Briefcase Tesla Coil build

[sportcoupe]

I have always had an interest in HV and always wanted to build a TC since I was young. I would love a large one but it's not really practical where I live so a small one, especially my first, was in order. I read and read here and settled on Peters (TeslaDownUnder.com) briefcase spark gap tesla coil (SGTC). It's simple, small and extremely portable.

It uses a 5kv, 20ma neon sign transformer, 3.5" x 7.5" secondary, 10 turn primary, double copper tube spark gap with 0.025" gaps across each and three banks of two 30KV 1000pf caps. The secondary RF ground is the same as the mains with no problems at all. I also did not use a safety gap. I borrowed a filter from an old microwave oven for the mains to transformer connection. It is almost the most basic SGTC I can imagine.

I don't know how Peter can interact so easily with his briefcase SGTC, mine stings the crap out of my hand when I tried. LOL.

Shot a short video. It's kind of dark though.

5MB in size. Link here.
http://www.blackgto.com/tesla/tesla_briefcase1.avi

Thumbnail pictures.

 

[jamilm9]

thats really awsome

 

[Meatball]

I LOVE this SC! I'm trying to get one going for next semester, but finding parts is taking forever!

You've got some beautiful looking arcs there! I prefer the purple stringy ones...

 

[Razako]

Nice! I have 2 SG TC's myself. One that works perfectly and puts out 4-6 inch streamers and a bigger one that can arc about 18 inches. The bigger one has issues though. For some reason it's got racing spark problems where little sparks are going up and down the coil.

 

[Flaminpyro]

Very Nice SC that looks like a lot of fun :evil:
I have a few TC parts laying around, if you decide to build a big one later and need to make a large spark gap I have some 1/4" tungsten rod for sale.

 

[sportcoupe]

Nice! I have 2 SG TC's myself. One that works perfectly and puts out 4-6 inch streamers and a bigger one that can arc about 18 inches. The bigger one has issues though. For some reason it's got racing spark problems where little sparks are going up and down the coil.

From what I've read (I am no expert) the racing sparks up the secondary are caused by too tight of coupling between the primary and secondary. Try loosening the coupling by either raising the secondary coil higher or increasing the primary diameter.

 

[brtaman]

From what I've read (I am no expert) the racing sparks up the secondary are caused by too tight of coupling between the primary and secondary. Try loosening the coupling by either raising the secondary coil higher or increasing the primary diameter.

Sound advice, that is exactly the culprit in play. I would also check if the grounding of the secondary is up-to-par. I have had problems in the past with racing sparks when my ground wasn't proper.

Razako: Do you have a picture of the coil and the way its primary is positioned/its geometry? Maybe we can help you diagnose the problem and have your coil back shooting sparks in no time. :beer:

 

[sportcoupe]

Shot a short video. It's kind of dark though.

5MB in size. Link here.
http://www.blackgto.com/tesla/tesla_briefcase1.avi

 

[Things]

Saw this on 4HV until the page stopped loading! Ugh! Capped internet

Anyways, thats a nice coil you have there! Without looking up TDU's breifcase TC, I think he used a flyback transformer, not a neon sign transformer like you. The reason it stings is probably because the NST is sourcing much more current into your primary, giving you a higher current arc.

That or it's the RF burns you are feeling.

 

[sportcoupe]

TDU used a NST for sure. I was sure to copy the same NST spec and all other components as well. It is a near exact copy electrically.

Here's the link to Peters (TDU) briefcase TC.
Tesla coil mini


.

 

[Arayan]

Very nice and professional Tesla coil :gj:

 

[photonaholic]

Very nice and professional Tesla coil :gj:

Hey that is what I was going to say.

Great work!

 

[Pilgor]

@ Razako,

how many layers of varnish do you have on your secondary? maybe applying another two layers of varnish would solve your problems

 

[Asherz]

Great build! put together very nicely

 

[sportcoupe]

Took some more pictures and a better, brighter video today. I also replaced the secondary top with a cleaner piece, it still has the magnet so I can add different attachments. I had a homemade mini toroid maybe 6" in diameter but I didn't get anything from it for some reason.

Video is 2MB in size. Arc is 4" (10cm) in length. Link here.
http://www.blackgto.com/tesla/tesla_briefcase2.avi

I appreciate the nice comments. I think this TC turned out rather well with minimal tuning.

 

[Things]

@ Razako,

how many layers of varnish do you have on your secondary? maybe applying another two layers of varnish would solve your problems

That will only work if the arcs were above the varnish layer. If they are under the varnish, you would need to wind a whole new secondary

Nice arc pics BTW