Lowering the Cost

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    I know using a Fresnel lens (>$3) you can tun any monitor into a projector. What simple low cost alternatives are there to the Kinect? What do we need to replicate the effect and lower the cost so anyo


    Using a stereo infrared range imaging setup, a 10″ LCD, Fresnel, and a rasberry pi, the cost could be drastically reduced. I know it wouldn’t be nearly as spectacular, and would need a much darker space, but I think making this available to the world at cost would drive the technology forward quicker, as well as make it possible to have, say, an array of networked sandboxes for the same price…


    It sounds like not having the water simulation running means it can run on some pretty basic hardware. Otherwise, you’re forced to use a fairly high-end graphics card. I’m guessing it won’t be long until an R-Pi can handle the basics. =)


    The Kinect is almost the cheapest part (still be cool to see it run on raspberry pi tho!).

    It took a few weeks and I had to order a power supply for $15, but I got the camera for free just by telling people about the project and asking who had a Kinect they weren’t using they would sell me. One even told me they threw theirs in the garbage the month before “because the games for it suck”.

    I’d love to find an alternative to the projector. How does this fresnel lens setup work?


    I’ve done several Pi projects, lots of gaming rigs with them, tried Home automation – horrible lag, tried media server, horrible lag… I’m not sure this project would run any better. Linux desktop – works great.

    in the future if they increase the power it will have lots more applications, but I don’t feel this will be one of them. without the water simulation it’s only half a project, it’s the water that really opens kids eyes. just my .02


    As Maphew said, the Kinect sensor shouldn’t be hard to find for cheep. I know that is the U.S., Gamestop stores sell used Kinect sensors with the USB adapter for $20-$25. I have purchased 3 at this price in Anchorage,AK.


    I bought 2 pi in the form of Kano Computing kits for my kids. The experience was underwhelming for them. Compared to ipods and laptops etc. it just didn’t grab their attention. Lag was a big part of that. (*I* thought they were cool, but my first computer cost $7k, took 3 years to pay off, and at 50Mhz was full order of magnitude and then some slower.)

    Anyway, back to topic: what’s this about fresnel projectors?

    Doesn’t take long to find some interesting starting points. Anyone here actually build or use one?

    http://hackaday.com/2014/03/13/make-an-hd-projector-for-next-to-nothing/ (mount LCD under old style overhead projector)

    http://macgyverisms.wonderhowto.com/how-to/make-diy-home-theater-projector-and-50-screen-for-only-5-great-for-march-madness-0144568/ (put display inside cardboard box, pointed at fresnel lens)


    I have find this kind of explications but I don’t know if the brightness and contrast is enough.


    but it’s interesting because it’s the only part who cost a lot.


    I’m currently in the midst of building my own projector out of an old laptop screen. It requires two Fresnel lenses (recycled from an overhead), a 13.3″ 1280×800 LCD (recycled from an old laptop), a triplet lens (cheap on eBay), and a 100 watt 8500 lumen! led ($25). I’m going to be playing around and seeing what the most basic and effective setup would be. Ideally we could run the whole thing on an orange pi’s native LVDS output, and use an extremely small LCD (the size of a 35mm slide) and just pop it into an old slide projector. The low resolution would probably take care of the low graphics capabilities of the pi. Wouldn’t look ideal, but it would probably work. Another reason to build our own Kinetic would be we wouldn’t be limited to InfraRed, we could experiment with UltraSound, use materials other than sand, maybe water or some other fun medium, really see where else this could go…


    really interesting, for the moment I have just a 20” so I think it’s a little big.

    I have imagine to use some other material than sand maybe with non-newtonian fluid (why-not ? It could be a interesting experiential sensation).

    Please keep us inform about your progression I’m trying on my side to make it and document this project in French.


    I have make some try with a TFT screen and a retroprojector, it’s in french but you can take a look : http://fablabo.net/wiki/Bac_%C3%A0_sable_en_r%C3%A9alit%C3%A9_augment%C3%A9e


    My total cost was about $750 USD.
    Patience, and finding used items on eBay and Craigslist, rather than getting everything immediately helped. Also, a long-throw projector is WAAAY cheaper than a BENQ short-throw. The obvious disadvantage is height above the sandbox.

    Broken down as follows:
    1. I ended up with a used Dell 1100MP projector I got on Craigslist for $60. (They’re also on eBay for around $100USD) It has 600 hours on it, but its lamp life is rated at 2000 hours. I figure at 3-4 hours a day at the elementary school where I built the sandbox, it should last a couple years.
    2. I had to buy a remote on eBay for $20, because the projector is up so high. (6.5 feet (2m) above the sandbox, which is about 9 feet (3m) above the floor, I had to remove drop-ceiling tiles!)
    3. The height required a VGA extension cable, and a short AC extension cord for the projector. ($5 each)
    4. I got a Core i3 tower on Craigslist for $150.
    The sandbox wood, brackets, bolts and Projector supports cost me about $160 at Home Depot
    5. I didn’t skimp on a $350 GTX970 video card.

    My total cost was about $750… Until I fried the motherboard.
    So, A word of advice: Re-seat your large video card if you transport your computer.

    I destroyed my original motherboard in the 10-minute drive between my home and the school. The video card is so big, it got slightly loose during the drive, and shorted-out the motherboard when I turned it on. This set me back over summer break, and another $65 for a replacement motherboard from eBay.

    – Rick
    San Diego, CA

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