We can’t wait to give this one a try. We’ve got a DIY HDTV antenna hanging out in the attic which was made from some scrap wood and eight metal coat hangers. It works great but it’s pretty ugly and not everyone has an attic to hide it in (not to mention the signal drop caused by the roof shingles). This is a fractal antenna anchored to some clear plastic so you can just hang it in the window and start picking up the over-the-air channels without much effort.
The pattern was modeled in SketchUp then printed out on two pieces of paper. One piece had it printed on both sides, which makes it easy to glue on a sheet of aluminum foil, then follow the pattern on the opposite side to cut out the important parts. The other template was used as an aligment guide when gluing the foil to the clear plastic. A coaxial adapter was then attached using nuts and machine screws. If you build it, let us know how it comes out!
[Grenadier] tipped us off about his method for building your own high-voltage capacitors. He thought the paper and foil capacitor project was a nice introduction to the concepts, but at the same time he knew he could produce a much more powerful device.
For the dielectric he is using acetate film. This is the material from which overhead transparency sheets are made. He stuck with aluminum foil for the two plates. Just roll the foil flat with a rolling-pin, use thin wire to minimize the air that will be trapped between the dielectric layers, and make sure the foil plates are at least 4cm shorter than the acetate film on each end to prevent leakage. After rolling and securing the capacitor with zip ties you’ll be ready for the 3nF worth of fun seen in the video after the break. [Grenadier] mentions that this can be improved further if you were to vacuum impregnate the device with beeswax.
Continue reading “Roll your own capacitors – high voltage edition”