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Registered Member #4290
Joined: Sat Dec 24 2011, 06:08PM
Location:
Posts: 5
I finished my new coil yesterday and i'm having issues getting decent discharges out of it. I've been testing it by bringing the secondary ends together (safety probe, obviously), does one end of the secondary have to be earth-grounded for it to tune correctly? because so far all i've been getting are 1 cm or so sparks to the safety probe. Any other advice is great too!
Specs: ResFreq: 1.4 Mhz Input: 12Kv @ 30ma Capacitor: ~7.5 nF beer-bottle capacitor Primary: ~7 turns 6AWG wire (adjustable between 1 and 30 uH) Secondary: ~500 turns 26AWG wire on acrylic (coated with acrylic varnish)
Registered Member #4108
Joined: Sun Sept 25 2011, 11:43PM
Location:
Posts: 149
The res frequency should be in the low hundred of kHz. You input power is also quite low which even when tuned will make for not very impressive sparks.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
FD3 -
Youi haven't provided remotely enough information about your coil to even begin to assist you with troubleshooting it.
Did you use a Tesla coil design program like JAVATC or WINTESLA to develop your design? If so, please post the output file giving all the mechanical and electrical parametsrs for your coil. If not, then download JAVATC (), enter all your parameters, and you may very well immediately see what your problem is.
A well-tuned and fully-optimized TC operating from a 12/30 NST is theoretically capable of generating greater than 30" arcs, although probably not with a salt-water capacitor.
You question the need to earth-ground one end of the secondary. If this is a horizontal bipolar coil, then no, no secondary ground is required. If this is a conventional vertical coil, then of course the lower ebd of the secondary must be connected to a counterpoise or earth ground.
Registered Member #4290
Joined: Sat Dec 24 2011, 06:08PM
Location:
Posts: 5
I've been wanting to order some Polyethylene caps for a while now, building a saltwater cap was attempted because i wanted to see how well it worked first, though i've had them work quite a bit better in the past.
For the question about grounding, i also wanted to know if having the ground end of the coil brought near the top load wouldn't produce a similar effect (albeit with one streamer) as having it earthed and then bringing a earth-bound electrode near the topload.
thank you for the JAVATC link, was wondering where that was!
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
Fd3 -
Again, without any further description of your coil it's impossible to answer your question about grounding, or give you any hints on tuning.
"500 turns of #26 AWG wire on acrylic" provides zero information on the secondary inductance. Was this wound on a 1/2" diameter acrylic rod, or a 12" diameter acrylic tube? What are the dimensions of your topload? What type of spark gap are you using? How have you determined that the resonant frequency of this system is 1.4 MHz? (which seems impossibly high, unless you have wound a really tiny secondary)
Have you built a bipolar coil with the primary located at the center of the secondary? Or a conventional "1/4 wave" coil with a vertical secondary and primary located at the lower end?
In either case, the primary is normally located either at the zero-voltage node at the center of the secondary (single bipolar coil), or at the grounded end of the secondary (1/4 wave coil). If you have built a 1/4 wave coil but do not ground the lower end of the secondary, you will usually get serious arcing between the bottom turns of the secondary and the inner turn of the primary.
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SGTC Tuning problems
