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Registered Member #206
Joined: Sat Feb 18 2006, 03:17PM
Location:
Posts: 72
I made 2 nano SGTCs, one prototype yesterday and a very pretty, a little smaller version. The first one died because of a plasma, that was generated inside the coil due to too thin walls of the plastic tube. The second one is dieing right now... racing sparks made little holes in the insulation and an arc to the primary has caused additional damage to the coil.
The first one:
It is 22mm thick and 50mm long, the coil itself is 35mm long. I bend an 35mm torid out of 5mm aluminium.
up to 5cm sparks but just if the sparks don't go anywhere else...
This coil was very ugly, so it was clear that there are some racing sparks.
The second one:
Tube: 20x50mm, coil 40mm
I made this 25mmx5mm torid out of a 25x25x5mm piece of the chopper rod, I had left from my railgun. It took very long to get it to look like this, but now I can use my nano SGTC either for HV as as a mirror
up to 7cm sparks with this coil, but they often (too toften) hit the first windings.
No racing sparcs on this pic, but after increasing the flyback's input power, it didn't took long until it smelled like burning plastic and varnish...
I drive both coils with a flyback and a 3.3nF mmc. Both of them have a resonant frequency of about 1.5MHz.
Is there any chance to stop the coils from burning away? I often see so little DRSSTCs that have longer sparks than their coil actually is, so why dont they just burn away like my nanos?
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
Usually racing sparks = bad tuning...
I once made a nano sgtc... I used a 1cm by 10cm form(3cc syringe) that was wound with 30awg wire. I had a 5 turn solenoid primary on a 1.5cm radius about 4cm tall (back before I knew better), powered by a tiny (like measured in pf, I forget how much) mmc, half wave rectified 30kv 20w plasma globe supply and I used 2 woodscrews wound into a piece of pvc for the spark gap.
It took like 30 minutes to build, and gave ~1cm sparks for my efforts...
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
my first coils were such tiny sgtcs
I used ignition coil as supply (not so much power like flyback) , coils were on 1,8mm PVC tube one 8cm high, other 15cm high and they did some 5cm + sparks, even with such low power. Used bottle caps and huge coupling (primary of 15 turns of 2,5mm wire, more than half of secondary high. Never had racing sparks or so, just lots of corona between primary and secondary.
5cm sparks could be drawn by hand, at 3cm very stable arc was formed and it wasnt so pleasurable any more.
of micro coils small SGTCs seem best preformers ( OK now we have DRSSTC that did beat them )
pity I have no pics of it working, one secondary is now working as SSTC that can be found in nearby topic
Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
Just the fact that the secondary is too small is the problem. The secondary has to be dimensionated for the power input, athough it will breakdown. The ignition coil/flyback transfomer, need a bigger secondary (4-5 cm diameter) to get best results- arcs to 8 inches or more. The small radius secondary will be proned to failure.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
my secondary was only 1,8cm in diameter, and about 15 high, it worked perfectly with ignition coil (power was not too big) Due to high coupling there were massive primary-secondary corona breakdowns but secondary never got burned or racing sparks, just lost little power (still produced +5cm sparks).
Topload was ping-pong ball sized sphere, and it sprayed around streamers (just like that toroid on picture) without any breakout point.
If coil burns it is because of too much input power, ignition coil is prefect for such coils (can be run AC, no need of rectifying because of low frequency, power is few to few tens of W, not too much nor too little...)
Flyback really seems overkill for such thing, putting 100W in such nanocoil will just cause it to go smoke.
Also maybe good idea is to make secondary longer but minimize the diameter (i wound such secondaries) this will allow longer spark for same power and less voltage between two turns, no racing sparks or arcovers...
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nano SGTCs
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