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First working Tesla coil.

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LAN_403

Tigeris

Wed Nov 05 2008, 10:20PM

Registered Member #1656 Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53

I finally got it to work, but i cant get streamer more than like 5 inches. They only hit that cause of a rod i have next to it. But when i move the rob back any more (turned off of course) i dont get anything.

I have approx. 850 turns on my primary, 3.50in tube. 12kv 30ma transformer, 8 point 2mm gapped spark gap. 12 12oz glass salt water bottles. Top load is 4.5 tall 15 across, made of metal dryer ducting. The primary is .5 inch wire. 10 turns. I have trying connection the wire from the cap bank to different locations on the coil and still nothing changes.

I have no way to measure the capacidence of the caps. but i have seen people do about the same thing with 12 bottles and theres work great. Also when i turn in on, it will crackle a second to 5 secs then just makes a vibrating sound in the cap bank.

Am i dont something wrong?

coillah

Thu Nov 06 2008, 04:20PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

Quenching?

Tigeris

Thu Nov 06 2008, 05:50PM

Registered Member #1656 Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53

No, but thinking about it

Hazmatt_(The Underdog)

Thu Nov 06 2008, 08:02PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Maximum you should see from a 12/30 setup is 18". You're getting 5-6" because you're almost there but not quite. You probably need one or two more caps, but only add one at a time to be safe. Then spend a while tuning, and use a breakout point for maximum arc length.

What you're seeing is that you don't have enough primary inductance/capacitence to match your secondary system.

Tigeris

Thu Nov 06 2008, 10:06PM

Registered Member #1656 Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53

Ok, i got it firing a little better, the gap doesnt stop firing and making that vibrating hum in the cap bank, i just dropped 2 of the points on the spark gap. But im thinking and agreeing with Hazmatt that i dont have enough primary. So i need to work on that, though getting the copper tubing is REALLY expensive.

I will post some more pictures soon:)

coillah

Fri Nov 07 2008, 09:35PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

you could add more capacitence instead of buying more copper?

Tigeris

Sat Nov 08 2008, 02:04AM

Registered Member #1656 Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53

huh, i didnt know if that would work. Im using saltwater bottles ... but i will try adding more to see if i can get bigger streamers.

Marko

Sat Nov 08 2008, 10:55AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi guys,

Hazmatt_(The Underdog) wrote ...

Maximum you should see from a 12/30 setup is 18". You're getting 5-6" because you're almost there but not quite. You probably need one or two more caps, but only add one at a time to be safe. Then spend a while tuning, and use a breakout point for maximum arc length.

What you're seeing is that you don't have enough primary inductance/capacitence to match your secondary system.

Hmm... really? I must be better than I thought as I'm getting 18 inches from a small 12/20 transformer... basically at first light. My spark gap was set too closely at the time, so I thought I could juice even a bit more.
Still such a stretched spark is very dim and only well seen in dark, I'd kind of like it more to have a biger power supply and run at more BPS.

I assume freau equation also assumes some cos fi for given VA of the transformer, which I'm uncertain what it is for a TC. Maybe 0.6-0.7 or so?

Assuming 0.6 a 12/30 transformer, it should be able to give some 25 inch sparks (I'm not sure how realistic that is still?)

For lossy saltwater caps, 18 inches might be just that though.

Marko

Hazmatt_(The Underdog)

Sat Nov 08 2008, 08:08PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

The best I could get with the 12/30 was 18". I think at this time I was using the mica doorknobs (which I do not recommend), and they were doing okay, but surely they were partially shorting.

They were old caps, drifting badly from their rated values and used when I got them. I could go back and see with the SrTiO caps will do on a small 3" system.

But my point is rarely do I see anyone getting more then 18" from 12/30. Now if you use H/D ratios of less then 4, you probably would see 20" of sparks. I'll have to check that out sometime, maybe with one of my test coils.

Tigeris

Mon Nov 10 2008, 10:22PM

Registered Member #1656 Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53

Well i got 15 turns on my primary with copper tubing now. Though im still not getting big sparks... I'm thinking like you guys said, i need more capacitors. Though i turned it on and got a couple sparks then it stopped, checked my cap bank and one of the bottle blew up. there was glass and water every were. Is there anything i can do to prevent this? o.O

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