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Re: Re Basics


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Sunday, August 03, 1997 3:59 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Re Basics

Hi all,
          A few comments:

> From:   Julian Green[SMTP:julian-at-kbss.bt.co.uk]
> Sent:   Friday, August 01, 1997 11:56 AM
> To:     tesla-at-pupman-dot-com
> Subject:    Re: Basics
> 
> >Greetings from Australia!  I have been "lurking" in the background for a while
> >and I must say this is a GREAT list!  Very informative, but a fair bit is
> >rather advanced for me at this stage, as I have yet to build my 1st Tesla coil.
> >Would appreciate it if someone good guide me on where to start in the midst
> >of all this excecellent technical information. I guess I should start on
> >something of lower voltage and ease of construction 1st.
> >Then advance to the "power user" class later!    :-)
> 
> Starting on lower voltages is slightly safer but by not much.   Getting a zap
> from a charged 0.02uF capacitor at 8KV could to be fatal.  Make sure you 
> discharge your caps before you make adjustments.
> 
> Don't go for a small coil.
> Small coils have a high resonance frequency and good sparks are difficult
> to get at these frequencies.  All you get is brush like discharge and loads of
> ozone - you will have to evacuate the room very soon after.

I have noticed that ozone/NOx generation seems to be very much higher 
for small high frequency systems. This may be an illusion or it may 
not. I wonder if E = hv is at work in this instance?? ?  Anyone 
measured the amount of gases from a small and large system and 
compared them?

> >From other posts on this list a 4" coil sounds good although my first coil
> was 7" diameter wound on plastic gas pipe and this has worked very well
> at low power and also at higher powers.  Its resonant frequency is 170KHz with
> 24" toroid and spark production is good.   I was able to generate 6" sparks
> on only 1.5Kv primary voltage.  I now get 45" from the same coil running at 
> 11Kv and 3KVA.
> 
> You want to aim for about 900 turns of wire on the secondary.  Chose wire
> size so that the winging length does not exceed 4 times the diameter.
> 
> Make the primary from copper pipe, refirgeration tube is good, but quite 
> expensive.  Coax makes a cheaper alternative remember that skin effect comes
> into play here so thin wire is no good - use the braid.

Aaarrrrgggghhhh!!!  Please _do not_ use braid. You will degrade 
primary Q _very_ significantly. Skin effect is exactly what makes 
braid a no-no. If you don't believe me, go ahead and use it and 
remember to wear heat proof gloves if you handle it after firing.
<snip>

Malcolm