Re: [TCML] 35 KVA Vacuum Tube Tesla Coil

[Futuret <futuret@xxxxxxx>]

Roger, Carlos,

Nice work guys!

For basic VTTC's I use the formula:

  spark length (inches) = 0.5*sqrt input power (wallplug watts)

So for 35kVA that gives a 93" spark length.  Often coils don't quite
meet the 0.5 factor, so it may be better to use 0.4.  That would
give a 74" spark length.  Also the true wattage will be somewhat
lower than the kVA figure depending on your power factor.  

Roger your system may be suffering due to insufficient current
stiffness from your pole pig at 35kVA.  Nothing makes normal
basic VTTCs suffer as much as power supplies that aren't stiff
enough.  Yes it will be stiff at 5kVA or even 10kVA, but not at
35kVA.  You can probably obtain the 49" sparks using 10kVA
if everything is optimized.  It's the current peaks that are needed
for long VTTC sparks, but it's at the peaks where voltage drop
will be greatest.  You can get around all that of course by
using Phillip Slawinski's method.  

BTW when I first was building my first 36" spark VTTC, it tended
to draw 75 amps (150 amps?).  Only after careful tuning and 
adjustment I got that down to 28 amps or so, with the same 
spark length.   

Yeah filtered DC doesn't let the sparks grow, some sort of 
pulsed action, such as raw AC as a minimum is needed for long sparks.

Cheers,
John

 

 


 

 

-----Original Message-----
From: Carlos Van Camp <carlos@xxxxxxxxxxxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Mon, Jul 4, 2011 3:21 pm
Subject: Re: [TCML] 35 KVA Vacuum Tube Tesla Coil


Hi Roger,

Nice job!

I have been using the next valve size up (a 4CX15000a), and it is capable of 

50kw input.

So far I have only put about 35kw into it so we are on a par there...

I am only getting 40" of arcs at best (6 individual brushes of 40" each 

coming of the top electrode), so you are doing well.

Unfortunately I designed the Primary/secondary in the hope of much bigger 

arcs (very long secondary coil) so I think this is my downfall in 

efficiency...

I am planning to rebuild the primary/ secondary arrangement, but first I am 

running a serries of controlled benchtop sized experiments to see if I can 

improve the overall circuit efficiency.

I am trying to get my head around what makes the arcs get fatter with CW 

operation, as oppose to getting longer as with pulsed operation.

The search for the holy grail continues...!



What circuit did you use?



Kind regards,



Carlos

----- Original Message ----- 

From: "Roger Smith" <rwsmith@xxxxxxxxxxxxxx>

To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>

Sent: Monday, July 04, 2011 9:45 PM

Subject: [TCML] 35 KVA Vacuum Tube Tesla Coil





>     I got a hold of a big ceramic triode (3cx10000a3) a few years ago and 

> I finally built a tube coil with it.  It is powered by a 5 KVA pole 

> transformer at up to 35 KVA and I am now getting 50"  fat bushy sparks. 

> Here is a link to the video on it 

> http://www.youtube.com/watch?v=B8536fYHvGM&feature=feedlik 

> <http://www.youtube.com/watch?v=B8536fYHvGM&feature=feedlik>      I 

> haven't seen any other  VTTCs like it so It's hard for me jug the 

> efficiency of it.   Any suggestions are welcome.

>

>     Roger

> _______________________________________________

> Tesla mailing list

> Tesla@xxxxxxxxxx

> http://www.pupman.com/mailman/listinfo/tesla 



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