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H~Tank~V

Sat Apr 19 2008, 12:55AM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

Im having issues with my Coil i just built. I tuned it pretty well, but im only getting about 12" arc's and there intermittent. They dont seem to be very constant. I used a little piece of wire on top to act as a breakout point, and I get about 8" sparks out of that, which are pretty consistent.

When I dont have the breakout point on, I occasionally see small sparks on my secondary, as in inside the secondary I think.

Can anyone help?

Thanks,

Andy

Ultra7

Sat Apr 19 2008, 02:40AM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Got any pic's, Andy?

What size is yer coil and all that.

PWR Supply, Sec, cap, toriod. . .
Stuff like that.
Lemme ask ya, did ya recently add a new topload, or did this just start happening?
Was the coil working fine then this happened, or is this just trying to get sparx out of initial tuning?

Sometimes your topload requires tuning out farther than Teslamap says.

J. Aaron Holmes

Sat Apr 19 2008, 03:00AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

H~Tank~V wrote ...

When I dont have the breakout point on, I occasionally see small sparks on my secondary, as in inside the secondary I think.

What is the diameter of your secondary? How about the minor diameter of your toroid? From the picture in your prior thread, they look pretty similar. 4" maybe? If they are very similar or identical, then you will likely have this problem. Streamers will want to originate from the object with the smallest diameter. One common design goal when selecting a coil form and topload is to ensure that the minor diameter of your toroid is arbitrarily smaller than the diameter of your secondary. If it is not, then you will likely have to use a breakout point to prevent breakout from the secondary. Some experimentation will be required to find the minimum breakout point size/length that guarantees consistent breakout from the toroid (not from the secondary). Too long, and streamer length will be severly compromised, as much lower voltages will be required to break out.

Cheers,
Aaron, N7OE

H~Tank~V

Sat Apr 19 2008, 04:03AM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

Here is a pic, Ultra.

Teslaalmost

This is a brand new coil, 15kV 30mA .01uF cap 3X12 Toroid.

J. Aaron,

My secondary is 4" in diameter. Im guessing by minor diameter that that is the internal diameter? If so its 6", I hope thats not to close!

Thanks alot guys!

J. Aaron Holmes

Sat Apr 19 2008, 04:30AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

H~Tank~V wrote ...

My secondary is 4" in diameter. Im guessing by minor diameter that that is the internal diameter? If so its 6"

No, "minor diameter" generally refers to the thickness (top-to-bottom, as you presently have it oriented) of your toroid. I'm guessing you have a 4"x13" John Freau or a 3"x12" Information Unlimited. Probably the latter, since you say the center diameter (of the "donut hole") is 6". Where exactly is the secondary breakout happening? Around the top edge of the secondary, or all over the place? In the latter case, you may be over-coupled, or it may yet be something tuning-related. Over-coupling is usually solved by raising the secondary a few inches above the primary. From the picture, the bottom windings of your secondary are about even with the primary windings, so that could spell trouble.

EDIT: Doh! You already said it was the 3"x12". I just read too fast. :-/

Cheers,
Aaron, N7OE

H~Tank~V

Sat Apr 19 2008, 10:39AM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

If it was over coupled, wouldn't the break out be down next to the primary?

The secondary breakout seems to be happening about 1/3-3/8 of the way up the coil, about where the red circle is.

Thanks alot guys!!

J. Aaron Holmes

Sat Apr 19 2008, 01:32PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

You might think so, but I've never heard anything to suggest that. Rather, the energy simply accumulates in the secondary faster than it can be dissapated via breakout from the top terminal, so it "chooses" somewhere else or takes shortcuts.

Cheers,
Aaron, N7OE

Ultra7

Sat Apr 19 2008, 03:16PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

H~Tank~V wrote ...

Here is a pic, Ultra.

That shoor is a pretty coil!

H~Tank~V

Sat Apr 19 2008, 03:58PM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

Thanks Ultra,

So J. Aaron, I should try and raise the secondary a tad?

Thanks!!

J. Aaron Holmes

Sat Apr 19 2008, 04:28PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

H~Tank~V wrote ...

So J. Aaron, I should try and raise the secondary a tad?

Yes, I believe so.

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