Wed, 02 Jan 2013
PF 2013
I wish happy year 2013 to everyone who reads this blog.
Tue, 20 Nov 2012
SMD Soldering
For the first time in my life, i have tried to solder SMD components (as I have written before, I am working on DYI LED lights for my bike). The component side looks OK, and soldering through-hole components went without problems. The SMD parts were a bit tricky, though.
I have used an ordinary soldering station with temperature regulation, but the results are not pretty. I wonder what is required to achieve this level of quality (watch from 14:10). One possible problem might be that some components on my board (especially the smallest sensing resistors) are connected to the highest-current and thus thickest paths, which suck great amounts of thermal energy when soldering.
Anyway, from the preliminary testing, it seems that my board works. So far I have found the following problems:
- The programming connector is bigger than I expected. I have solved this by using the angled variant instead, and adjusting it using knife :-)
- The silk layer labels marking the polarity of components (electrolytic capacitors, diodes, etc.) can be placed under the components, except for the labels of connectors, which are needed even after the components are soldered!
- I should have added low-pass filters to the A/D converter inputs, at least for the feedback of the PWM-regulated converters. I think I would be able to overcome this in the firmware, though.
- Next time, I would probably design the board with round corners :-)
Now it's time to finish the firmware and to start adjusting the mechanical parts. I have already made the front spotlight and rear spotlight, and I want to make a LED string. Any tips about making a waterproof LED string out of 3mm through-hole LEDs will be appreciated. Should I use silicon, shrink-wrap tube, or what?
Thu, 15 Nov 2012
Printed Circuit Boards
For my bike lights I needed a PCB. Out of several services for manufacturing PCBs, I have chosen Itead Studio PCB prototyping service (the other candidate was Seeed studio). Here are the preliminary results:
I have placed my order on October 29th evening (Central European Time), according to Hong Kong post, the package was received by them on November 7th, it left Hong Kong on November 11th, and I have received it today, on November 15th.
They also have an interesting "Open source" program - the customer declares that his design is open source (mine is anyway), they make few more boards in addition to those the customer has ordered, and they send them to their other customers. The original customers gets his orderd boards, and in addition to that, two more boards from other open source projects. I have in fact got their demo board (on the right side), and one open source board (the white one). Apparently, it is Arduino 512KB SRAM expansion board. I currently don't use Arduino, so if any Arduino user is interested in this PCB, just let me know.
Okay, now it's time to take a soldering iron and play more with the hardware :-)
Tue, 06 Nov 2012
DNS Lookup :-)
It seems my registrar will
discontinue their "free" hosting (as in "bundled with the domain
registration") soon,
so I will have to move my domain yenya.net mail and WWW servers
elsewhere. There is no problem with that - I have a 24/7 running computer at
home with good connectivity. There is one challenge, though:
The new DirectNIC service allows only one A record in the registered domain, when the domain is hosted on their DNS servers (no AAAA and no DNSSEC). So I am considering running my own DNS server in addition to mail and WWW servers. This would allow me to have A and AAAA records, SSHFP, and possibly the new DANE records. So I need someone to host a secondary DNS server. The requirements are:
- Static IP address, running 24/7
- IPv6 connectivity, if possible
- DNSSEC enabled
- Hourly update interval if possible
- Preferably outside the SmartComp/Nebox network
Of course, I am willing to provide the same service to the other party. Is anybody interested? Thanks in advance.
Tue, 30 Oct 2012
Bike Lights
I have a new personal project: I am trying to build a set of lights for my bike. So far my setup is quite simple: I use a 700 mA Buck Puck current regulator to feed a front Cree XM-L white LED and three rear 350 mA red LEDs. It can only be switched on or off, and cannot blink at all. So I wanted to make something more sophisticated.
I have been playing with electronics many years ago in my teen-age years, but I have been doing only software since then. So I have taken this as an opportunity to find out what progress the world of DYI electronics has made, and to learn programming of microcontrollers. I want the resulting electronics to have the following features:
- LED drivers for high-power LEDs:
- Atmel AVR Tiny CPU, programmable in-system (various blinking modes, etc.).
- Power: 7 to 12 V battery pack (either lithium or NiMH).
- Ambient light sensor (for automatically setting the mode depending on the conditions).
- Battery voltage monitoring.
- Cycle computer illumination LED.
- Two status LEDs.
- Two buttons for adjusting modes, switching on/off, etc.
- Software on/off.
- High-power software switched output driven by a MOSFET transistor (I don't know the purpose yet, I just had a spare pin and MOSFET :-).
I have managed to learn how to use the gEDA suite of tools, and created my first PCB with it. Yesterday I have sent the result to the fab. Anyway, I have made the Project Bike Lights page for my project, where it is possible to watch the progress or look at the firmware code, schematics, and PCB design.
Sat, 13 Oct 2012
Those Annoying Endorsements
Recently LinkedIn has added a new feature, endorsements. The most annoying thing is that the requests for endorsements are now near the top of the page, and people are clicking on it. So I have several mails each day saying "$somebody has endorsed you!" (with an "and you are expected to return the favor" subliminal message). So, my dear LinkedIn contacts: feel free to not endorse me and don't bother to write recommendations, as I don't plan to do the same either.
Tue, 09 Oct 2012
Zacyklení 2012
I like outdoor puzzle-solving games, and last weekend I managed to take part in a really special kind of puzzle-solving competition:
Zacyklení is a puzzle-solving outdoor game for cyclists. And what is even more interesting, we have managed to create a purely recumbent team for this game. Those who can read Czech, here is the report from the game. Those who can't, follow the link anyway for more photos :-). We have not made it in time, but among all the teams we have finished somewhere around 5th place. Congratulations to the winners, and thanks to the organising team!
Thu, 20 Sep 2012
Hanwag Boots
Afters about 10 years, my Hanwag Alaska boots have disintegrated while I've been walking in the forest during this year's Svíčky. I will need a new boots. Which boots do you recommend, my dear lazyweb?
I have been satisfied with Alaska, and I have chosen them because the big part of the boot is made from one piece with only one seam i the back. However, the middle part of the sole has completely disintegrated. The consipration theory follows: I wonder whether it could be intentional from the manufacturer, in order to not allow their customers to use the product for more than 10 years. In my opinion it should be possible to find a material which lasts almost indefinitely. That said, from my previous experience the sole was the weakest part of all my previous boots in terms of endurance. So maybe it is perfectly OK to expect the boots to last only 10 years. What do you think?
Wed, 19 Sep 2012
Playing with Prezi
A while ago, I've came across Prezi presentation tool. It is completely different approach to presentation than slides with bullet-points. I didn't like the dependence on either the on-line access with Flash, or on the Windows executable (with embedded Flash, of course). Today, I did my first presentation using Prezi (together with Šimon).
We have been given 10 minutes to present our approach to two sub-tasks of the Plagiarism Detection task of PAN 2012. We used Prezi in order to be able to focus on explaining our approach without devoting too much time to explaining the structure of the talk to the audience. I think this is a great strength of Prezi, if used correctly.
So, my dear readers, do you think Prezi can be a useful tool, or do you instead agree with Peter (in Slovak), that it is just an over-glorified eye-candy? You can see our presentation here. Thanks to Yuri for the photo!
Sat, 14 Apr 2012
My New Bike
Several months ago, I have written about choosing a new bicycle. Here is the outcome:
Introducing my new AZUB Apus. I have rented and extensively tested several recumbents from AZUB (20" Eco with above-seat steering, 24" Max with under-seat steering, and 26/20" Apus with above-seat steering), and I have decided to go for Apus with under-seat steering.
The next thing to decide was gearing. After testing 24" Max with 48-38-26 chainrings and 11-34 sprocket (about 570% ratio) I've got the feeling that I could occasionally use even slower gear (and with 26" rear wheel of Apus the 26/34 gear would be a bit faster than on a 24" wheel), and I can definitely use more faster gears. Recumbents are fast, especially going downhill, because of lower aerodynamic drag. So I wanted gearing with ratio larger than 570% and with the slowest gear slower than 26/34. This is hard to achieve with current components, so I went for triple gearing: I have got SRAM DualDrive in-hub planetary gearbox (three speed gearbox and 8-speed derailleur), combined with tree chainrings, giving me 3x3x8=72 gear combinations and over 920% ratio. One of the biggest advantages is that the gearbox gears can be changed even without pedaling, for example after having to stop unexpectedly.
After five months with Apus, I am still excited with it. I really enjoy being faster on flat surface and on downhills, being able to pedal even while turning, having excellent view with zero neck, wrists and backbone pain, being able to brake without the danger of falling ahead, sitting lower in case of fall, and so on.
The drawbacks are worse view when entering street crossings, being slower uphill, and not being able to jump over obstacles higher than about 10 cm). And the front suspension of the SASO carbon fork is not as good as I expected. I plan to try softer coil spring.
If I had to choose again, I would buy the same bike, possibly with not-so-steep sprocket (11-28 instead of 11-32). Also, having used really narrow tyres on my previous (road) bike, I did not pay much attention to the brakes - I have got V-brakes on my Apus, and I am not able to make the front wheel slip even when braking really hard (on asphalt roads). So probably next time I would get disc brakes instead (at least on the front wheel). Anyway, watch this guy's commute riding Apus on forest paths:
Mon, 18 Jul 2011
Which Bike?
The 30 years old frame of my bike broke several weeks ago, so I will need a new bike. We have already decided to buy a new bike for my wife, so I have took the frame of her present bike, and remounted some components of my former bike to it. So I don't need a new bike right now, and I have more time to decide what I want.
My previous bicycle was road bike with drop handlebars. I ride on paved roads mostly (altough many roads in Brno resemble off-road riding :-), and we occasionally do touring as well. I am considering the following options:
- Using the frame of my wife's bike until it breaks :-)
- Buying a cyclo-cross bicycle, which is essentially a road bicycle with hardened frame and different tires.
- Buying a touring bicycle, something like Author Avion, which even has a carbon frame.
- Something really different. Last week I rented a recumbent bicycle, AZUB ECO. It was really interesting, very comfortable, yet a bit difficult to drive. I would like to try a bigger one with under-seat steering, like AZUB 5 as well. The only problem with recumbents is that it is not possible to use them with trail gator tow bar.
So, my dear lazyweb, do you have anything to recommend?
Fri, 03 Jun 2011
Citroën Xsara
It has been seven years since I have bought my Citroën Xsara. At that time, I have considered several models, looking for an estate car for my family. Having used several Škoda Felicia cars in my previous job, I have definitely wanted a car from some other manufacturer. My opinion was "the car can have its problems, but at least let it be different problems than Škoda have".
That said, I have never considered Citroën, and in fact I did not know much about Citroëns. When I have been offered a 4.5 years old imported Xsara, however, I have found it "good enough" for me to buy.
Subsequently, I have been pleased to find out how comfortable my Xsara was, and how well equipped compared to the cars of similar age and class it was. It provides enough leg room in back seats (especially when compared to Octavia), and the 82 kW engine provided enough power for most of my needs. During almost 100,000 km in seven years I had only few malfuncions, the most serious one was a broken exhaust pipe because of corrosion.
Even though I did not originally considered buying Citroën at all, the next car which I have bought and which I use these days is also Citroën. So, my dear lazyweb, is anybody in your social network interested in buying a cheap, well-equipped, used car? If so, look here.
Mon, 31 Jan 2011
Is My Teaching Getting Bad?
The results of the final exam of the UNIX - Programming and System Administration I course make me wonder whether I am getting gradually dumb or bad at teaching.
I used to think that as I teach, I am getting to know more and more about the subject, as well as have less errors and more clean formulations in my presentations. My lectures are now available from the video archive, so the students can rewatch me presenting the topics they have not understood the first time again, if they wish. I have switched the presentation format from old and boring black-and-white DVI slides to new, colored, shiny and graphically rich LaTeX-beamer format (thanks to Jiří Boček from servistech). Also the exam format and even some of the questions are still the same as they have been since eight years ago.
So what am I doing wrong?
Tue, 04 Jan 2011
Outgoing Mail
I archive every e-mail message I have sent since April 1999. Today during making backups of this data I have decided to count how many messages I have sent each year:
| Year | Messages | Bytes | Bytes/message |
|---|---|---|---|
| 1999 | 2110 | 5082832 | 2408 |
| 2000 | 3211 | 9393052 | 2925 |
| 2001 | 4693 | 30317777 | 6460 |
| 2002 | 7122 | 22466804 | 3154 |
| 2003 | 7669 | 25649473 | 3344 |
| 2004 | 5664 | 19496614 | 3442 |
| 2005 | 5311 | 22807724 | 4294 |
| 2006 | 5375 | 22106651 | 4112 |
| 2007 | 4828 | 33458711 | 6930 |
| 2008 | 4575 | 28287830 | 6183 |
| 2009 | 4715 | 27140012 | 5756 |
| 2010 | 4727 | 35894517 | 7593 |
The variance is relatively high, but apparently e-mail messages are getting bigger with time (no surprise here), and I have sent less messages than I used to send five to eight years ago.
Mon, 03 Jan 2011
PF 2011
I wish happy year 2011 to everyone who reads this blog.
The image is from Pink Granite Coast in Brittany, France. I plan to post a follow-up series about the places I have visited last year, including this one.
