This file is one of the Wolfstone archives of the Halloween mailing lists. You can find out more, and reach the entire collection here: http://www.pobox.com/~wolfstone/_r/HalloweenArchive.html This particular archive deals with "high voltage" topics. This includes: o jacob's ladder o Tesla coil o high voltage cautions and safety tips It does NOT include related topics: o wiring, especially 110VAC Some of the clips near the top are lacking headers - sorry! - - - - - > Here's where I see the problems with this, in my purely > feeble grasp of the fundamentals... > The potential to sustain an arc across a gap wide enough > to work on 8 feet of rods (likely a couple of feet, to > be effective) will be high. Uh, Why feet? You've made an assumption that is not valid. I have a 5' tall laddeer that I run on 15KV 30mA. The bottom seperation is about 0.5", the top about 2.75". That arc chasing up 5' is very impressive, even if the top gap is not huge. The divergence is *just* enough to keep the arc rising, and to ensure that it goes out at the top. I used bare 12AWG for one side, and 14AWG for the other (threw it together from scraps). - - - - - << I recently purchased a transformer from the HVAC dept. at home depot... I don't think it's what I was supposed to get? I think it's only like 40 watts and 25 volts output & I really don't think it's gonna work. my Budweiser sign has a Franceformer on it that's only 3,000V, I want something BIGGER than that...a real "show" if you know what I = mean. let me know what I can do with that home depot special. or if I bought the wrong thing or something. >> My oil burner transformer if 12,000v. It sounds like you bought a newer tranny used on gas furnaces. I have never tried it but i dont think it = will work. We used one of those on a prop thap shoots a 6 foot flame. The = igniter would only spark across a gap no bigger than 1/8". - - - - - Date: Sat, 18 Apr 1998 20:18:25 -0400 From: Jim Kadel Subject: HALL: Re: Jacobs Ladders.... Mike, First of all your hi voltage transformer should be 15 Kilovolts with at least 30 ma current. Higher current would be better for the purpose but as these currents can kill at this voltage, higher current transformers are not easy to come by. Try neon sign distributors. For a jacob's ladder, the ANGLE of separation between electrodes is critical, I believe that it is 2 degrees, from the vertical (for each electrode) meaning that the total included angle between electrodes is 4 degrees. Anything less than this angle and the spark won't climb; more than this angle: the spark extinguishes before reaching the top. Your example of a six foot "ladder" would have a 5 inch electrode separation at the top. The electrodes must be *straight* in order to maintain the critical angle along their length. I found (depending on the overall length) that 3/16 to 5/16 inch steel rod is great and easily found at the local hardware store. Jim =================== REF =========================== At 06:38 PM 4/18/98 EDT, Mike wrote: >Also, last year in my haunt, my partner's dad procured a 6 ft tall jacobs >ladder. The dad is like the CEO of 'charger bikes' which makes these really >cool bikes that arent totally electric, but a torque sensor feels how much >force you are putting in, and you can have it, up to, quadruple it. well,they >use the ladder when they goto bike shows for extra effect and to stress the >electric thing. it was six feet tall. I've seen directions for ladders that >call for two foot tall copper wires. the wires used were not copper, and not >two feet tall. the wires looked like magnesium, but magnesium would have >ignited... which leads me to: what kind of wire and what kind of >trannsformer/adjustments do you need to make to make a ladder like this. an >employee of charger made this ladder, and i dont know how to contact him..... - - - - - From: JMeils42 Date: Sun, 19 Apr 1998 11:45:41 EDT Subject: Re: HALL: Peppers Ghost's and Jacobs Ladders.... Dear Mike, The Pepper's ghost you want to create, do you want it to become fully solid, or remain transparent? If the latter, your can light/bow tie arrangement will work just fine. All the talk of cross fading from one set of lights to another is in order to create a "dissolve" effect, rather like the Dr. Who Tardis fading from view. As to Jacob's Ladders: I think I can speak with a little authority on these things, since I build about a dozen of them every month. (we make a six footer, BTW...) The electrodes can be made of any conductive metal. We use 1/4 steel rod in ours. These electrodes can be of any length you like, provided they are gapped about 1/8 of an inch apart at the bottom, and end at the top about 3 inches apart. A neon sign transformer of at least 30Kv is required, and you will need to put a small cooling fan on it so it won't burn out too quickly. Above all, the electrodes need to be inside some kind of non-conductive shield. The transformer will put out somewhere around 3 amps, so it is DEADLY to come in contact with them. Try sealing them into a clear acrylic tube. (we use lexan, because it's almost indestructible.) The fire marshall will also demand this, because having the arc in the open will constitute an "open flame". Allow air to flow in at the bottom and at the top via some small holes. This will allow the convection to draw the arc up between the electrodes much more efficiently. Good luck, and remember, saftey first! - - - - - From: "Derek Schwab" Subject: Re: HALL: Re: Jacobs Ladders.... Date: Mon, 20 Apr 1998 23:56:14 -0400 If it's a neon sign transformer, it may be bad or arcing to your inclosure (wood is a conductor for such high voltatages. If it's a microwave oven xformer, it may need power factor correction -- install a cap of the type used for motors across the primary. - - - - - From: jim.fosse at bjt.net (Jim Fosse) Subject: Re: HALL: Re: Tad's Jacob's ladder Date: Tue, 21 Apr 1998 06:39:17 GMT On Tue, 21 Apr 1998 00:56:06 EDT, JMeils42 , you wrote: >Tad, > From the sound of it, you have a direct short somewhere. Are the elecrtodes >gapped properly? Are they just barely apart from one another at the bottom? If >they are, and the problem continues, you may have a short in the transformer >itself. A short on the secondary of a neon sign transformer will NOT cause it to draw excessive current. All arcs, be they neon, air, copper; look like a short circuit. The transformer has been designed to limit the current supplied to the arc to the value listed on the faceplate. So a 15kV 30ma neon will supply 30ma to an arc - ~450 watts. a 15kV 60ma neon - ~900watts which at 120V is 7.5 amps but, that may trip a 10A breaker because of "power factor". > Unfortunately, the only solution to this is to replace it. Actually, NO, neons usually fail by carbon tracking the tar inside them (a short, yes) this can be fixed by melting the tar and allowing the neon to cool. This will not, however, cause them to draw excessive current. Email me for more info. - - - - - Date: Tue, 21 Apr 1998 02:09:03 -0500 From: Eddie White Subject: Re: HALL: Re: Tad's Jacob's ladder not trying to start an argument here, but this is not true. transformers are designed to limit their inrush current when powered up at some point other than zero crossing of the sine wave. neon transformers are designed to tolorate the brief high current when a neon tube first ionizes. when a gas first ionizes, it appears as a short. the transformer has a "built-in" saturable reactance that allows it to handle the brief overload. there is no current limiting device in standard potted neon transformers. if you short it out, you will kill it. eddie At 06:39 AM 4/21/98 GMT, you wrote: > >A short on the secondary of a neon sign transformer will NOT cause it >to draw excessive current. All arcs, be they neon, air, copper; look >like a short circuit. The transformer has been designed to limit the >current supplied to the arc to the value listed on the faceplate. - - - - - From: milwiron at btprod.com Date: Tue, 21 Apr 1998 04:20:16 -0800 Subject: Re: HALL: Re: Jacobs Ladders.... At 06:32 AM 4/21/98 GMT, you wrote: >On Mon, 20 Apr 1998 23:58:29 -0400, "Derek Schwab" >, you wrote: > >>Where does one obtain a distribution transformer? >>Just climb up a pole and yank it off? :~} :~} Most neon supply companies carry them or can get 'em. Not a sign shop but the suppliers they buy from. I've got one in my shop that's part of the bombarder setup for manufacturing neon tubes, I treat it with the utmost respect. - - - - - From: TDDoggett at aol.com Date: Sun, 6 Jun 1999 04:27:40 EDT Subject: Re: HALL: NO2 Gas Created by Jacobs ladder Congratulations on your smog machine. The spark creates ozone and oxides of nitrogen which are the fundamental components of photochemical smog. Add some unburned hydrocarbons and you get the cocktail that I grew up on here in LA. :) It is very hard on rubber, lungs and eyes. -Tim www.hauntinggrounds.org In a message dated 6/5/99 9:58:39 PM Pacific Daylight Time, Daft420@iname.com writes: > The last time I tried to use my Jabob's ladder(homemade) in a haunt, I > wasn't counting on the fact that large quantities of noxious gasses would > accumulate quickly under the plaxiglass cover I had designed for it. As the > air inside turned increasingly reddish/brown, I was forced to remove the > display. My question is: does anyone have any suggestions as to what the > best method of ventilating the jacob's ladder would be? - - - - - Date: Sun, 06 Jun 1999 08:23:24 -0400 From: Jim Kadel Subject: Re: HALL: NO2 Gas Created by Jacobs ladder ..and add some holes at the bottom to allow fresh air to enter.. Jim ========== REF ============== At 01:20 AM 6/6/99 -0700, you wrote: >If your Plexiglas cover doesn't have a hole in the top of it, you need to >cut the top out to let the gases escape - - - - - From: JMeils42 at aol.com Date: Sun, 6 Jun 1999 12:30:14 EDT Subject: Re: HALL: O3 Gas Created by Jacobs ladder Hi, Yes, the ozone created by the arc is pretty nasty! It's best to use these devices in a room that has some air flow through it. As far as ventilating the Plexiglas enclosure, the others who have responded are quite right. Simply drill a few holes in the top and bottom of it, and heat convection from the arc will do the rest. BTW....an interesting effect can be had by feeding a bit of cigarette smoke into the space....usually, it will turn the arc a bright green or yellow. - - - - - Subject: Re: Hall: Dr. Mark's Jacob's Ladder From: "Brian Lorsung" Date: Thu, 11 Nov 1999 15:17:04 -0600 I used 3 ft copper welding rods on mine and it worked great. They worked much better that straightened wire, because they were stiffer and perfectly straight. That was with a oil burner transformer ( Johnstone Supply L86-143 per Larry Lund's instructions ) 10,000v 30mA. I just bought a 15,000v, 60mA, 42 lb, monster on ebay. I think I'll try to do 4-6 feet on this one. Keep in mind that the arc starting distance is mostly determined by voltage and the longest the arc will stretch is determined mostly by current. The arc can only be stretched so far, regardless of the length of the ladder. - - - - - Subject: RE: Hall: Dr. Mark's Jacob's Ladder From: "Coiler" Date: Mon, 15 Nov 1999 07:29:30 -0800 > This is true. Basically you can make it as tall as you want. The > voltage of > your transformer pretty much only controls the size of your spark > gap. for > example with a 12kv transformer you gap at the top of your coil > will only be > about 3" apart. To make it look cool you want something like a 48kv > transformer (this should give you about 8" if your lucky). > Not quite true I am afraid. The voltage determines the minimum strike distance for the lower arc. A fancy way of saying how close together the bottom of the 'V' must be. After that however, its just pure power that determines how long the arc will stretch. Here is why: once you've struck the arc, you form a ion/plasma channel in the air. That 'arc' is superheated air and hot ions, it conducts electricity. But it has a high resistance. So as the arc stretches and you climb the ladder, the resistance keeps rising. Eventually you reach the point where the transformer does not have the current to maintain the voltage drop across the arc channel, and the arc goes out. This is why a measly 2KV microwave oven transformer can build a better JL than a NST *if* you can get it to strike the arc at the bottom. 1000watts (2KV 500mA) vs 360 watts (12KV 30mA). The catch is that for a Microwave transformer, you must get the start of the V very very close, and often it just gets stuck. - - - - - Subject: RE: Hall: Dr. Mark's Jacob's Ladder From: "Coiler" Date: Thu, 11 Nov 1999 21:51:44 -0800 No no no no!.. the arc will rise on parallel wires just fine, as the plasma in the arc is on the order of 2000 deg C. Plenty hot to create a convection current. The = widening makes sure that the arc does not get stuck. My 5 foot ladder started at .75" and went up to about 4". Worked great. - - - - -- - - - - Subject: RE: Hall: RE: Smell from a Jacobs Ladder From: "Coiler" Date: Thu, 11 Nov 1999 21:51:39 -0800 *LOL* I dunno about him, but I have one that is 5' tall. Great fun when I run it off my 5KVA transformer - - - - - Subject: RE: Hall: Dr. Frankenstein's Lab equip ?? From: "Coiler" Date: Thu, 11 Nov 1999 21:51:42 -0800 > > my Budweiser sign has a Franceformer on it that's only 3,000V, > I want something BIGGER than that...a real "show" if you know what I = mean. > let me know what I can do with that home depot special. > or if I bought the wrong thing or something. You did buy the wrong thing. You need enough voltage to bridge the gap at the bottom. 2-3KV minimum. The current is then what make the arc = channel - - - - -