-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 This thread has gone horribly off topic. There's more noise about noise than there is about the original question.
Prentice Bisbal Linux Software Support Specialist/System Administrator School of Natural Sciences Institute for Advanced Study Princeton, NJ Robert G. Brown wrote: > On Wed, 13 Feb 2008, Jim Lux wrote: > >> That's what the big Tesla Coil or quarter shrinker is for. > > Mad science. > > Oh, yeah. Let's put a great big tesla coil right in with all those > computers! Wait, I hear it now... > > Fzzzzssszzzssszzzssst. > > (...that's the sound of all those itty bitty gaps on a circuit board or > NIC arcing at the same time...;-) > > OK, funny story time, sort of. Stop me if you've heard this one. > > My kids in E&M get to do an extra credit project for a 1/3 of a letter > grade promotion at semester's end, and maybe a decade ago I had a > student who wanted to build a tesla coil for his project and I said, > sure, cool, go for it. So off he went and with whatever web browsers > were around and pre-google alta vista found some howto sites for > building coils, and a few weeks later ran down a neon sign transformer, > built a saltwater-aquarium-wine-bottle capacitor array, assembled a > fan-quenched spark gap, and hand-wound the coils and added a toroid on > top. > > We still had our "old" lab rooms for the intro courses -- no computers, > stained lab benches and tables a big lead sink and gas and air nozzles > in the central bench(es) up front. Imagine old wooden (oak) chassis lab > equipment in glassed cabinets around the walls, a huge beam balance with > brass weights that was probably worth a kilobuck as an antique on top of > a tall cabinet in the back, that sort of thing. So my student rolls his > creation on a big cart into this, and I and the class all gather to > watch. > > Naturally, we turn off all the lights and darken the shades the better > to see the lightning. Student hooks it all up, flicks the switch on the > neon sign transformer to power it all up, and bzzzzaaappppppp -- the > spark gap starts going off like a machine gun and footlong purple > lightning starts zapping off the top toroid, impressive as all hell. > > And every fluorescent light in the room goes on. > > And they were turned OFF, remember. They were "on" being driven by the > radiated RF power coming off of the thing with no other source, just > like Tesla dreamed. > > In addition, as I walked around the room, I noted that pretty much every > metal gap a millimeter or less was arcing. Little arcs zapping across > the fixtures in the sink, the bolts on the tables, no doubt across the > wires holding up the drop ceiling. I could imagine arcing occurring > across my teeth if I grinned just right. > > After a few minutes of harmless fun and demos (which involved yours > truly taking a 100+ kV "hit" straight in through the >>glass<< of a > fluorescent tube that I inadvertently waved too near the toroid and > drawing down the fire to pass through me to ground through my rubber > soled shoes, which amused the heck out of the kids but which was NOT fun > for me) we powered it off and it went into class history as one of the > coolest projects ever. > > Three years ago, a second round of students wanted to build one, and did > so using 1F caps that you can apparently now buy over the counter -- > back when the first one was built I used to tell students that a 1F > capacitor would end up being the size of a bench or good sized filing > cabinet, but this is no longer true. In the meantime, all the lab rooms > were gutted and rebuilt, and each workstation has its own computer. The > entire building is now filled with computers. The computers are now all > unshielded twisted pair networked, not thinwire ethernet. If I were to > turn on a tesla coil inside the building ANYWHERE (unless it were inside > a faraday cage, of course), I'd probably blow $10,000 worth of > equipment, as a tesla coil is sort of a steady state EMP bomb or solar > flare on a table. > > We demo'd this one OUTDOORS in the parking lot, figuring that the > building steel would act as enough of a cage to protect the interior, > with a surge protector inline to help keep the primary power cable from > carrying back too much of an RF harmonic onto the building wiring. I > was a bit worried about the cars nearby -- if you drive an arc at e.g. > the cap on a gasoline supply it can be a bad thing -- but cars tend to > have metal on the outside and again cage off their guts. No worries -- > or at any rate none of the cars exploded or blew their starter coils. > > But putting one in a server room, with all of those wires strung around > in loops and connected to electronics that really hates high voltage > even at very low current -- that's just plain funny...:-) > > rgb > > (P.S. -- every few years I have to explain to one student or another > that no, they are NOT permitted to build an EMP bomb for their project. > They are driven by high explosive and -- however much fun it would be -- > where and how would we test it? Without, of course, bringing out the > mob with pitchforks and torches afterwards...) > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iD8DBQFHtEAD2n4m8G8ypgARAsNwAJkBNHmRv08KlOJ7hKgYR6PsIzKiwACfZ6+Q glcfL56pIpueiZeUKB0voR4= =220d -----END PGP SIGNATURE----- _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
