Galaksija: Thanks

31.01.2007 23:08

Thanks to everybody who sent me advice on how to solve the flipped-character problem. I was pleasantly surprised at how many of you are following my Galaksija project - especially people from outside former Yugoslavia.

It turned out that flipped characters were the least of my problems. I figured out the cause after some 15 minutes and I only had to reprogram the character generator EPROM with the bit order reversed.

Poor video quality, power supply overheating and audio interface insensitivity were a bit harder to solve. I'll post some details (and hopefully a screencast) tomorrow.

Posted by Tomaž | Categories: Life | Comments »

Galaksija: It's alive!

29.01.2007 10:22

Now just to figure out why the characters are flipped...

Posted by Tomaž | Categories: Digital | Comments »

Galaksija: Populated motherboard

27.01.2007 19:51

I finished populating the motherboard with components. I'll start testing it (and burning stuff :) tomorrow.

After bridging around 200 vias with wire I now fully appreciate the invention of through-plated holes.

This is a photo of the board with all integrated circuits and the big extension connector (bottom right) missing.

Getting real close now

Posted by Tomaž | Categories: Digital | Comments »

Galaksija: Motherboard, plan B

24.01.2007 18:55

I just got a finished PCB for Galaksija's motherboard from our Faculty's Laboratory for semiconductor electronics. Thanks!


Update: some more pictures

Posted by Tomaž | Categories: Digital | Comments »

Life's not just ones and zeros

23.01.2007 22:22

In analog electronics it's in fact mostly noise. Doubly so if there's a protoboard involved.

This the first working prototype of an ultrasonic to audio range heterodyne down-converter I was working on last week (I had some time for playing with this since I was waiting for the Galaksija motherboard to be manufactured).

Bzzzzk k kschhhhhhhhhhhhhh

I just hope that all the white noise I'm getting from it is in fact coming from bad connections between components and the protoboard and not from the opamps themselves.

Posted by Tomaž | Categories: Analog | Comments »

Fancy hidden Firefox feature

21.01.2007 22:27

I've just heard about a well hidden and very useful feature in Firefox from FLOSS Weekly podcast's interview with Ben Goodger. If you right-click on a search field on some website you can add a shortcut to your address bar that makes searching a lot faster.

For example, if you make a lot of searches on, you can do something like this: right click on the text entry and select "Add a keyword". Then type a keyword (like "tablix" for example) in the dialog window that pops up.

Talk about easily discoverable user interfaces

You can now search Tablix documentation simply by typing "tablix" and some search terms separated by spaces in the address bar of your Firefox.

Posted by Tomaž | Categories: Code | Comments »

Things that suck

21.01.2007 0:51

Because I feel like ranting today, here's a list of technical things that have recently been bothering me:

  • Noisy operational amplifiers and the faculty not teaching us enough about how to deal with (or even accurately calculate) amplifier noise in real-life cases.
  • An analog electronic circuit (involving said opamps) which works on the protoboard and for which I'm not able to show analytically why it works (anyone who knows his or her way around trigonometric functions and Fourier analysis wants to help? It all boils down to a simple looking mathematical problem I don't know how to solve)
  • iTunes suddenly forcing me to delete 1/4 of my music collection because there is not enough space on my ipod even though this same collection was stored on this same ipod for a year or so with 100 MB to spare.
  • Ugly Iceweasel thing replacing Firefox in Debian Testing. Suddenly I have three icons in my applications menu that all look like a green blob - one for a mail client, one for a web browser and one for some kind of a profile manager I never bothered to start. Now that kills usability.
  • Having to fix a mail loop on Friday evening at half-past midnight to prevent millions of email messages from being automatically sent across the net by stupid software that was chasing its own tail.
Posted by Tomaž | Categories: Life | Comments »

Tablix on Vista?

14.01.2007 20:36

Somebody obviously did the hard work of porting Tablix and G-Tablix to Windows Vista instead of Boštjan and me :)

This is from, one of the hundreds of "free software directories" that popped up recently on the net and that are disgustingly full of adds. The funny thing is that the download link doesn't even point to the Windows port of Tablix...

Posted by Tomaž | Categories: Life | Comments »

Web two point oh

14.01.2007 14:02

Do you think all this Web-two-point-oh You-control-the-information-age stuff was made possible by fancy XML, Javascript and other technologies I haven't heard about?

Wrong. I think user-provided content on large web sites was feasible only after the use of Captchas became wide-spread. All web pages would be filled with links and advertisements for casinos and porn sites without this inaccessible, politically incorrect and unfortunately also the only reasonably effective way of detecting a living brain on the other side of the HTTP connection.

This post brought to you by last year's disappointment at the impossibility of creating a spam-free comment system that is accessible from a text-only browser (and ignoring specialized solutions such as this interesting example).

Posted by Tomaž | Categories: Ideas | Comments »


10.01.2007 20:19

Today I found this while cleaning up a cabinet in the workshop. It's the first circuit I've put together with the help of my father. Unfortunately it doesn't have a date on it so I don't know when I made this. I also don't remember exactly what I wanted to use this thing for.

It's a simple 1-of-10 encoder made with signal diodes and some LEDs to show the result. It still works :)

Posted by Tomaž | Categories: Digital | Comments »

Galaksija: Motherboard PCB

09.01.2007 10:16

This is printed circuit board for Galaksija's motherboard. I've made it this weekend out of a Bungard presensitized board (the black areas on the photo below are parts where I tried to fix damaged photoresist with a marker).

Motherboard PCB

Unfortunately this material had different properties than the board I used for the keyboard. I should have figured out something was wrong when I saw that the photoresist was brown, not purple and smelled differently.

It seems that 4 minutes exposure under my 500W halogen lamp wasn't enough and after developing there was still some photoresist on the exposed parts of the board. I tried to compensate for this by leaving the board in the etching solution for some more time.

The results aren't encouraging. While the quality of the exposure (sharpness of lines and alignment of solder and component masks) is pretty good there are a lot of holes in the copper that shouldn't be there. It looks like the photoresist got scratched.

This pretty much makes this board useless. I can't make a prototype with a PCB for which I can't be reasonably sure that it is flawless.


I guess it's time for plan B.

Posted by Tomaž | Categories: Life | Comments »

Airport wireless security

01.01.2007 11:55

This popped-up in my Bookmarks menu today at Munchen Airport (via multicast DNS or Rendezvous as Apple prefers to call it. I did nothing special really):

I hope they remembered to order a new imaging drum in time. It's certainly going to wear out quickly when someone sets that each printout must come in 99 copies...

Posted by Tomaž | Categories: Code | Comments »

23C3: General impressions

01.01.2007 11:41

Note: I was writing this in very early morning on 30 December.

I'm currently on train to Munchen. Unfortunately I haven't been able to stay in Berlin for the whole duration of the Congress (this year it's also one day longer - the closing talk will be later today). So far I've mostly posted photographs and didn't write much about my general impressions of 23C3. Now I have several hours to waste on the train and I intend correct that.

Comparing with 21C3 I can say that there were fewer really interesting talks. From the titles and abstracts in the Fahrplan I must say that I expected more. However this may be just because 21C3 was my first visit of such an event and I was mostly amazed at everything I saw then. Anyway, here are some of the most interesting talks I've attended:

Detecting temperature through clock skew by Tobias Gruetzmach was a quite impressive demonstration of how the minute effect of the temperature on the resonant frequency of quartz oscillators can be exploited to track machines on the internet, detect honeypots and even communicate between machines in a rack (defeating the so-called air-gap security).

In the talk How to build a complete FPGA-based DVB-T transmitter Tobias Gruetzmach and Thomas Kleffel also presented a DVB-T (terrestrial digital video broadcasting) system they designed. It was a very interesting introduction into how DVB works and they also showed how relatively simple transmitting equipment can be made for much less money than the cost of professional equipment.

I've already mentioned the Sputnik project in one of my previous posts.

In Console Hacking 2006 Thomas Kleffel presented the state of the art in game console hacking. It's an interesting topic because consoles like XBox are systems that are designed specifically to prevent any tampering and employ a number of intriguing hardware features to achieve that. The talk unfortunately left an impression that the manufacturers are beginning to get more successful - none of the last generation of consoles can currently be modified in a convenient way to run home-brew code.

Finally, Functional body modification by Quinn Norton also deserves to be mentioned. Although not exactly my field of interest, it was impressive to listen about her first-hand experience with a magnet implanted in a tip of one of her fingers. Although I'm a bit skeptical whether this will become a normal thing for people working with electronic circuits in the near future I can certainly agree that it would be quite useful if you could sense electromagnetic fields with your bare hands.

Some notes on the hardware I saw around the conference: two years ago I was surprised at how many people had Apple laptops. This year I believe other brands of (x86) laptops were again more common, however I would estimate that approximately one quarter were still Macs. On the other hand I was surprised at how often I saw Nokias 770. Obviously all that excitement of Gnome developers over this little Linux-running computer had some results.

The theme of the Conference was Who can you trust? remember? Well, at least one participant had some advice to share on that topic. He had the following text written on the back of his T-shirt: Who can you trust? Trust us!

Posted by Tomaž | Categories: Life | Comments »