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Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
1. is it a bad thing in a tesla coil if the primary cap is very close to the resonant value capacitor for the nst?
does it not really matter, because of the inductance of the primary?
2. This isn't specifically tesla coil related, but what would happen if a capacitor of the resonant value for nst was attached to the output with no way to short or dissipate energy?
Would voltage just rise until the NST or cap bank failed, or the voltage got high enough it could arc from one cap terminal to the other?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
1. It doesn't matter as long as you use a static gap and don't open it too far 2. The voltage would rise until the core saturates (and the voltage would stabilise) or the winding insulation breaks down, whichever comes first.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
magnet 18 -
Both of your questions are covered in detail here: The inductance of the primary has nothing to do with the risk of resonant voltage rise.
You know that using a resonant value cap can ring-up an extremely high voltage in the tank circuit, but that's not the problem. The real "problem" with a resonant value tank cap is one of operator self control. Here's the usual scenario:
1. You get your coil running well with a conservative spark gap setting. 2. After a while, you open up your spark gap slightly, and get a noticable increase in streamer length. Wow! 3. You open the spark gap a little further still, and performance increases even more! The coil is really running spectacularly! 4. You invite several of your friends over to show them how well the coil is running. After all the ooh's and ah's, you decide to open the spark gap up just a little further, to really, REALLY impress your buddies. 5. After adjusting the gap, you switch on the power, the coil is shooting hot streamers everywhere, longer then ever before, when suddenly .......... silence. No streamers, no activity at the spark gap, no sizzling, no corona, no smoke .......... nothing. 6. You flip the power switch on and off a few times, desperately hoping to "resurrect" the coil ........... nothing. You quickly close the spark gap down to its previous consevative setting and hesitantly flip the power switch a few more times .......... nothing. You have killed the NST (or your tank capacitor, or maybe even both). 7. You ask yourself - why, WHY did I continue to open up the gap when I knew the risk involved with a resonant (or near resonant) cap value? Moron! Imbecile! 8. You send your smirking friends home, drag the remains of your coil into the garage, turn around and shut the door behind you.
It's dead ....... totally dead. Your hard-to-find, non-GFI NST is dead. Your coil is dead. It's over.
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
Thanks!
Right, so, set a safety gap at a reasonable voltage to keep myself from flucking it up too bad, and once I get it working good, don't open the spark gap too far.
Sooo... anyone know what the maximum voltage the average 15kv nst can handle before insulation failure?
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Couple quick questions about resonance
