Re: troubleshooting tesla coil (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 14 Jun 2007 20:55:22 -0600 (MDT)
From: Chip Atkinson <chip@xxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: troubleshooting tesla coil (fwd)

Here's a thought.  It could be that a multimeter doesn't measure a short
because the multimeter's voltage is so low that it wouldn't be able to
jump any gap at all.  At 5500 volts, you can jump some gap so it could be
shorted out.

One way to debug that is to disconnect one of the leads from the NST to
the gap.  Put it on a wooden or non-conductive stick so you will be plenty
insulated from the current.  Then bring this disconnected lead up to the
point where it connects and see what kind of spark you get.  If it's kind
of a flaming spark you have a short.  If it's a really loud crackly snappy
spark then your cap is fine.  

Try that and let us know what you see.

Chip

On Thu, 14 Jun 2007, Tesla list wrote:

> 
> ---------- Forwarded message ----------
> Date: Thu, 14 Jun 2007 19:32:17 -0400
> From: Marko Ruban <Marko@xxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: troubleshooting tesla coil
> 
> Hello all
> 
> I was looking for some help on tesla coil construction, and joined this 
> list as a result.  Looks like I came to the right place :)
> 
> I'm building my first tesla coil, and could use some help "debugging" 
> it.  All of the coil parts have been assembled, according to various 
> recipes out on the web, but when put together, the spark gap doesn't fire.
> 
> I've got the circuit down to a bare minimum:  5.5KV, 30Khz NST provides 
> the power, spark gap connected across the transformer output leads, and 
> a capacitor in parallel with spark gap.  Without the capacitor, spark 
> gap fires just fine, with it, I just hear humming sound (I think coming 
> from the vibrating capacitor plates), but no spark.
> 
> Capacitor was home built, consists of 8 copper sheets separated by
10mil 
> Mylar insulator, roughly 8"x6" area.  Measured C is 7nF.  When DC power 
> is supplied (through a rectifier circuit), makes the gap fire at 
> intervals, indicating that cap is storing charge.  I thought this could 
> be my problem component, so I built a different type of capacitor (beer 
> bottle salt water, 800pF), but that didn't change a thing.  Neither 
> capacitor is shorted out, according to my multimeter.
> 
> Is there any definitive way to test the capacitor for faults?  Am I 
> missing something else?  What could be going wrong?
> 
> Thanks, for any thoughts you can provide on the subject.
> 
> Marko
> 
> 
> 
>