Twitter can be a great tool for keeping up to date with your favorite person/company/band/etc. You can find a Twitter client for just about anything that plugs in these days, but sometimes we find that we simply need a break from our computers and smart phones – even if just for a few minutes. What happens when you want to unplug, but still need to know what everyone is up to?

[Patrick Dinnen] asked himself the same thing, and decided that the solution was a mechanical Twitter feed display. The display consists of a static user list strung up against the wall, with a mobile speech bubble mounted next to it. The bubble moves to the user who has most recently updated their status (presumably using a pair of servos), and uses a projector to display their messages. The effect is pretty neat, and it still allows you to get your Twitter fix without staring blankly at your computer screen or smart phone.

We think it would be even cooler if it used a projector on both sides, enabling it to dynamically shuffle through users and status messages at the same time. [Patrick] says that for right now it is merely a proof of concept, so there is no telling how he’ll tweak it going forward.

Continue reading to see his mechanical Twitter feed in action.

[via Adafruit]

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Augmented reality might be all the rage these days, but when you take a closer look at the technology, you will find that these sorts of optical illusions are not new at all.

Artist [Sebastian Schmieg] was pondering augmented reality for a bit and decided he could replicate the effect using old and obsolete technology. His creation, called “81 Points of View”, uses an old Kodak slide projector and an elaborate mechanical setup to simulate the effect.

The slide projector resides on a platform that can be rotated around its center in 81 steps. After each movement, the mechanism swaps out the current slide, selecting the next image depending on which direction the user turns. The resulting effect is similar to the implementations of augmented reality you might see today, with a 3d visualization superimposed on the surrounding room.

The concept dates back all the way to the 1860′s, when [John Pepper] first demonstrated the technique. Using mirrors and panes of glass, he was able to project translucent images in front of his audience, which is the same idea [Sebastian] uses in his project. You are likely quite familiar with the effect, if you have ever visited the Haunted Mansion at a Disney theme park.

It’s a neat project, though the resultant augmented reality display is obviously not quite as smooth as you would see from a smartphone. Either way, it is definitely worth checking out. Keep reading to see a video of the project in action.

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[Devon] recently repaired a handful of Phillips LCD projectors which he was quite excited to use. The only problem is that he didn’t want to mess with replacing the bulbs after every 2000 hours of use at $100 apiece. He was pretty confident that he could find a better way to drive the projectors, so he disassembled them once more and started looking around for bulb replacements.

He figured that a high-powered LED would do the trick, so he ordered a handful of parts and went about his first retrofit. Using his oscilloscope, he found that the control board pulses the high voltage board when the projector is powered on, and continues to pulse a signal until the machine is turned off. At this point, the HV board powers down the bulb.

He created a small circuit using a PIC that is used to interpret the initial pulse from the control board as well as watch for the steady “heartbeat” pulses that occur while the projector is powered on. This board is used to control the driver board for the high-powered LED he purchased.

His bulb replacement works well as far as color fidelity is concerned, but is not nearly as bright as he hoped for. He has plans to source some far brighter LEDs or automobile HID lighting in the very near future, and we look forward to seeing if he can match the brightness of the original bulbs.

[Jose Carlos Veloso Junior] has been working on his 3D printer to improve the resolution. We looked in on his project back in October when he was printing the blue busts like the one seen above.

We were impressed by the resolution he was able to achieve back then, using liquid resin that is cured with visible light. The resin creates a thin layer on a glass tray, and is cured when a projector shines precisely positioned light from below. The cured resin is then lifted on the Z-axis, and the next layer in the printing process is hardened by the projector’s light.

Well, this newest rendition far outperforms the initial iteration. The bust on the right looks like it’s been hand-buffed to remove the layer lines, but it actually just came off of the printer. [Jose] made a video of the new equipment in action, which you can watch after the break. He’s keeping most of the juicy bits to himself but he did tell us that the improvement he achieved were due to multiple changes in the process. He tweaked the software to use a more precise curing time, the resin formula has been improved, the ability to isolate pixels without hardening resin around them has been stepped up, and he’s made changes to the way the printer is calibrated and how it lifts the hardened model.

This is fantastic. Kudos to you sir!

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[Jon Howell] came up with what he calls a gratuitous project which projects his name on his office door. The thing is, his office door slides on tracks so he made a projector that can follow the movement of that screen. He used a laser printer to make a black and white pattern that indexes the movement of the door using a quadrature encoder. When it senses door movement a servo motor rotates the projector to match the change in the door’s location. As you can see in the video after the break it works even if the door is moved quickly.

We do agree with [Jon], this is a bit much. But it might be something to build into smart white boards that are mounted on sliding tracks. We guess that if you don’t plan to change the message being projected, which is the case with [Jon's] office door nameplate, this would be a great way to use the image projector build we looked at yesterday.

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There’s a pretty good chance that you already have everything needed to make this image projector. We thought that yesterday’s video projector was simple, but this one makes it look like a super-computer in comparison. [Esrun] grabbed a flood light, some transparency film, and a common magnifying glass for use in his still-image project. This is more-or-less an overhead projector without the mirror, but we though it was worth sharing in hopes that it would spark your imagination and produce some other projector-oriented hacks.

The real tricks in this build are alignment and focal length. A single piece of lumber was used to help keep everything in a straight line, leaving just the vertical alignment to account for. In order to get the image in focus, [Esrun] had to do some testing for positioning the transparency film and the lens. In the end he added strips of velcro to the base to make the components easy to move. He plans to add an enclosure and change from an incandescent bulb over to a set of LEDs. We’d like to see the addition of a carousel that can house multiple transparency sheets. That or a side-scrolling roll to give it more of a film-strip feel.

Here’s a video projector that [Matt] hacked together. He needed a small and inexpensive solution to use with his R2D2 build. As you can see in the video after the break, it has no problem playing back the Princess’ distress call. But even if R2D2 is not one of the droids you’re looking for, we think this can be useful in other ways. One use that pops into mind is for projector-based Halloween displays.

As with past projector hacks, all you really need to pull this off is a light source, an LCD screen on which you can playback video, and a lens to focus the light onto a screen. Usually the LCD is the most expensive part of the project and building an enclosure to the correct dimensions can be a bit difficult. [Matt's] solution was to use an MP4 knockoff media player. The rest of the setup is a ’50s era slide projector. The screen from the media player is about the same size as a single film slide, so he removed the screen from the case and put it where the slides go.

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Strap yourself in, it’s going to be a bumpy ride. No really, if you don’t believe us, check out the video after the break of this bouncing and rolling game system. [Shawn McGrath] built it to compliment the gaming experience for Dyad, an indie game for which he is a developer. His wife was kind enough to demonstrate the machine, which utilizes one motor to rotate the display and cockpit, and another to add vibration to the experience. The parts for the system were mostly salvaged, with the addition of a projector for the display and a PlayStation SixAxis controller to sense the motion of the rig. The motors are powered by a 600W computer PSU and controlled by an Arduino. It helps that [Shawn's] a developer because he was able to add feedback hooks to sync with the gameplay.

It’s not as intricate as the best flight simulators we’ve seen, but it will be fun for that next kegger.

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