Wireless power has become a hot topic as wireless charging of mobile devices is get getting some popularity. Wireless charging isn’t something new; the technology exists since 1981 and Nikola Tesla has made first wireless power experiments over 100 years ago. Wireless charging for Qi technology is becoming the industry standard on smartphones (pushed by →
The rise of direct current using devices and direct current generation have some rethinking the use of alternating current in the grid. Let’s start from history of electric power transmission: In the late 19th century both alternating current (AC) and direct current (DC) were both used to power devices like motors and light bulbs. Over →
Electrical grid is said to be vulnerable to terrorist attack. I can agree that electrical power distribution network would be quite vulnerable if someone tries to sabotage it and knows what to do. I know this because I design software and hardware for control systems for electrical companies. Some days ago I saw in Finnish →
In my previous posting Current sensor for multi core cable is talked about measuring AC current flowing on cable where you don’t get access to individual wires. In that posting I mentioned that I saw Modern Device blog article Current Sensor that seem to be doing exactly that. This sensor is designed for providing an →
There are many ways to measure current. The traditional methods of taking current measurements by inserting a shunt resistor or using a current transformer have the disadvantage of having to break the circuit conductor. For current transformer there are also models that can be installed in place without cutting the cable (more expensive and usually →
Selecting the Best Battery for Embedded-System Applications article tells that non-rechargeable (primary) batteries find wide use in mainstream embedded-system applications. This category of batteries includes alkaline devices, which manufacturers typically fabricate using manganese dioxide and zinc powder with a caustic alkali of potassium hydroxide as an electrolyte. The nominal voltage of an alkaline cell is →
Should the power wires be overhead or underground? Underground power line feasibility article talks on the feasibility on using underground lines instead of overhead lines. Both underground and overhead lines have their good and bad properties. Burying power lines is not cheap, it is said the cost would be $1M per mile to convert existing →
An electromagnetic field (also EMF or EM field) is a physical field produced by moving electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction. It is one of the four fundamental forces of nature. EMF measurement →
It is sometimes suggested that a mains power isolation transformer might be used to solve the ground loop problem. It is true, that many times a mains isolation transformer does help, but not always. A system with properly used isolation transformer is still safe, it can be even safer than system without isolation transformer. Remember →
Grounding and shielding is an often misunderstood process. It is common to hear quotes ranging from “it’s just black art!” to “the rules change all the time!” and “there’s no way to understand it!” These statements are often repeated but not true. There is a process, it hasn’t changed, and the more one knows about →