Neon sign transformers for Tesla coil

[DerStrom8]

Alright I bought a 10k volt 23mA oil ignition burner transformer and am on the lookout for another one of the same rating.

Awesome! That should at least get you started. It's no beast, but it should be enough to get you a spark. Could you post a photo please?

 

[billybob]

 

[billybob]

Here the tesla coil so far.

 

[DerStrom8]

Looking good!

 

[shortbus=]

I didn't think you were serious about buying an oil furnace ignition transformer, but if you decide to get another one they are still available, brand new for less than you paid on Ebay for an old one. Just make sure it doesn't say "electronic igniter" in the description.

https://www.supplyhouse.com/sh/cont...n transformer?searchText=ignition+transformer

 

[gary350]

Ebay has neons. I sold all 14 of my neons on ebay 10 years ago.

 

[billybob]

what kind of amperage would be suitable for my tesla coil? The output for the one Oil ignition transformer is 23mA at 10,000 volts. Would another of the same rating work when in phase or should I suck it up and get three?

 

[DerStrom8]

It looks like your secondary diameter is about 4.5" in diameter (wound around 4" PVC)?

The more transformers you put in parallel, the more balancing will become an issue. 23mA at 10kV is a bit on the small side for a coil of that size, but that's not to say you wouldn't be able to make it work. More in parallel would be ideal if you can afford it, but take care to keep your run times short, and definitely use all of the recommended filtering (look into Terry filters, if you haven't already) to prevent permanent damage to the OBITs. These transformers aren't really designed to be run in parallel and if there is any imbalance in voltage (which is likely), then they will damage each other over time.

 

[billybob]

Yes that is correct. I will look into the terry filters. Still trying to find my way around teslamap and the input parameters are a little confusing sometimes I might post a few questions on that later.

 

[billybob]

Also does anyone know of a way to prevent the copper tubing from rusting? It already has a coat of oxidized copper and just didn't want it o go any further.

 

[Pommie]

I've never had anything to do with Tesla coils and I'm assuming that balancing paralleled transformers is so they both supply the same current. Could two primaries achieve the same thing? Ignore if this is a stupid question.

Mike.

 

[DerStrom8]

I've never had anything to do with Tesla coils and I'm assuming that balancing paralleled transformers is so they both supply the same current. Could two primaries achieve the same thing? Ignore if this is a stupid question.

Mike.

The concern is that one transformer might produce a slightly higher voltage (due to tolerance in the voltage ratings). If simply connected in parallel, this could, over time, damage the "weaker" transformer.

 

[DerStrom8]

Also does anyone know of a way to prevent the copper tubing from rusting? It already has a coat of oxidized copper and just didn't want it o go any further.

I'm afraid I don't have an answer for that. That would be a good question for a chemist.

 

[rjenkinsgb]

does anyone know of a way to prevent the copper tubing from rusting?

Polish it, degrease it and give it a coat of polyurethane varnish.

 

[DerStrom8]

Polish it, degrease it and give it a coat of polyurethane varnish.

Varnish is probably a bad idea for a tesla coil, since generally you want it electrically conductive for tapping.

 

[rjenkinsgb]

Varnish is probably a bad idea for a tesla coil, since generally you want it electrically conductive for tapping.

OK, I did not realise it needed a changeable tap.

In that case, sand lightly with very fine abrasive or use wire wool to get it clean, then saturate it with WD-40 & leave to dry (as much as it ever does).

That's what I used to preserve aluminium antennas for amateur radio - no sanding in that case, just let it soak in to the surface oxide. They would stay like new for ten years or more.

I'm guessing skin effect is quite critical for efficiency with the tesla coil, so copper would need any tarnish removing as that is conductive but also resistive.

 

[shortbus=]

Also does anyone know of a way to prevent the copper tubing from rusting? It already has a coat of oxidized copper and just didn't want it o go any further.

Rusting? I have some rolls of old copper tubing that belonged to one of my grandpas I've had it since shortly after he died, when I was 14. I'm now 73, and while it's not "bright" now it isn't oxidized to any real amount. Are you sure it is rally copper tube, or is it copper plated steel? There was a time that some car brake lines were copper plated steel, could you have some of that?

 

[gary350]

I've never had anything to do with Tesla coils and I'm assuming that balancing paralleled transformers is so they both supply the same current. Could two primaries achieve the same thing? Ignore if this is a stupid question.

Mike.

I did lots of parallel neons it works good. All the transformers need to be the same voltage, connect only the HV terminals and NOT the ground terminals. Put spark gap on the first transformer then connect 120 volts, next connect 2nd neon in parallel if NO arc swap the 120 volt wires to make both neons be in phase. Make sure all other neons are in phase. I had 7 neons in parallel once it works good 15K 30ma = 15K .210ma.

 

[billybob]

The tubbing is copper, it’s just turning a darker color that’s all.

 

[billybob]

Thank you all for the advice. I heard however that it is a bad idea to phase OBITs because the secondary resistance is so high is this true? And if it is how can I go around that without damaging my transformers