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Giant Jacob's Ladder Project Answered


Many, a many moon, ago I found an old Popular Science Magazine that detailed how to make one --it was an old issue! Any ways, about 13 years ago when the builder's for our neighborhood left, I took the flag poles from the front office with the intent of making an enormous Jacob's Ladder.

Well, cleaning out some brush I found them again and want to make it again.

I am sure the transformer will have to be huge but I am willing to go forth on this project. Does anyone here have any experience on making a giant one?


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electronbee (author)2010-08-01

Well, I was hoping someone would have had actually built a larger one. As, when one increases anything in scale certain obstacles are met. Very rarely is anything ever linear.

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steveastrouk (author)electronbee2010-08-06

No, in the limit linearity breaks down, but plenty of phenomena are linear. In this case breakdown field strength, which is admittedly a function of geometry of the electrodes is linear with voltage. Big poles, big gaps, huge voltages. Its inevitable

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electronbee (author)steveastrouk2010-08-06

So, Would the correct equation to calculate the power required for the spark gap be: P = ( L / 1.7)^2 With L being the length. So, for a 5' (60") spark I would need 1245 watts, about 83ma at 15KV.

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steveastrouk (author)electronbee2010-08-06

No way. Free breakdown of air takes (liberal estimate)~25kV per inch, so 60 ", 1.5 million volts, or more than 3 in dry air, with polishes circular electrodes ! That power figure probably assumes ionisation in the channel is complete. Steve

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electronbee (author)steveastrouk2010-08-06

Now we're talking! Some helpful info here. 1.5 to 3 million is a lot. I will have to email the authors of some sites that I have seen. A standard transformer is out of the question at this voltage level. Hee! Even better!

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electronbee (author)steveastrouk2010-08-06

Hrmm... so, you think I can take a small one or the design I saw on here with the copper tubing, and just maintain the proportions, and go big? That's be great!

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steveastrouk (author)electronbee2010-08-06

Absolute gaps drive these things to begin with, once the gap is fully ionised, and is conducting well, its different, but you have to strike the arc to begin with.

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Kiteman (author)2010-08-01

How big is "giant"? How long are these poles?

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lemonie (author)Kiteman2010-08-01
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electronbee (author)2010-08-01

They are about 20' tall on the short side. Possibly 25' end to end.

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lemonie (author)2010-08-01