Yesterday I was doing some shopping in Paris when I came across the following advertising sign:

(sorry for the very low quality of the picture; it has been taken with my cellphone as I didn't think I'll encounter such a "thing" to photograph ! I'll take one with a real digital camera ASAP...)

As you can see (circled in red), the owner of the shop (or his electrician or ...) removed the insulation layer from the mains cable coming out from the wall and from the two bare wires coming out from the electric sign, twisted the cables two by two, and isolated his ugly twisting with scotch tape...

No need to say that it is a very dangerous installation and that it is against the most basic safety rules !

With the constant increase of the available bandwidth for consumer broadband Internet connections, people are starting to download more and more stuff (music/videos but also pictures, software, e-books, ...). Furthermore, digital cameras or digital camcorders are starting to be quite cheap. With all these new electronic toys, we need more and more storage available. Hard disk drives are available up to 500 GB, but that's for an high-end drive, and what happens if the drive fails ? You loose 500 GB of data, personnal photos, and so on. Not funny.

Commonly used in servers, RAID arrays offer an elegant solution to prevent loosing data in case of a hard drive failure while giving a lot of storage space. A RAID setup consists of a RAID controller, connected to several hard drives (from 2 to many). The RAID controller can then use the hard disk drives in different ways, according to what the system administrator decided, each way corresponding to a certain level of security and available space. Typically, the more security you have, the less space you have, because fault tolerance is achieved by storing special data in one or more hard drives, thus these hard drives can no longer be used to store real data. For more information about how RAID works, check out this page at the Advanced Computer & Network Corporation website.

For example, in a RAID 5 array, you have N+1 drives of equal C capacity. These N+1 harddrives will be seen by your computer as a single drive, of capacity N*C. There is some capacity that is lost because of the parity system that allows to find the data even if a single hard drive is faultly. RAID 5 offer a good security level at a very moderate cost. The problem is that RAID controllers are typically expensive, and it's the same for the physical arrays used to store the hard drives.

A wise guy at Inventgeek.com took a metal case, some cheap SCSI drives bought on eBay for a few dollars each, and a SCSI RAID controller also bought for a few bucks. He then simply screwed the drives in the case, and powered them with a big fat power supply unit. Simple ? Yes, for sure. But it's usually the simplest ideas that are the hardest to find, especially when they are elegant. Undoubtly, this one is.

Check out the project description !

Thanks to the Inventgeek.com team for allowing me to put the picture of the RAID array in this post.

You have probably already seen one of these nice POV (Persistence Of Vision) clocks, that quickly move some LEDs in the air to display the time, giving you the impression that the imte is floating in the air...

Today I came across a nice POV gadget: the SpokePOV. By attaching a row of leds to each of the wheels of your bike, you can display some nice pictures and even some simple animations. Unfortunately each wheel can display only one color, but it's still enough to do some pretty good looking displays :

[waiting for the right to put a picture here]

You want one ? Guess what ? Some kits and parts are available here.

Thanks Ladyada for sharing this great concept with us !

Take a few LEDs, a few magnets, some spray conductive paint, and some other common do-it-yourself gear, and you may end up with the pretty cool fridge lights of sockmaster as seen on this page.

I'd like to say more about it, but I have to to build one like that right now ! It's so cool !

The photos in this post are from sockmaster and are published here with his kind permission.

Sometimes there is a power outage there and there. Generally it happens when there is a combination of high wind speed and snow. Thus, wind is generally considered harmful by electricians, although you know that it can be used to produce electricity. What you do not know, however, is that you can make your own wind turbine out of a few pieces of wood and metal.

Even more interesting, you can find a four page guide explaining how to do that on Otherpower website, here. This wind turbine has very good performance as it can easily produce 2kW, and up to 3,8kW in fast wind speeds.

You have no excuse to miss any new DIY directory post as of now as you can produce your own electricity for your computer !

Home automation is something that most people are dreaming of, while being a bit afraid of, because most of use think that having a fully automated house requires some maintenance and knowledge. There are, however, systems that are totally autonomous once they have been installed. Edward Cheung successfully built one of these system.

As he says on his home automation website,

Few of us can afford a butler. Fortunately electronics and technology can compensate for this by allowing us to remote control many devices in our home. However, home automation does not mean just being able to control your home's appliances from a distance, but also includes intelligence in the system to better serve our needs.

Thanks to his installation, he can control most of the electrical appliances of his house just from his watch ! He also automated most of the annoying tasks, from opening/closing the windows to irrigating his garden. He was also able to precisely estimate the cost of a shower by installing some sensors in his water system, his water heating system, and his electrical system. The amount of radioactive Radon was also quantified, and he was able to remove it thanks to a homemade geiger counter. As you can see, things can go pretty far once you're in it.

I can only recommend you to check his home automation website if you are interested in home automation. I am sure it will give you some ideas. Even if you do not end up with such a complex system, you could install some simplier, yet useful, home automation components.

There are the watches, the LED clocks, the LCD clocks, the flip clocks, the nixie clocks, and the scope clock.

The Scope Clock is a clock that uses an oscilloscope tube to display the time, giving it a very original look.

Check it out here !

Note: OZ2CPU, who made a cool home made watercooling system, also made his scope clock:

The photo in this post is from OZ2CPU's scope clock page and is published here with his kind permission.

The Railgun 2 is the sequel of the first railgun that Sam Barrow presented on his website, the Powerlabs. A railgun is a linear magnetic accelerator, a device that can basically fire any small metallic object at an incredible speed, using a huge amount of electrical power.

The objective of this railgun is to, as stated on the railgun 2 page, to

successfully design and construct a linear electromagnetic accelerator capable of accelerating a lightweight payload to velocities greater than 1000m/s so that hypervelocity erosion in the rail/armature interface can be studied and a means for minimizing this erosion be investigated.

The railgun 2 is the result of 3 years of research on the subject. From what I have understood, it works by first accelerating the projectile with compressed gas, then it accelerates it more using a very strong magnetic field generated by the mean of electricity.

If you want to learn more, run to Sam's Powerlabs railgun 2 page !

The photo in this post is from the Powerlabs website and is published here with Sam's kind permission.

Mike's Electric stuff is a website mostly full of crazy high-voltages projects. Mike is a freelance electronic engineer that usually design low power microcontroller-based devices... but in his spare time, he likes to play with various high-voltage things. When playing with some high-voltage generator, he invented a new musical instrument: the spark-o-phone was born.

This interesting device uses some resonant tubes and a high-voltage generator. When an electric discharge, a spark, is done in one of the tubes, the latter starts resonating and produces some sound in a certain frequency, determined by its length, its diameter, and other physical parameters. By controlling in which tube the discharge is done and when, some interesting musical patterns can be done. The results are promising, however I think that Mike should hire a compositor

Read more on the Spark-o-phone webpage on Mike's electric stuff. Do not hesitate to browse this website, as it was quite hard to choose what to publish here !