Recently in Hardware Category

About two weeks ago I received my shiny new N900 mobile computer. This is the latest model in Nokia's internet tablet series, which includes the 770, the N800 and N810. Unlike its predecessors, the N900 now also works as a phone. I had previously owned only the 770, so the switch to the latest model was quite a leap.

The 770 was released almost exactly four years ago, and if you put it side by side with the N900 it becomes obvious that much progress has been made. The N900 is slightly smaller, albeit thicker and heavier, but it easily fits in a pocket. It lacks the screen protector though, so some kind of a carrying case or pouch is a must to avoid scratches. N900 still uses a resistive touch screen, meaning no multi-touch. The screen feels similar to the one in the N97 phone and is clearly optimized for use with a finger, whereas 770 was best used with a stylus.

The slide-out keyboard is much faster to use than 770's virtual keyboard, although this feature was actually introduced in the previous N810 model already. For short texts, the finger friendly virtual keyboard is also quite fast to use now.

The software side has seen great improvements as well. The UI in general looks very modern and feels much snappier and more responsive than the 770's. Especially the web browser is much nicer. Being Firefox based, it renders pages just like on a desktop PC. The flash player has been updated and it can now even play Youtube videos. Most importantly, the new browser is fast! Visiting a large page with the 770 would lock up the browser, whereas the N900 is snappy and smooth even on JavaScript heavy pages like Slashdot.

Another cool thing is that the N900 comes with an X terminal built-in and sudo gainroot.sh is all it takes to get root access. This is something most "regular" users probably won't care about, but I for one appreciate it when the manufacturer actually lets me do what I want with the hardware I bought, rather than actively discourage it.

The N900 is by no means perfect though. Syncing the calendar or address book with Ovi is not supported, which is odd considering how much Nokia promotes it. There's even a Ovi Store icon in the application menu, which just brings up a page saying the Ovi store for maemo is not open yet. Ovi maps is strangely limited. It takes ages to load and hogs the whole screen while doing so, meaning I can't switch to some other app while it loads. Basic features like voice navigation and location bookmarking are missing and the maps seem to be a bit out of date.

At first glance, the actual phone functionality seems almost like its hidden. It becomes clearer, however, when you understand that the N900 is not a phone with a built-in computer, but a computer with a built-in phone. With this in mind, the phone features (including Skype, Google talk and SIP) become easy, even intuitive, to use.

Despite the problems, many of which will undoubtably be fixed in future updates, I would say the N900 is an excellent mobile computer/phone. Is it the iPhone killer? No. In terms of ease of use, the iPhone is still miles ahead. But N900 is the phone for engineers and nerds.

From a quick peek over at Hack a Day and other electronics blogs it seems like everyone and their cat are doing Arduino projects nowadays. I finally caved in and decided to see what all the fuss is about, and ordered an Arduino Duemilanove from sparkfun, which arrived today. I've only had it for a few hours now, and I already love it. Arduino, together with a breadboard and sparkfun's premium M/M jumper wires equals prototyping bliss ;) With help from the sample programs that comes with the Arduino IDE, I managed to put together a quick IR-reflector controlled servo test thingy in just a couple of minutes with no prior experience with the platform. Doing the same with a PIC would have taken me much longer, despite my greater experience with them.
Installing the PC software was fairly straightforward, even though I run 64 bit gentoo on my desktop. I followed the gentoo instructions and just had to replace the bundled Rxtx.so with a link to the one provided by the distribution. The FTDI driver I had compiled earlier, so the rest was plug and play.

New TC picture added. I increased the size of the top load, tuned the coil better, and managed to increase the spark length from 15cm to about 20cm.

On top of the toroid I put a sharp screw to act as a breakout point so I could more easily judge the length of the discharge. I then adjusted the tap point in until I got the longest sparks.

I also adjusted the spark gap spacing. Finding the optimum distance between the electrodes can be tricky. If too narrow, the capacitors don't have time to charge enough or the gap won't quench; too wide, and the transformer might burn out. I previously had a problem where the coil would run for about 30 seconds, then the gap would simply stop firing and the transformer emit a buzzing sound. Luckily no lasting damage was done. I narrowed the spark gap a little, and the problem seems to have gone away now.

Just added a new page about my Tesla coil.
I first started building the coil over ten years ago, but never got around to finishing it. My new coil is not exactly same as the one I first started building, but I did use the components from the original one.

The coil is around 35cm high, uses a 4kV neon sign transformer as its power supply, and currently produces sparks about 15 to 20cm long.