Re: larger than resonant (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sat, 02 Jun 2007 10:06:40 -0400
From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: larger than resonant (fwd)

Bart,
     For the small coil, I always used salt water caps, Pickle jars, the 
calculated capacitance of which is about 1.2 nf.  I use 3 of them to get the 
coil in tune, with only 2, I believe my primary is entirely too short.  With 
4, it seems  less than 2 turns is required to put it in tune, and 
performance is kind of lousy compared to just 3 capacitors.  I think the 
primary is 8 turns, tapped at about 6, I have to check.  The top load is 
3-15, it looks big for the small secondary, and will usually only produce 1 
or 2 streamers at a time regardless of whether a breakout point is used.  
Any thoughts would be appreciated.
Scott Bogard.


>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: larger than resonant (fwd)
>Date: Sat, 2 Jun 2007 07:31:26 -0600 (MDT)
>
>Original poster: List moderator <mod1@xxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Fri, 01 Jun 2007 21:57:00 -0700
>From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: larger than resonant (fwd)
>
>Hi Scott,
>
>Sync operation is different. Best bet is 120 or 240 bps and the
>difference is negligible between the two other maybe the sound of the
>break rate you might personally prefer. 250mA is a decent amount of
>current and in the PT category. You really could head either direction.
>Your in that borderline area. The MOT's may will probably due better
>nearer to resonance than an NST. Since were not sure of resonance, you
>would have to make some MOT measurements to find our (short and open
>circuit test).
>
>The 3" coil will run at various primary cap configurations, regardless
>of what you have experienced. The primary resonant circuit can be made
>to resonate at the secondary's resonant frequency with various L and C
>values. If you had problems running at other values of C, maybe you
>could detail those particulars? If the C value was larger, then L would
>have had to be smaller to make up for it (and the tranny would need to
>be beefy enough for the size). Almost any value can be made to work,
>it's just a matter of making sure the primary L and C are resonant to
>the secondary and that adequate charging current is available.
>
>Take care,
>Bart
>
>Tesla list wrote:
>
> >Original poster: List moderator <mod1@xxxxxxxxxx>
> >
> >
> >
> >---------- Forwarded message ----------
> >Date: Fri, 01 Jun 2007 23:40:53 -0400
> >From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> >To: tesla@xxxxxxxxxx
> >Subject: Re: larger than resonant (fwd)
> >
> >So, what would be best if using a sync spark gap, on a MOT powered 6-in
> >coil, LTR or STR?  I still am unsure as to the exact amount of current 
>going
> >through my MOTs, but I think 200-250 mA is a good estimate, at around 8 
>kV.
> >I currently use 75 nf, which I believe to be close to "resonant" sized,
> >which may be a bad thing according to what I am hearing.  Also, I have a
> >small coil, a three incher that will ONLY run in tune with a small 2.9 nf
> >capacitor, I have tried lots of other values, but it always stops working 
>at
> >higher or lower values, regardless of where you tap the primary.  It is 
>10
> >kV at 92 mA.  It has a 3-in secondary wound 12 inches with 20AWG (300 
>some
> >turns, which is low, but it is what I had at the time).  Any more 
>thoughts
> >would be appreciated.
> >Scott Bogard.
> >
> >
> >
> >
> >>From: "Tesla list" <tesla@xxxxxxxxxx>
> >>To: tesla@xxxxxxxxxx
> >>Subject: Re: larger than resonant (fwd)
> >>Date: Fri, 1 Jun 2007 20:43:02 -0600 (MDT)
> >>
> >>Original poster: List moderator <mod1@xxxxxxxxxx>
> >>
> >>
> >>
> >>---------- Forwarded message ----------
> >>Date: Fri, 01 Jun 2007 19:20:25 -0700
> >>From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
> >>To: Tesla list <tesla@xxxxxxxxxx>
> >>Subject: Re: larger than resonant (fwd)
> >>
> >>Hi Scott,
> >>
> >>Smaller transformers like NST's will almost always run LTR. Larger
> >>transformers like PT's and PIG's will often run STR. Gary mentioned bang
> >>size. This is a big deal for both NST sized transformers and large pigs.
> >>If you were to run STR with an NST, the cap would be small and the bang
> >>energy would also be small. Your better off from a spark length
> >>standpoint to run LTR with one of these smaller transformers. The reason
> >>has to do with a transformers ability to charge the cap which is based
> >>on the cap value and the current available from the transformer. That is
> >>the reason why we only go "so far" with LTR sizes. Thus, each
> >>transformer rating has it's own LTR value.
> >>
> >>Larger transformers like pigs, if run LTR, would have an incredible bang
> >>energy that could be devastating (and expensive). There is some limit to
> >>transformed energy for every coil before the coil turns into a blaze of
> >>glory, but one we almost have to blow it up before we actually find that
> >>limit. In most cases, large transformers are better off running STR to
> >>keep the bang energy within a coils abilities.
> >>
> >>In both cases, the spark gap, when running without a failure, will limit
> >>the breakdown voltage. If a static gap, it's a constant limit that
> >>usually decreases with time due to heat buildup, but for a rotary gap,
> >>the timing of electrode alignment and the current available to charge
> >>the cap is the limit for voltage. It is possible to run very high bps,
> >>but the balance between current and capacitance must be met. If either
> >>is not designed well for the bps ran, sparks can diminish, but if done
> >>right, spark lengths can be very good. I personally like a 300 to 340
> >>bps myself when I run my variable rsg. If I were to change capacitance
> >>or transformer for the same coil, there would be a different bps range
> >>where the coil runs best.
> >>
> >>Take care,
> >>Bart
> >>
> >>
> >>
> >>Tesla list wrote:
> >>
> >>
> >>
> >>>Original poster: List moderator <mod1@xxxxxxxxxx>
> >>>
> >>>
> >>>
> >>>---------- Forwarded message ----------
> >>>Date: Fri, 01 Jun 2007 05:54:39 -0400
> >>>From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> >>>To: tesla@xxxxxxxxxx
> >>>Subject: larger than resonant
> >>>
> >>>Hey everybody,
> >>>    Can somebody explain to me the advantage to using a "resonant" or
> >>>"larger than resonant" tank capacitance?  I seen coils get huge sparks
> >>>
> >>>
> >>using
> >>
> >>
> >>>LTR and also very small tank capacitors, so what is the point?  Thanks.
> >>>Scott Bogard.
> >>>
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