[Nirav] liked the idea of having his own personal Earth at the tip of his fingers, and since that’s not happening any time soon, he decided to build the next best thing. Sure, he could have simply gone out and purchased a globe, but there is no fun in that. Instead, he shows us how he put together an interactive spherical display that won’t break the bank.

The sphere uses a Microvision SHOWWX to drive its display, which projects an image inside of a frosted glass light fixture. The pico projector gets some help from a 180° fisheye lens along the way, enabling the picture to be stretched across the entire inner surface of the globe.

[Nirav] used his 3D extruder to build a base for the globe, which attaches to the projector via a printed mounting plate. A GorillaPod was used to keep things upright while he dusted off his trigonometry skills in order to figure out how to get the image just right.

We think that he did a great job – it definitely looks to be on par (albeit a bit smaller) than the eye of Sauron globe we saw a while back. We can’t wait to see a video of this thing in action once it’s completely finished!

[Ytai] let us know about his POV globe, all four parts of its current progress. While he says he was inspired to write up the project from a YouTube clip, we know the real reason. Regardless, the plan is to have a 2 foot diameter globe with 256 LEDs spinning at 50 revolutions per second streaming images from an SD card using SPI. While the project isn’t completed yet, we know [Ytai] will pull through like he has in the past, and you can be sure we’ll keep you up to date on his progress.

Here’s a slick version of a POV globe(google translated). Created by [Riko], this globe has 32 LEDs and is powered by a rotating coil. The layout looks fairly solid in operation, with the POV effect showing up very nicely on camera.  You can get the schematics and source code from the project page.

We found this project, just like the previous fantastic LED globe on HackedGadgets.com. Apparently someone linked to this project in the comments. That is fantastic, that is what the comments should be for. Please help keep our comments polite and helpful as well, even if you are just linking to a project that you think is better.

[Ben] told us about his POV globe yesterday. We took a look and saw just one photo and the code with no real explanation of his project. He certainly set to work over night and now we see all the goodies we look for in a great build log. He even threw the Hackaday logo up for our enjoyment. His build is well executed and he found some creative ways around the common problems in these projects. We take a closer look after the break.

[Ben's] design looks much like an actual globe, with a base, a frame, and a rotating ring mounted with its axis tilted (just like the earth). 72 surface mount LEDs are used for the display, a PC fan with the blades removed provides the rotation, and a reed switch in conjunction with a magnet is used to sync the rotation with the display parsing.

Surface mount components are meant to be placed and reflowed on a circuit board. They are usually considered too small for free-form circuits. [Ben] made this process work for him by lining up all 72 LEDs face down on the sticky side of some masking tape. This made it much easier for him to solder together the multiplex needed to interface them with the microcontroller. You can see he is using varnished wire that can be soldered directly without the need for stripping. [Ben's] using a slice of a clear DVD-R container cover as the rotating ring for the display. On the right side of the picture above you can see the completed LED multiplex installed in this transparent ring.

Getting power to the rotating part of a POV display is always an issue to consider. [Ben] tried feeding the connection through a brush motor but had problems with power loss. His next attempt involves using a headphone jack and connector as the pivot point. Regulated power and ground are passed through two of the connections and he’s had great success with this system. Above, you can see the connector before it is fully inserted in the jack on the protoboard.

A reed switch is glued to the transparent ring and is actuated when it passes a bar magnet on the frame. This allows the microcontroller to measure the rotation of the ring, and sync the display output.

[Ben's] done a great job here. He salvaged a lot of the parts, including the LEDs. He’s chosen an Atmel AVR ATmega8 for the microcontroller. This is an inexpensive and readily available chip that is pin compatible with the more powerful ATmega168 so there is a possibility of future upgrade if animations or other functionality are desired, requiring more programming space. We would suggest a decoupling capacitor on the power pins of the uC in order to help filter out any noise on the lines, especially considering the rotating connection used to provide the regulated power.

WE WANT ONE!

There is much more information on how they got the pieces to work together, as well as some videos in french showing the device working. One thing that stands out though is that they decided to use direct association on their Wiimote, thus stopping rogue Wiimotes from gaining control. Who would carry a Wiimote around just to hijack public displays? We would.

[thanks Leucos]