Kanazawa: nicotech and tourism

I had wanted to visit Kanazawa city for more than 8 years, since my Japanese teacher in Spain (Hattori-sensei) made a reference to it during a class. After the Shinkansen to Kanazawa was finished a couple of months ago I had no choice but to visit it.


What a better excuse than the celebration of the Nicotech event in Kanazawa, which gathers DIY hackers/makers to show their new crazy inventions such as a dice that always comes up 6; or a relay-controlled melodica presented by nezumi-san. Other inventors: natok (@natok), and @mayusaki3 (check the twitter hash #NT金沢).


If anything, Kanazawa is famous for its splendorous Kenrokuen (兼六園) garden, developed by the Maeda clan and one of the 3 great gardens in Japan. If you were only going to spend a few hours in Kanazawa, the Kenrokuen garden would be the thing to see. When you are there, try to find a sign with a haiku written by Bashō that says: あかあかと日は難面もあきの風 (akaaka to hi wa tsurenaku mo aki no kaze). As many other haikus, this one also talks about the change between seasons, in particular from Summer to Autumn. My personal translation would be something like: "The sun shines red, ignoring the Autumn winds". Here are a few other translations. A decomposition of this haiku can be found here (in Japanese).


Other attractions in the city are its tea houses (Chaya). There are two famous tea house districts: Higashi (east) and Nishi (west) Chaya. However, I'd suggest you to check this non-touristic tea house called Shōkōan (旧園邸・松向庵). See the access map and pictures from inside.


Kanazawa also has a famous fish market called Ōmichō, where you can buy different types of fish and seafood. There are also a few restaurants if you want to try sushi, crab, kaisen-don (a bowl of rice with different slices of raw fish) or any other delicatessen. Here is a nice guide to the food of Kanazawa in pdf. I would also recommend the restaurant "arroz" (rice in Spanish) where you can eat a delicious "cocido" as the one in the picture above.


Kanazawa has also a Samurai district called Nagamachi (長町) though it's not as big as the other tourist attractions.


What I liked the most about Kanazawa was its relaxed atmosphere; the river that crosses the city which was very close to the place I stayed in; and the fact that you can rent a bicycle to go around the city.

Getting an amateur radio operator license in Japan (4th level)

About one year ago, I went to see the Japan Ham fair in Tokyo. Despite having studied about radio communications at University, the amateur radio (ham) world was still unknown to me.


Near the entrance there was a stage with talks about the ham world. Many of them were introductory so I listened to a few. I wanted to learn what's so fun about amateur radio that you can't do with the Internet. These are a few ways to enjoy amateur radio that I learned of at the ham fair:
  • Talking to your neighbours: a good way to make new friends.
  • Hiking a mountain and trying to get far-away signals from the top.
  • Talking to people from all around the world: I was pointed out by someone that amateur radio operators are usually well-educated people and allow for good conversation.
  • Enjoying it from a technical point of view: improve your equipment with better antennas or transceivers.

The ham fair wasn't just about introductory talks though. There were many booths organized by amateur radio fans and radio equipment sellers. In a way, it reminded me of a Makerfaire exhibition. In fact, this fair can be very convenient if you need to buy oscilloscopes, function generators or frequency counters at a low price tag.


With all the excitement, I decided that this was cool and elitist (kidding!), and that it might be worth giving it a try. I bought a book for the 4-th level (easiest) of the Japanese amateur radio operator license test, which is all you need to get started. On the spur of the moment I also bought an entry-level walkie talkie valid for the 144MHz and 430MHz bands (see other frequency bands here).


I took the test the Japanese way. That means I had to learn many Japanese technical words. In retrospective, I'm glad I went the hard way because now it's easier for me to talk about amateur radio with other Japanese fans. Note however that you can also take the exam in another country and have it validated by JARL (Japanese Amateur Radio). The test is held in several Japanese cities. If you live near Tokyo, then you are lucky because you can just show up on the test day without previous registration. Check the dates here. You just need to go to 日本無線協会 (map link) bringing with you a copy of your 住民票 (get it at your ward office), 2 photos, a pencil and the money for the exam (~5070 yen) and the operator license (~2270 yen). The test is divided in two parts: engineering and law. As I went through the book I tried to summarize most of the knowledge required in the two diagrams above. I have also prepared a cleaned-up text version here in English for you. I hope it's useful to someone. After passing the exam, on the same day, I applied for the operator license. A couple of weeks later, I got my license card by post and next I applied for the radio station license (you need two licenses: operator and station). Ok, I guess that's all for this post. Hope to see you at Japan ham fair 2015!!

Makerfaire Shenzhen 2015

Last weekend I visited Shenzhen to attend the Makerfaire. I used a low-cost airlines called Vanilla Air (20,000 yen for a return flight from Narita airport) to get to Hong Kong airport. From there I took a shared limousine car to my hotel (220 Hong Kong dollars). There are cheaper ways to go. However, this was the best choice as I would later realize that it would have been a nightmare to find my hotel otherwise.


This were the views from my hotel room (Shenzhen She & He Apartment Shenlan). The hotel was actually an apartment in a tall building. Despite its low price, the apartment was rather clean and it had a fridge and a kitchen. It's location was perfect for going to the Makerfaire on foot.


Makerfaire's location was awesomely situated among several modern buildings, and was decorated with numerous posters and maker-related objects. However, it was mostly open air so I was wondering what would happen if it started to rain. Fortunately, Shenzhen is a very sunny city and apart from a light rain on the last day we had mostly good weather.


As usual, all booths were filled with creativity and new ideas. There were booths showing hobby projects as in many other Makerfaires I've attended. Surprisingly though, there were many more booths showing already finished products. I think that that was the main difference with other Makerfaires I've been too. As a manufacturing hub, I guess that living in Shenzhen makes it easier to develop your ideas all the way to the final product. There were also big commercial booths from companies such as Seeed studio (who announced Genuino in partnership with Arduino) and Mediatek.


Once I had seen all of the booths several times, I decided to go downtown and checkout Shenzhen's electronics town. I took the subway (Shekou line) and stopped at Huaqiang North (华强北) station. Then I tried to find buildings with the name SEG or 华强电子世界 (Huaqiang electronics world) on them. There were several ones actually. Typically, the first floor is dedicated to small booths selling electronic parts, and booths on higher floors sell consumer electronics and the like.


My impressions of Shenzhen as a city were very good. It was a clean and safe city with modern buildings and department stores. There were lots of new buildings in construction so I expect Shenzhen to become one of the biggest cities on Earth in a near future. I'm sure I will be back here.

Periscope-type DVD Spectroscope

A few months ago I became a member (友の会) of the Japanese National Museum of Nature and Science. One of the benefits of being a member is that you have free access to the installations any time of the year. In particular, this is useful if you plan to attend seminars and workshops organized by the museum. A month ago I participated in a workshop organized by professor Fumitaka Wakabayashi. The topic of the workshop was building a periscope-type DVD spectroscope.


I was gladly surprised when I arrived at the workshop and received a folder containing: professor Wakabayashi's papers, a light map, a periodic table, and of course the materials to build the spectroscope which were:
  • The main body: made out of a sheet of card stock (the internal side should be black). The spectroscope pattern can be downloaded here.
  • A 45° (1/8) sector that was cut with scissors from a cheap DVD after heating it at 60~70°C. This is used to refract the observed light source, in a similar fashion as a prism. You can use methanol to clean the surface.
  • A 15x15mm mirror plate (available at Tokyu hands with the name ミラープレート) or alternatively an acrylic mirror.
  • Double-side sticky tape: used to fixate the mirror and DVD onto the main body.

The way the spectroscope works is very simple. The light whose spectrum we want to measure enters through a slit (a very thin hole) into the spectroscope, and gets reflected in our mirror. Then it travels towards the DVD sector, where the light gets refracted. On the viewing window we can install a camera (e.g.: your smartphone's camera) in order to capture the spectrum of the light.


For instance, this is the spectrum of a Toshiba FHC34ED-Z lamp as captured from my smartphone's camera.


To analyze the picture, we can use the software ImageJ following the next steps:
  • Image>Transform>Rotate: straight up the image so that it is horizontal (or vertical). You can check the "preview" checkbox for an interactive manipulation. Also, make sure that blues (lower wavelength) are on the left (or top) of the picture.
  • Select a thin rectangle with the rectangle tool
  • Analyze>Plot profile (Ctrl-k, or Ctrl-Alt-k if the image is vertical): a intensity graph appears.
  • Click copy and paste the data in libreoffice calc or excel
  • Convert pixels to wavelength(nm) by identifying well-known wavelengths (e.g.: 404.6565nm, 435.8335nm, 546.75nm, 576.961nm, 579.067nm). You can do this with Analyze>Calibrate in ImageJ or with a spreadsheet/script able to calibrate the wavelength of the spectroscope.

Finally, you can check your lamp's catalog and compare the spectrum you got and the one measured at the factory.


There are other ways to create a simple spectroscope. For example, I built the one above using a chips box and a linear diffraction grating sheet from Edmund optics during another session at the Japanese National Museum of Nature and Science.

Reference papers:
  • Fumitaka Wakabayashi, Kiyohito Hamada, A DVD Spectroscope: A Simple, High-Resolution Classroom Spectroscope, J. Chem. Educ., 2006, 83 (1), p 56.
  • Fumitaka Wakabayashi, Resolving Spectral Lines with a Periscope-Type DVD Spectroscope, J. Chem. Educ., 2008, 85 (6), p 849.