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my secondary coil, is this OK?

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raff

Tue Sept 01 2009, 11:31PM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

I see.. I charged the home made cap(7.8nF) with 80watt flyback driver, it gave out max NOISE(bang) with 4mm gap distance, beyond that, no more arking.. higher GAP, lower charge-discharge cycle, lower gap (say 1-2mm) results in faster charge-discharge cycle... Thanks

raff

Wed Sept 02 2009, 07:29AM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

almost done

blower or sucker? its from a cheap hair dryer...

still working on that fan motor(for gap) and the topload... otherwise, its done...

(mod edit: oversized pics cruelly squidged! Edit your post to see how)

raff

Wed Sept 02 2009, 09:31AM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

guys,

does the topload HEAT up during operation? If I cant find a metal or aluminum duct, maybe I will use a plastic ang WRAP it with many layers of aluminum foil..

Mads Barnkob

Wed Sept 02 2009, 01:29PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

raff wrote ...

guys,

does the topload HEAT up during operation? If I cant find a metal or aluminum duct, maybe I will use a plastic ang WRAP it with many layers of aluminum foil..

There should be no significant heating on the topload on such a small flyback driven SGTC, unless you draw an arc closely for some period.

I have only experienced real heating on the topload, where it felt warm to the hand, when running 3kW CW mode on a SSTC.

Coronafix

Wed Sept 02 2009, 11:15PM

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

You should turn that hairdryer around so that it blows between the gaps.
If your primary is solid copper, then you could strip the insulation and tap it where you want to.

raff

Thu Sept 03 2009, 12:25AM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

guys,

made a 1st run.. primary used was that shown in photo.. inner diameter was 4.4" and spark gap no BLOWER yet.. powered it up with 12w flyback driver..it works! but I had to draw the arc going >> to the GND end of the secondary..or there is arcing between primary and secondary(w/c has OD of 3")... I have also seen that there is MORE output with topload compared to NO topload... with 12watt power from flyback driver, I could draw 1cm spark from it(no tesla connection).... with the tesla connected and running, I could get close to 1.5" (with topload) using the Hv out of the secondary and its GND connection...

this morning, I have integrated the hair dryer motor(as blower) to the gap..done! and I have REdone my coil (just expanded it only) so I could make 6" ID coil..resulting in 4.5T total.... I did THIS so there will be no arcing between primary and secondary... here are the results:

flyback driver = 78watts
WITH topload I just get 1.5" arcs (to GND connection)????
no topload, I could get 2-3" arcs (to GND)
but arcs are kinda THIN...

this means its seriously detuned, right?

I had better results with the 4.3" diamter primary than this 6" diameter primary...

EDIT:
after a few hours of tweaking, I made a new primary coil , flat pancake but looks like a cone

I think its in tune now, 5T for the primary and had to put up again my topload.. powered it up with my zvs@320watts, and bwweeeeeeewww there goes the noise.. with spark gap of 1mm, arcs(to gnd) are fast continouos, can reach to 4 or 5" in length..with gaps of about 4mm, I get whiter sparks(and longer too,about 6-7").. but its MORE noisy than ever, and I seem to have prob with my home made cap, the internal aluminum sheet sometimes arc to the connecting wire.. need to make another one with smaller foil dimensions... with 1mm of gap, my cap SEEMS to conk out.. dunno how to call it, seems like it would want to fire or not, something like that, and output seems a bit diminishing when this happens..

ill post video of this soon.. once we get clear skies here...

raff

Sun Sept 06 2009, 10:59AM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

guys,

is this normal behaviour?

#1> when SGTC is close to being in-tune, tank CAP (sort of) heats up a bit than when you where just off resonance?

#2> with my secondary coil resonating at around 680KHz, putting an IDEAL topload, what would be the final resonant freq? just an estimate

pls

brtaman

Sun Sept 06 2009, 11:39AM

Registered Member #2161 Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247

Hey raff,

Nice project you are working on, using a blow-dryer is a good idea, it worked great for me on my flyback TC. As coronafix mentioned, you want it blowing on the spark gap.

To answer your question about the spark gap tunning, in the case of flyback SGTC's (have yet to make an AC charged SGTC), the tuning of the spark gap does have an effect on the tuning. Particularly, the higher the BPS (smaller gap width) the longer the streamers. I have noticed in my case when I was doing a final tune that changing the primary geometry (adding and subtracting turns) affects the BPS of the system so I had to adjust the spark gap for a given amount of primary. I believe that this is mainly due to the coupling coefficient and ring-up, as they affect the transfer of energy from primary to secondary.

Also the FKP-1s in my coil do seem to heat up quite a bit when running for 15 minutes+.

Please post up some vids when you are done, I really want to see what 320W of flyback input power does in action. :) Is the flyback ZVS driven?

Thanks
brtaman

raff

Sun Sept 06 2009, 12:42PM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

Hi brtaman

yup its flyback zvs driven (40Vdc@8A) ... I could get almost 8" arcs to GND with the SGTC.... I do FINALLY see arcs (on the topload) even with a non-proper grounding of the secondary :) 3 meters of gnd wire still NOT connected to EARTH ground... but its better now than before.. note: I have been DOING the tuning on morning/afternoon only (outdoors) so sparks are a bit hard to see(or thin looking).. cant do it YET on evenings (SGTC are notoriously noisy)..

I changed again my primary to using 0.04" diameter HOOKUP wire (helical = 9T/4.2" ID about 19uH inductance), this has much better coupling than with the flat pancake style.. though I lowered it up a bit becuase of arcover with pri/sec.. I know pictures say more than words BUT.. dont worry i will post tommorow...

right now im just a bit frustrated

(though its my part to blame) because I have to make another tank cap (mine was from hvwiki).. two times I have made but I used fewer sheets of transparency to upper the capacitance, after a few runs (few minutes actually)with the SGTC (w/c happen to be almost tuned) it died..but it DID work as expected...

this time Im going to REALLY FOLLOW those 15 sheets transparency total.. mine was only totalling 5 sheets

and maybe ill have to redo my blown spark gap, maybe ADD another metal in-between(to make up a series SG for a better quenching...

one more thing I noticed, SGTC doesnt really need high amperage input(from zvs) but wants HIGHER voltage.. that is what I have noticed... flyback driven zvs with 15V @2A has more Hv output (on sgtc) than 12V @ 6A...

till then..

brtaman

Sun Sept 06 2009, 01:23PM

Registered Member #2161 Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247

Hey,

You really should ground the secondary. You will be in for quite a surprise performance wise. ;)

I agree SGTC's are VERY loud, but flyback SGTC's are even worse I think, my TC screams like an angry banshee. Earplugs are mandatory.

I think the main reason you are not seeing larger streamer/high performance when upping the voltage input is that you are limited by your cap size. Even though you are applying more power, all that is doing is charging up the cap quicker and effectively increasing your BPS, the bang energy is remaining constant, with extra caps you will increase your bang energy greatly, but with the increased supply of power the caps will still "fill" at a BPS similair to now, which will in turn increase your coils performance drastically. I suggest making an extra two three caps and hooking them up one at a time while increasing voltage input.

Anyway enjoy your project, building them is the fun part imo.

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