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Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
... wrote ...
The streamers from any tesla coil are extremely hot, and will burn you regardless how small the coil is. Lucky you have a nice layer of dead skin that is vaporised before you do too much damage, so you can usually get away with touching the output of a coil for short periods of time without too many ill effects. Unfortunately you are also passing large amounts of current through your body as you do this, which can cause internal problems (there haven't really been a whole lot of studies done on this, so we don't really know how much damage is done).
I would also recommend building a SSTC, as they are in general considerably safer and more controlled than a SGTC. Touching the output of a sstc putting out 8" of streamers is only borderline insane, 8" of STGC streamers is going to hurt quite a bit.
This is bad advice. Both the primary and secondary voltage, from even small Tesla coils can be enough to be lethal. Streamers from a Tesla coil are NOT hot, they are electrical current. Heat is only a byproduct of this electrical current flowing through a resistance (impedance.) The pain you feel on your body when you contact a streamer is due to localized heating effect (again not because a streamer is hot), but the effects do not stop there. Electrical currents still flow through your body, and in SGTCs and DRSSTCs, the current is a pulsed current which can really affect heart rhythms as well as cause internal nervous damage.
Primary voltage, even from an NST should be considered lethal. That is 50/60Hz electricity and it only takes a few milliamps through the right parts of your body to cause serious harm. Under the right cirumstances (or should I say wrong), a 12kV, 30mA can be downright lethal.
Also, for the same power levels, the output of a SGTC and SSTC is not much different as far as how much it can damage your body. The streamers from a SGTC will hurt a bit more (i'll also add DRSSTCs to this category) because the currents absorbed by the body have a shorter duration and higher peak current than SSTCs which tend to operate "softer." But the currents through the body are the same (average sense).
Registered Member #1083
Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256
If you're going with a sgtc and money isn't an issue, go with an MMC. That will probably cost anywhere from $80 to $200 depending on the values you need. If money is a problem, then try making one using brand new, notebook sheet protectors and aluminum foil/aluminum roof flashing. For 12kV you will probably need at least 2 sheets (considering they are around 6-7 mils) between each plate of aluminum. Once you've stacked the necessary amounts of alternating sheets of foil and protectors, put it in a water tight container and fill it with mineral/transformer oil. If you have one, use a vacuum pump to suck out as much air from in between the sheets as possible.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Christopher Miles wrote ...
Good day,
One thing that has saved my butt a few times is always keeping one hand in my back pocket. This way if you get a hold of HV, you will not draw the current across the heart. In the old days all equipments was HV due to vacuum tubes and can not tell you how many times B+ has come out and bit me. But since one hand was in my back pocket Be safe, Ch
Yes, that is a good tip to follow. Also, most of that old equipment was chassis grounded either i don't think making it that much worse.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
I am in the same position (thinking of building a TC). I have read & am continuing to read all I can especially about safety both for myself and the "fire & damage" issue.
However one thing that I would really like to know from "old timers" is where they have good sources of parts??? I know about Microwaves * TV flybacks but it's tough to get neon sign transformers in my area....Therefore what I was wondering is what sources have been implemented as unique, or new (if any)??? Not only for transformers but high voltage caps and in general, tough to find parts....
Registered Member #1157
Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307
quicksilver wrote ...
However one thing that I would really like to know from "old timers" is where they have good sources of parts??? I know about Microwaves * TV flybacks but it's tough to get neon sign transformers in my area....Therefore what I was wondering is what sources have been implemented as unique, or new (if any)??? Not only for transformers but high voltage caps and in general, tough to find parts....
Thanks for any new ideas or directs!
I dumpster dive. . .
Sounds nasty, I know, but every time I drive through a neighborhood on heavy trash day, I coast real slow. You'd be surprised what folks throw out. Industrial dumpsters are even better, but sometimes you can have the guys chase you out of the lot or call the cops on you. Apartment complex dumpsters are a great source of TV's, microwaves, computers, ceiling fans (Caps and motors), monitors, and dirty baby diapers. All my PVC pipe for my coils comes from newbuild construction area dumpsters. This is also a good place to get various pieces of discarded lumber.
I'm a Cable guy, so I drive around a lot every day, and so I have more opportunity to dive than the average cubicle worker.
For caps, the best are MMC's and they are expensive. But for some inexpensive caps, you can do the party cup cap. Saltwater caps with beer bottles work very well.
NST's are a pain to find for cheap, but they can be found on Craigslist sometimes. I got 5 of them for $100.00 off of Craigslist, with 2 12K/30's and 3 15K30's. The guy has promised me that I get all of them he finds. Also, free microwaves and tv's, and monitors can be found there as well.
Motor rewind shops have boatloads of Magnet wire, and they will usually hook you up with the dead or short reels for the weight/cost of the copper, or maybe even for free if you play your cards right.
The other option for HV was the OBIT, just be sure that it is a transformer, not a switched device. I live in Texas, so we don't have these down here, but if you live where it is cold, and you use oil for you heating, chances are that the local heater repair guy has some in his truck. Call him up and ask him if he'll hook you up.
I'd say that the most expensive thing in the Tesla coil is the MMC. My coils are mostly dumpster specials, costing me next to nothing. If you don't mind the dumpster dive, then you can prolly build one for less than 200 bucks.
Miles is right about Ebay too. I lurk there for about an hour every night and see what I can find.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
THAT'S the stuff I was interested in hearing! ...I live in deep Southern Arizona, I occasionally can find older TV's. but I had not considered "diving". And I am not above an occasional adventure in trash picking. I recently heard about several things that used HV components and the more I think about WHAT uses those components, the better equipped I'll be to complete a good 1st project.
Pricing out some of this stuff especially the caps and the hundreds of yards of wire, the more I know I'll need to not buy retail if I hope to really have some fun. I saw what the bear minimum materials would cost from places like Information Unlimited and it's about $300 per entry-level coil...really steep!
Another few opinion oriented questions: I was watching with great interest the fantastic videos of the coverage of the Convention in Arizona and came across other related Tesla Coil videos of people making "Mini-Coils". Is this just a sham or can mini-coils be made with less material investment for a "first coil"? Obviously a standard sized coil has not only investment but very specific safety issues within not only the primary but even the secondary coil and voltages thereof. I am not seeking a way to minimize the need for safety criteria but the assorted issues of a full size coil are not light-weight! Could a "mini" coil provide the learning modalities with less overall danger? Or are the dangers inherent in the coil hobby just as important a learning agenda as the theory itself?
Registered Member #952
Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388
Mini-coils can be made with a lot less material than big coils. A mini coil can be made with less than 20 bucks if you want it. Some of them use really basic parts which should be easily available anywhere.
I've myself had a "soft start" and started with mini coils. I'll probably never make anything big, I'm trying to focus at efficiency.
IMO mini coils are a good way to get familiar with HV. However, particularly with SSTCs, as coils get smaller, the frequency also increases which makes gate drive difficiult. However, my first coil was about 2.5MHz and it ran just fine...
Also don't try to run your first coil straight off mains. Instead limit the primary voltage at something like 12-30V. It'll be quite safe.
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Thinking of building Tesla Coil
