David,
When I bought the tungsten spark gaps and fan I received this email:
*Most folks use them in series and reduce the gap width on each one. For
example for a ¼ inch gap (a good place to start) they use two gaps in
series set a 1/8”. I have had excellent results using them in parallel. For
the amount of current you are using I would use two gaps in parallel both
set at 1/4 inch. It works great and is easier to line up with the fan.*
Should I be using them at 1/8" gaps in serial then?
Tim
On Tue, Apr 7, 2015 at 8:26 AM, David <zipo@xxxxxxxxxxx> wrote:
> Tim - Here is my take on spark gaps. First you say you have two gaps in
> parallel, not series but parallel? Only one spark at a time can happen in a
> parallel gap set up, maybe it will switch back and forth from one to the
> other but only one at a time. A single gap can provide the least resistance
> and more current in the primary circuit but does not quench and control
> ring down very well. putting multiple gaps in Series seems to provide an
> improvment in quenching and ring down control. To experiment with series
> multiple gaps would seem to be a logical next step, two, four, maybe even
> six gaps in series. A lot of people have had good results with the Richard
> Quick multi gap and is not to difficult to construct. The next step up
> would be a sucker gap, a lot of people like these and they give real good
> results, there are examples on the net. But I believe the best and most
> difficult is the Sync Rotary gap. my recommendation would be to experiment
> with the progression of gaps above but keep an eye to words the sync
> Rotary. Some thing I wish more people would do too, is cover your spark
> gap, put a largish box over it to block the light from it and to quiet it
> down a bit, doesn't have to be fancy, just a simple wooden box placed over
> it wile your running. Nasty gasses build up inside but for the length of
> time most of us run our coil it will be ok. For a 15kv NST the max voltage
> it can handle is about 25kv +- a bit peak, so you want the largest cap you
> can charge to 25kv. The Geek group capacitor chart is very good at
> appropriate cap values for a type of setup/gap being used.
>
> Thanks
> David
>
> On 4/7/2015 8:00 AM, Timothy Gilmore wrote:
>
>> David,
>>
>> 72" WOW as I have similar specs but only get 36-48" or so.
>>
>>
>> Here are my specs:
>> 15kv, 120ma <-- Same (2 15kv 60mA NSTs)
>>
>> 3 levels of 0.010uf in parallel for 0.030uf mmc (30kv) <--- Seems like
>> your double of what mine is
>>
>> 2 parallel tungsten gaps "about" 1/4" separation each (with a squirrel
>> cage
>> fan blowing on them) <--- *Should these be tighter since there are 2 of
>> them? (i.e. 1/8" inch each)*
>>
>> Secondary - 6"dia x 31"lg 1400 turns No. 24
>>
>> Top load - 6" x 25" aluminum dryer ducting and foil pizza pans with foil
>> wrapped cardboard between and nylon toilet bolt <-- NOT wrapped in 3"
>> aluminum tape
>> (Would wrapping this improve the length significantly). I have the
>> materials for an 8" aluminum dryer ducting, aluminum tape, 17.75" x 1"
>> circular wood table (to be wrapped in foil and then glued and possibly
>> aluminum taped). *Should I just wrap the 6" more flimsy version or go with
>> the bigger 8" more solid heavier version (to construct) - OR use both on
>> top (wrapped/unwrapped in aluminum tape)?*
>>
>> Primary 0.25" copper refrigerator coil in single layer tapped at 12.5
>> turns
>>
>> I was thinking of the rotary gap motor version for the spark gap but have
>> no idea where to even start on this. I was hoping to get everything the
>> best I could first before and if I go down that route.
>>
>> *So what has the greatest impact on spark length - the rotary spark gap or
>> the wrapped aluminum tape on the toroid - or are both necessary?*
>>
>>
>> Thoughts?
>>
>> Tim
>>
>>
>>
>>
>> On Mon, Apr 6, 2015 at 8:56 PM, David <zipo@xxxxxxxxxxx> wrote:
>>
>> Timothy, List - I too have recently put together a 15kv, 120ma coil. I'm
>>> still tweaking for best out put. So far I'm getting 72" output and based
>>> on
>>> the way it was running and the way it was tuned I believe it will do at
>>> least 80" after it's fully peaked. I can only run outside so I'm having
>>> to
>>> wait for good weather.
>>> Here is a brief over view:
>>> 15kv, 120ma
>>> .0625uf mmc
>>> sync rotary gap @ 120 breaks/sec
>>> secondary - 7"dia x 27.3"lg 1500 turns No.26 wire
>>> Top load - 5" x 20" spun aluminum toroid
>>> primary - 10 turn 2 layer spiral
>>> Tesla equi drive circuit.
>>>
>>> There are two aspects of tuning and peaking that seem not to get the
>>> attention that they should (in my opinion).
>>> First is that if tuning with a signal generator and a oscilloscope you
>>> need to simulate the added capacitance of the spark. Adding a piece of
>>> wire
>>> the length of the spark your expecting to the top load and then tune with
>>> sig gen and o scope. This seems to be overlooked a lot. Java TC shows
>>> this
>>> very well. If you ad an additional cylindrical top load, on JTC, .02dia x
>>> length of spark (JTC will point it straight up) you will see a marked
>>> reduction in res. frequency.
>>> Second is that the safty gap or static gap width has a large impact on
>>> output. There are way of setting these gap for safest operation. However
>>> I'm guessing these gap widths get pushed a bit by savvy coilers but don't
>>> talk about it. At least on a sync rotary safety gap width has a big
>>> bearing
>>> on output. I would find it very interesting to hear what gap width people
>>> are using with what setup. And in full disclosure :) I have set both of
>>> my
>>> safety gaps at .22 using rounded brass draw pulls for electrodes.
>>> It just seems to take a lot of time to get every thing tweaked to
>>> Perfection.
>>>
>>> Carry on
>>> David
>>>
>>>
>>>
>>> On 4/6/2015 9:34 AM, Timothy Gilmore wrote:
>>>
>>> Has anyone put together any sort of a listing of others Tesla Coils
>>>> built
>>>> with parameters listed such as:
>>>>
>>>> (for example): I have 2 NSTs (15kv, 60ma) each, 6" diameter, 31" high
>>>> secondary, torroid is ....
>>>>
>>>> I am getting 3-4' sparks and wondering if I should be getting longer
>>>> sparks. Is this normal? or should I add another NST or bigger Toroid
>>>> (working on an 8" diameter ducting bigger one). How do I know since the
>>>> Tesla Map software says I should get "ideally" 72.6 inch sparks and I'm
>>>> getting about 1/2 to 2/3 of that. Just wondering if it's not tuned
>>>> properly
>>>> (but I think it is) - or making a larger toroid is worth the effort if
>>>> I'll
>>>> gain a foot or more sparks.
>>>>
>>>> How does one know they are getting close to the best they can get in
>>>> spark
>>>> length?
>>>>
>>>> I have attached my Tesla Map file of current settings.
>>>>
>>>> Thanks,
>>>>
>>>> Tim
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>>>>
>>>>
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