Tot Zeins writes: >I would certainly turn the GPS OFF during an electrical storm, or place it >in a metal box or even wrap it in aluminum foil. I spoke about this with two engineer friends, one who owned a defense electronics business for many years and another involved in RF interference protection for one of the automotive companies. What I learned was instructive. Turning it off won't help, as the damage results from voltages induced in the antenna and, if the strike is close enough, on the board itself. A lightning strike has a very broad energy spectrum and a lot of that energy is at wavelengths short enough to induce damaging currents on a chip. Placing the unit in a metal box may not help, either, unless you have a good electrical connection all the way around the box. Any sort of slit, no matter how narrow, will admit plenty of energy. Even with full shielding, a *very* close strike can induce enough voltage *inside* the box to destroy CMOS componants of a fully sealed metal box. So there's no way to absolutely protect electronic devices when there's that much voltage about. On the other hand, if your life depends on on a device surviving difficult conditions, a foil wrap might night be a bad idea, and for expeditions where electrical storms are common, making a shielded box would be a good investment. I've constucted shielded boxes (for other uses) and it's actually pretty simple if you're handy with tools. I make the boxes out of surplus double-sided fiberglass printed circuit material, whihc is a sheet of 'glass with copper on both sides. The pieces are cut to size on a heavy duty paper cutter and joined with solder, using 1/4" brass angle from the hobby store. A radio or GPS won't work in such a box, but it'll make for safe storage. It's possible to make a box with an external antenna that is bypassed and protected, but that gets more complicated than is appropriate for a short message. I think I'll prototype something and put it on a web page this summer. Might even sneak it into a local EMF test chamber for testing. Anyone wanna donate a GPS unit for (possibly) destructive testing? ;-) -- mike ------------------------- Michael Edelman mje_at_spamcop.net http://www.foldingkayaks.org http://www.findascope.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Wed Mar 28 2001 - 18:25:40 PST
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:30:40 PDT