Voltage/Length (fwd)

From: 	Robert W. Stephens[SMTP:rwstephens-at-headwaters-dot-com]
Reply To: 	rwstephens-at-headwaters-dot-com
Sent: 	Monday, January 19, 1998 6:21 PM
To: 	Tesla List
Subject: 	Re: Voltage/Length (fwd)

> ---------- Forwarded message ----------
> Date: Mon, 19 Jan 1998 19:17:09 +0000
> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Voltage/Length (fwd)
John Couture wrote:
>   Jeff, All -
> These tables are based on spark conditions and
> using apparatus that is very different compared to Tesla coils. For this
> reason these tables cannot be used for Tesla coils.
> Also, the equation is based on benchmarks that have
> been used by coilers in the past, such as 60 inches represents one million
> volts for Tesla coils. 


In my own experimental experience the distance benchmark you give of 60 inches
for 1 Megavolt is not accurate for a Tesla coil discharge.  The actual terminal
voltage required for such a distance feat is, in my own experience, considerably
less than 1 Megavolt.  Although there are at least two examples of so-called 
professional suppliers of commercial Tesla coils for sale out there who employ 
similar claims in their own advertising, actual laboratory measurements 
would surely more-often-than-not show such marketing claims as highly

Greg Leyh has, as I understand actually measured the output terminal 
voltage of his older 45 kW Tesla coil as no more than some 500kV 
while producing streamers between 20-30 feet in length (if memory and 
attention serve me correct).  His finding follows my own measurements 
albeit at somewhat reduced streamer lengths and input power levels to 
his own very impressive achievements.

I am in the process of constructing a HV capacitive divider column 
probe to be able to measure both peak voltage and waveform shape on 
Tesla coil outputs up to either 500 kV or 1 MVolts (haven't decided 
how tall to make this sucker yet as one will be an inside capable 
tower, the other only outside capable given my present state of the 

John if you err on this fundamental variability (and this particular 
parameter appears slippery in the present state-of-the-art), and employ it as a 
"hard reference" in any of your software, your output data may not 
mimic reality at the level of accuracy implied.  You may wish to avoid making 
hard claims in "spark length VS voltage for Tesla coils" until more 
is known through actual physical measurement by researchers working 
in this field.

Greg, would you like to share your own measurement experience again with 
this list?

Always searching for the truth,

Robert W. Stephens
Lindsay Scientific Co.
RR1 Shelburne, ON Canada L0N-1S5
Tel: 1-519-925-1771   Fax: 
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 and special effects work.
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