Re: New guy questions (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 18 Jul 2007 23:32:42 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: New guy questions (fwd)

Hi Dan,

The archives are a perfect place to get info. Good start...

>Hi all,
>
>I wanted to introduce myself by way of asking a few questions.
>I started getting interested a few months ago, doing some research, starting
>a design, scoring some hardware, and joining the List. Thought I stop
>lurking and ask-away.
>
>I have also been following the recent FAQ thread btw, and I can understand
>the difficulty such an undertaking might offer, since some of my questions
>focus on some well intentioned yet mildly contradictory input I collected
>from browsing various sites.
>
>1) How critical is the Secondary HD ratio?  I found some guidance, but I
>also see some folks seem to ditch the convention - for example, maintaining
>an HD of 4 to 4.5 for a 4" coil form. (I haven't run any what-if analysis
>since I've been waiting for the math refresher to hopefully sink into my
>brain).
>  
>
HD in my book is "smart". Yes, all other h/d's will produce sparks, but 
when it comes to a value of L and C for a classic 2 coil Tesla Coil, the 
4:1 to 5:1 ratio is optimum for best inductance without great dc wire 
losses, number of turns in a 1000 to 1500 range, and getting the coil to 
a mechanical height that serves the purpose of spark production without 
a lot of problems with primary strikes (if sparks are what your after).

>2) If I can afford an acrylic/plexiglas over a PVC Sec form, is it worth it?
>(considering dielectric, looks, ease of using an adhesive, etc)
>  
>
That's completely up to you. Acrylic is pretty and works just fine. PVC 
isn't as pretty but works just as good. This is not a criticle issue. 
Sometimes topics come up on the list and a few have their differences 
here, but there have been a "HUGE" number of pvc forms that have worked 
excellently without any prep. If you are in a very humid area, then it 
might be wise to seal the pvc as it is hygroscopic. Moisture does change 
a coil. Keep the moisture out, and the coil remains the same.

>3) Best place to score some Cornell Dubilier caps for an mmc: does the Geek
>Group really sell them? to non-members? Should I try eBay or another source?
>  
>
Check with Dr. Resonance here on the list. I was the first to buy the 
Geek Group caps back when they first offered the caps, but I don't think 
they sell them any longer. I've been referring people to D.C. Cox (Dr. 
R) ever since they stopped selling them. Dr. R. is using them in his 
professional coils and would likely be the most dependable source for 
the CD caps.

>4) One curiosity question, in my past acquaintance with circularly polarized
>antennae, I was just wondering if there was a winding-sense convention (left
>or right-handed) that applied to coils as well. I've found no such advice
>(probably for an obvious reason). Does it help or not matter at all?
>  
>
It doesn't matter for spark production. But, I always wind my primary in 
the same direction as the secondary (it doesn't hurt to try aiding). The 
top of the coil will be the hot end regardless of direction. If you were 
looking at my secondary's from the bottom looking up, my winding 
direction would be clockwise. Why? Simply because I'm right handed and 
when winding a coil horizontally on a slow spinning form, I always start 
at the left and work right. I also turn the motor clockwise so that I 
can see the winding over the top of the coil. This is mechanically 
practical for me. What is practical for you is the way to go.

>Too many questions? Reply here or to my address - whatever is better,
>  
>
Not many at all. And welcome to the TCML!

Take care,
Bart