Hackaday Links: March 20th, 2013

March 20, 2013 by Ryan Fitzpatrick 23 Comments

Giant fresnel lens is dangerous fun

Here’s an interesting, and rather dangerous, use for those old big screen TVs that are frequently listed for FREE on Craigslist. With the lens from the old TV built into an adjustable wooden frame, [Grant] was able to melt a stack of pennies, instantly burn wood, melt spots in concrete, and serve his family a cooked egg… Cool.

Projection mapping app helps create hologram like performance stage

projection-mapping-app-creates-live-desktop-stage

[Aimino] used an iPad, a mobile projector, and a mosquito screen to create a trippy hologram like stage. It might not seem like much at first, but it’s actually a pretty interesting effect. Watching the video makes me wonder what other applications this could have in the near future.

The world’s strongest magnet

worlds-strongest-magnet

At a cost of over $14 million dollars and weighing in at 35 tons, the 45 Tesla Hybrid is the strongest DC magnet on Earth. It’s powerful enough that the film crew couldn’t even safely get in to take footage of it. Over half of their camera tapes were wiped clean just while being in the same facility that houses it!

Virtual Body chair uses 4 of our 5 senses

virtual-body-chair

Created in the hopes of providing a VR experience for seniors with mobility problems who can no longer travel the world, Tokyo Metropolitan University’s Ikei Laboratory presents the ‘Virtual Body’ exhibition. Included are a 3D monitor, a pair of headphones, a fan to create breezes and spread scents, a chair that moves and vibrates, and moving foot pedals.

Iron Man laser gauntlet pops balloons with ease

functional-iron-man-laser-gauntlet

If you’re an Iron Man fan with disposable income, you might want to check out this functional full metal laser gauntlet. Built from scratch using no blueprints or guides, [AnselmoFanZero] sells them for around $3K USD.

Everything You Need To Build A Light-cured Resin 3D Printer

March 6, 2013 by Mike Szczys 28 Comments

dlp-projector-resin-printer

[Rachel Levine] was one of the mechanical engineers on the team at the Rochester Institute of Technology who built this resin-based 3D printer. She wrote in to show off the fantastic work they’ve been doing. Their project website is daunting to take in at first, which shouldn’t be all that surprising since the concepts used here are fairly advanced. But give yourself a few minutes of blind clicking and you’ll begin to grasp the scope of this fantastic piece of engineering. The bad news is you’re not going to whip the thing together in a weekend. The good news is that if you’re determined to build one this should give you the lion’s share of the background you’ll need to make it happen.

The rig pulls a printed object up from the ooze on the build platform. They’re using resin that is cured with visible light. That’s why you see the level in the foreground; the bath needs to be a uniformed thickness so that it solidifies correctly when the light hits it from the underside. The build table is made of glass sandwiched between gaskets where it comes in contact with the frame, keeping the liquid in place while letting the DLP projector shine through. Check out the fast-motion build video after the break to see how each layer is exposed to light, then pulled upward to make room for the next. We estimate the build was around two hours of real-time and you can see that a technician replaces the extracted resin at regular intervals during the process.

DLP Projector based printers have been gaining in popularity. Check out this roundup of several offerings from last year.

Continue reading “Everything You Need To Build A Light-cured Resin 3D Printer” →

Add Motorized Blinds To Your Home Theater

February 7, 2013 by Mike Szczys 20 Comments

motorized-blinds

[Chipsy] found himself with an interesting problem. The room that serves his home theater has a wall mirror which reflects part of the screen during viewing. In an otherwise dark room this was very distracting. His solution was to add a blind that covers the mirror during viewing, but who wants to constantly pull that down and back up again? Since the motorized projection screen he is using has a remote control he figured out a way to motorize the blind and synchronize it with the screen’s remote.

The screen uses mechanical relays to switch the motor. He patched into these with an Arduino to detect whether the screen was going up or down. It was easy enough to use his own relay and motor with the blind, but he needed a way to stop the blind once it was in position. For covering up the mirror he simply sets an 18 second timer, but for retracting the blind he wanted precise alignment so he added a magnet and sense its position with a reed switch. See the synchronized screen and blind in the clip after the break.

Continue reading “Add Motorized Blinds To Your Home Theater” →

Never Pay More Than $10 For A Projector Mount

September 28, 2012 by Mike Szczys 8 Comments

[Lou] needed to mount his projector to finish up his home theater. But he was rather put off by the cost of commercial solutions. He ended up building his own projector mount for about ten bucks. The technique reuses some scrap metal and sources connectors from the hardware store. If your projector will be mounted flat to the ceiling we think this will work just as well for you as it did for him.

To the left we get a good look at the two parts which make up the mounting bracket. [Lou] is reusing a metal warning sign. One large piece is attached to the back portion of the projector and hangs over the end about a half-inch. On the front there is a tab with a slot in it made out the same sign. The slot accepts the head of a three-inch drywall screw. There are two holes in the rear piece which also receive screws. Once the projector is in place the screws can be adjusted to achieve the proper projection angle. [Lou] does a full walk through of the project in the video after the break.

This goes perfectly with the $50 projection screen that he built.

Continue reading “Never Pay More Than $10 For A Projector Mount” →

16×8 Pixel Laser Projector

September 14, 2012 by Mike Szczys 4 Comments

[Michiel] gave us a little shout-out by drawing the Hackaday logo with his recently completed 16×8 pixel laser projector. It uses a spinning set of mirrors mounted at slightly different angles to redirect the path of the red laser diode.

The projector is driven by an Arduino. To give it more than just a hard-coded existence [Michiel] included an Xbee module. This lets him connect to it with a computer in order to stream messages. One of the demo videos linked in his project log shows the web interface he coded which will push a message typed in the submission form out to the projector where it is scrolled like a marquee.

This type of spinning display is one of a few common methods for making laser projectors. In the image above you can see the optical sensor which is used to sync the diode with the spinning mirrors, each of which is responsible for a different row of pixels. He lists off several things that he learned when working on the project. We think the most important is the timing issues which go into something like this.

Building A Passive 3D Projection System In Your Attic

September 13, 2012 by Caleb Kraft 16 Comments

While the whole 3d movie/game craze seems to be ramping up, it really isn’t a new thing. We all recall those fancy red-blue glasses that were popular in theaters for a while, but I’m not talking about that. Passive 3d projection (using polarized glasses) has been around for a while too. Many people have figured out cheap ways to build these systems in their homes, but only recently have we seen media created for them in quantity. Now that you can buy 3D games and movies at your local box store, the temptation to have a 3d system in your home is much higher.

Here’s a great read on how to put together a fairly simple projection system that uses two identical projectors with polarizing filters. Basically, all you need are two projectors, two filters, a screen, and the glasses. There are plenty of tips for mounting and setup in the thread to help alleviate any headaches you might encounter.

This system is primarily used with a PC, because it requires two video feeds to function. A cost breakdown might make you wonder why you wouldn’t just jump on amazon and get a 32″ 3d tv for under $400, but sitting in front of that giant screen might make you understand.

128-inch Silver Screen For Your Viewing Room

August 21, 2012 by Mike Szczys 16 Comments

This huge projection screen fills an odd alcove in [Dodge Boy’s] screening room. He built it himself for under $200. The materials, tools, and techniques make this a possibility for anyone who wants their own projection setup.

The frame is made of pine 1×3 dimensional lumber. To keep the fabric from touching the supports in the center of the frame he added quarter-round trim to around the perimeter. From there he painted it black and went for a test-fit. The bad news is that the drywall is neither perfectly flat, nor parallel/square. He ended up taking the trim off and ripping down one side of the frame. That did the trick and he went on to stretch spandex over the whole thing. The frame hangs from a french cleat on either side of the opening. From what we can tell, the surface is just fabric and not painted as we usually see with these setups.

[Dodge Boy’s] utility room shares the back wall of the screening room. That’s where he stores the HTPC which feeds he project, with an RF remote to control it through the wall.

[via Reddit]