Plywood

Electromagnetic Aluminum Levitator

Electromagnetic Aluminum Levitator

About 13 years ago I learned of some military research into a satellite- and missile-defense device that would propel projectiles using Lenz’s law, which governs the direction of electrical current induced by a changing magnetic field. I decided to make a little gadget based on the same principle for my kids, to get them interested […]

Continue Reading
Non-Pesticide Patio Pest Control Device

Non-Pesticide Patio Pest Control Device

How to fabricate, out of mostly recycled materials, an ultraviolet nighttime bug trap, since ultraviolet light attracts most insects. Tired of nighttime critters and drowning in bug spray? Try this blacklight device to control mosquitoes and other nighttime insects.

Continue Reading

555 Timer Ball Whacker

This project uses a simple 555 timer chip and a feedback loop to control a servo-controlled wooden arm. Whenever an object comes close to a photosensor mounted on the end of the arm, it blocks the amount of light detected, which triggers the arm to swat the object away.

Continue Reading
Marble Adding Machine

Marble Adding Machine

Computers add binary numbers constantly, but we never see how. This elegant machine does the math using glass marbles. I started building marble track machines years ago using Lego. I experimented with all sorts of crazy ways for the marbles to descend. One was a rocker that shunted a stream of dropping marbles one-by-one to […]

Continue Reading
Homemade Frame

Homemade Frame

Some scrap plywood and a sheet of plexiglass fitted with a few cents’ worth of hardware is all it takes to get those must-frame items out of your drawers and onto your walls. This framing project can be built to suit, but for the sake of a starting point, I’ve sized the frame to accommodate […]

Continue Reading
Lunchbox Laser Shows

Lunchbox Laser Shows

Back in the 1970s, my friend Wayne Gillis and I used to do light shows at science fiction conventions. We had the usual panoply of overhead, slide, and custom-made projectors, and a single, very expensive, helium-neon laser from Edmund Scientific. Calling ourselves Light Opera, and later, Illuminatus, we performed at ConFusion conventions in Ann Arbor, […]

Continue Reading
The Chinese Windlass

The Chinese Windlass

In the summer of 1860, the Second Opium War was reaching its climax. Three years earlier, Britain and France had invaded Canton, China, in order to expand their trade in such unsavory commodities as opium and indentured servants. Chinese Emperor Xianfeng had resisted the outsiders, and a low-intensity war continued in fits and starts. The […]

Continue Reading