Tesla Coil Build Thread

[Sigurthr]

I'd expect at least 6" streamers.

What was the output current and voltage of that trafo again? I'll dig up that online calc I used for mine.

 

[Fiddy]

Wow that big? its 9kV @ 20mA

 

[Sigurthr]

DeepFriedNeon says 7nF tank cap, but that sounds awfully small to me, let me poke around a bit.

Edit; I goofed my math. Make that 11.4nF. I forgot to multiply by Phi.

 

[Fiddy]

hmm well im running a 30nF tank @ 40kV

 

[Sigurthr]

Most likely the caps aren't getting fully charged due to the impedance mismatch. That's way far out from optimal. Probably a lot of reflected power there, I don't feel like doing the SWR calculations though.

Can you modify your tank to as close to 11.4nF as you can get? At 9kV input you only need a voltage rating of; 9 x 1.414 x 1.5 = 19kV. If you trust those caps' ratings that'd be about 4caps in parallel iirc. If you can do this then give a try.

JavaTC confirms my hunch that a pancake primary of 5turns of ~10ga with a 6" ID and 10" OD will resonate near 550kHz. Yes I actually took an educated guess on params and it worked out, lol. Does that mean I'm doing this too much >.> ?

 

[Fiddy]

hmmm so the tank cap isnt getting fully charged? putting 4 caps in parrallel will render 120nF.. Dont you means in series? 3 in series should get me 10nF?

Ill have to rewind the primary coil for that i have 3 turns atm, is it better to have more than that you reckon?

Edit jut ran JavaTC again and it confirmed a static gap error "PRIMARY CAP TOO LARGE TO CHARGE" will go make the changes you said Sigurthr!

 

[Sigurthr]

Err I though those were 3nF caps, not 30! Lmao.

Do whatever to get close to 11.4nF (0.0114uF).

Edit; oh and I'd say go for 6turns on the primary so you can tune as needed.

 

[Fiddy]

Hehe Will do! i will work through the night. Thanks for your help on that :beer:

 

[Sigurthr]

Of course, anytime!

Get some video of it running when you're done too, I suspect you'll need some pointers on the gap quenching too.

 

[Speedy78]

Damn Fiddy. Looks like you will be beating me to this sg build. Should be winding the secondary today though. Will update with pictures Any ideas for a simple turn counter? Was plannibg on counting the 1400 turns in my head but that may be a pain in the ass.

 

[The Lightning Stalker]

It depends what you are holding the coil with and weather you have something which can increment and
display numbers. If you don't have an electromechanical incident counter, you might have something if
you're willing to sacrifice a pocket calculator. It has to be the kind that will count up when you hit 1 + 1
and repeatedly press the = button. You would arrange the coil winder so that something hits the =
button as the coil goes around. Or you could solder a couple wires to the = button contacts and
arrange them so they touch on every revolution. Some PC calculators do the same thing. You could
use an old keyboard or mouse to do the same thing. An Arduino is perfect for this kind of thing.

 

[Speedy78]

I may try the calculator. The coil is in a winding jig so something attached to the formwr hitting a button should work. Should be easy enough to have an arm hit the button or something. My keyboard is bluetooth for my.computer so I can go that route too. Thanks!

 

[Sigurthr]

Eh I wouldn't bother counting turns. Due to the de tuning effect the coupled magnetic field has your secondary will resonate lower in circuit than it does in free space. That's why I just make it and ping it to get an idea or make it according to a JavaTC model. The turns calc built in seems to be reasonably accurate too, just make sure you know about the coating of your wire, makes a big difference.

 

[DashApple]

Quick video of my CW SSTC , full power run was 8 seconds as in abit nervous to run it any longer

Mini CW sstc test run - YouTube

Two pictures coil running full power and full bridge .


IMG_0172[1] 644 by TwirlyWhirly555, on Flickr


IMG_0173 by TwirlyWhirly555, on Flickr

 

[Operator]

That 1st shot is awesome!!!

 

[Sigurthr]

Beautiful little monster there, Twirly. I don't know how your stubby secondaries don't melt, haha.


Update: Finished the circuitry part of my MCU Interrupter:

http://youtu.be/DaVfxf2_evE