Power Supply

When designing an electronics device you want to make sure that it won't go in smoke under unexpected circumstances. You never know what may go wrong during life time of device especially if it is powered from mains. Jon Chandler made a great overview of common and pretty simple power protection circuits that may help to avoid lots of trouble. Small circuit between your battery and device may protect it from mistakes like reverse power polarity.

His lists starts with simple series diode which is cheap but may help protect from reverse polarity. Like any other it has a downside – voltage drop (0.7V) that may be a pain for low voltage devices.

You might find there are many cheap half-height Compaq desktops, such as EVO d500 SFF available on the market. Some people are deciding to replace the browsing pc downstairs with EVO d500 SFF, however it’s not as easy as you think, as when it comes to Compaq, it’s mostly a non-standard proprietary PSU.

The first cell phone has been invented on April 3, 1973 by Martin Cooper, a Motorola researcher and executive and the first commercial citywide cellular network was launched in Japan by NTT in 1979, but the most unfortunate thing is: There's no any inventor that want to invent the universal charger for the cell phone in the past 30 years!