Re: Re Second change for longer sparks (fwd)

---------- Forwarded message ----------
Date: Thu, 16 Jul 1998 07:57:12 +0300
From: Marco Denicolai <marco-at-vistacom.fi>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Re Second change for longer sparks (fwd)

At 21:43 15/07/98 -0600, you wrote:
>---------- Forwarded message ----------
>Date: Wed, 15 Jul 98 10:09:55 EDT
>From: Gary Lau  15-Jul-1998 0954 <lau-at-hdecad.ENET.dec-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re Second change for longer sparks
>>From: Marco Denicolai <marco-at-vistacom.fi>
>>After using a bigger toroid and getting improvements:
>>air streamers from 20" to 31"
>>streamers to grounded point from 20" to 24"
>>I have reduced my RQ spark gap gaps from 0.0275" to about 0.007". This was
>>mechanically not so easy and I ended up with a clearance between 0.005" and
>>0.01" (about) different between different sections. Not good...
>>Before I was using two series of 0.0275" gaps in parallel. Now I could use
>>a single series of 10 gaps and have the safety gap strike intermittently. I
>>tested with this setup and I didn't notice any improvement (or worsening) of
>>the streamers. Spark gap sound was intermittent as with the old gaps.
>>Then I started reducing the number of gaps until I was using 5 gaps. The spark
>>gap sound was then almost continuous and I got longer streamers! About 35"
to a
>>grounded point and over 40" into air.
>>My problems:
>>- the gap gets extremely hot very quickly
>>- some of the gap sections get filled with some black stuff (cupper oxide?)
>>- I don't quite understand what is going on!
>>Please, help me to figure out what I am doing...
>>- I suppose I have just increased the spark gap breakout repetition rate
as well
>>as I have fed the primary with less voltage. Higher discharge rate seems to be
>>better for longer sparks than higher voltage. Am I right?
>>- Higher repetition rate stresses more the spark gap that gets really hot. Is
>>that the way it should work or what should I do?
>>- My ideas (also after reading the list mails) about the relation between:
>>   - spark lenght
>>   - primary voltage at gap breakout
>>   - breakout repetition rate (60 Hz, 120 Hz, more?)
>>   - spark gap quenching
>>are VERY confused. Could please someone give a brief (or long if he can)
>>explanation about the above factor interaction?
>A little more info is required.  What kind of power supply are you using?

A double MOT plus voltage doubler supply: that gives about 6.5 Kv and about

>A simple gap arrangement like you describe is fine for small-medium
>coils, but not so good for high current multi-KW jobs.  Also, do you have
>any air flow over your gaps?  

Yes, I have a simple blower fan.


 Marco Denicolai                   Vista Communication Instruments, Inc.
 Hardware Development Manager      www.vistacom.fi   

 marco-at-vistacom.fi                 Kaisaniemenkatu 13 A
 fax:    +358-9-622-5610           SF-00100 HELSINKI
 phone:  +358-9-622-623-15         Finland

   Remember, Murphy was an optimist! I am not...