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Neon sign transformers for Tesla coil

DerStrom8

Super Moderator
Most Helpful Member
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?
 

DerStrom8

Super Moderator
Most Helpful Member
Looking good!
 

billybob

Member
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

Super Moderator
Most Helpful Member
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

Member
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

Member
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

Well-Known Member
Most Helpful Member
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

Super Moderator
Most Helpful Member
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

Super Moderator
Most Helpful Member
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.
 

DerStrom8

Super Moderator
Most Helpful Member
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

Well-Known Member
Most Helpful Member
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=

Well-Known Member
Most Helpful Member
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

Well-Known Member
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.
 
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billybob

Member
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
 

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