has been changed from CCFL to LED.
Samsung is trying to promote this LED backlighting technology as an entirely new category of TV, which is a little misleading I think. It is true that LED backlight technology has some benefits (potential to consume less electricity) and potential for future enhancements (local dimming can give really nice contrast and black levels if used on some future models). And the idea to use LED for LCD technology display backlight is nothing new and it has been used earlier by many companies on many other types of LCD displays.
More material on this topic can be found at the articles
How is Samsung LED TV Different From LCD HDTV?, CCFL Characteristics and LCD Backlighting for LCD Displays.
Entertainment Technology Blog
Monday, June 15th, 2009John Huntington, the author of Control Systems for Live Entertainment book, is keeping an interesting John’s Entertainment Technology Blog at http://www.controlgeek.net/. It is worth to read. There are lots of material on different shows going on, including nice backstage technology tours on some shows.
Ban on incandescent lamps
Friday, June 12th, 2009Ban on incandescent lamps is coming to Finland and other EU countries. Decision makers think that consumers and the environment alike would benefit from replacing the familiar incandescent lamps with energy-saving compact fluorescent light bulbs or LEDs.
At present, some 80% of the electricity used for lighting by Finnish households is consumed by incandescent bulbs, the standard filament lamps. Replacing them with energy-saving lamps is expected to save around 900 gigawatthours of electricity, which equals the annual electricity consumption of 50,000 households. Article Ban on incandescent lamps discussed by Finnish Parliament discusses on banning old light bulbs in Finland and in EU. Should There be a Ban on Incandescent Lamps? gives a view to what is happening in Australia.
Using more efficient lighting would reduce the carbon dioxide emissions, but not for the full amount of the saved electricity. During winter time (and spring and autumn) most of the electricity wasted as heat in light bulb heats up the space it is operated. When you replace the lamp with energy saving lamp, you need to turn up to heating to keep the temperature same.
The compact fluorescent light bulbs contain mercury, which in turn adds to the problem-waste problem. According to Should There be a Ban on Incandescent Lamps? article many compact fluorescent light bulbs are not very good in construction, which will cause shortened life span and possible danger of fires.
LEDs are advertised to be super efficient light sources. They are much better than normal light bulbs, but they are far form ideal. Today’s high power white light LEDs are only about 18% efficient. This means 82% of the energy put into an LED dissipates as heat. LED inefficiencies EDN blog posting will list out where this 82% of energy is lost. There’s a lot of room for improvement in each of these areas of loss – especially the white light conversion process.
Acording to LED lighting: panel debates quality versus cost posting LEDs won’t make a replacement for screw-in light bulbs any time soon. A typical 5mm LED produces about 6 lumens. So a big commercial fixture built out of them would require thousands of LEDs to be as bright as the original bulb. This will create all kinds of challenges to the designer. And in the end the result is that the created bulb will consumie about the same power as a florescent fixture of the same output. The typical 5mm LEDs are not very good for lighting applications anyways. When you drive or overdrive that small LED in hot environment, it will degrade the epoxy encapsulant. The epoxy turns yellow, and then it starts to crack. Once you get a crack, the LED will fail. So this is not a good use of these LEDs.The products built carelessly in this way will not live up to the promises of the LED technology and the advertisements of those products.
The big advantage for LEDs in lighting applications will not be replacing the existing light bulbs or fluorescent lamps. Best LED lighting results are obtained when the lighting instrument that used for the purpose is specifically designed for LEDs in mind. Then you can achieve output efficiency, directability of the beam, and reliability that you can’t get any other way.
Regular light bulbs are also getting better. Halogen light bulbs are better efficiency than normal light bulbs. There are also light bulbs nowadays energy efficient that look like normal light bulbs, but they actually small halogen light bulbs packet to package that makes them to fit to the place of normal light bulb. There is also energy saving halogen light bulbs, for example new energy efficient halogen light bulbs promise to give same light as “normal” 300W light bulb with only around 200W of power. There are some research results that a Laser Blast Makes Regular Light Bulbs Super-Efficient: Laser Process Doubles Brightness for the Same Amount of Energy. I expect that it will take some time until this new innovation will come to use, if ever.
