Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx> Hi Dave, At 06:33 PM 11/22/2006, you wrote:
Hi all,
I'm considering running a low powered Tesla Coil at a car show,
since I've found out they are quite the crowd draw. The car in this
case is so old there's nothing semiconductor to kill.
That's good! But is there a transistor radio with an exposed antenna? Best to disconnect that if so or just pull out the radio.
My concern is simply crowd safety. I don't want to kill any hearing aids, my son's waist-mounted insulin pump, a pacemaker, things like that.
A lot depends on distance. Power probably falls off as the square of distance. Beware that the "spark gap" and its 5MHz to 5GHz hash might be a greater problem. Streamer arcs to ground are like 10nS - 1000S of amp fast events that can probably destroy a lot if things near enough to pick up the direct magnetic fields.
Barring putting the coil inside of a Faraday Coil and effectively bottling it up (which is one possibility), what are some realistic limits here? Hold it down to an inch of spark, or, test for a given voltage induced at the closest approach to the crowd?
Could the thing be run "inside" the car? If the coil was inside it, then all that Detroit iron would be the shield. You can even put chicken wire over the windows which could be practically invisible. You would just have to be sure it arced to safe points that would not burn the seats or anything. Run ground wires directly back to the secondary base. Removing the front seats is a possibility for more interior room depending on the situation.
If you run it in the center of the hood or roof, then the vast metal plane there will absorb a lot too. However, you should have it grounded right at the base of the coil then too. I assume you can't drill ground studs into these surfaces but perhaps there is a trim strip or something already there..
I'd be interested in any help, since some of you have conducted public exhibitions, although I think you've done more of the higher powered coils (grin).
Nice to know more about the coil, car, event, and distances... If the coil would be run with a warning or a special announcement as opposed to just running all the time. A "little" tube CW or solid state coil is far less of an issue. For most demonstrations one can give the usual "pacemakers, life support systems, electronic gizmos.." warning first.
Cheers,
Terry
Feel free to contact me off list.
Thanks,
Dave Small