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Re: First light great.



Original poster: "Bart B." <bartb@xxxxxxxxxxxxxxxx>

Hi David,

As Gary mentioned, the center disk doesn't contribute to field control and adds only a small capacitance to the total capacitance of the resonator. In most cases, the toroid proximity to the secondary is such that the disk plays only a slight capacitance effect, thus, changing the resonant frequency slightly. However, in cases where the toroid inner radius is large compared to the secondary diameter, then the voltage stress shielding ability of the toroid is reduced and a center disk would be preferable and perform a shielding role. My first coils never included the center disk and ran fine. As Gary also mentioned, the conductive center makes for a very simple connection and makes an easy to mount toroid. These days, I always throw in a conductive center regardless of toroid size, mainly for the later reasons. Using the plastic salad bowl would only be a problem if it raised the toroid too high above the top turn and you were experiencing top turn breakout, etc..

Take care,
Bart B.

Tesla list wrote:

Original poster: "david baehr" <dfb25@xxxxxxxxxxx>


Does the inside really need to be conductive ??? My toroid is settin' on an upside down plastic salad bowl.............I just spiral ( ? ) the wire up to the toroid..................it works, but heck,I dont know!!!





>From: "Tesla list" <tesla@xxxxxxxxxx> >To: tesla@xxxxxxxxxx >Subject: Re: First light great. >Date: Fri, 27 May 2005 11:29:20 -0600 > >Original poster: "Bart B." <bartb@xxxxxxxxxxxxxxxx> > >Hi Daniel, > >Tesla list wrote: >>Original poster: "Daniel Koll" <dk_spl_audio@xxxxxxxxxxx> >> >>Ok, thanks. I will try making a toroid first but have some >>questions. When I make the disc out of wood, should I cover the >>whole thing in AL tape? > > >Yes. This is just a simple way to place a center disc into the >toroid. Obviously, anything metallic will also work, but I usually >have wire spool ends around so I use them for the purpose. Simply >find something like a round wire spool end or whatever that is >already round and near to the inner diameter of the toroid >selection. If for example, you choose a 3"x12" toroid, the inner >diameter would be a 6" disc. Before you cover with Al-Tape, drill a >hole through the disc. The hole would be for a small diameter bolt >(rounded head) used for attaching the top secondary wire to. Cover >in Al-Tape completely (top, bottom, and sides). Use a glass jar or >similar to rub the Al-Tape as smooth as you can get it. Then, place >the bolt through the pre-drilled hole and fasten with a nut. The nut >side should be inserted from the bottom of the disc up to the top so >that the side which is facing the secondary has minimal protrusions. > >>Even the bottom? Anything else I should know? I will start with >>the 3"X12" that you recommended unless someone on the list doesn't >>think that is a good starting point. > > >After building the inner disc, simply form the flex tube to the same >shape so that the disc rides center of the inner diameter. You >should use Al-Tape again around the entire toroid to make it as >smooth as possible. I just tear off strips and place them one at a >time until it's to my liking. This will secure the disc to the tube >and create a nice small toroid. Use the glass jar on the tube as >well to rub out any protrusions from the tape. > >I set up a little coil a few weeks ago and had an old Al-tape toroid >I used. I decided to go into the garage and take some photos. >Sometimes pictures are better to explain these things. I'll pop them >up to my website. >http://www.classictesla.com/temp/Img_0615.jpg >http://www.classictesla.com/temp/Img_0618.jpg >http://www.classictesla.com/temp/Img_0619.jpg > >Be careful with the Al-tape. It can be sharp. >>If I would have known about the coupling I would have changed my >>design. >>This is my first coil and I had never heard of this ever being a >>problem. I ran the coil for probably 2 1/2 minutes total with this >>issue. The secondary seems to be fine and in as good condition as >>when I started, I hope the streamers didn't make pin holes through >>the enamel and polyurethane. If the new toroid does fail then I >>guess I will remove some of the secondary windings. My secondary >>is wound for 16" so if I take off a 1/4-1/2" I don't think the >>output will be reduced too much. > > >No, the output would not be affected. There are many things which >could have happen. Coupling and tuning are two most common problems >coilers run into. Both can cause racing sparks and can often be >difficult to distinguish which (or both) may be the problem. There >are other possibilities as well. If a visual inspection of the coil >looks ok (both inside the form and out), the coil is likely ok. They >can take some abuse to a degree. >>Finally, many people said that maybe it was just out of tune. >>Isn't the coil tuned when you achieve the largest spark output? >>All I did was trial and error until I saw what I think was the >>biggest sparks. >This is a perfectly suitable method to tune the coil as long as >nothing is damaged in the process. With high powered coils, this can >be chancy. Your coil is not high powered, so I think it's fine. >However, a far more precise method is to calc the system first. >Unless the user made an error in the calculations, usually only >minor adjustment is necessary for best output. > >It would probably be a good idea to give further specs on other >parts of the coil. Such as: cap size and type, spark gap, primary >turns, primary inner and outer dimensions. These are the common >specs for running a pretty good analysis on your coil. With that >info, the coupling and tuning can be calc'd very precisely. JAVATC >will tell-the-tale if you give it accurate data. If your >uncomfortable with the program, just give your specs here and I'll >run it for you. > >http://www.classictesla.com/java/javatc.html > >Take care, >Bart B. > >>Thanks >> >>>From: "Tesla list" <tesla@xxxxxxxxxx> >>>To: tesla@xxxxxxxxxx >>>Subject: Re: First light great. ........