I has been very hot and dry in Finland. Some kind of irrigation system or manual irrigation seems to be necessary to keep the plants happy. Livehacker reports on an interesting Build an Arduino-Powered, Tweeting, Self-Watering Garden System. It’s extremely simple. And, not only will the Arduino water the soil when it starts to get →
Chipshow’s LED tube page gives some views what LED tubes look like. As you can see there are many LEDs inside a LED tube. The most economical way to run sich LEDs from mains power is to connect many LEDs in series and then use some current limiting circuit to set the drive current right →
The idea if replacing fluorescent light bulbs with LEDs seems to become popular. There are different kind of products made for that purpose. LED bulbs utilizes large arrays of high power LEDs to provide up to provide light. They are at best an economical way to replace commonly used fluorescent tubes. Since introducing LED based →
Toolkit: A Look at the Gear That Experts Use to Spy on Spies is an interesting article. Kevin Murray heads one of the most sophisticated surveillance-detection firms according to the article. Wired asked Murray about the bevy of gizmos he and his staff use to sniff out corporate espionage. →
Oh, batteries. Can’t live with ‘em, can’t live without ‘em. Then I saw some news on this field. Potatoes May Power The Batteries Of The Future article tells about a potato powered battery. It promises to be simple, sustainable, robust device can potentially provide an immediate inexpensive solution to electricity needs in parts of the →
Power-line networking has been increasing in popularity at some areas but the success does not become without problem. Power line tech could crash aircraft and shut down the Archers article says that an extensive study commissioned by Ofcom concludes that power line networking could crash airplanes and block Radio 4 in UK. According to the →
iPhone mag-stripe reader stalled article tells that Square, the expected to be breakthrough business launched by twitter-founder Jack Dorsey, won’t be shipping as scheduled. Interesting is that Square was just a magnetic-stripe reader, and that there were a dozen credit card-processing applications on the iPhone. Only this time, it comes with a plastic lump that →
Ground loop can cause considerable currents to flow on all cables on the loop. It is not uncommon to have a voltage of 1V RMS between the earth connections of power outlets that are wired separately back to the switchboard. This small voltage, with a total resistance of perhaps 0.2-0.5 Ohm, will cause a loop →
An ungrounded system is one in which there is no intentional connection between the system conductors and earth. When the neutral of the system is not grounded, it is possible for high voltages to appear from line to ground during normal switching of a circuit having a line to ground fault. These voltages may cause →
Differential Scope Primer is a good introduction to oscillospe measurement. This web posting is a shortened version of the information on that document related to ground loops. I have also added here some of my own comments. Most oscilloscopes are designed to measure voltages that are referenced to earth ground, which is connected to the →