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Step 4Set the spacing
Set the spacing at the top of the copper pipes. I used a laser cut piece of acrylic. Something like drywall could also work. Eventually, the spark hung out under the acrylic long enough to ignite it. In later versions I put a gap between the two holes to allow the spark to pass through.
You have to experiment with the spacing; start around 2 inches and go as wide as you can.
You have to experiment with the spacing; start around 2 inches and go as wide as you can.
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Oct 22, 2008. 1:25 PMkscience
says:
12kv only arcs 3"? In a tv shoot years ago I used a 14k4v potential transformer for a jacobs ladder much shorter of height than this one. Ran 10awg copper for the ladder; had to start them at 3/4" apart, but it sent flaming arcs up to the maximum distance apart at the top of at least 18". However- we had a 50 amp tap off the generator, and it would run for about 20-30 seconds between breaker trips........ ;>)
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Nov 30, 2008. 9:03 AMchriskarr
says:
Well, yeah, that makes sense. If you get a microwave oven transformer, which has an output of 2kV at 500mA (.5A), and you start an arc off of it and pull away quickly you can get arcs that are about six inches long.
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May 21, 2006. 7:06 AMPrometheus
says:
Alternate to what is shown above, two similar pieces of acrylic can be screwed together to act as a clamp between the two pipes (screws on outside, never on the inside), which would not only keep the acrylic out of the spark's way, but also allow manual adjustability. 12-15kV will jump 3 inches at best at the top of a Jacob's Ladder, so if the spark lingers at the top, widen the gap little-by-little until the spark simply cannot reach the top, and then reduce the gap at the very top by 1/8" or so, to allow it to arch at the top for ideal effect. Flaring, or curving the tubes outward slightly can have a positive effect, however is difficult to tune. Go straight at first, and then work from there....
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Dec 26, 2005. 7:24 AMdtgriscom
says:
The Jacob's ladders I've seen have flared tops, so that the spacing increases more and more quickly as you reach the top. This lets the spark get close to the top, while never actually reaching the top. I believe that the angle of the flare must be shallow enough so that the rising hot air keeps moving the spark upwards until it extinguishes. Otherwise, the spark might just hang out where the conductors bend out, making it much less interesting.
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