Things have been crazy here in Tokyo for the past few days. After the Tohoku earthquake, there's been constant streaming of horrible visual images of the disaster on Japanese news. Along with that, there have been warnings of aftershocks up to a magnitude of 8.0, potential nuclear disasters, rolling blackouts, lack of transportation, and dwindling supplies in local supermarkets and grocery stores. It's a stressful situation in Tokyo which has over 25M people and life is anything but normal. It's a chore just to get to work and many feel powerless to do anything but watch the unfolding nuclear situation and hope that it can get contained before a disaster happens. In writing this post, it gives me an excuse to tear myself away from the fear mongering news streams which I'm constantly glued to.

In the hackerspace, we'll be holding our meeting tonight and will probably start hammering out plans to figure out how and where we can help. There are many things that are needed right now in the quake stricken area. There is no power, internet access is extremely limited, food and clean water are dwindling, and transportation to the area is limited. What we decide on will probably depend on what's needed and available at the time.

In any case, one immediate thing that can be done is to provide a source of light to people. With no electricity and limited supplies, flashlights and batteries are a luxury. In the hackerspace, we designed the Kimono Lantern as a solar rechargeable lantern to decorate gardens and patios with. However it has a much bigger use right now as the quake victims have no power and many are spending their nights in the dark. Also, parts of Tokyo will be suffering from blackouts until the power grid can get back to normal levels. With a major nuclear generating plant offline, this could take from weeks to months. 

So although it's outside the original sphere of intended use, it looks like the simple Kimono lanterns we designed can play a small role in providing comfort and at least give a small feeling of safety to people that are going through this horrific experience. I'm currently kitting up as many lanterns as I have parts for to bring to the hackerspace tonight. I'm also donating the complete design to the open source hardware community. I've updated the files to v1.1 and the package includes the BOM and full gerbers. Its a turnkey package that can be taken and sent directly to the PCB fab. The design has already been proven working. I'm also going to email PCB Cart to see if its possible to share my mask files for the lantern with other accounts. That way, people can just reference the mask files and order PCBs directly without having to pay for the PCB mask charge. 

The lantern consumes ~18 mA at 1.2V which is the rechargeable battery voltage. The solar cell that I'm using is a 2V, 80 mA solar cell from Futurlec (SZGDDIA58). On a good day's charge, I think its possible to assume about the equivalent of 3-4 hours of good sunlight which should yield at least 200 mA-hours, taking into account inefficiencies, leakage, bad positioning, etc. This should theoretically power the lantern for over 10 hours, although actual time will depend on how long you can suck on the batteries. The solar cell is also used as a light detection sensor so that the lantern would automatically be shut off in the day time. There is also an on/off switch that can force a shutoff and in that case, the circuit just serves as a battery solar trickle charger. 

I want to donate this design to the community because I think that it would be more effective than just donating money. It's a simple design, but its available now and it's ready to go. Some ways that this design can be used to help the quake survivors are:

  • Kit up the design and sell them in your shop. Some or all of the proceeds can go to the relief effort of your choice. We also need donations at Tokyo Hackerspace for volunteer work and classes.
  • Build a bunch of lanterns and donate them to the quake victims. You can send them to Tokyo Hackerspace and we can make sure they go to relief workers that can distribute them.
  • Donate PCBs or parts to Tokyo Hackerspace. We can have volunteers assemble the designs and have them distributed. The most important parts are the solar cells, NiMH batteries, and the PCBs which are the most expensive.
  • Improve on the design. Saving power, making it more efficient, lowering the cost, tailoring it to specific needs unique to a situation, etc are all welcome.

That is by no means an exhaustive list and there are probably many other ways the design can be used to help out. I'm also hoping that by releasing this design, it can be used for other humanitarian purposes, as well as for people to personally enjoy.

Thanks for listening to me ramble and I hope you enjoy the design. Thanks to Tokyo Hackerspace and iNMOJO for collaborating on this design with me.

The files and assembly tutorials can be found on the Tokyo Hackerspace website below:



Updated 2011-03-15: If you want to donate money for lanterns for the quake victims, you can donate via paypal using the following email: This email address is being protected from spambots. You need JavaScript enabled to view it. . Please leave a note saying that they are for lanterns. All donations will be used to purchase PCBs, solar cells, and NiMH batteries. The rest of the parts will be supplied by the hackerspace. Thanks for all the support and inquiries!
Updated 2011-03-16: Thank you for all the donations. Another 100 solar cells were purchased for the Kimono Lanterns. Looks like things will be busy at Tokyo Hackerspace. THANK YOU!

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