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Finn Hammer

Mon Jul 05 2010, 06:39AM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

UbuntuNinja wrote ...

I thought it said on the first page that the bridge was 40N60s.

If does. But that was only to develop the Predikter, a not insignificant subassembly of the coil.

UbuntuNinja wrote ...

Do you have a picture of the process you used to bend the pipes into shape? How did you manage to keep them so perfectly round and what pipe size did you use?

Thanks,
UbuntuNinja

This is a standard plumber job, and I have no pictures. Using a proper pipe, and the necessary skill, a roller bender normally results in near perfectly round rings.

Cheers, Finn Hammer

UbuntuNinja

Wed Jul 07 2010, 07:39PM

Registered Member #2677 Joined: Mon Feb 08 2010, 03:06AM
Location: Palo Alto, California, USA
Posts: 64

Finn Hammer wrote ...

This is a sandard plumber job, and I have no pictures. Using a proper pipe, and the necessary skill, a roller bender normally results in near perfectly round rings.

Cheers, Finn Hammer

All right, thanks. What type of pipe do you recommend?

Finn Hammer

Thu Jul 08 2010, 03:45PM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

There are a lot of "if's" to the choice of pipe.
Diametre: *around* an inch, to one and a half.....
Wall thickness: thick enough to avoid dents, not so thick as to get too heavy.
Hardness: Soft enough to bend well, not so soft that it bends too easily when you move it around.
Weldability is a must.

Allu grade: Different systems in Europe and US

Hard question to answer...

Cheers, Finn Hammer

Dr. Mario

Tue Aug 03 2010, 09:04PM

Registered Member #3059 Joined: Tue Aug 03 2010, 04:09AM
Location: My turf
Posts: 18

Nice tesla coil project! However, I like your Prediktor primary coil setup - nice to see that your tesla coil have a brain keen enough to find such a nice sweet spot for suchj a big spark.

Would want to do that one too! ^____^

( About ten-year gathered parts, I must agree with that one, the envy of the basement tweakers. :| )

Reaching

Thu Aug 12 2010, 08:54AM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

Hey Finn.

I read this thread with enthusiasm ^^ first of all i wondered what this predikter thing would do and why it has become so popular within a few weeks. so i had to try it on my own. first of all i simulated some things and calculated a bit.. that was boring ^^ But i wanted to simplify the design and get rid of this symmetrical power supply.

yesterday i build my predikter version into my drsstc9 and was surprised. it worked after a few minutes of fiddling, and the signals went better and better.. the perfomance increase is frightning^^ dont know if my coil was not in tune or something but after i build in that predikter, it worked fantastic!

attached is my simple predikter version ^^

Finn Hammer

Fri Aug 13 2010, 05:08AM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

Reaching,

Thanks for sharing.
Obviously, I have to say:" Of course it works better with the Predikter" but still it is nice to hear confirming reports.
Particularly from the experts, like yourself

Cheers, Finn Hammer

Dr. H.

Sat Aug 14 2010, 01:21PM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Good day and great work guys !

Reaching - what is the function of L3 ?

Cheers

Reaching

Sat Aug 14 2010, 02:23PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

L3 is build close to L2 and is picking up some noise from it, around 5mV which is in phase with the incoming feedback signal. so i have a small signal sinus at the noninverting input of the comparator which is slightly positive at the positive halfwave and slightly negative at the negative halfwave of the sine. dont know if that makes much sense, but i wanted to be shure that no noise straiing into the comp or the feedback ct(through ground loops etc) can trigger the comparator back within a positive switching transition.

for sure i could add a resistor instead of L3 but then the signal at the non inverting input of the comparator is sligthly positive at all time, and then the comparator doesnt put out a nice 50/50 squarewave. or i could have put the pin on gnd,, but then i would be afraid of oscillations of the comparator. i think everything from a 3turn coil to a resistor with 0,1ohm or something would be suitable..

Finn Hammer

Sun Aug 15 2010, 07:48AM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

Reaching,

Brilliant thoughts led to L3, I like it!
I just biassed ground leg -8mV(ish) and be done with it. Perhaps at the first transition, where input from CT is low, it leads to measurable assymmetry in output squarewave, but at 4kA+, with like 6V in from CT, hardly a concern.
Nevertheless, a nice, elegant addition to the predikter.

Cheers, Finn Hammer

Finn Hammer

Fri Oct 22 2010, 07:41PM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

Seing a feature described with words, or a picture sometimes, just doesn't cut it. A video is the thing.
Here is a video of Daniel and myself, erecting the secondary of Thumper.

This is to show the convenience of having a hinged platform at the bottom of the secondary.

Cheers, Finn Hammer

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