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I'm thinking of building a Jacobs Ladder for this years haunt. They're pretty straightforward to make from an electronics point of view but I'm curious if anyone else has built one and can offer any tips?

Thanks!
Mine was built around a 15KV neon sign transformer and 4 ft sections of 1/2" copper pipe for the rods. The rods were fitted into PVC pipe fittings and mounted to the top of the transformer with about 2 inches of space from the rod ends to the transformer. Car spark plug wires and connectors are fine for the high voltage side connections. I ran into two issues with mine that I had to solve. The first issue was to be able to adjust the spacing between the rods so that the arc would start and travel consistently. Second was to block wind from interfering with the arc and more importantly keep hands out of the way.
I built a solid wood base under the transformer and wood sides then placed 1/8" plexiglass panels on the front and back with a small gap at the top and bottom to allow heat to escape. Once your spacing at the top and the spacing at the bottom (spark gap) is set, it should run and restart on it's own.
 

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I have built several of these, very similar to Deathly's method. I picked up some Carlin Model 41000 Oil Igniter Transformers (14KV) on E-bay for under $20.00 each. The nice thing about this transformer is that when it sits flat, the high voltage terminal posts point straight up. I had some scrap 10 gauge copper wire, I bent it so the gap at the terminal end was about 3/8" and tapers up to about 1.5 inches - you do have to play with your gaps to get it right. I cover the wires with 4" clear acrylic tubes (also from Ebay). You definitely want to keep these protected from wandering hands. Great prop for an evil laboratory!

Joe
 

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I built a couple a few years back, and they are pretty simple. As everyone else has pointed out, electrode gap is the biggest problem, along with avoiding spark 'stall out' where it just sits there and fails to fire. A remedy for this is the use of a Gabriel electrode. It consists of a third, small electrode connected to one of the outputs by two 1 Megohm resistors and placed at the central base of the long electrodes. This acts as a starter for the spark and insures consistency. You can find a good description and pictures here: Make a Jacobs ladder.

Here's mine (ignore the music)
ImageShack - Image Hosting :: 1000013ka1.flv
 

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Funeral Crasher
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Hey, bradg--your jacobs ladder looks awesome!!
I'd be afraid I'd kill someone if I made one. Possibly myself!
 

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The Evil Apparitionist
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Darn, one of my dads friends worked for a transformer company and sold 15k transformers
and he got fired. The company was called franceformers google it.
Check and see if you've got any sign companies around (one's that make/repair neon signs). They usually have several old transformers laying around the shop. I bought four used ones from a local shop at $10 each. I've used the oil ignition type before but they do not put out much current (5milliamps) where as a neon transformer will put out around 30milliamps and a nice fat arc.
 

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Psychomaniac
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Discussion Starter #8
Thanks for all the comments. I'm going to start looking around locally for a transformer. They're not light so finding one in town will probably save me some money. My biggest concern has been the cabinet and massive amounts of plexiglass required. I was going to build it out of wood instead with a plexi front and Brad's looks a lot like what I had in mind. I was going to mirror the inside but I think I like it blacked out better so I'm glad I got a chance to see the video.

I'm debating between copper pipe and just using steel rods. Brad, can you tell me what you used?

I'll definitely mock it up first to get the gaps figured out before I permanently mount anything.

This should be a good effect and worth the time, as long as I start now!
 

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I used brass brazing rods, 3/16th I think, they can be found at Home Depot or any hardware store that has brazing/welding supplies. Nice, thin solid rods with excellent conductivity. Usually come in about 3' to 4' length. And yes, I just built a wood cabinet with a plexi front piece, easy too see and maintain.
 

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Psychomaniac
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Discussion Starter #10
I finally got my transformer. It's a 15,000 volt neon unit that has screw terminal secondaries under a cover at the top. I found someone local who delivered it for $15! I also found the exact insulator standoffs I was looking for today. They'll allow me to adjust the bottom gap as desired with ease (the nails will be replaced by screws).





I was wondering where to get the wire? I'd rather no deal with spark plug wires but no one I've checked locally so far has high voltage wire. I found places on-line selling 20,000 volt wire (14 gauge) for electric fences but I'd rather not buy 50 feet worth.

One more question about the rods... how long do you think I can get away with using a 15,000 volt transformer? I'd like to make it as tall as possible. Also, would steel or aluminum rods work well or is brass the best bet?

Thanks!!!
 

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HV Wire

I have a Jacobs Ladder in progress also. I got my wire by the foot, from a buy-it-now dealer on ebay. HIGH VOLTAGE WIRE 15KV - TESLA, LASER, NEON - eBay (item 350111512805 end time Aug-13-09 08:16:19 PDT)

I have a 10KV neon transformer (also ebay) but haven't started construction yet. I like the brazing rod suggestion for electrodes. We just had a new Big R store open last week, with a big welding section.

I'm looking for a piece of scrap granite/quartz/marble countertop for the top, both for looks and as a better insulator than wood at the operating voltage.

Steve
Lights Alive
Halloween Props, LED Lights, Holiday & Animated Lighting by Lights Alive
 

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The Big Kahuna of Fright
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bradg, that Jacob's Ladder kicks butt! I used a pair for our Mad Scientists Lab several years ago, but I placed them ATOP the machine that energized the Monster. I was afraid of someone getting burned. But, sitting 6' above floor height, we only had about 16" of rod to strike the arcs. It was impressive, but NOTHING like yours. Live and learn...
 

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my jacobs ladder

Hello everyone.

I did a ton of research last summer on Jacob's ladder designs, and I ended up building mine out of a hybrid of all the ideas i found, and at a lower cost than some of those ideas..

I used the following parts. Total cost of about $75...

- a 15,000V Franceformer I picked up off eBay for about $40 I think
- wine glass stem holder - the kind the wine glasses hang from at bars pipe grounding clamps ($10 on ebay)
- 15,000v rated wire I acquired from work
- 2 tube lights that dim for effect ($5 lowes)
- home made plywood box
- Couple safety switches ($5 at radio shack)
- 110v LED up front to tell me that the main power is on (in case the lights were off) ($5 ebay)


I've posted some photos below, but pretty much I have an IEC power cord go into the back of the unit with a Main power switch for the whole unit. I then have a dimmer on the front that dims a couple of "tube" fish tank lights. When the main power switch is on, it'll turn on the lights. Then around front is another toggle switch which will turn on the Jacob's ladder. I did this for extra safety. I wanted to make sure I had some good safety power switches to help prevent anyone from getting shocked..

I used the glass stem holder as the electrodes. I cut them from their mounting brackets and screwed into the grounding clamps. I had to trim the grounding clamps almost in half. Otherwise they'd be too close to each other and the arc would start there - no good!

I then housed the electrodes in a plywood case, with a Plexiglass front.

I only have 1 change I am going to make.... I think I need to cut a couple of 1 inch holes at the base of the plywood electrode housing. What I found was the arc was getting stuck (as you can see in the video). Without the housing it was fine. I believe this is because in order for the current to rise, it heats the air above it. The convection is what does the climbing, but you also need "cold" air below the arc to help push it's climb. Right now with the housing it's pretty much "air tight", and no fresh cold air is able to get under the arc. So this year I think I will be cutting a couple 1 inch holes at the base of the plywood, and glue in some mesh screening to help prevent any wandering fingers from getting inside. This supply of fresh air below the arc should be what I'm looking for to help with the climbing issue I was having.

Anyways, here's a video and some pictures!


 

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Thanks for the link on wire. That's perfect. Drsprite, that ladder looks excellent. I like the tubes! Do you remember what kind of rod you used?
The rod is the wire glass hanger... Here's a link to one I found on eBay. I believe I may have bought this exact... 24" long. The eBay link is for a set of 6...

I just cut them from their mounting bracket, and screwed them into the grounding clamps. They almost look like they were made for Jacob's ladders! :cool:

Pack of 6 Wire Glass Hangers, 24", GHC-24 - eBay (item 330315294656 end time Aug-14-09 12:58:42 PDT)
 

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Psychomaniac
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Discussion Starter #16
Sorry, you put that in your original post but I missed it. I need to think more and post less! I searched for sign companies near me and found a neon manufacturer less than two miles away. They gave me eight feet of high voltage wire for no charge. On the way back I got two 48" 1/8 lengths of welding rod and two terminal clamps. All I need to do now is build the box.

The neon shop had some 60ma transformers! The guy said they make one hell of a spark.
 

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The only things you will have to play with are the distance between the electrodes, you should be able to get away with a 36" long electrode, but the gap at the top will only be about an inch and a half maximum (just be REAL sure the voltage is off before you attempt adjustments, sounds obvious, but folk's get in a hurry making changes). You will need to have an open vent at the bottom of what ever you use to enclose the arc rods. It will need a fresh air source because the air inside the enclosure becomes ionized and does not allow the spark to rise consistently. Once you get it running, just watch at what area on the rods the spark stops traveling, measure that gap distance and adjust the top of the rods to that width, should run the full length after that.
 

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Psychomaniac
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Discussion Starter #18
It's alive! Alive!


It fired off on the first test. The bottom gap is about 1/2". The arc got stuck at the top a few times but I'm not going to worry about it until it's in the enclosure and the tops are stabilized (they were waving around the a politician's arms).




Here's a closer look at the insulator setup...



Now I just have to build the cabinet.
 

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Looks great! Nice sound and great popping at the end. Makes me want to fire mine up ;)

I went out to get some nylon screen material, so I am going to make some holes in my enclosure for the fresh air to come in, then I'm going to cover the holes with the nylon screen. Should help keep everything black, and help prevent fingers from getting in.

What kind of enclosure are you thinking of building?
 

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Psychomaniac
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Discussion Starter #20
I was really pleased with how it worked. It ran the full length on the first try. The sound is great too! I'm going to build a box out of plywood with a plexiglass front. I haven't decided if I'm going to make it stepped like yours or monolithic. I'll be adding vent holes to mine too.
 
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