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IamSmooth

Wed Nov 01 2006, 01:26AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

When I built a Tesla Coil years ago while in high school I would hold a piece of metal and draw sparks off of the top. The sparks were only 12". I now understand that if the sparks are long enough they can strike the primary and 60hz current could flow through the body to ground. For this reason I have seen some use strike rails.

I would like to know from the experienced coilers do any of you draw off streamers with your hand under any circumstances; or, was I doing something totally stupid under any conditions? If you do draw off streamers, is there a limit to the spark length you will go before saying this is too much?

Nik

Wed Nov 01 2006, 02:01AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

No, never touch the sparks from a tesla, ever.

ragnar

Wed Nov 01 2006, 02:18AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
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Posts: 1425

FYI, my smaller SSTCs usually have a floating ground (e.g. copper plate on wooden bench). Arc length isn't a good measure of the power or frequency you're passing.

You'll find discussion regarding the drawing of sparks to extremities is generally frowned upon here. =P

Drawing sparks off CW coils, regardless of size is generally a no-no. =P
If you know what the RF envelope "feels" like, interrupted coils aren't so bad up to maybe 2ft, but nasty burns result if you're not careful with grounding and pass too much current, or hit the primary, etc. You could probably die if you tried hard enough.

Some might consider standing on a milkcrate or similar to reduce the risk of being near a nice ground, but for the record, you'll A) look silly, and B) probably fall on the coil.

If you can, try to stick to using an insulating rod (e.g. blue nylon pressure-piping) with a groundwire/probe tacked firmly to the end you're not holding. If you must take arcs to your body, from the surface-burns point of a view, a firm hold on a metal rod (and arcs to the rod) isn't too bad... remember -- you have no idea where the current's going to go. If you realise that you'd been quietly burning away at, say, the bottom of your big toe to a floorboard nail/waterpipe, it really sucks to find/feel the burn later, so take care.

I hope the guys don't flame you too much for asking.

I never found SGTCs to have an agreeable sensation unless the sparklength is <~10cm or so =P

Steve Ward

Wed Nov 01 2006, 02:18AM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Let me say this... i used to draw sparks to my body when i was younger and naive. I have personally experienced pain in my joints after "direct exposure" to my SSTC sparks. I never touched SGTC sparks much, since they usually had a nasty low frequency component that i could definately feel!

Just use a grounded target instead of your body.

IamSmooth

Wed Nov 01 2006, 03:27AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
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Posts: 1567

I appreciate the comments. I am in no way advocating touching the streamers. If anything, I would hope your comments serve as a warning for people not to touch them.

I guess I was naive back then. Luckily, nothing bad happened.

Marko

Wed Nov 01 2006, 11:08AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Drawing sparks off CW coils, regardless of size is generally a no-no. =P

yup, I aslo wouldn't reccomend anyone doing it - nastyness of burns simply isn't worth of it.
I do it sometimes just by tingling streamer tips, hopefully when coil is interrupted, but don't reccomend if you don't know what are you doing.

Holding a piece of metal usually dramatically helps there by increasing surface of contact to skin and preventing hot plasma contacting it; but you can also get in trouble if coil is to big and metal-hand contact surface small! SO don't do it either.

Generally, at TC frequencies only effect of current to body is heating, there are no electrochemical effects nor nerve effects (can't stop your heart, lungs, brain , etc) humans seem to be capable of passing much more current than with, etc, 50Hz mains.

Some people on this forum (IIRC, they all lived) used to light small lightbulbs by passing current trough their bodies. Once contact to skin (or capacitance) is good enough body resistance may drop to some 1500ohms, and if you pass current of 100mA it would be 150W dissipation on body, and 25W bulb shining brightly. (I hope this will discourage you from drawing SSTC arcs).

About primary-secondary strkes on SGTC; when they happen, there are couple of things that actually 'prevent' the secondary acting as pilot transformer for 50Hz current;

First, if it happens, and secondary is well grounded, 50/60Hz current will simply get grounded trough secondary base and spare us from shock (but not with poor grounding(!)
Also, power supply is shorted each time gap fires so worst we should see is bps-frequency component.

Another good protection from such shocks is using side-tapped grounded supply (wich is rarely used simply because of insulation purposes) and grounding the primary well.
That's probably best protection from flashover shocks we can have.

Sparks from disruptive coils themselves do shock because of high peak poewr and current from topload, on low frequency (about same-type of shock as VDG). I don't remember anyone dying of it, but it's definitely unpleasant.

So, I can't recommend anyone to 'play zeus' with TC's, no matter what I do.
As nik already said, simply don't do it and use a chicken stick...

vasil

Wed Nov 01 2006, 03:06PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

You can do the trick with low power coils, but not with bare hand.

http://www.youtube.com/watch?v=VS-iRY3H5S0

http://www.youtube.com/watch?v=0UBRkb7qTH8

I do not recomand it for more than 100 W powers. The VTTC seems "softer" for the bare hand, but still they can produce internal damage.

Dr. Drone

Wed Nov 01 2006, 04:49PM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
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Posts: 1673

ragnar

Wed Nov 01 2006, 11:46PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

The white labcoat is a nice touch in some of your newer photos, Chris =D

Terry Fritz

Thu Nov 02 2006, 05:01AM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

Many people play with Tesla coil arcs directly.

7.3Meg but really worth it

Didn't have a good link for Danielle Stampe...

These people can die very quickly.... They have 25+ years of experience...

The more we learn of Tesla coil arcs, the further back we all get *;-))

People that play with arcs and live for a long time know a LOT!!! A lot more than most...

Air streamers will fry your vessels and nerves. Ground strikes at thousands of amps do completely unknown things to you. They killed Henry Transtrom...

Recent medical data suggests that there is a very vulnerable "instant" in the heart beat cycle where electrical shock is vastly more fatal... The doctor that discovered it, killed himself trying to study it

Many play the "shark suit" game...

But recent info is very scary there too

Be very aware that today's "highly power engineered" Tesla coils deliver vastly more power than the old screwed up coils of the 20's... Circuits like used in the SISG PIRANHA coil will blow large chunks of flesh off you in flames if you get across it wrong!! (It's ok since your already very dead :0)) There ain't no current limiting in that case... I spent all day today working on four layer insulation for the primary...

DRSSTCs too have virtually NO current limiting....

I have played with CW coils

) But they were completely computer controlled circuits that I know very well... They cannot deliver "DC" and can't arc over... I have taken many arcs in the past and it seemed easy... But the "potential" for harm is high...

In general, if you don't know enough about the circuit to be sure your are safe, you are NOT!!!

You will see many people playing with arcs... The more I know, the more I fear for them... It is sort of like those "highly expert" BASE jumpers:

Cheers,

Terry

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