Hackaday Links: March 20th, 2013

Giant fresnel lens is dangerous fun

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.

Comments

  1. M says:

    Totally unrelated, but the magnet video made me wonder, where the hell are youtube’s captions any more?

  2. Nick says:

    Liked the Fresnel lens video except where he pours gasoline directly on to it, other than that, it was great!

  3. Ed Minchau says:

    We built something similar 5 years ago using ten Fresnel lenses that size, focused on ten boilers connected in series, with the resulting dry steam running a turbine. Very dangerous and lots of fun. http://www.youtube.com/watch?v=4C97-i7N36Q

  4. JoeJoeBoom says:

    We had some of those at a local museum’s TinkerFest. We roasted marshmallows :)

  5. Timmmmm! says:

    I thought that you couldn’t make an electromagnet with DC? Also, why were they using “tapes” for the cameras? If they were using digital cameras with SD cards would that have happened? Because the information is held in transistors, right?

    • ino says:

      Either AC or DC generates a magnetic field. And I guess they used tapes because it’s standard for professional recording equipments.
      Does a strong magnetic field influence a FLASH memory ? I don’t know but I’m gonna look for an answer.

      • ino says:

        It seems like it wouldn’t be a problem for a solid state recording.
        So just throw a gopro in this big ass magnet and let’s see what happens ! :)

        • Timmmmm! says:

          Wow, thanks for the research. The reason I asked about the DC current making a magnetic field is because I was recently in an electronics class room and I was told inductors create a magnetic field and the reason a DC circuit would not be affected by an inductor is because the inductor could not make the magnetic field it needs to function properly.

          • Brooks Moses says:

            That information is true but incomplete — an inductor relies on having a changing magnetic field. (Basically, the changing current creates a changing magnetic field, and then changing magnetic field then induces a reverse current flow.)

            DC current creates a static magnetic field, and a static magnetic field doesn’t induce any current.

          • Timmmmm! says:

            Awesome. Thanks. Thats good to know.

    • dave says:

      you’re right, solid state recorders in the cameras would have prevented this. My guess is that they weren’t using a solid state system to record the show, possibly because it was price-prohibitive when they shot it (it wouldn’t be nowadays though). Switching cameras in the middle of a production can be a huge hassle as well depending on where you are, rental locations, budget etc.

    • John says:

      You cannot make a transformer with DC, however electromagnets work just fine. A constant current produces a constant magnetic field, whereas a change in magnetic field is required to generate a constant current.

    • RichC says:

      That video is from a Discovery Channel program “How Do They Do It?” filmed in 2006-2008. Robert Llewellyn did links between items and a few extra features when it was repackaged for UK’s Channel-5. It seems to have been re-appropriated to drum up subscribers for a channel ranting about various conspiracies.

  6. In the name of... says:

    I wouldn’t be so sure that super strong magnetic fields wouldn’t corrupt SS media. Since this is DC, there probably isnt eddy currents that will fry things unless you’re moving the camera around a lot. but that is where I would expect SS media to be corrupted if it were to happen. Also, most cameras have motors in them for focusing and zoom, and this thing would probably mess with those as well.

    • Blue Footed Booby says:

      This is into the range where the magnets are strong to levitate frogs and strawberries (search youtube). Like, they won’t let you be in the same room when it’s cranked up to full power. I suspect it can trash pretty much any electronics, except maybe something hardened against the pulse from a nuclear bomb.

  7. Matt says:

    Re: “hologram-like stage”
    “Watching the video makes me wonder what other applications this could have in the near future.”

    You mean like this, from 2.5 years ago?

  8. Bill says:

    Haha, I got my engineering degree a few hundred feet from that mag lab. Seen that magnet in action. Pretty cool stuff.

  9. storyMan says:

    Re: Giant Fresnel lens:

    Can anyone explain why we don’t solve the energy crisis with lenses? Apart from hydro-electric dams, we generate electricity essentially by heating water and turning turbines, wouldn’t this at least be feasible on sunny days, and only resorting to non-passive methods?

    • Ren says:

      “and only resorting to non-passive methods?”
      Huh? non-passive? Do you then mean active methods, such as sun tracking motors
      and controllers?
      I could see a solar boiler like that useful for supplemental domestic heating and hot water. But it would need to be ruggedized for high winds, inaccessible to children and pets and would deteriorate (cloud and become fragile) over time due to UV exposure.). Such lenses could also be used for cooking/baking foods in African villages;
      with adults keeping watch over children, not much need for lawyer induced safeguards.

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