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Re: [TCML] new pig driven coil VSVFSG
I agree, I think your spark gap has reached its limit. I have posted this several times before over the past 10 years here it is again. A variable speed vacuum fan spark gap (VSVFSG) works just as well if not better than a rotory spark gap and it is a lot easier and cheaper to build. It only takes about 5 seconds to dial in maximum spark output. The variac controls the speed of the vacuum cleaner motor, as the motor picks up speed you can see a noticable increase in spark output length. When you reach a certain speed spark length will be at maximum. If you increase the motor speed more spark output gets shorter. It is very easy to turn the dial back and forth a few times and dial in maximum output in just a few seconds. I have used the same spark gap on all 8 of my coils from 1 neon to 14 KW. All you need is a vacuum cleaner motor, 2 toilet flanges, and a simple RQ spark gap. My gap has 8 gaps spaced .030" each with a 1/8" slot cut in the PVC pipe directly in front of each gap. The fan suck air in the slots and keep the 3/4" x 2" long copper tubing cool. You can get a vacuum cleaner motor from a cheap vacuum cleaner at Goodwill Stores or yard sales. Here are some pictures. I get 12 foot streamers from my 10" coil on 10KW in dry low humidity weather.
http://home.earthlink.net/~gary350/tc10-4.jpg
http://home.earthlink.net/~gary350/tesla2.jpg
http://home.earthlink.net/~gary350/tc2.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap1.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap2.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap3.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gap4.jpg
http://i67.photobucket.com/albums/h292/mikeweaver/gaps5.jpg
-----Original Message-----
>From: David Rieben <drieben@xxxxxxxxxxx>
>Sent: Oct 13, 2010 1:06 PM
>To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
>Subject: Re: [TCML] new pig driven coil
>
>Hi Joe,
>
>As the builder of the 8 ft. tall Green Monster Tesla coil,
>http://www.youtube.com/watch?v=H3pfStBx2qY, I have
>to agree with Scott's summation. When there is plenty of
>available raw power for running your coil (which a pole
>pig can generously provide), an asynchronous, higher break
>rate, a significantly STR primary cap and a huge topload is
>the best way to extract long and bright sparks from your
>coil system. My coil runs with a 14,400 volt, 10 kVA rated
>pole transformer, a 0.1 uFd primary capacitor, and a 12"x
>56" topload and the sparks regularly reach into the 11 to 13
>ft. point/point range.
>
>Also, when you mention that your ouptut sparks actually
>start to decrease with additional power when the variac
>knob surpasses the 80 mark, I am wondering if your SG
>setup is reaching its limits in quenching. I personally have
>never tried the propeller style RSG but it's pretty obvious
>that the "propeller's" quenching ability is going to be limited
>according to the power throughput, cross-section diameter,
>length, thermal mass, ect. You mention that your runs are
>pretty rapidly eroding the ends of your gap electrodes so
>it sounds like proper quenching could be a definite issue
>for you. When quenching starts to falter, the output will often
>begin to deminish at that point. My ARSG is the disc type
>with a 11.5" diameter x 1/2" thick G-10 disc, set with (8)
>evenly spaced 3/8" x 2" long pure tungsten flying electrodes
>and 2 pair of stationary 1/2" x 3" long pure tungsten electrodes,
>with each pair set 180 degrees apart on opposing ends of
>the disc. I originally had just a single stationary electrode pair
>on one end of the disc, but ended up adding a second pair
>due to improper quenching at the high power levels that I
>run. My particular system seems happiest running around
>350 bps.
>
>Hope this helps,
>David Rieben
>
>
>
>----- Original Message -----
>From: "Scott Bogard" <sdbogard@xxxxxxxxx>
>To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
>Sent: Tuesday, October 12, 2010 5:31 PM
>Subject: Re: [TCML] new pig driven coil
>
>
>> Hi Joe,
>> Just a word of advice, using a SRSG on a high current system (which
>> depending on your ballast a PIG generally is) is going to really quench
>> your results with such a small cap, using Java TC you can calculate your
>> optimum BPS for a given cap size. You simply must build a variable ASRSG
>> (both for learning curve and for performance) unless you are so wealthy
>> you can buy enough caps for LTR on a PIG (or you use a high enough
>> multiplier in your sync BPS, so you might be Ok as I see now you are using
>> 240 instead of 120.) I would still recommend it, they are fairly easy to
>> build compared to SRSG, high break rates give awesome effects, and you
>> don't need to change your cap size when you upgrade your circuit breaker
>> to allow more current flow (just run it faster!) My unballasted twin MOT
>> system (just raw AC, no doubler or other nonsense) runs 750 bps sweet
>> spot. The day I upgraded from SRSG I cut my power supply in half and
>> tuned it to the point I was getting longer sparks with half the power (by
>> almost a foot, 69-inches is my record with just 2 MOTs and ASRSG and 61
>> was my record for 4 with SRSG!) I've seen a pig coil running just a .05
>> cap do 15 feet using an ASRSG running a high break rate, it is the way to
>> go as far as I'm concerned, infinitely cheaper, more fun, just as long if
>> not longer sparks, I'll never run SRSG again, not even on little OBIT
>> coils (well I might, because now it sits around doing nothing, but I'm
>> going to try ASRSG with a small cap anyway...) Just my 2 cents, take it
>> for what is is (ramblings of an exhausted, half crazy man with nothing
>> better to do at the present moment...) Also note that if your current is
>> kept to about 250 mA or less you're actually Ok with a 240 BPS and that
>> cap, but someday you'll open up your ballast for 600 mA and be
>> disappointed when the sparks don't change AT ALL, this was my big mistake
>> with ballasted vs unballasted MOTs...
>>
>> Scott Bogard.
>>
>>
>> On 10/12/2010 1:54 PM, Joe Mastroianni wrote:
>>>
>>>
>>> I have built an anachronism. Of course, the very concept of the coil is
>>> anachronistic, but through the tutelage and mentoring of Dave Leddon, I
>>> have acquired and assembled the components necessary for a pole pig
>>> driven srsg coil.
>>> I got a 5KVA pig from Dave some months ago, and since then he's been
>>> supplying me with various wisdoms though schematics, e-mails, and his
>>> surplus parts. I have been beavering away diligently in my garage,
>>> assembling the various components I get from Dave and a seemingly
>>> endless stream of eBay auctions. No doubt I have assembled for a couple
>>> hundred American dollars what would have cost thousands had I bought
>>> everything retail (if that was even possible).
>>>
>>> The spark gap is an SRSG propeller gap rotating at 1800rpm inside 8
>>> stationary electrodes for 240bps. I am using a John Freau phaser on the
>>> SRSG.
>>>
>>> The power supply has 4 corcom-style 30A line filters in serial/parallel
>>> arrangement. Using the guts from a cheepo adjustable 100AMP arc welder
>>> as a current choke. An ABB EH175 serves as my contactor and I have a
>>> 2-phase superior electric 1296 powerstat for the main power Variac.
>>>
>>> Also, I had my safety gap set too wide (obviously). With the tuning and
>>> the gap set "correctly" or as close as I could get I was able to achieve
>>> several runs, most of which at only 2/3 max on the current shunt. Spark
>>> production was better than with my NSTs, as we would expect. The
>>> propeller gap was brighter than ever, to the point I began to worry
>>> about how quickly the electrodes would erode.
>>>
>>> I also noticed that the max-output power occurred at about 80% power on
>>> the variac output. Increasing the output past 80% actually DECREASED the
>>> power output a perceptible amount.
>>>
>>> I have come to expect that there is an issue with one of 2 things -
>>> either 1) I have wired the variac wrong (though I have reviewed the
>>> connections and I can't see how I did) , or 2) the inductance of the
>>> variac is interacting with the primary windings and affecting f0.
>>>
>>> And since writing the above, I am noting that I have connected my
>>> current shunt to appear in the circuit in series between the power
>>> source and the variac, instead of between the variac and the primary.
>>> Perhaps that has something to do with it. I need to experiment to find
>>> out.
>>>
>>> Other things I have noticed - even at 15/240 my primary connections
>>> never got hot (except when mistuned). Now they seem to get warm all the
>>> time, which I suspect is just an expected artifact of the higher
>>> currents. I do think I may have to reconsider the spring bronze and my
>>> connection methodology for fear they present too high a resistance and
>>> will eventually heat to the point of melting the polycarbonate supports.
>>>
>>> Cheers,
>>> Joe
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxx
>>> http://www.pupman.com/mailman/listinfo/tesla
>>>
>> _______________________________________________
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>>
>
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