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Re: Why am I getting small sparks? Am I underpowered? (fwd)
---------- Forwarded message ----------
Date: Sat, 11 Aug 2007 14:17:48 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Why am I getting small sparks? Am I underpowered? (fwd)
Hi Trevor, Scott,
Trevor, when Scott is defining how to adjust the gap here, he is
absolutely correct. This is the proper method of adjusting the gap to
prevent overvolting the NST.
Regarding multisegment gaps, I've had good ones and bad ones. The ones I
dislike the most is when a coiler builds a series of multisegment copper
pipes on a piece of laminate (where the gaps are all at the same
horizontal level). I've never had great performance with those gap
styles, but also when I built them, I used 1/2" diameter copper tubing
(I later realized that was a bad choice). Once I went to a TCBOR style
multisegment gap, performance was much better even using the 1/2"
diameter copper tubing. Once I went to large 1.25" copper tubing,
performance was fantastic! The large surface area of the tubing greatly
aids the ability to maintain a constant temperature over relatively high
power ranges. I use a high powered squirrel cage fan which sucks the air
into the pvc tubing across all surfaces of the copper tubes. I'm not
sure of the cfm value, but it's high. For pig power, I use a G10/pure
tungsten 3-phase variable rotary.
Scott, I think you dumped the multisegment gap too soon. They can be
built to do far better than most other static gaps including sucker
gaps. Sucker gaps are good, but a properly built TCBOR style gap will
out perform it by 1 or 2 KW (yipes, the sucker gap guys will hate me
saying that!).
Here's a quick pic of a simple high performance multisegment gap:
http://www.classictesla.com/photos/ba45/s2752.jpg
Note, I epoxied a pvc tube onto the fan itself and painted it green (the
only color onhand at the time). The white pvc simply is pushed into the
green pvc tube. The white pvc has the 1.25" copper tubes epoxied in
place. Very simple to build. In this pic is a similar white pvc with
solid brass electrodes. They sucked compared to the copper tubing (good
for a few seconds but quickly heated and could not dissipate the thermal
energy well). This simple to construct gap allows me to insert any
electrode arrangement I desire. Since the large copper tubing was used,
the performance was better than anything else since. The white pvc I
epoxy my electrodes onto is simply a cap. I cut out one end of the cap
and left a 1/4" lip which the electrodes rest on while the epoxy cures.
Using epoxy to secure electrodes also allows precision gap distance
setup between each electrode (I lay a feeler gauge between the
electrodes during the cure to ensure the pipes are perfectly parallel
and at the gap distance desired. Cure 1 electrode at a time.). I've run
3 to 4 KW on this gap regularly. This gap is used more than any other
gap in my collection simply because it performs damn well.
When I started multisegment gaps, I was at first disappointed. It took a
lot of tinkering to finally figure out "why" a gap does well and "why"
it does not. A gap that performs well will "maintain" a "constant"
temperature (within reason) that allows a stable arc voltage on each
break without varying over a given power range. That is the key
ingredient. Even a 2 bolt gap can do well if air is used and the power
is low enough to not cause a major variation. But, as power is
increased, a simple 2 bolt gap just cannot be stabilized and performance
will plunder. When you hit the 5 to 10 KW range, a rotary gap becomes
the best choice.
Take care,
Bart
Tesla list wrote:
>---------- Forwarded message ----------
>Date: Sat, 11 Aug 2007 14:50:48 -0400
>From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: RE: Why am I getting small sparks? Am I underpowered? (fwd)
>
>Trevor,
> I forgot to point out the most important part of setting a single gap,
>when you are flipping the transformer on and off to establish how far an arc
>can be made, it must be disconnected from everything, tank cap, primary,
>everything. Basically you are finding out how far 15kV can jump by itself
>with no help, that way when you get resonate voltage rises from the tank
>circuit, it cannot exceed 15kV. Some people are suggesting you use
>multi-segment gaps, I never had good luck with them, as I never had the
>patience to construct one properly (they melted, or just wouldn't fire due
>to poor insulation), when I "mastered" the single gap, I went strait to a
>rotary. Use your discretion.
>Scott Bogard.
>
>
>
>
>>From: "Tesla list" <tesla@xxxxxxxxxx>
>>To: tesla@xxxxxxxxxx
>>Subject: RE: Why am I getting small sparks? Am I underpowered? (fwd)
>>Date: Sat, 11 Aug 2007 08:46:48 -0600 (MDT)
>>
>>
>>---------- Forwarded message ----------
>>Date: Fri, 10 Aug 2007 22:13:43 -0400
>>From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
>>To: tesla@xxxxxxxxxx
>>Subject: RE: Why am I getting small sparks? Am I underpowered? (fwd)
>>
>>Trevor
>> Nooo! Don't open your gap too wide! Set it like this, turn the
>>transformer on and off, starting close enough to make an arc, and keep
>>opening it a tiny bit at a time (like a millimeter) until it won't start an
>>arc, then, leave it there. What you may find, is that once you install a
>>good fan of some kind, you may need to close it some for best performance.
>>I just use a tiny 1/32 hp squirrel cage fan for inflating the layers of
>>greenhouse plastic, to improve their insulation value, but this may or may
>>not be enough for you, but since your low power, it may very well be fine.
>>As for your caps popping, how do you have them wrapped, do you use foil, do
>>you use any glue, do you have them sitting in a tub of salt water, what are
>>you doing? I have found you can get small but worthwhile improvements by
>>wrapping the jars in tightly fitting foil tape, and then aluminum foil (to
>>bridge the connections between tape strips) and then an insulator (like a
>>few layers of electrical tape). I personally prefer one gallon pickle jars
>>(about .001 uf or 1nf a piece, so your larger than resonant value would
>>need
>>about 7 or 8 jars, assuming you could tune your secondary to this
>>combination), and glue never seemed to work for me (so I use tape)! Also,
>>you can increase the efficiency of your caps by experimenting with the salt
>>you use, I find more caustic stuff to be slightly better (I use NaCl,
>>MgSO4,
>>HCl, Vinegar, and CuSO4 all mixed, but your electrode will not last forever
>>with a concoction like this!). Also make sure they are sitting on a well
>>insulated surface, like Styrofoam (although your system is probably fine,
>>as
>>if this were a problem you would not have much happening in your spark
>>gap).
>> Good luck!
>>Scott Bogard.
>>
>>
>>
>>
>>>From: "Tesla list" <tesla@xxxxxxxxxx>
>>>To: tesla@xxxxxxxxxx
>>>Subject: RE: Why am I getting small sparks? Am I underpowered? (fwd)
>>>Date: Fri, 10 Aug 2007 16:34:27 -0600 (MDT)
>>>
>>>
>>>---------- Forwarded message ----------
>>>Date: Fri, 10 Aug 2007 22:28:37 +0000
>>>From: Trevor Keast <trevor_keast@xxxxxxxxxxx>
>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>Subject: RE: Why am I getting small sparks? Am I underpowered? (fwd)
>>>
>>>Thanks for the comments. I am currently using two threaded rods as the
>>>spark gap. I have no fan or anything like that at present. I did make a
>>>quite elaborate multi gap spark gap out of about 7 short lengths of
>>>
>>>
>>copper
>>
>>
>>>pipe. Strangly enough, when i use this spark gap I get no sparks from
>>>
>>>
>>the
>>
>>
>>>top load whatsoever and the sparks going across this spark gap seem quite
>>>tame in comparison to the single spark gap.
>>>
>>>If I open up the single spark gap too much it start setting of some
>>>
>>>
>>rather
>>
>>
>>>alarming pops and banks in my beer bottle capacitor bucket and I have no
>>>idea what that is happening!! It scares me.
>>>
>>>Trevor
>>>
>>>
>>>
>>>
>>>
>>>>Date: Fri, 10 Aug 2007 16:04:57 -0600> From: tesla@xxxxxxxxxx> To:
>>>>
>>>>
>>>tesla@xxxxxxxxxx> Subject: Re: Why am I getting small sparks? Am I
>>>underpowered? (fwd)> > > ---------- Forwarded message ----------> Date:
>>>Fri, 10 Aug 2007 16:53:21 -0400> From: Rich Winders
>>><rwinders_3@xxxxxxxxxxx>> To: tesla@xxxxxxxxxx> Subject: Re: Why am I
>>>getting small sparks? Am I underpowered? (fwd)> > > i had the exact same
>>>problem as you did with spark length.. and what i> did i was exactly as
>>>chiris said .. try varying the distance between the> electrodes.. this
>>>
>>>
>>will
>>
>>
>>>send a diffrent amount of charge to your tank> capacitor but if you
>>>
>>>
>>change
>>
>>
>>>that value enough your also going to through> of your tuning so good
>>>
>>>
>>luck!
>>
>>
>>>... what kind of arrangement are you using?> Eg nuts and bolts ... or
>>>copper pipes or are you using roatating spark> gap?> >
>>>
>>>
>>>(MDT)> >> >---------- Forwarded message ----------> >Date: Fri, 10 Aug
>>>
>>>
>>2007
>>
>>
>>>15:48:34 -0400> >From: Crispy <crispy@xxxxxxxxxxx>> >To: Tesla list
>>><tesla@xxxxxxxxxx>> >Subject: Re: Why am I getting small sparks? Am I>
>>>underpowered? (fwd)> >> >What are the details on your spark gap? I made a
>>>similar> coil, and had> >a similar problem. When I changed the fan to
>>>quench the> spark gap to a> >more powerful one, spark length improved
>>>
>>>
>>from
>>
>>
>>>around 6" to> around 4' .> >> >Chris> >> >On Fri, 2007-08-10 at 12:54
>>>-0600, Tesla list wrote:> > > ---------- Forwarded message ----------> >
>>>
>>>Date: Fri, 10 Aug 2007 18:38:35 +0000> > > From: Trevor Keast
>>><trevor_keast@xxxxxxxxxxx>> > > To: tesla@xxxxxxxxxx> > > Subject: Why am
>>>
>>>
>>I
>>
>>
>>>getting small sparks? Am I> underpowered?> > >> > > Hi Guys,> > >> > > I
>>>managed to reach 'first light' with my coil last night> however I was
>>>unable to get the spark length that I was> hoping for and feel I may be
>>>underpowered.> > >> > > A basic overview of my coil is as follows:> > >>
>>>
>>>
>>>
>>>>6 inch secondary diameter> > > 24 inch secondary length> > > approx
>>>>
>>>>
>>900
>>
>>
>>>windings on secondary (24 AWG magnet wire)> > > 13 Turns on primary made
>>>
>>>
>>>from 1/4 copper tube> > > static spark gap> > > beer bottle cap (14
>>
>>
>>>bottles)> > > 15,000V 30mA NST> > > 4 inch dryer tube toroid (approx 12in
>>>diameter)> > >> > > I tuned it as best I could but was unable to get
>>>sparks> bigger than about 6 inches. They were also quite dim and> could
>>>hardly be seen unless in the dark.> > >> > > I am wondering if I am
>>>underpowered? How can I improve> spark length?> > >> > > I greatly
>>>appreciate any advice or comments.> > >> > > Regards,> > >> > > Trevor.>
>>>
>>>
>>>
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>
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