How to know what "safe" is with a TC / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

How to know what "safe" is with a TC

1 2 next

Move Thread

LAN_403

HM_Murdock

Fri Aug 06 2010, 04:27PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

Hi all! Newbie here, but I am interested in learning more on designing and one day building a small SGTC, most likely using a NST. I am self-educating in the following areas:

1- how to properly read a diagram, and what the symbols mean
2- basic understanding of the various components in a SGTC, and how they work

Rigth now, I am learning all I can on capacitors. Once I feel I have a decent base of knowledge there, I will move on to the next component...I am doing the research and trying to learn the basics the right way first. I have no desire to kill or injure myself or my kids.

My question for now is this...

When considering the output arcs and streamers on a SGTC (or any TC I suppose), how exactly does one make it "safe" to touch? I have seen videos of people touching these (even with a tongue on here), and have seen folks shoot lightening from their fingers, so obviously there is some way to come into contact with the output without harm.

Is it a matter of the voltage and amps in the output? (if so, how much?)
Is it a result of a certain method of grounding the coil or person?
Is it a matter of using a certain type of power supply or coil design?
How do you test the actual output to know what you are getting power-wise?

Basically, what components and methods should I be researching in order to get sparks in the 2" to 12" range that can be "handled"? I have read where using a grounding ring above the primary coil can keep it from arcing back to the primary and getting the 60Hz feedback. What else needs to be considered?

Thanks in advance for the advice!

Goodchild

Fri Aug 06 2010, 05:13PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Tesla coils are very low current devices, which means that it can be touched depending on the power.

Ive touch many of my coils and the bigger the sparks the more it hurts

also at higher powers it can burn the skin, Ive done it to my fingers before and my fingers smelt funny for a couple of days.

In the end it's up to you, if you want to touch the sparks go for it, but no one on this forum (including me) is going to tell you that it's "totally safe"

HM_Murdock

Fri Aug 06 2010, 05:23PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

Thanks for the reply!

Not looking for "totally safe", looking for more of a guide to "reasonably safe".

Something like TDU's briefcase TC...I have seen pics of the public interacting with it...that's what I want to aim for...something that looks impressive enough but can be interacted with without real danger of general harm.

what is it about the design (or output, or grounding, or what have you) that makes that type of smaller coil safe to interact with?

(Note - not looking for some sort of binding guarantee here, just trying to learn and start small)

Or, an even less risky question to answer...

I have seen pics of TDU's briefcase coil, where he is letting young girls in dresses touch the sparks. Obviously, he knows what he is doing, and he isn't the sort to gamble on someone's life (I assume), so there is a measure of safety involved there...

So what is it? what about that design makes it "safe" or less painful to touch over a standard coil?

I am just trying to get a grasp on the overall concepts at work here, so I know where to focus my studies.

[Edit: Double post]

Goodchild

Fri Aug 06 2010, 08:47PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

What makes his coil relatively safe is the power level. The mode of operation of a TC also plays a part, SGTCs and DRSSTCs are transient mode coils(pulsed) while SSTC and VTTC can be run CW.

Maybe it's just me but I find that transient mode coils hurt a lot more to touch

If you want to be safe just keep power very low, as I said before in my previous post I take no responsibility for anybody's actions

btw if you don't want to make the mods mad, don't double post

HM_Murdock

Fri Aug 06 2010, 09:29PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

(sorry, should have edited my previous post...double-post was not purposeful)

Again, thanks for the reply...

I would never expect anyone to take responsibility for my actions but me. At least your answers give me a direction to go in for learning, and that's all I am looking for here.

So when we are talking "low power", is this attainable with a SGTC while still retaining the ability to arc to the air? If so, what would you consider low power?

A theoretical question for anyone...if you were to want to design a "relatively safe" SGTC, that you would feel comfortable letting people touch, what would you use for a powers source? I also assume the capacitor design plays into the "low power" aspect? What other design features would you consider requirements to make it "safer"?

(on a side note, I do plan to start out my practical experiences in HV by building a simple flyback transformer as described in the wiki section here...still LOTS to learn first though)

Goodchild

Fri Aug 06 2010, 09:54PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Well the thing is there is no real way to denote low power, I personally don't feel safe touching sparks longer than about 3 inches on my DRSSTC as it hurts a lot

The biggest thing to worry about with a tesla coil is not what is up top but the stuff down low (primary, tank caps NST, etc...) that is were all the lethal currents hide out waiting to strike. The secondary circuit is relatively harmless compared to the primary circuit.

The currents from the secondary circuit are in the uA range but at high voltages, were the currents in the primary circuit can be 10s to 100s of mAs at lower voltages (when I say low I mean low compared to the secondary circuit) which can be lethal.

HM_Murdock

Fri Aug 06 2010, 10:03PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

I knew the current on the power supply and caps were lethal, but didn't realize the primary was (again, LOTS to learn).

I wonder if there is some way to 'seal off' the primary to keep it away from accidental touch...that wouldn't affect the operation. Maybe something like a layer of plastic lighting grid between the primary and strike ring? Again, I may be talking out my rear (and probably am), just trying to get the overall concepts down here.

Edit: by plastic grid, I mean the "egg crate" type of grid with the holes in it...not a solid sheet...

Goodchild

Sat Aug 07 2010, 04:25AM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

You could use a plastic sheet, lexan or plexy come to mind, as they are both good electrical isolators and they are clear.

I use 1/4 lexan for my primary supports on my DRSSTCs and it works great.

HM_Murdock

Sat Aug 07 2010, 11:46PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

I was thinking more like something mounted above the primary coil...so that everything from maybe the middle of the secondary down would be encased more or less

dex

Sun Aug 08 2010, 06:50PM

Registered Member #2566 Joined: Wed Dec 23 2009, 05:52PM
Location:
Posts: 147

As concerns SGTC ,the input power should be below 100 W for coil stremers to be relatively safe to touch.
Sensation of streamer current felt can be reduced ,in most of the cases,by detuning the coil a bit (15-20 %).But you will get smaller stremers then too.

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob