Hey again Steve, I wanted to add more to the last mail but the text wouldn't break away from the link. Sparky is wound on a 8" pvc around 44" long. The winding is 38' of 20ga, the cap is 2-1.5mfd 45,000 volt Maxwells for .75mfd. The torroid is 32" major and 8" minor with a 12"x3" underneath. Power supply is a Sola 15K bombarder. It sparks around 13' to 15'.
Stan
From: Steve White <steve.white1@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Friday, August 11, 2017 10:01 AM
Subject: Re: [TCML] First coil
I didn't mention it because I thought that it went without saying but yes the end of the secondary winding is grounded with 1" wide copper braid.
I did use javatc extensively and the tap point was very close to that predicted. I further refined the tap point based on my own outdoor resonance measurements with an oscilloscope and signal generator. I don't think that javatc accounts for increased capacitance due to streamers so that is why I think I can get a little more out of the coil by adjusting the tap point some more to lower the resonant frequency of the primary circuit a little more.
That might be an interesting feature to add to javatc. Enter a streamer length and the top load capacitance will be adjusted accordingly. I have no idea if the effect of streamer length can be mathematically predicted in such a way that it can be programmed into javatc though.
----- Original Message -----
From: "paul" <tcml88@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, August 11, 2017 12:26:32 AM
Subject: Re: [TCML] First coil
Steve White wrote:
> I currently have a copper-clad steel rod driven 3 feet into the
> ground for the RF ground. This is as deep as I could drive it.
You may not need to go deeper - consider the skin depth of your
earth/ground material at your operating frequency. No point in
going down more than a skin depth.
> I only run mine outdoors.
> ... I can set it up outdoors in about 10 minutes.
Roll out a chicken wire ground mat early in the set up.
Or perhaps you can use shallower ground rods but more of them,
spread out around the coil.
Your list of things connected to the RF ground didn't include
the secondary base - I guess we can take that for granted.
Certainly the strike rail but others may advise about the other
RF grounded items. RF ground can have some RF volts and
transients (during strikes) relative to the domestic/AC/safety
ground.
> surprisingly it worked the first time that I fired it up.
> I made extensive use of javatc to design this coil.
Those two statements are often strongly correlated. Did you
find the tapping point predicted by JavaTC was close to optimum?
That would be a good sign that everything is working according to
design.
--
Paul Nicholson
http://abelian.org/
--
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