Jacob's Ladder Build

Hi LPF! :wave:

I've gotten my hands on a neon sign transformer and built myself a Jacob's Ladder. I'm sure you've seen it in old sci-fi movies. It creates an arc that climbs up along two rails with a deadly buzzing noise.

The reason why the arc climbs up the diverging ladder is because the arc heats up the air above it. Then, the electrical resistance of the air decreases as it becomes hotter. Although seeming contradictory, since electricity takes the path of least resistance, the arc climbs up the ladder.

I spent quite time finding a NST because in Korea, neon signs are being replaced by LED's. I spent over an hour snooping around shops to find one. Here's a shop that professionalizes in LED signs:




Anyway, I found a NST that sold for 20 bucks new. It's rated at 15KV and 30mA current:




There seemed to be two types of NST's, electrical and mechanical. I chose electrical because it had the advantages of being compact and light. Also, it had a few safety features such as powering off when there's either a short circuit or a completely open circuit to prevent fires.


So I wired everything up, soldered the two 220V input terminals, and connected the 15KV output wires to a clothes hanger. To prepare the hanger, I had to first strip the white insulation off and straightened it out. Then, I cut it to about 30cm/1ft. I mounted it with electrical tape for a temporary base on the box the NST came in. I then turned it on:



The camera blurs the arc because I couldn't get a shutter speed fast enough.

Some videos of it working:

(Take One)

After some adjustments (Take Two)

I'll need to find a solid base for this guy.

Thanks for looking!

That looks like an awesome shop, and $20 for the old iron NST's isn't bad at all either!

I made a jacobs ladder in a nice acrylic and wood case a few years back, picked up a 15kV 25mA free for my birthday - some deranged kid I was

Things said:

That looks like an awesome shop, and $20 for the old iron NST's isn't bad at all either!

I made a jacobs ladder in a nice acrylic and wood case a few years back, picked up a 15kV 25mA free for my birthday - some deranged kid I was

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Yup, the lighting equipment stores spanned across many blocks, and some were really bright!

I do need to get this sucker a nice case and a base.

Cheers!

Me likey! great job

Thanks! Glad you like it.

As Seoul_Lasers has said, I'll try bending the end of the poles so that it has a breaking gap.

Thanks for the input!

Hey I am thinking about getting one of those SSNSTs for a 70W Shortwave sterilizer I am going to make. It is intended for make as much ozone as possible. How much was the unit? What store did you go to?
Is it across from the bulb shop I found?

Btw, I am back from Sokcho today visiting my inlaws. Today Sokcho set a record high of 31c near the water and about 33.2c near my place. Tomorrow sounds like rolling blackouts if this heat continues for parts of Seoul and possibly Kangreung.

Korea is getting a little taste of what Eastern US has been in for the last 2 months.

Seoul_lasers said:

Hey I am thinking about getting one of those SSNSTs for a 70W Shortwave sterilizer I am going to make. It is intended for make as much ozone as possible. How much was the unit? What store did you go to?
Is it across from the bulb shop I found?

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I wasn't sure where the specific bulb shop was because there were tons of lighting stores around! If you go out exit 15 in jong-lo 3ga (종로3가) and turn left until two or three blocks then go straight. That alley should be crammed with electronics stores, but I'm not too sure which one I went to. I'll tell you tomorrow as I have to visit there again because the NST broke. : (

Mine was rated at 70W at 15KV and 30mA, and paid 25,000 won for it. I think out of the many shops I had visited only two supplied NST's anymore.

I drive my UVC lamp by a normal CFL ballast. Not sure if they can be run via a NST though.

If you don't plan on coming to Seoul soon, I probably can ship one to you.

Cheers!

Ah, looking at the NST in your pic now, I can see it has a rating of 25Khz. This most likely means it's an inverter based NST, and they are a right pain in the @ss to have fun with.

They're loaded with protection circuitry actually designed to stop them from arcing (TO prevent burning buildings down), and same thing for open circuits.

I'd see if they have any of the really heavy iron core types, as those are basically impossible to destroy, because the inverter ones really aren't up to this kind of work, and you'll probably just keep killing them.

Things said:

Ah, looking at the NST in your pic now, I can see it has a rating of 25Khz. This most likely means it's an inverter based NST, and they are a right pain in the @ss to have fun with.

They're loaded with protection circuitry actually designed to stop them from arcing (TO prevent burning buildings down), and same thing for open circuits.

I'd see if they have any of the really heavy iron core types, as those are basically impossible to destroy, because the inverter ones really aren't up to this kind of work, and you'll probably just keep killing them.

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Oh shoot, I think you're right.

Today, my NST stopped working. I must have killed it.

Thanks for the tip though. :beer:

Yeah, inverter technology is a pain when it comes to making sparks, inverter based MOT's suck like that too. Nothing like a good ol iron core transformer when it comes to abuse like this.

I have a 15kV 25mA I believe, "F.A.R.T" (Probably named after the sound the arc makes ) brand ResinBlock NST, it'll sit there and arc for hours and not even break a sweat.

If it weighs over 5kg or so, very good chance it's an old transformer type, but they're being phased out (Or have been), so a bit more difficult to get new/from shops, most people find them in junkyards,being given away etc after building renovations, demolitions, etc.

I personally just walked in, asked if they had any old style transformer ones, and walked out 5 mins later with a free one

Yeah, I think I'll have a walk around a junkyard. Since NST's aren't as common and shops have been using LED's I think I can pick one up for free.

Cheers! :beer:

.... They are usually salvaged for their massive amount of valuable copper wire!
You're looking at about $150-200 new. $70 used. They are about +20Kg a piece and are potted in tar.
I have seen a few 15mA ones around Seoul. They are cylindrical in shape. I bet they are no better than an OBIT for durability too.
About the SSNST's... actually don't throw out your transformer (driver). There is all sorts of goodies under the case. You can fix the GFI so it doesn't pop.


I'll see if I can find the fix.

Seoul_lasers said:

.... They are usually salvaged for their massive amount of valuable copper wire!
You're looking at about $150-200 new. $70 used. They are about +20Kg a piece and are potted in tar.
I have seen a few 15mA ones around Seoul. They are cylindrical in shape. I bet they are no better than an OBIT for durability too.

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Wow, that's pretty darn heavy. I've seen a 20cm by 10cm by 10cm unit that was an iron core NST. Maybe I'll pick up one of those. Hope I don't kill myself. :undecided:

Do you happen to know junkyards around Seoul?

Cheers! :beer:

ryansoh3 said:

Yeah, I think I'll have a walk around a junkyard. Since NST's aren't as common and shops have been using LED's I think I can pick one up for free.

Cheers! :beer:

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Found a 15kv 20mA NST today (solid core) not solid state for
35,000 won. still availible. Diagonally across from DRSN building.
It's about 20kg worth of XMFR

They aren't _that_ heavy

Mine is 15kV 25mA rated and it's probably only 5-10kg or so.

Things said:

They aren't _that_ heavy

Mine is 15kV 25mA rated and it's probably only 5-10kg or so.

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hmm.. well I didn't have a scale.. just estimating. I'd say it's over 15Kg at least.