Laser power system keeps UAVs flying indefinitely

Drone technology is driving the aerospace industry as companies trip over each other trying to develop the next big thing. Here’s a good example of what we’re talking about. Lasers can no be used to keep a UAV in the air indefinitely. The trick is to add an array of photovoltaic cells specifically tuned to an IR laser’s wavelength. A ground system then directs a high-intensity laser beam onto the aircraft’s cell array to transfer energy while in flight.

After the break you can catch a video from a trade show where a Lockheed Martin employee describes the successful testing of such a system. But there’s a lot more information available in the white paper (PDF) which Laser Motive has released. They’re the folks behind the technology who have teamed up with LM to implement the system. The laser unit on the ground can track a UAV visually, but there is also a method of using GPS coordinates to do so in the case of overcast skies.

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Firefly cap has no battery and is meant for indoor light harvesting

[Michael Ossman] wrote in to show off his newest project. He calls it the Firefly cap, which we think is something of a play on words. You can see that it serves as the cap of a Mason jar, but it also uses a supercap instead of a rechargeable battery.

Posts about firelfly jars go way back. And [Michael] mentions that a similar firefly project was his first embedded project. The concept uses LEDs suspended in a jar. When a light detector senses the target level of darkness, the lights inside begin to twinkle like their insect namesakes.

We like this design for two reasons. It’s aimed at collecting light in an indoor environment so you don’t have to worry about placing it in the sun. And it uses a super capacitor instead of a battery so this should truly keep going and going without wearing out the energy storage components. We also like the fact that although this is a Kickstarter project, everything you need to build your own is already available at the Github repository.

Crunching the numbers: using solar cells indoors

[Mathieu] was interested in using more solar cells for his everday electronics. He looked around but couldn’t find much information about using pholovoltaic for small indoor devices. We remember hearing some of the same things from [Dave Jones] in one of his EEVblog installments from a few years ago which looked at solar calculators; the only indoor solar gadget we can think of.

The quest for knowledge was on and [Mathieu] decided to build this indoor solar cell test platform. It’s a stable piece of hardware that allows him to run reliable tests in many different conditions. It’s designed to compare two identical cells. One is charging the Lithium cell, the other is driving a load directly. A second battery powers the platform separately from the solar circuits so that it can be used as a data logger. He collects, dumps, and graphs info from his test runs, then discusses his findings. We won’t spoil it, but the results are not great. Mostly you need sunlight to get real results as it’s just so much more powerful than artificial lighting.

Printable solar cells that can be folded up when not in use

Here’s a photovoltaic cell that can be printed onto paper. The manufacturing technique is almost as simple as using an inkjet printer. The secret is in the ink itself. It takes five layers deposited on the paper in a vacuum chamber. But that’s a heck of a lot easier than current solar cell fabrication practices. In fact, is sounds like the printing process is very similar to how potato chip bags are made. This is significant, because it could mean a fast track to mass production for the technology.

It isn’t just the easy printing process that excites us. Check out the video after the break where a test cell is placed on top of a light source while being monitored by a multimeter. It’s been folded like a fan and you can see a researcher sinch up the cell into a small form for storage. It’s a little counter-intuitive; for instance, you wouldn’t want to make a window shade out of it because it would have to be down during the day to get power. Be we think there’s got to be some great use for these foldable properties. [Read more...]

Solar powered cellphone a true hack

The polished quality of this hack isn’t quite there, but we love the ingenuity and exploration exhibited. [Paulie1982] shows us how to make an old cellphone work with the rays of the sun.

You can see above that he’s added photovoltaic solar cells to the back case of what looks like an old smart phone. He grabbed the cells from two inexpensive solar landscaping lights and inserted them by cutting holes in the case and using black silicone sealant to glue them in place. Each can pump out about 3V and together they get above the 5V threshold that he needs to do some charging. See the build process in the video after the break.

From what we’ve seen there’s zero consideration of current in this hack and that’s what makes us skeptical. Still, we love the idea of trickle charging and we’d love to see some speculation in the comments about how to improve upon this. Surely the additional hardware necessary for proper regulation, etc. could be fit in a custom case cover like the one used for this inductive charger hack.

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Thermoelectric Solar Power


[Colin] has put together an instructable for a solar power generator that uses the thermoelectric effect instead of the photovoltaic (PV) effect. We have seen Peltier devices used in cooling cans, solder paste, backs, and hacked hard drives. This is the first hack we have seen where a Peltier device is used to generate electricity from heat, essentially running the device backwards. The thermoelectric effect is the same principle that is used to generate electricity in radioisotope thermoelectric generators used in deep space probes such as Cassini. What applications can you come up with to use the thermoelectric effect as a power source?