Fun Stuff to Buy and Build

[Flaminpyro]

Mac you never cease to make me laugh, keep it up good Buddie :beer:

Here are a couple more fun toys, albeit these most certainly have great potential to inflict harmful effects upon living tissue:

It may be just me but anything having "High Voltage Plasma" as part of the description sounds like it could provide endless hours of good clean entertainment.
High Voltage Plasma Generator Kit - BIN US $90.64 + Free Shipping

Like it is going to take a second spark for a screwdriver to leave your hand at an involuntary high rate of speed? :crackup:

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Yeah, this looks like it will be just about enough uncontrolled energy to scorch, char, and render useless any body part that inadvertently becomes part of this circuit.

High Voltage Diode Rectifier Array Single Plase Three AC DC Tesla Coil Power 5KW - BIN US $199.99 + $30.00 Shipping

btw, You got me as to what “Single Plase Three AC DC” is supposed to mean.

 

[Seoul_lasers]

Alternate Title - Toys That Can Maim & Kill You

Periodically I come across stuff that pretty much fits the alternate title above and I thought this would be a good place to make note of some of these fascinatingly dangerous play things.

I would like to start this off with a benign looking government surplus item that looks like it could make very nice brilliant blue arcs (and also quite easily short circuit vital organs):

Pulsed Energy Source, Tesla Coil, Capacitors, Transformer High Voltage
Starting Bid US $0.99 – BIN $300.00 + $85.00Shipping

Correct me if I am wrong, but that looks like a surge tester to me...
used to test components again high voltage spikes.

 

[Sigurthr]

Discharge tubes like that are actually rather safe as long as direct contact is not made between the glass and the TC output and no streamers are allowed to form between the two. Of course the power output of the TC is quite important as well. The designer of these tubes intends these for use with <50W solid state coils.

I may be buying one of his pure Xenon ones if I can talk him down from his buy it now price of $150.

I have an artisan thermionic valve (vaccuum tube) maker and glassworker making me two high power linear discharge tubes of special gas mixes/pressures designed for use with high power solid state tesla coils. These would not be safe to hold in the hand and require grounded RF shielding on the user (butcher's mesh gloves / chainmail works well). His price is only $90/tube but cannot provide Xenon or Krypton.

 

[Atomicrox]

Do you mean dangerous as in RF burns/shock or as in X-rays?

What about using regular incandescent lamps as plasma globes, is that dangerous?

 

[Sigurthr]

I meant dangerous as in RF current based neuropathy. This is a condition caused by nerves carrying large AC currents above the frequency-threshold of pain (about 50KHz). Both chronic and acute exposure can cause the condition but so far there have been no reports of it occuring from capacitively coupled exposure to Tesla Coil. Only DIRECT exposure has shown to cause the condition. RF current neuropathy presents symptoms similar to parkinson's disease, with uncontrollable muscle spasms and loss of motor control.

No xrays should be created from any tube with enough pressure to allow for streamer based propagation of current in a rarified gas atmosphere (xrays require far lower pressure). These tubes are likely at a couple hundred Torr, xrays are usually under 1Torr of pressure.

RF burns are possible with any RF source; for indirect (capacitively coupled) or direct (contact or streamer or spark) current transfer. RF burns to the extremities are not any more dangerous than regular burns, so normal common sense applies. If the operating frequency is low enough that the RF current can penetrate deeper than the skin then extra damage can occur to the underlying tissues, but generally RF burns are to fingers are minor inconveniences. Above about 800MHz care should be taken to shield the eyes as blindness can occur from corneal RF burns. Only Microwave equipment presents this hazard. For general RF-to-fingers/hand safety just maximize the surface area of the connection and ease in to the RF field. Back out if it feels too hot, don't just switch hands/fingers!

Re: lightbulb plasma globes; I do it from time to time with my TC set on very low output (100W or less) and it is no more dangerous than real plasma tubes given you never allow direct (as in non-capacitively coupled, not as in "DC") current transfer. Lightbulbs have filament wire and supports which are sharp points that very high voltage gradients can develop on, so they are far more likely to create a sparks/arc that can punch through the glass and make direct contact with the TC. I use a large clear nitrogen/neon (only about 2% Ne) filled 60W bulb when I do it and ake sure I keep the largest distance between the bulb and the TC I can while sustaining the plasma. It is important to wrap your finger around the base to maximize contact area between you and the metal so that RF burn hazard is reduced.

Re: madmacmo's above post: For regular spark gap or mains-powered-solid-state coils the primary side circuit IS LETHAL. A spark/streamer/arc from the secondary to the primary will carry the primary side power with it! This is how many coilers get killed. In a standard low power SSTC the primary is only carrying <60VDC and should present only a minimal shock hazard.

 

[Atomicrox]

Thanks for all the info, I had never heard of this RF neuropathy before.
I'll certainly read that whole page before building my first TC, madmacmo!

While we're talking safety - I've heard ozone production from TCs might get to dangerous levels but what about flyback ozone? It's definitely there since I can smell the thing almost every time I turn my flyback on. I try to keep windows open whenever I play with it, just in case.

 

[Sigurthr]

Only spark gap based TCs generate a lot of UV and ozone (99% of the ozone is from the uv). All HV above [some critical voltage level] will produce some ozone, and you'll be able to smell it, but it is generally pretty harmless as long as it is not an intense smell and there is adequate volume of unoxidized air in the room. You have to remember that lightning, strong down currents, and other atmospheric phenomena produce ozone and pose no threat to your lungs. It is all abotu quantity. A small spark gap on a low power TC can produce GRAMS of O3 per hour. A small commercial O3 unit may produce a few hundred milligrams an hour. I had a very small semi-commercial O3 unit when I was younger that put out up to 40mg/hr and it was unbearable after only about 10min of use on the lowest setting. A very small amount of ozone can produce a fresh clean scent that many (I do) enjoy.

A sustained arc almost never produces a large amount of ozone, it is brushy corona discharges and pulsed sparks which produce the most.

 

[Atomicrox]

Cool, thanks!

 

[LaserCo]

madmacmo, I had built a square acrylic tube to encase a JL, it ran from a 12kv 30?ma xfrmer wired up using that yellow silicone used in auto ignition, it was awesome looking, stood about 6 foot tall, the xfrmr was also its own acrylic box down at a level below with wheels to make it easier to move around.. some people hated the sound after a while so i built an acrylic lid for it.

The front panel of the spark area was hinged so I could easily get into it and tweak the electrodes, because it was a sealed enclosure gasses would build up in it, when I opened the front access panel I could feel sort of a moistness to the air and things would rust quickly within it.

I still have several xfrmrs and each year around this time I contemplate building another like before but yet I no longer have access to large (free) sheets of plexi like I did before.. and this nasty gas or whatever that makes things rust inside of it sucks.

Have you had that problem before? know of a way to "soak it up"? like a dessicant or something?

that JL in your first picture... it must be using aluminum wheels for the top and bottom?

cool thread!!

 

[Sigurthr]

Edit: I'll wager even money that Sigurthr would be able to provide both first hand advice and be better able than I to explain the cause and the means of mitigating the source of the corrosion you have described. I have found Sigurthr's sharing of his talent and experience which he has expressed within his many previous Tesla Coil detailed technical posts always make for interesting and most informative reads.

Much obliged!

When N2 and O2 pass through an arc they form NO2 which combines with water vapor and oxygen to make Nitric Acid (HNO3).

3 NO2 + H2O → 2 HNO3 + NO
2 NO + O2 = 2 NO2

If you want to stop the reaction you have to remove one or more of the reactants. Either remove the water vapor or the oxygen, whichever is more efficient for you to do. If you can make the container air tight just buy an argon cyllinder (or a bunch of Helium baloons (if you do this your seals must be excellent and not with He-permeable materials)) and purge the air leaving only an inert atmosphere. Or you can try dessicants to remove the water vapor but they will need changing and they will only slow the process.

Keep in mind this is only good for low-frequency arcs. You can't use inert gas atmospheres with RF as it becomes conductive.

If you want to use inert atmosphere with RF you have to use SF6 (sulphur hexafluoride) which isn't easy to come by. It also has a vastly higher dielectric breakdown voltage so you'll have to adjust your spark gap dimensions. SF6 is used in power grid distribution networks as electrical insulation and as a pneumatic fill gas.

That took me far longer to remember than I care to admit, it has been many years since I did chemistry... and I mean the science, not the class.

Any transformer over 15kV @ 9mA CAN KILL YOU. The average person is about 1MOhm from arm to arm, and it takes 10mA to stop the heart. Some people (like myself) have a much higher resistance given that the skin is not wet or broken (mine is 4.6MOhm) and can theoretically withstand a higher voltage or non-current-limited HV source, but it isn't worth risking things.

My first TC was actually one from KR_Scott and I learned a LOT from his coil... mostly what NOT TO DO. Ken's coils, while visually inspiring, are made from the cheapest materials possible and severely undertuned. Primarily, the primary inductor is of high impedance braided STEEL wire that is used for BICYCLE BRAKE LINES NOT ELECTRONICS and is NOT ELECTRICALLY INSULATED FOR HV. Secondly, his capacitors are HIGH LEAKAGE (bad) and not pulse rated for the kind of stress a TC puts on a primary capacitor. The other issues are that his spark gaps are made with brass and not bronze (this is important!) which causes massive ablation at the ionization point leading to a widening of the gap with use which can defeat the intrinsic safety feature of a parallel spark gap (it will open so wide by itself that the breakdown voltage of the gap exceeds the safe operating voltage of the capacitor). It seems he has since fixed the most grevious issue with his secondary coils though, at least that is to say the one pictured looks well done (as in wound nicely and correct in aspect ratio), but he doesn't insulate or coat his secondaries which means they WILL FAIL with normal use. Secondary coils need to be coated with dielectric varnish (polyurethane) in as many layers as feasible to protect them and prevent destructive electrical problems (corona, shorted turns, flash over, racing arcs, carbon tracking, etc etc). His earlier secondaries had problems with unwinding and turn-slipping (because they are uncoated) and also were far too skinny for SGTC use.

Yes it is a real TC, yes it will work, but it is a very poor performer. You'd be better off with $5 of copper pipe, a cheap russian RF doorknob capacitor, a piece of PVC tubing, a spool of 30ga magnet wire, and an extension cord (primary inductor). I rebuilt my KR_Scott coil with a REAL Tesla Coil rated capacitor and a REAL primary inductor and it literally destroyed the spark gap and then destroyed the secondary.

 

[Sigurthr]

No worries mate! Tesla Coils are the type of thing that you can't tell what is good or bad until you've been there and done it and learned first hand. Plus I think he purposely severely limits the output of his eBay coils for legal/safety reasons. A lossy capacitor stores no charge once power is removed, leaving no danger. A high resistance primary wastes energy as heat, which reduces output current even more. An unprotected secondary which blows apart when properly maximized prevents dangerous output if better components are used. All are like built in safety features for inexperienced/dumb customers. I'm sure he could build a mean coil if he wanted to.

P.S. I mentioned a few months back that I had some special stuff comissioned. It just came in the mail. Expect video soon.

Edit: Here's the video as promised! I may repost it in the TC build thread too, but someone will have to reply to it first so I don't double-post.

http://youtu.be/JbWwSZtN1sI

 

[LaserCo]

wow, thanks you two for such detailed response to the electro-gas-dilema, this corosive lung ailment surely sounds risky and is something I surely do not need to add to my list of ailments.

Did you guys ever mess with HVDC?

===More Fun Things===
It was around the same time in life when I had built that fancy JLadder that I also began my high voltage DC experiments, this was the mid 80's when you could quick and easily kick in the back of a TV set to gain access to the flyback with its HV rectifier wired onto it, not like how later on they began to be embedded into the flyback itself and I had a large collection accumulated. Some of the surpluss electronics places in the cities had awesome HV capacitors also, you would find them with a shorting wire across the leads.
So, lets see:
lots of HV caps + lots of HV diodes = voltage multipliers!

my experiments surrounded this little HVDC box I built and the several varieties of multipliers I would connect to it:
While being point to point soldered together and in circuit, driven by a dual 3055 driven flyback (in its own little box which later served nicely to power HeNe's with a simple stage of rectification contained within) I could get lots of voltage.

I could remove that external rectification stage from it and hang it from a plastic coathanger and it would sit and make sizzling sounds for well over an hour.


Then I finally contained all those sizzling components into their own plexiglass little box and filled it with wax, this made one hell of a change!

If left running, things in my room that were metallic and nearby would accumulate enough charge to be arcing to each other, dozens of arcing points were all over in the room making their timely *click*. Even houseplants would bend towards each other till they arced, returned to ZERO to regain charge and repeat. My hopes of stimulated plant growth had failed!, the leaves would be upset at the points of arc. Along with that there were the painful shocks when touching something with a lot of metallic mass.
4 foot fluoro tubes even would stay lit after I turned this all off.
When I turned it on I could feel like a cold rush of wind.

It was all built to send out electrons in the negative direction, a way overpowered negative ion generator. people described the feeling of something coming over them as they got closer to my room down that hallway.. They even reported to feel as if they were on speed!

at this point in time the closest thing to a computer I had (or existed) was a TTL data terminal... It did not survive. Nobody would want to play around like this these days.

Waaay before this it was a model T Ford coil I had...
I would connect to its output thin enamel wire that I strung all over this chair and strap my little sister down to it with a belt and give her little short zaps!! she does not remember this... Could my parents still remember? they seemingly hate me still.

 

[Sigurthr]

Yeah back in my earliest days of HV experimentation I got in to small oscillator driven CW multipliers. I used to have an "ion ray gun" that I made from one of Information Unlimited's kits which would charge up an ungrounded metal surface from about 10ft away. Unfortunately I grabbed the positive polarity model instead of the negative one, which had much better output. I also had some ion rotors, ozone/corona cells, and neg ion generators too. Even a large Van De Graff at one point, but it had problems with the brushes making good contact, and the sparks were comparatively tiny.

 

[Sigurthr]

I recognize that last one, that is EVR's design! He does NOT reside in Egypt... this is either a scammer or someone reselling his kit (and I think, at a higher price too!).

 

[ped]

I cant beleive people still use cardboard to wind their secondarys on to.

I learnt the hard way, a long time ago NOT to do that.

 

[Sigurthr]

I hear that. Hell, I dislike PVC even, as I've had carbon tracking issues with it when NO arcing ever took place against the PVC. Just chemical breakdown from corona causing carbonization. It grows in lightning fractal shaped patterns, beautiful to watch... aside from that fact that it destroys hard work. One day I'll get a GLASS or ceramic coilform made and will use that and never have to worry. PVC is cheap and easy to get though.

I wound up getting a very expensive huge spun toroid to supress air breakdown at the HV end of the secondary, which works exceptionally well.