Archived - Allanson NST

[Scott Moroch]

I recently purchased an Allanson 6,000 volt 30ma no GFI neon sign transformer. The transformer is used however appears in good condition. I will be testing it with a 5 amp variac very soon. I have one question about the wiring. For the input and output, how do I know which is negative and which is positive? Is their a general rule that one is on the left and the other is on the right, or does it change depending on company or type of transformer? I have attached some images of the transformer below.

Scott Moroch

[Richard Hull]

There is no postive and negative on any of the older standard neon transformers. They are AC transformers. AC current has no fixed polarity. As such, they will not work on any fusor without diode rectifcation of the high voltage to convert the output to DC (direct current). Suitable wiring diagrams for doing this are found in the FAQs. Read the FAQs

Richard Hull

[Scott Moroch]

Thank you Richard that answers a lot. The last question I have for wiring my NST is the input. Right now I have a black, white, and green wire. I know where the green gets hooked up and I know the black (negative) and white (neutral) get hooked up to the input knobs. My question is which color gets hooked up to which input knob. For example, is the negative hooked up to the left and white to the right? Or does the order not matter.

Thank you,

Scott Moroch

[charlie_mccartney]

Like Richard said, AC does not have a fixed polarity therefore it does not matter wire goes where, as long as the input is connected to the input, and the output (two large ceramic knobs) are connected correctly. Also I would recommended a 7.5 amp variac or higher.

[Scott Moroch]

Thank you charlie, that helped. I may get a 7.5 amp or 10 amp variac soon, however, all I have now is a 5 amp variac. Hopefully it will work with my neon sign transformer.

[Ross Moffett]

A 5A variac is fine for this transformer. 6000 VAC @ 30 mA is 180 VA. As long as the NST is greater than 25% efficiency (almost certainly) then a 120VAC @ 5A variac is more than enough.

[Chris Bradley]

how do I know which is negative and which is positive?

"If we knew what we were doing, it wouldn't be called research. -Albert Einstein"

... it probably wouldn't be called dangerous, either!

[Jack Rosky]

Chris,
How was the necessary to post? I just don't see how that is productive to the conversation at hand...

[Chris Bradley]

Jack, Something is probably lost in the translation from British cynical humour, but if there were any chance it might incentivise someone to think twice about whether such a question is a sensible thing to ask (and this misguided question has been asked before, so exactly how constructive is it to ask the question a second time when it could have been searched for?) then the comment has served its purpose.

By what means do you suggest to encourage people to do their homework before asking such questions? The best help a person can get is the help they give themselves by researching the facts before showing how little they know. Sometimes, the questioner understands so little about the question they are asking that they do not even understand the answer. That is unproductive.

Suggesting a 6000 VAC / 30 mA NST is 180 VA is also unproductive. As is the suggestion it is at least 25% efficient when, with no load, it is 0% efficient (or 100% efficient as a heater, if you like) and is variable dependent on the load characteristics. Lots of unproductive comments here. Mine included. So I apologise for my comment.

[Scott Moroch]

I may not have understood how the NST works. However, as it turns out, i did understand the answer and now I have a correctly wired NST. I believe that is productive. I gained knowledge and learned the proper wiring for it.

[Chris Bradley]

The FAQs are your original source for information here, Scott. If these do not answer your question, then maybe post indicating in what way you think the FAQs don't address your question. They can then be improved, if you can explain how they did not answer your original question. Good luck with your project.

[Scott Moroch]

Hi thank you chris I am sorry for my questions

[Rich Feldman]

I gained knowledge and learned the proper wiring for it.

But you could have gained the same knowledge by reading the NST FAQs, or asking someone you know in person, instead of cluttering the forum with a n00b question in a post that's many times redundant.
Same applies to today's thread about cylindrical fusors.

I stand with Chris here.
We see a lot of baby birds being taught that they can feed themselves by sitting and begging.
Richard Hull: for all your talk about self-sufficiency and learning by doing,
you've lately been quick to step up with the feeding spoon.
I guess you really do have a heart.

[Scott Moroch]

Rich,

I understand the mistake I have made and I will try my best to make sure it does not happen again. The truth of the matter is that I understood the concept of wiring the NST however after seeing a video of a fusor running without rectification it confused me. In the video he just had one output going to the inner grid and the other grounded to the outside of the chamber and it created plasma. This video confused me and I just wanted to clarify.

I apologize,

Scott Moroch

[Rich Feldman]

No problem, Scott.

We're just hoping that fewer people race to fusion while skipping the step about learning electricity.
That can (and has) been done thanks to fusor.net.
Would you mind posting a link to the video with one NST output connected to a chamber or outer grid? Sure it could work, and would qualify for plasma club here. Depending on construction details, it could also start a glow discharge between outer grid and a vacuum pump or electronic vacuum gauge. If NST case has no connection to green wire ground, it could become an electric shock or fire hazard.

One must walk a fine line to be an effective teacher. I try to do the right thing without the benefit of training in education.

Chris made a good point about safety. Suppose you had found online a recipe for making, say, some explosive compound. Not understanding the chemical reactions, and not having seen the lab equipment and glassware before, you find some instruction ambiguous and put the question to a forum. Gray-haired guys who survived that phase of their youth will be quick to say "go learn the basics properly".

Have fun with your NST.
The lack of a Jacob's Ladder club registry here does not make the exercise a waste of time.

Rich

[Scott Moroch]

Thank you for the words of wisdom. The last thing I want to do is skip steps. I am in absolutely no rush use this
NST. I want to make sure I have everything right. Here is the link: http://en.ria.ru/science/20130603/181489613.html
The video is on this page. Thank you for all of your help.

Scott Moroch

[Ross Moffett]

Suggesting a 6000 VAC / 30 mA NST is 180 VA is also unproductive. As is the suggestion it is at least 25% efficient when, with no load, it is 0% efficient (or 100% efficient as a heater, if you like) and is variable dependent on the load characteristics.

If it's unproductive, why is it printed on the label? Perhaps, so that the user may extrapolate the primary current, and figure whether the supply (in this case a variac) is adequate. Which it was. Which is why I posted. There's no need to muddy the water while newbies play with high voltage by bringing in irrelevant theoretical conditions.

[Chris Bradley]

If it's unproductive, why is it printed on the label?

180 VA is printed on the label? Really?

Iron core neon transformers work as naturally shunted devices, by the behaviours of the saturation of the magnetic cores. They are designed to be essentially immune to short circuit, which is ideal for throwing a high voltage into a plasma that can suddenly change its impedance. In fact, just like a neon light would do when it starts up (funnily enough). So the transformer will put out high volts low current until a plasma discharge is sustained, at which point the load's impedance then changes causing the coupling in the transformer to a lower voltage higher current. The rating is the open circuit volts and peak circuit current, which aren't achieved together. In a way, the transformer is designed to be deliberately inefficient under low load impedance, to tolerate short circuits.

[Rich Feldman]

Scott,

Since your NST is already in hand, it would be good to learn its primary current requirement.
Let's measure that, rather than read an online debate about it.
You may gain some practical knowledge about electric current, and will be in a better position to choose a variac.
"Small" variacs are less trouble to ship (and less generally useful), so are more likely to be given to you by people like me.

I want you to measure and report the 120 volt input current of your NST under three conditions:
* output open circuit (nothing connected)
* output short circuit (won't hurt the NST, in fact a lighted sign is much closer to short than open)
* output producing an arc in air, e.g. in a Jacob's Ladder. Please get an adult to oversee the experiment.
You can practice by measuring the input current of, say, a desk lamp or a blender.
No need to modify any devices under test, if you modify an extension cord or power strip to facilitate current measurement.

Getting yourself equipped to measure current in an AC mains circuit is a great first step.
Later you'll need to measure current and voltage in HV circuits, to properly run a fusor (even a respectable demo fusor).

You have several options for instrumentation.
* You could buy an analog or digital panel meter that indicates AC amperes.
* Some multimeters have AC current ranges, and can be connected in series with the NST primary.
* There are clip-on AC (and even AC/DC) ammeters that go around a wire without electrically touching it.
* Most analog and digital multimeters can measure AC voltage. To use one of those, connect a low-ohms power resistor in series with the NST primary,
and measure the voltage across the resistor. If you need a suitable resistor I'll send you one. But not before you present an appropriate ohm value and watt rating, and explain how you will convert your raw measurements into NST input current values.

[Scott Moroch]

Rich,

Thank you for all of your help and I will do all of those calculations as soon as I can. Currently, I have a mulitmeter. Would you like the URL of it. I am not sure if it is suitable for my application with my NST. I am going to do research through books and the forum to wire the multimeter (if it is the correct one) to my NST.
I really appreciate your help Rich it means a lot to me

Scott Moroch

[Richard Hull]

I really hate doing all the work constantly for the newbs. I had gone to many hours of trouble doing a special report on neon transformers way back in the late 90's and posted here, in the "files" forum, my paper on why neon transformers act as they do. I reposted this and have re-introduced this URL many, many, time here.

Down load it, save it and read it........

viewtopic.php?f=19&t=7945

Richard Hull

[Ross Moffett]

180 VA is printed on the label? Really?

Yep, actually 190 VA. Zoom in on the pic posted in post #1 of this thread. I disagree with your assessment using the (true) facts you posted based on books I've read, actual trafo ratings, and etc. but don't feel like participating in an internet war over it. My only point was that it will work with a 5A variac fine.

Nevertheless Scott, I wholeheartedly agree with Richard's opinion on the matter. Take care to follow the one-hand rule during your measurements, meaning that you should not be probing both hands near the electrical circuit at the same time. Only a few tens of milliamps will stop your heart, and this is a thousand times that amperage. Sounds like you're real new to electricity, watch youtube electrical safety videos and instructions for using multimeters to measure amperage, voltage, resistance.

In college I used a similar transformer to make a jacobs ladder with copper wire mounted directly to the output posts, try that too, it's fun. Again, youtube ought to have some videos that talk a bit about safety for doing that.

[Chris Bradley]

Yep, actually 190 VA. Zoom in on the pic posted in post #1 of this thread. ...My only point was that it will work with a 5A variac fine.

OK, fair enough! I'm happy to be put straight on my lack of attention on that, I was out of turn.

[Scott Moroch]

Ross,

Currently i have started studying electricity from the internet, physics books, and youtube. I want to make sure I am fully prepared to run any tests with the NST and want to take full precautions. Are there any books you can recommend for learning about electricity and wiring?

Scott Moroch

[Tom McCarthy]

Did you read the book Jack got? If you haven't, I'm pretty sure he has it - "The Art Of Electricity."

Tom