There might be an MCU in this design to help manage energy, but even if there is no MCU, this nifty device is a great fit with our tagline: "Changing the world, bit by bit." It is a gravity-powered LED designed for rural areas far from power utilities, and scheduled for field trials in Africa.
The device came to my attention through a reader post here on Microcontroller Central. (For those who don't know, there are Reader Message Boards where you can start up discussions of your own. Click on "Messages" above the orange line, then on "reader boards" on the page that comes up.) I thought it was a marvelous idea as well as a clever bit of engineering. It is the GravityLight, and it aims to bring reliable, low-cost electric lighting to rural areas.
Basically, this is an LED lamp with a dimmer and a built-in generator. The key thing is that the generator is powered by gravity, using a falling weight as in a grandfather clock to create up to 30 minutes of lighting. No battery. No hand crank. No solar panel. It can be set up and used virtually anywhere, and only needs user action every half hour or so to keep the lights burning. From the video it appears to be fabricated mostly out of high-strength plastic, including the gearing that turns the slow drop of the weight into the fast spin of the generator that provides the electricity. If there is an MCU in there, it probably serves to control the LED drive circuitry.
There are several things I admire about the engineering that has gone into this design. One of them is the abandonment of the more traditional battery approach to use pure energy harvesting to power the light. Another is the efforts made to keep the design simple and rugged to maximize its field life. Cost-saving measures such as re-using the storage bag as the weight holder, and using local dirt or rocks as the weights, are another noteworthy touch.
The GravityLight is still in prototype stage, and the creators, who work for design consultancy Therefore, are looking for funding. They aim to fabricate a prototype run of 1,000 units for donation to villages in Africa, where they will provide the villagers with free electric lighting and the creators with a field trial of their design. Their funding effort with Indiegogo runs through January 15.
Aside from the great social benefit this design can provide, I am impressed with its merits as a commercial product. I can imagine backpackers, for instance, carrying one along instead of gas lanterns or batteries. It would also make a great compact emergency light for home use. It could have been very handy for those folks without power on the US East Coast after Hurricane Sandy a few months ago.
MCU or not, this seems to me worthy of mention here as a well-thought-out bit of design engineering. Simple, elegant, functional, practical, durable, and inexpensive. Wish I could have done half so well with my efforts.