3D Printing & Imaging Science
 PVC Van De Graaff generator
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Adam Wolf of Wayne and Layne built this Van De Graaff generator out of a cheap hobbyist motor, a rubber band, some Shape Lock, a pop can, a toothpick, and other el-cheapo components.

I built this in one afternoon at my parent’s place in Wisconsin–in a town that lacks good hardware stores. While building it, I was thinking of making something that was simple but awesome for a Women in Engineering outreach event we do at my day job. The total cost was about $16, but that included a full roll of electrical tape, a whole
box of toothpicks, and a large bag of thick rubber bands.

It generates nice thick sparks of about two inches that are visible in a lit room, beautiful thin fractal ones of about 6 to 8 inches in the dark, and it’s actually strong enough to generate a visible, bright blue corona around your finger tips if you turn the lights off.

He brought it to the Hack Factory last Wednesday, and we shut off the lights to check out the sparks and corona discharges. While the sparks weren’t crazy huge, we employed ancient electrostatic volt meter and were able to measure 6kV — not bad for a few bucks in parts.

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As a derivative project, Hack Factory member Jon Barclay designed a 3D-printable enclosure as a substitute for the PVC — a printable VDG generator! He has entered the project into the Rubber Band Contest currently being held on Thingiverse.

(OK, so it’s a bit inaccurate to say the VDG costs only $5, but it’s really, really cheap.)

24 thoughts on “$5 PVC Van De Graaff generator

  1. A *few* details, for non-MakerBot equipped makers would be nice…

    The original PVC design looks very simple and practical. While converting it to desktop fab is cool, it seems like offering a solution to a non-problem.

    Dave

  2. What is missing in this design is what is missing in many designs which is a source of electrons. The design is based on friction only, and will not perform optimally without the electron source. Thankfully adding an electron source is fairly easy… Just an an incandescent light. Adding the light will improve the performance significantly!

      1. I would put it in the base so that electrons coming from the globe will go onto the belt and then get captured on the plate at the top. On the top there would normally be a conductor from the rubber band to the aluminium top. At the bottom the electron source needs to be on the same side of the band so they can be captured. The incandescent light gives off electrons thanks the the Thermionic Emissions.

        Obviously this does not work with LED’s or CFL’s :-)

        High school teachers complain how the machine does not work well and and do not realize the globe is blown.

        http://en.wikipedia.org/wiki/Thermionic_emission
        http://en.wikipedia.org/wiki/Vacuum_tube

  3. The bottom roller is made from shapelock wrapped in electrical tape, but you could skip the shapelock and make it completely out of electrical tape if you need.

    The top roller is made of a glass fuse, heated until the ends come off. The top support is made from a toothpick, but something studier would also work.

    The bottom brush is stranded copper wire, frayed, with the end almost touching the bottom band. The other end of the bottom brush has the insulation removed from it, and comes out a hole of the side of the PVC. Contacting this wire provides a source of electrons, similar (but not exactly the same) as a high voltage electron source. This could also be connected to a big fat ground, but you sometimes don’t have that available–hence the personal contact.

    You can definitely tell when someone is holding the bottom brush or not!

    The top brush is also made of stranded copper wire, and nearly touches the top belt, but doesn’t quite touch–exactly like the bottom brush. The other end of this wire is uninsulated as well, and is connected to the inside of the pop can.

    The belt is a 1/4 inch wide rubber band used for securing garbage cans in garbage bags. They are usually available at office supply stores.

    The motor is a cheap surplus DC motor that runs at something like 6V. You can connect it to batteries or a wall wart.

  4. What I was actually hoping to do was to build a pair of these, with inverted polarity. Tie the bottom brushes together and to ground, so as to develop approximately twice the voltage, between the top collectors.

    This entails swapping the electropositive and electronegative rollers, so the second unit would have the glass tubing on the motor and the top roller wrapped in electrical tape.

    Dave

    1. Dave,

      Depending on what tools and how complicated you want to make it, it might be a pain to make the bottom roller from glass. You could use nylon tape on the bottom and vinyl on the top roller and it would be reversed, and easier to work with (in my opinion) than glass on the bottom roller.

      I want to do that same thing with two, and see what sort of fun arcs I can get between them!

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My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal nerdage.net

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