I got a NST!

I recently bought a 11kv, 30mA Neon Sign transformer. I can get nice arcs off of it and everything (maybe about 2 inches? when rectified it makes shorter high pitch arcs), but I'm wondering about protecting it. after a couple hours of playing with it there was a loud pop in the case and it stopped working. I opened it up (it was held together by rivets, I just drilled the rivets out) and it's a switched mode neon sign transformer. I thought it was a bit light! So I found a (transistor? To-220 case) that had it's face blown off, luckily I found the other piece and I'm going to order the component and replace it. So, is there a cheap easy way of preventing this happening? While opening the case I added a number of saftey features, a saftey switch, and a "ON" indicator.

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guyfrom7up (author) 9 years ago
Here are some of the inside Pics you can kinda tell where something is missing the left side of the circuit board is kinda messy since I added a few saftey features, such as a status light and a saftey switch (before it was just a pull light switch, and you didn't know if it was on or not until you plug it in, scary!)
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Nice! The transformer looks almost like a flyback transformer. And the circuit is interesting, it uses a GDT, what all solid state tesla coils uses.
guyfrom7up (author)  Plasmana9 years ago
thanks, the only reason I think this blew is because I used no NST protection, so I think switch mode neon sign transformers are fine, and the same thing would have happened to a regular one, it's just that this is cheaper to fix. I think the huge inductive kick back just blew the mosfet. Hopefully when replaced it'll work, I'm going to put in RF filters and a saftey sparkgap.
Yeah, you might be right about the inductive kick back theory... Good luck making a filter for your NST! (BTW, what type of filter are you going to use?)
guyfrom7up (author)  Plasmana9 years ago
I'm just going to use 2 inductors and a spark gap, any advice on the coils?
I think it is good enough.
guyfrom7up (author)  Plasmana9 years ago
any advice on the coils? I don't know how to make a HV inductor...
It is really easy to make HV inductors... You wrap a few hundred turns of enameled wire on a 1 inch diameter and a few inches long PVC pipe. It is really like making a tiny tesla coil.
guyfrom7up (author)  guyfrom7up9 years ago
the transistor is getting 10 cousins from singapore, riding third class!
guyfrom7up (author) 9 years ago
well, replacing the transistor didn't fix anything... sigh
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