Anti-static cordless ESD wrist strap ...THAT ACTUALLY WORKS!!!

Oct 30, 2016 1 Replies

Heh. No, seriously.



And no need for 500uCu of Po-210.



When performing the VandeGraaff classroom hair-raise demo, I noticed something cool. The kids without any long hair, instead I always have them hold some rice crispies in their hand, and the cereal flies away via repulsion. Volta's Hailstorm. With one particular kid it didn't work at all. He had a sweaty crew-cut hairdo. Apparently the sharp, conductive hairs were acting as a wingtip static-discharger wick, and a fairly good one.



Years later an Israeli company sent me a sample of their camel hair carbon fiber dust-brush. Anti-static, for discharging the surfaces of slide film and vinyl records; avoids re-attracting dust. They mentioned that it could act as a "static discharge wick."



I tried it out, and yes it worked. If attached to a metal brace- let on your wrist, the sharp pointy carbon fibers would leak your body-charge away. But only down to one or two kilovolts. The sharp points require some voltage in order to produce a conductive corona. Enough volts still remain on your body to produce a tiny "click" spark whenever you touch grounded metal.



So, VERY NOT USEFUL for preventing electronics ESD hazard. Also, the retail price for the conductive-handle conductive-brushes was a bit steep.



Yet for the people who constantly experience the pain of huge 10KV millijoule sparks in winter (for example, when running on tread- mills, or when reaching for a can of soup at the grocery,) such a bracelet would end their pain. Aircraft static discharge wicks for peoples.



FINALLY someone has started marketing exactly this device!



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They use a strip of silver-plated conductive fabric with torn fiber ends. They work best if worn on the arm which approaches a large ground-plane (so the e-field becomes concentrated, so ion- leakage from the sharp conductive points will ignite at an unusually low threshold.)



Prices a bit steep though, for the jewelry-bracelet version. Buy some conductive fabric swatches from Sparkfun or Adafruit. Or a spool of "Static String" conductive fabric braid ($1/ft.) Make some bracelets as xmas gifts for your static-plagued elders.



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(((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))) William J. Beaty

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beaty, chem washington edu Research Engineer billb, amasci com UW Chem Dept, Bagley Hall RM74 x3-6195 Box 351700, Seattle, WA 98195-1700


You could make it work down to essentially zero volts by making a floating ~2 kV supply and wiring it between two corona points. Once you're creating free air ions in enough quantity, they'll zero your net charge pretty well. You only need a microamp or so, which means that the battery life is potentially reasonable.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net

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