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Problems with SGTC, Low Sparks

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MRacerxdl

Wed Oct 17 2007, 09:48PM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Hi all, I buyed some poliester capacitores here, and I putted on my tesla coil.

I was using a 1.44nF capacitor bank, with a horizontal Primary with 15 Turns and 7cm of height 9cm of radius.
My secondary is a 39,5cm coil with 1580 Turns arround 5cm of radius.

I know, I was totally out of Sync.

But now I have bought some capacitores and I made a new capacitor bank. Now I have 14nF (+-)

Now I need to reduce my Primary, to 24uH (it was 56uH). I reduced and now its in 23uH.
All still the same, the topload is only a tamp of metal in top of tesla coil. I think its a 2pF..

But I still have Low Sparks on the high side (max of 6cm)

My Transformer is a Linsa 5kV 30mA. By the calc of the Power (250W) I can reach 50cm max with 25nF of capacitor.
In the proportion its 25cm of sparks for that tesla coil.

Why I still have Low Size Sparks in the High Side??

Ah I almost forgot, My SparkGap its a 3 Titanium Tubes of 1cm of radius and 4cm of width.

Coronafix

Wed Oct 17 2007, 10:52PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Just try tapping at different points on the primary, but with 250W I don't know if you will get too great a performance increase. You meant a vertical primary didn't you? It might be good to make a flat pancake primary and increase the number of turns, I'd say you need more turns. I always found I needed more turns than calculated.

Hazmatt_(The Underdog)

Wed Oct 17 2007, 11:07PM

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

1. Make a fast Toroid from 3" dryer duct or 4" dryer duct and make sure its pretty smooth, then put a single breakout point on the surface.

Maximum spark length you could expect from that power is probably close to 18", That's what I got from ~ 300W

2. Flat primary or inverted primary should be fine for this coil. As mentioned before change your taps higher and lower to see where the approximate best tuning point is, then slide along the best turn for optimal.

3. Titanium Burns. Tungsten or Brass would be a better choice for the spark gap.

4. I tried using a 1600T secondary but its performance wasn't quite as good as my secondaries in the 950T to 1100T range with 4-4.5 H/D aspect ratio. Stay inside this ballpark for better results.

5. I would probably use a 30* inclined primary with 1/4" copper tube for a small coil like this. And the first turn of the secondary would be level with the first turn of the primary for more coupling.

MRacerxdl

Thu Oct 18 2007, 12:45AM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Alumminium its better than titanium? I choose Titanium before because of his High Temperature Support.

Hazmatt_(The Underdog)

Thu Oct 18 2007, 02:00AM

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

Aluminium is for the Toroid.

Tungsten is for the Spark Gap.

You might want to re-read the reply.

EDY19

Thu Oct 18 2007, 03:23AM

Registered Member #105 Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408

I also think that 1/4 inch copper tubing might be a little overkill for a coil of this size, but then again, it shouldn't hurt anything, just your wallet

Hazmatt_(The Underdog)

Thu Oct 18 2007, 04:04AM

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

1/4" copper tubing is more redily available then 3/16" or 1/8", even where I live which has 8 hardware stores within 10 miles! There is only 1 store where I can find 1/8" or 3/16" without special order and that's ACE Hardware.

I was giving advice while considering availability.

MRacerxdl

Thu Oct 18 2007, 07:56AM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Here , Tugsten Tubes are pretty dificult to find (same for Brass ones) I think if I cant get those, the better is copper, correcty? The topload I need to find something for that, I have made a toroid here, but it isnt so uniform.
I think its easier to find a metal ball, I see some videos, and I think the performance its better, or it just the energy gets better disparsed on all ball??

Coronafix

Thu Oct 18 2007, 09:13AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Copper tubes for the spark gap works just fine. I use five next to each other with a small gap.

EDY19

Thu Oct 18 2007, 03:33PM

Registered Member #105 Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408

Yeah, i've tried searching for 1/8 or 3/16 tubing to no avail as well, however i just meant wire might be a slightly cheaper option then tubing. Just my 2 cents

With my ~250W tesla coil, i managed about 12 inch sparks, but it really does all have to do with the tuning!

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