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Neon Sign Transformer

9518 Views 9 Replies 7 Participants Last post by  dmxtothemax
I am planning on wiring up this vintage NST i found but I Need to know how to properly wire it up. On the side with the 3 big wires it says for the top 2 are the hv output wires but the one located below says common. So can someone tell give me some info about this transformer? I attached pictures. (I hope this is on the right forum)


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WHat is on the other side? It looks like two wires.

What are you planning on hooking this transformer to? Neon tubes or some other shady project? :)

Usually there are two primary and two secondary wires for 110 operation.

On an older unit like this, you need to make sure that the common is hooked to neutral so that the case isnt energized if it was grounded internally.

Also, this one is 50 HZ...odd.
I played with many of these as a kid, up to 35kv. They can probably cause cardiac arrest but I don't have any data on this.
It's a center tapped transformer.

If you couldn't figure that out yourself, maybe you should start playing with lower voltages first. The neon transformer will still be there in a few weeks. You only get to make one mistake with 3500/7000 volts.
We used to crack the old thick Coke bottles in half with the spark from these things.
The spark actually makes its way through the glass from both sides, and when you get to the bottom of the bottle you turn off the current and wait. The current leaves a trail in the glass.
Within a minute or so the bottle falls into pieces, almost noiselessly.
Great fun! We had 6" sparks, yellow with a blue center.
As Gigs said, it's a center tap transformer. You get 3500 volts from each leg to the common or 7000 volts across the two hot leads. Pretty low voltage for a neon transformer. Typically current limited to 20ma to 60ma output but still can be deadly.
In particular read the safty info on the Wiki article above.
One time I brought so many of these NSTs home on my bike that the thing almost couldn't be steered.

For a real shock, while barefoot on a concrete floor try forcing an auto radio vibrator
into one of those four prong tube sockets from way old radio sets.
The guy standing next to me never felt a thing!
Actually I am planning on making a tesla coil with this peticular NST. I have used NST's before but not a Center Tap Before. Also it is pretty old so i dont want to screw something up (including my life) if I connect it wrong. More info on the transformer is it has 2 cloth wires on the other side of it. one of the cloth wires has a stripe on it which i assume means it is neutural. The other wire is plain black. Is there any need for me to ground it or I can just use neutural (doesnt have grounding wire, I think)
OMG! I just stumbled on this thread Googleing my DIY & after seeing this, I bet Bobenson didn't make it.:eek:
It would make a lovely jacobs ladder ?
But be super carefull as they are super dangerous thing,
To be handled with GREAT CARE.

Unless you are 100% confident you know how to use it safely
then dont use it at all.
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