Made a jacobs ladder!

[absolom7691]

The center tap on NSTs are fixed and can't be bypassed or removed. I don't know how NSTs are "down under", but here in the US, they are potted in resin. They center tap them to keep the potential to ground lower. Think or your 15kv NST as two 7500V transformers sharing one primary with the connecting ends of the secondaries tied to ground. This way, there is a smaller chance of arcing to ground and the insulators can be smaller since each side is only seeing 7500V instead of 15KV. Just wanted to let you know. I don't want to see anyone fry their nice toys. NSTs are not so strong in that deparment. I have fried about 6 of them throughout my tesla coil history playing around with them.

BTW, you ladder looks great. Try using different metals, they have slightly different color characteristics when they arc!

[Things]

Yeah, this one is a FART resin block type. Ive heard these things are supposed to be fairly hard to kill. I had 2 other really bulky NST's before this one tho, but they didnt work at all, so I guess not that tough. And yes, it is centre tapped, though the centre tap ISNT merged to ground, its just a seperate terminal on the top, not connected to anything.

And yeah, ive tried putting salt on the rails for a nice orange arc. Today when I show it @ school I might be able to convince my teacher to let me spray a few different ones on there

[tocket]

I was going to comment on that arc color, but forgot about it. It looks like you have a bit of sodium or something organic in the plasma in the pics/vid. It looks nothing like a typical air/nitrogen plasma. What metal are the rods made of? Mine are copper.

Try putting boric acid on the rails. Should make a pretty green arc

I can send you some boric acid and strontium chloride (red) if you're interested.

[mixedgas]

or just mount the whole NST in a thick (1/4") lexan box like I used to do. Then its center tap, what center tap! :-)

Steve

[Mr.Coffee]

if you have an nst lying around that you think is fried, you can try pulling it out of its casing and heating the coil up in an oven. sometimes the resin will get traces burnt through it from the HV, it is possible to "reflow" some of these. this guy did it here( http://www.hv4fun.se/Nst%20Repair.htm)
and you can find a bunch more if you look up repotting or depotting, though that may only work with the tar filled transformers of yestermonth.

[absolom7691]

After building an MOT stack, I don't think I will go back to NSTs. Granted, most anything besides and NST or OBIT is not current limited, but that is easy enough.

Offer is still there if anyone wants them. I have four(4) 12KV/30ma NSTs if anyone wants them. They work, but are cosmetically unapealing. Free to anyone, but you pay shipping. Again, they could be linked in parallel for a nice ladder or Tesla coil PSU.

PM me if there are any takers. Like I said, I was gonna sell them, but now I will just be glad to get them out of my garage. That and my wife will make my life easier!

[Mr.Coffee]

I'd love to take them off your hands, but i'm out of the country in a week, then back, and on the road in jan. not the easiest thing to lug around on a tour bus.

that being said, we have a ups account here, I may take the 15k jobbies off of you, if I can convince the boss we "need" them for something.

with the one i've got already, that'd make for 15kv at 90ma. pretty decent for a jacob's ladder.

[Things]

k well, showed it to my science teacher today, and I was getting a picture taken with it, when I noticed the bottom of the box going yellow!

Once the photo was taken, my teacher also noticed it. I decided to take the lid off, and out came yellow smoke/gas/vapour!!

We decided to put it in the fume cupboard to release the gas, not knowing what it was at the time. As everyone that plays with HV knows, it makes O3 gas, but all the times I have run it, ive never come across it going yellow!

I asked a guy on laserchat, and it turns out O3 itself IS yellow !

Is this true??

[Mr.Coffee]

did you get a whiff of it? did it have a tingly, cleanish metallic smell? that's what ozone smells like. ozone actually damages your sense of smell, and im pretty sure it's poisonous, so you'll need to be careful around it.

but you said the gas was inside the box, is there arcing inside the box? if there is no arcing inside the box, there is probably no ozone, could be the box itself, or the insulation of the wire burning. I'd leave one side of the box open, and run it in a well-ventilated area/outdoors to see if you can tell what's making the smoke. just make sure you can shut it down remotely, and perhaps have a fire extinguisher on hand.

[tocket]

Yay, more chemistry!

Ozone is actually somewhat bluish, but I doubt you'll ever see this color as it's not that strong. If you condense it you'll get a dark blue liquid.

It isn't the only gas formed in the plasma though. You'll also get nitrogen oxides. In particular nitrogen dioxide, which happens to be a reddish brown gas. Diluted, it will appear yellow. It has a smell similar to ozone as well, the smell of your nose getting oxidized it is sometimes said (I don't know if this is actually true though, but it doesn't seem completely unreasonable).

The Norwegians actually used (or tried to) an arc discharge method for producing nitrogen dioxide for making nitric acid (needed to make explosives ) during WW2. It's quite practical since all you need is air, water and electricity. All of which were abundant in Norway.

Oh, nitrogen dioxide isn't very good for you either...
http://msds.chem.ox.ac.uk/NI/nitrogen_dioxide.html