Dan, thanks for your input. Sorry I wasn’t clear in my original post. My question was really “What would have to be done, to make this apparatus functional at full power with the antenna attached?”
That is, view this as someone today trying to tune their magnifier for full power operation with this huge top load? I want to stay on topic, and I’m not interested in anything else other than the above question.
We know pretty much every technical detail of this magnifier up to mid December 1899, so what is the best educated guess at what all would have to be changed?
Thanks again,
Bill
Sent by Macak‘s humble servant.
> On Nov 25, 2018, at 2:41 PM, tesla-request@xxxxxxxxxx wrote:
>
> Send Tesla mailing list submissions to
> tesla@xxxxxxxxxxxxxxxxxx
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://www.pupman.com/mailman/listinfo/tesla
> or, via email, send a message with subject or body 'help' to
> tesla-request@xxxxxxxxxxxxxxxxxx
>
> You can reach the person managing the list at
> tesla-owner@xxxxxxxxxxxxxxxxxx
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Tesla digest..."
>
>
> Today's Topics:
>
> 1. Re: Where is everyone? (Donald Murray)
> 2. Re: An O.T. weighs in (Greg Leyh)
> 3. Re: Tesla Digest, Vol 132, Issue 6 (Greg Leyh)
> 4. Re: Where is everyone? (Chris Reeland)
> 5. Re: Where is everyone? (Greg Peters)
> 6. Why Was Tesla?s 1899 Colorado Springs Magnifying Transmitter
> Never Fully Developed for Full Power? (William Fox)
> 7. Re: Adventures in SRSG (David Rieben)
> 8. Re: Tesla Digest, Vol 132, Issue 6 (Frank)
> 9. Re: where is everyone (Antonio Queiroz)
> 10. Re: where is everyone (Phillip Slawinski)
> 11. Re: Why Was Tesla?s 1899 Colorado Springs Magnifying
> Transmitter Never Fully Developed for Full Power? (Daniel Kunkel)
> 12. Re: Adventures in SRSG (Daniel Kunkel)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 22 Nov 2018 12:31:28 -0800
> From: Donald Murray <don@xxxxxxxxxxxxxxx>
> To: tesla@xxxxxxxxxxxxxxxxxx
> Subject: Re: [TCML] Where is everyone?
> Message-ID: <a0728657-dd91-2103-1556-be7ab55d1607@xxxxxxxxxxxxxxx>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I have been lurking for a long time. I did buy a belt for my VDG from D.
> C. Cox. And I sold a secondary bushing for a pole pig to David Rubin. I
> have the VDG and a Wimshurst machine, I have not made a TC yet. I have
> collected a few neon sign transformers, a couple of 10KVA pole pigs, and
> a nice matching pair of 5KVA pole transformers with different taps on
> the primary. I have 3 large capacitors from a utility, several 2400volt
> PTs, and a few 12KV oil switches. I have 240V 3-phase delta on my
> property. I retired in '06, been traveling and doing other things, spent
> 34 years as a high voltage lineman/foreman/troubleshooter.
>
> Don Murray in Sacramento, California
>
>> On 11/20/2018 6:54 AM, Steve White wrote:
>> When I first joined the TCML back around 2002,I used to receive about 20 messages per day from the TCML. Now, I am lucky if I see a single message every few days. On occasion, I will see periodic bursts of postings in response to specific questions from members. Have all the members moved on to other interests or died? We need to determine a way to get new people interested in this hobby. I fear that most of the potential younger members are absorbed in computer-related things. There is nothing wrong with that. I spent most of my engineering career developing real-time embedded DSP software. We just need to discover a way to expand their interests into the world of physical hardware, especially high voltage. I built my first tesla coil, a small VTTC, when I was 16 and this is what got me interested in electrical engineering as a career. I periodically display my coils to kids in my neighborhood. I also plan to take my smaller coils around to schools for demonstrations.
>>
>> Thoughts?
>>
>> Steve White
>> Cedar Rapids, Iowa
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxxxxxx
>> https://www.pupman.com/mailman/listinfo/tesla
>>
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 22 Nov 2018 15:23:15 -0800
> From: Greg Leyh <lod@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxxxxxxxxxx
> Subject: Re: [TCML] An O.T. weighs in
> Message-ID: <5BF73A63.2080407@xxxxxxxxxxx>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Yeah, let's meet up! Not so many coilers out here on the Left Coast.
>
>> On 11/22/2018 2:03 PM, tesla-request@xxxxxxxxxx wrote:
>> Message: 10
>> Date: Wed, 21 Nov 2018 14:06:08 -0800
>> From: Dave Leddon<dave@xxxxxxxxxx>
>> To: Tesla Coil Mailing List<tesla@xxxxxxxxxx>
>> Subject: Re: [TCML] An O.T. weighs in
>> Message-ID:<885619879.20181121140608@xxxxxxxxxx>
>> Content-Type: text/plain; charset=us-ascii
>>
>> Hello Ken,
>>
>> Wednesday, November 21, 2018, 11:25:48 AM, you wrote:
>>
>>>> Greetings, Tesla List-
>>>> So...interest is diminishing, is it? Well, I,m sorry to hear it but the
>>>> same here, tho the fact that I'm now 90 will have a lot to do with my
>>>> own loss of it. Plus...my and my lady-friend's morbid fascination with
>>>> our current & lamentable White House soap-opera. I remember the huge
>>>> 3-phase 440V SG coil on display once, down south of San Francisco.
>>>> Secondary wound with cable used in locomotives as I recall. 20 ft or so
>>>> screaming, streaming and deafening arcs dancing all around, plus the
>>>> accompanying SG. Yea!...Hooray! (Can't remember who made it...)
>>>> But my interest was in SRSS coils since that's the technology Tesla
>>>> himself would surely have used. His sparks were, of course, just to
>>>> entertain prospective investors, since he wanted to broadcast power
>>>> rather than make sparks. Cockamamie idea, that, but he didn't know
>>>> (altho he may well have come to suspect it).
>>>> Either whenever I can get to them from storage or else after, I will
>>>> have 2, 12" x 3 & 4 ft undamaged secondary coils (self-resonant at ~100
>>>> & 125 KHz), a Landergren 6" x 24", 6061-alloy toroid, and an unfinished
>>>> primary assembly to offer up, in the East Bay area of San Francisco.
>>>> The primary assy incorporates 4, "pancake"-style coils arrayed radially
>>>> in order to create 4 flux paths thru the secondary. Those coils
>>>> together with their s.s drivers are made and in place on a 4' x 4'
>>>> platform. The rest of the primary apparatus consists of power supplies &
>>>> misc. stuff, all intended to establish an overall positive-feedback loop
>>>> from secondary-coil current-input to primary coil current-output. I'd
>>>> supply prints of the schematics--some as finished, some not so.
>>>> And BTW about the List's format: how come there are so many repeats of
>>>> messages? Clutters it up way too much IMO.
>>>> Ken Herrick
>>>> Kensington, CA USA
>>>> _______________________________________________
>>>> Tesla mailing list
>>>> Tesla@xxxxxxxxxxxxxxxxxx
>>>> https://www.pupman.com/mailman/listinfo/tesla
>> Hey Ken,
>>
>> That sounds like one of Greg Leyh's coils. Are you still mobile? We ought to meet up at Greg's warehouse in Oakland and check out his new coil. I'd love to find out how he came up with that inflatable toroid and see what kind of solid state topology he's running.
>>
>> Dave Leddon
>>
>> -- Best regards, Dave Leddon
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 22 Nov 2018 15:30:49 -0800
> From: Greg Leyh <lod@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxxxxxxxxxx
> Subject: Re: [TCML] Tesla Digest, Vol 132, Issue 6
> Message-ID: <5BF73C29.9070206@xxxxxxxxxxx>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Hi Steve,
>
> Windage is the biggest issue. The Fan Laws [
> https://en.wikipedia.org/wiki/Affinity_laws ]are merciless as you scale
> rotor size, speed and # of rotors. Even with aero shrouding, Electrum
> took 28.5 HP on the 30HP gap motor.
>
>
>> On 11/22/2018 2:03 PM, tesla-request@xxxxxxxxxx wrote:
>> From: Tedd Dillard<tedd.dillard@xxxxxxxxx>
>> To: Tesla Coil Mailing List<tesla@xxxxxxxxxx>
>> Subject: Re: [TCML] Tesla Digest, Vol 132, Issue 5
>> Message-ID:
>> <CABebsSmOTy+syG067FzyQN+mAkJep0PMKOT4hjT7PGU9sDby7A@xxxxxxxxxxxxxx>
>> Content-Type: text/plain; charset="UTF-8"
>>
>> Greg,
>> I am missing something, please help me understand sir.
>> I do not understand why the rotary spark gap motor would necessarily need
>> to be so big as the size increases.
>> The diameter of the rotor would get bigger and so the weight would also
>> increase so the starting torque would also increase.
>> But as there is no mechanical friction involved the only power increase it
>> seems would be the increased windage from the rotating parts.
>> I can see maybe 5 horse power or so and if the motor is a regular induction
>> motor modified to be a synchronous motor there would be a loss of torque
>> due to the increases air gap but I must be missing something. So getting it
>> going could be an issue but once it was up to speed where is the large
>> power going?
>> Teddy
>>
>> On Wed, Nov 21, 2018 at 5:20 PM Greg Leyh<lod@xxxxxxxxxxx> wrote:
>>
>>>> Hi Steve,
>>>>
>>>> Turns out that IGBTs become easier to deal with than rotary spark gaps
>>>> as the coil scales in size. Here's a few reasons:
>>>>
>>>> a) The freq drops with increasing size, and in the lower 10's of kHz
>>>> range the bigger traction IGBTs start to work quite well.
>>>>
>>>> b) The motor size on a rotary gap starts getting rather unwieldy at
>>>> higher power levels. Electrum needed a 30HP motor. This 40ft coil
>>>> would need almost 100HP... not a very portable rig!
>>>>
>>>> c) IGBTs can work at much lower impedance, typically a small fraction of
>>>> an ohm, compared to many ohms for spark gaps. That allows this coil to
>>>> work with primary voltages <1kV. Electrum was 44kV, and this coil would
>>>> have to be 60-80kV for a rotary gap system.
>>>>
>>>> Since I had no funding, this scale prototype design had to pursue
>>>> cutting costs as far as possible. IGBTs provided the best value
>>>> overall. However, I totally agree that a rotary gap system for 240kW
>>>> service would look much cooler than a box of IGBTs. ;>
>
>
> ------------------------------
>
> Message: 4
> Date: Fri, 23 Nov 2018 00:49:57 -0600
> From: Chris Reeland <chrisreeland@xxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Where is everyone?
> Message-ID:
> <CAPVCm=Pkf7tryTiX+dh_0fAv7VwuCods4CE-nhNRVr0m5PgfVA@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi Steve and all,
>
> I have only been subcribed to the list since sometime 2017. But I have been
> a lurker for many years reading the list through the site very often. The
> site also was always coming up on certain Google searches also when I was
> looking for information. Would always go to these first. Not really sure
> why it took me so long to subscribe to the list, but I finally did last
> year. Me, I am currently in lurker mode, not completely by choice, so not
> many posts recently by me and most current posts are out of my "realm", but
> I read them all with interest. Me, I am mostly a tube man. I love the glow
> of a vacuum tube :-) And with a career change, I have been busy working 6
> days a week with quite a bit of OT with a bit commuting time also. So not
> much time. So only one real day to do coiling for me. All is good though,
> decent pay and I like what I am doing. Have some extra coin within reason
> for some components that I could not justify before for current coils and a
> two project coils currently going.
> Still also experimenting with my one now 304 VTTC, still testing more tubes
> that I have gotten recently. No real new developments lately testing and
> still a bit puzzled on some things. Still need to do some measurements of
> values of several things. Depending on some measurements I may rewind my
> secondary again. Even though it is performing very well, I just can't stop
> messing with this little coil originally built in sometime in the mid
> 1980's, even though I am pulling myself away from current coil projects.
> So, I guess I just broke out of lurker mode somewhat, just as some others
> here. Got the whole Thanksgiving weekend off and just got done testing
> another tube. Planning to finally make some measurements and do more
> thorough experimenting this weekend, since I finally have some more time.
> If I have some interesting results, I will post. Me, I feel like, but I
> could be wrong, that there is not really too many active people using tubes
> in coils currently. And locally when I tell people to try to get them
> interested, I get some puzzled looks from people no matter the age range
> when I tell them about using vacuum tubes and coiling. The only people that
> seem to understand are at the Hamfests that me and my father go to. They
> are also dwindling in size over the years. Changing technology and lack of
> interest in younger people.
> I used to be newspaper printer for quite a long time. Complete changing
> world there also. Not many young people interested in reading newspapers
> these days. Okay, enough rambling here...I probably can keep on going
> here...
>
> Chris Reeland
> Ladd Illinois USA
>
> Sent from my LG V20
>
>
> ------------------------------
>
> Message: 5
> Date: Sat, 24 Nov 2018 11:59:38 +1000
> From: Greg Peters <greg.j.peters@xxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Where is everyone?
> Message-ID: <5bf8b090.1c69fb81.f8c89.e25d@xxxxxxxxxxxxx>
> Content-Type: text/plain; charset="utf-8"
>
> Thanks Greg,
>
> Sorry, you just make me want to know more! Are you saying this is not a DRSSTC design but more akin to a ?normal? SSTC?
>
> What IGBTs are you using and how are you driving them? Do you have any protection circuitry and what kind of duty cycle? What is the primary voltage and how many turns on that secondary?
>
> I hope one day you write a detailed paper on this thing.
>
> I very much hope I can visit the US one day and come see it in operation, or better yet the full-size towers themselves.
>
> Regards,
>
> Greg
>
>
>
>
>
>
>
> Sent from Mail for Windows 10
>
> From: Greg Leyh
> Sent: Thursday, 22 November 2018 8:20 AM
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] Where is everyone?
>
> Hi Greg,
>
> No real secret there, the primary drive is just a straight-up
> non-resonant H-bridge, like the ones used in VF motor drives.
>
> There's no high current series capacitor, or feedback from the
> secondary. The secondary freq is measured beforehand, and the primary
> drive is manually set to that frequency. It's a simple yet robust
> system with high predictability... good to have when there's lots of
> silicon at risk.
>
> Since it's a cost-sensitive design, the IGBTs are of course loaded way
> beyond their continuous ratings. I've lost two IGBTs so far, both when
> I tried raising the current limiters to coax higher drive levels.
>
> As IGBTs get cheaper/better I'll upgrade the primary drive capability.
> The coil will throw ground strikes already, but my ultimate goal is to
> generate the highest peak voltage possible without breakout at low BPS.
>
>
>> On 11/21/2018 9:10 AM, tesla-request@xxxxxxxxxx wrote:
>> Message: 6
>> Date: Wed, 21 Nov 2018 20:53:03 +1000
>> From: Greg Peters<greg.j.peters@xxxxxxxxx>
>> To: Tesla Coil Mailing List<Tesla@xxxxxxxxxx>
>> Subject: Re: [TCML] Where is everyone?
>> Message-ID:
>> <CA+bpwPCPR-rv_5BjkoLM_zuoRu3m9U8qSXYct7jb2FT=-JagUQ@xxxxxxxxxxxxxx>
>> Content-Type: text/plain; charset="UTF-8"
>>
>> Hi Greg,
>>
>> Amazing coil! Is there anywhere we can see some more specs around the IGBT
>> and driver configuration? Guessing it's a secret but would love to know
>> more about what's going into that thing.
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxxxxxx
> https://www.pupman.com/mailman/listinfo/tesla
>
>
>
> ------------------------------
>
> Message: 6
> Date: Fri, 23 Nov 2018 20:49:58 -0500
> From: William Fox <wm9fox@xxxxxxxxx>
> To: tesla@xxxxxxxxxxxxxxxxxx
> Subject: [TCML] Why Was Tesla?s 1899 Colorado Springs Magnifying
> Transmitter Never Fully Developed for Full Power?
> Message-ID: <82E6BE7C-5C4E-4438-A01C-C4E6CEAE10CF@xxxxxxxxx>
> Content-Type: text/plain; charset=utf-8
>
> Hello everyone! I?m a very long time ?listener? and found this forum to be such a broad wealth of information. So, I thought I?d submit my first post.
>
> Among my greatest interests is Tesla?s development of his coils from 1891 to the shutdown of Wardenclyffe in 1906.
>
> Within that timeline, I have wondered what Tesla would have to have done to operate his magnifier at full power with his 142 foot ?structure of iron pipes? connected? There are surely many obstacles that he would have had to overcome & perhaps that?s part of the reason (besides blowing through his available cash) why he never returned.
>
> FYI, my library includes the Colorado Springs Notes, Richard Hull?s excellent work, ?The Tesla Coil Builders Guide to the Colorado Springs Notes of Nikola Tesla,? and John Ratzlaff & Fred Jost?s ?Tesla / Scherff Colorado Springs Correspondence? all of which I?ve studied for years.
>
> Any thoughts on this subject will be greatly appreciated. Thanks in advance!
>
> Best regards,
>
> Bill Fox
>
> Sent by Ma?ak's humble servant.
>
> ------------------------------
>
> Message: 7
> Date: Sat, 24 Nov 2018 12:29:15 -0600
> From: David Rieben <drieben@xxxxxxx>
> To: Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx>, Tesla Coil Mailing List
> <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Adventures in SRSG
> Message-ID: <726C9B35-DA20-4255-88AB-CE24491F5678@xxxxxxx>
> Content-Type: text/plain; charset=us-ascii
>
> Hi Bert,
>
> I always enjoy getting your input on this subject matter, as I always seem to acquire more info that I was previously unaware of. I was completely unaware that there are TWO LTR methods of running a coil system. From your description, the inductive kick LTR sounds pretty persnickety, to say the least! Sounds like standard LTR is the way to go and I assume that is what most coilers are referring to when they speak of LTR tuning. I learn something new every day ;-)
>
> Seasons greetings,
> David
>
>
>
> Sent from my iPhone
>
>> On Nov 22, 2018, at 12:27 AM, Bert Hickman via Tesla <tesla@xxxxxxxxxx> wrote:
>>
>> Hi Dan,
>>
>> If the safety gaps are set properly, they should seldom fire in a stable LTR system. If your safety gaps are firing frequently, partial cancellation of the NST current limiting function and main resonance are likely occurring.
>>
>> There are two types of LTR approaches: standard LTR and inductive kick LTR. A good discussion of standard versus inductive kick LTR systems (versus classical mains resonant systems) can be found in the archives:
>> https://www.pupman.com/listarchives/2000/August/msg01085.html
>>
>> A regular LTR system just barely charges the tank cap to the maximum rated output voltage of the NST twice on each mains cycle. Either a static or rotary gap works well with this setup. The tank cap is ideally sized to 1.57 times the mains resonant value, so for your 15/120 system, this would be about 33.3 nF.
>>
>> Because of the heavier capacitive load on the NST, the size of the PFC capacitor bank can be significantly reduced or PFC can be eliminated entirely. A standard LTR setup with a much smaller PFC bank is the configuration I would recommend. The PFC bank may, in fact, be causing part of the problems you're seeing.
>>
>> If you want to use an inductive kick LTR setup, the tank cap size can be estimated using the following formula:
>>
>> C = 0.83*I/(BPS x V)
>>
>> Where:
>> C = LTR Tank cap (Farads)
>> I = NST bank short-circuit output current (Irms, in amperes)
>> V = NST output voltage (Vrms)
>> BPS = Break rate (2X mains Hz or 120 BPS for your system)
>>
>> For your 15/120 NST bank the ideal LTR size works out to be about 55 nF or about 2.6 times the resonant cap size.
>>
>> However, there are a couple of significant disadvantages using an inductive kick LTR system. It requires a properly phased SRSG where the gap fires 3-4 milliseconds after zero crossings. More importantly, the SRSG can be difficult to "start". The tank cap will only charge up to about 30% of the NST open-circuit peak voltage if the gap doesn't initially fire. However, if the gap does start firing, then the tank cap voltage will significantly increase to near the level of a standard LTR setup. This occurs as energy (stored in the magnetic field in the NST's secondary inductance) provides an inductive "kick" that boosts tank capacitor voltage. But this can only occur IF the gap starts firing at the right time.
>>
>> If your rotary gap is configured to have a total of four gaps in series (two sets of gaps located 180 degrees apart on the disk), the total SRSG breakdown voltage may be too great to "start" your LTR system. This sounds like the problem you encountered when trying to drive your Maxwell 60 nF cap. To alleviate this, you may want to use only ONE set of stationary electrodes (i.e., only 2 total gaps). This will allow you to maintain adequate mechanical clearance while also allowing the gaps to initially fire at the reduced starting voltage in your LTR system.
>>
>> I don't recommend an inductive kick LTR approach since its benefits may not justify the added setup complexity and gap firing difficulties.
>>
>>
>
>
>
> ------------------------------
>
> Message: 8
> Date: Sat, 24 Nov 2018 12:34:37 -0800
> From: Frank <fxrays@xxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Tesla Digest, Vol 132, Issue 6
> Message-ID: <86.1F.14178.3E5B9FB5@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> Look up a Baker fan to get the idea. This is just an axle with two or
> 4 flat paddles on it. As it rotates it generates wind resistance and
> will consume all the horsepower based on size and rpm. This principle
> is used as governors in music boxes and larger versions were/ are
> used a loads for tractors.
> The rotor on a spark gap will generate wind resistance and load the
> motor. If the gap is synchronous, the motor has to be big enough to
> run at a constant speed based on the rotor design and size. Even a
> asynchronous gap will require a proper size motor to spin it as if an
> AC motor is used as the motor still has to run at its rated speed or
> it will draw too much current if it cannot to get up to speed.
> As the size of the spark gap increases and the number of flying
> electrodes, the gap will require xxx horsepower to spin it at rated
> rpm. No real way to "calculate" the horse power because of too many
> variables and more of a trial and error.
>
> At 03:30 PM 22/11/18 -0800, you wrote:
>> Hi Steve,
>>
>> Windage is the biggest issue. The Fan Laws [
>> https://en.wikipedia.org/wiki/Affinity_laws ]are merciless as you
>> scale rotor size, speed and # of rotors. Even with aero shrouding,
>> Electrum took 28.5 HP on the 30HP gap motor.
>>
>>
>>> On 11/22/2018 2:03 PM, tesla-request@xxxxxxxxxx wrote:
>>> From: Tedd Dillard<tedd.dillard@xxxxxxxxx>
>>> To: Tesla Coil Mailing List<tesla@xxxxxxxxxx>
>>> Subject: Re: [TCML] Tesla Digest, Vol 132, Issue 5
>>> Message-ID:
>>> <CABebsSmOTy+syG067FzyQN+mAkJep0PMKOT4hjT7PGU9sDby7A@xxxxxxxxxxxxxx>
>>> Content-Type: text/plain; charset="UTF-8"
>>>
>>> Greg,
>>> I am missing something, please help me understand sir.
>>> I do not understand why the rotary spark gap motor would necessarily need
>>> to be so big as the size increases.
>>> The diameter of the rotor would get bigger and so the weight would also
>>> increase so the starting torque would also increase.
>>> But as there is no mechanical friction involved the only power increase it
>>> seems would be the increased windage from the rotating parts.
>>> I can see maybe 5 horse power or so and if the motor is a regular induction
>>> motor modified to be a synchronous motor there would be a loss of torque
>>> due to the increases air gap but I must be missing something. So getting it
>>> going could be an issue but once it was up to speed where is the large
>>> power going?
>>> Teddy
>>>
>>> On Wed, Nov 21, 2018 at 5:20 PM Greg Leyh<lod@xxxxxxxxxxx> wrote:
>>>
>>>>> Hi Steve,
>>>>>
>>>>> Turns out that IGBTs become easier to deal with than rotary spark gaps
>>>>> as the coil scales in size. Here's a few reasons:
>>>>>
>>>>> a) The freq drops with increasing size, and in the lower 10's of kHz
>>>>> range the bigger traction IGBTs start to work quite well.
>>>>>
>>>>> b) The motor size on a rotary gap starts getting rather unwieldy at
>>>>> higher power levels. Electrum needed a 30HP motor. This 40ft coil
>>>>> would need almost 100HP... not a very portable rig!
>>>>>
>>>>> c) IGBTs can work at much lower impedance, typically a small fraction of
>>>>> an ohm, compared to many ohms for spark gaps. That allows this coil to
>>>>> work with primary voltages <1kV. Electrum was 44kV, and this coil would
>>>>> have to be 60-80kV for a rotary gap system.
>>>>>
>>>>> Since I had no funding, this scale prototype design had to pursue
>>>>> cutting costs as far as possible. IGBTs provided the best value
>>>>> overall. However, I totally agree that a rotary gap system for 240kW
>>>>> service would look much cooler than a box of IGBTs. ;>
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxxxxxx
>> https://www.pupman.com/mailman/listinfo/tesla
>
>
> ------------------------------
>
> Message: 9
> Date: Sat, 24 Nov 2018 22:13:37 -0200
> From: Antonio Queiroz <acmdequeiroz@xxxxxxxxx>
> To: tesla@xxxxxxxxxxxxxxxxxx
> Subject: Re: [TCML] where is everyone
> Message-ID: <8772906d-3764-4c99-59ed-cadc5c793cbf@xxxxxxxxx>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Em 21/11/2018 19:03, Mark Stolz escreveu:
>
> After I moved to other research subjects, my coils were made primarily
> for verification of synthesis procedures, my participation become rare
> here, but I still read everything that appears. I notice that even the
> forums (as 4HV) have far less movement. There are a few groups in
> Facebook dealing with Tesla coils, but the level of detail is quite low.
>
> Antonio Carlos M. de Queiroz
>
>
>
> ------------------------------
>
> Message: 10
> Date: Sun, 25 Nov 2018 11:49:44 -0600
> From: Phillip Slawinski <pslawinski@xxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] where is everyone
> Message-ID:
> <CAA=w+ci+o5JaYz1tjAT4juOn8oWnpL3JQdD5ApDmtLd8LJx87A@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="UTF-8"
>
> I think Mads assessment of social media platforms is correct. In addition
> to the issues previously pointed out, platforms like facebook, instagram,
> etc. do not reward long form content in the same way that forums or mailing
> lists do.
>
> I'm not sure that social media is entirely to blame though. From my
> observation of the solid state coiling community there hasn't been that
> much that has changed about building coils in recent years. Gone are the
> days when solid state coils were new and poorly understood. Since 2008 or
> so many of the developments I've observed in the field of solid state
> coiling have been related to modulation of the RF envelope and allowing
> dual resonant coils to run longer pulse lengths. These developments were
> documented and put up on sites that are searchable.
>
> So far as I can tell there are more people 'building' coils than ever. The
> thing is that a lot of people build kits now. I'm not sure that a kit is
> the best way to get into the hobby, since you tend to learn less than
> having to design the system from the ground up. That said, maybe some of
> those kit builders will decide to start tweaking things to get better
> performance and end up building their own custom coils.
>
> Not sure if anyone else has suggested this, but reddit seems like it could
> be a decent place for discussion related to Tesla coils. Reddit is a very
> popular platform, and allows long-form and short-form posts. The subreddit
> https://www.reddit.com/r/TeslaCoils doesn't have many subscribers, but you
> guys could help with that.
>
> -Phillip Slawinski
>
>
> ------------------------------
>
> Message: 11
> Date: Sun, 25 Nov 2018 13:06:01 -0600
> From: Daniel Kunkel <dankunkel@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Why Was Tesla?s 1899 Colorado Springs Magnifying
> Transmitter Never Fully Developed for Full Power?
> Message-ID:
> <CAA7NYCf3gKXkr+Q4t2Z+Vjy5LDb1cF-RF_d5gnPhwL8RxoUBOg@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="UTF-8"
>
> Bill,
> I am not sure exactly what your question is..." I have wondered what Tesla
> would have to have done to operate his magnifier at full power with his 142
> foot ?structure of iron pipes? connected?"
>
> The large mast on the Colorado Springs lab was only constructed to measure
> the effects of elevated capacitance. It was never intended, nor did it,
> emit any sparks. The summation from Hull's notes shows that the input power
> was 2-30 KV (22.5 KV being the most commonly used). We don't know the
> amperage or KVA, but again, Hull surmises 15+ KVA. We also know all the
> arcs Tesla created were for publicity to gain the interest of investors.
> Arcs were not desirable for wireless radio or power.
>
> Tesla's actual words on the mythically claimed 125 foot streamers were have
> all heard (CSN page 330):
> "These streamers were about the longest produceable in the present
> building, with the roof closed, measuring from 31-32 feet in a straight
> line from the origin to end. Taking into account the curiously curved path
> the length was probably more than twice this, so that taking the discharge
> from tip to tip of these longest streamers, the actual path of the
> discharge through the air was from, say, 124-128 feet!"
>
> As best as I know, Tesla never produced any arcs from the Wardenclyffe
> Tower. But there is a section in the CSN where Tesla notes how to design a
> topload to minimize the physical size, while maximizing capacitance, and
> PREVENTING arcs. And when we look at the Wardenclyffe tower, we see that
> funky knobby looking topload...designed NOT to make sparks.
>
> To what if Tesla ran Wardenclyffe at full power??? Read the article on page
> 194 of Hull's Notes...pretty hopefull and inspiring...and I have given up
> on 'wireless' a long time ago.
>
> ~Dan
> Kansas City area
>
>
> ------------------------------
>
> Message: 12
> Date: Sun, 25 Nov 2018 13:10:58 -0600
> From: Daniel Kunkel <dankunkel@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Adventures in SRSG
> Message-ID:
> <CAA7NYCeDcAsA8y-8uJhCXuMbRn1VyDRErs5QuFZQsbdx3wUgjw@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="UTF-8"
>
> Bert,
> Thanks for the detailed reply! There is a lot of information to go over
> here.
>
> I have good and bad news and good news to report...
>
> I removed the PFC's, re-implemented the safety gap, removed some C from the
> tank cap (I probably shouldn't have). I ran the coil amp draw dropped to an
> acceptable 20a range, spark output also noticeably dropped as well. Then
> spark output dropped completely! Arg. I think I fried am NST or two. I
> haven't had time to inspect yet. HOWEVER!
>
> I found a killer deal ($200) on a 2KVA 13,200 potential transformer (with
> fuses).
>
> So now I'll need to build a ballast and still need to build a phase
> controller for the SRSG.
>
> Thanks,
> ~Dan
>
> On Thu, Nov 22, 2018 at 4:03 PM Bert Hickman via Tesla <tesla@xxxxxxxxxx>
> wrote:
>
>> Hi Dan,
>>
>> If the safety gaps are set properly, they should seldom fire in a stable
>> LTR system. If your safety gaps are firing frequently, partial
>> cancellation of the NST current limiting function and main resonance are
>> likely occurring.
>>
>> There are two types of LTR approaches: standard LTR and inductive kick
>> LTR. A good discussion of standard versus inductive kick LTR systems
>> (versus classical mains resonant systems) can be found in the archives:
>> https://www.pupman.com/listarchives/2000/August/msg01085.html
>>
>> A regular LTR system just barely charges the tank cap to the maximum
>> rated output voltage of the NST twice on each mains cycle. Either a
>> static or rotary gap works well with this setup. The tank cap is ideally
>> sized to 1.57 times the mains resonant value, so for your 15/120 system,
>> this would be about 33.3 nF.
>>
>> Because of the heavier capacitive load on the NST, the size of the PFC
>> capacitor bank can be significantly reduced or PFC can be eliminated
>> entirely. A standard LTR setup with a much smaller PFC bank is the
>> configuration I would recommend. The PFC bank may, in fact, be causing
>> part of the problems you're seeing.
>>
>> If you want to use an inductive kick LTR setup, the tank cap size can be
>> estimated using the following formula:
>>
>> C = 0.83*I/(BPS x V)
>>
>> Where:
>> C = LTR Tank cap (Farads)
>> I = NST bank short-circuit output current (Irms, in amperes)
>> V = NST output voltage (Vrms)
>> BPS = Break rate (2X mains Hz or 120 BPS for your system)
>>
>> For your 15/120 NST bank the ideal LTR size works out to be about 55 nF
>> or about 2.6 times the resonant cap size.
>>
>> However, there are a couple of significant disadvantages using an
>> inductive kick LTR system. It requires a properly phased SRSG where the
>> gap fires 3-4 milliseconds after zero crossings. More importantly, the
>> SRSG can be difficult to "start". The tank cap will only charge up to
>> about 30% of the NST open-circuit peak voltage if the gap doesn't
>> initially fire. However, if the gap does start firing, then the tank cap
>> voltage will significantly increase to near the level of a standard LTR
>> setup. This occurs as energy (stored in the magnetic field in the NST's
>> secondary inductance) provides an inductive "kick" that boosts tank
>> capacitor voltage. But this can only occur IF the gap starts firing at
>> the right time.
>>
>> If your rotary gap is configured to have a total of four gaps in series
>> (two sets of gaps located 180 degrees apart on the disk), the total SRSG
>> breakdown voltage may be too great to "start" your LTR system. This
>> sounds like the problem you encountered when trying to drive your
>> Maxwell 60 nF cap. To alleviate this, you may want to use only ONE set
>> of stationary electrodes (i.e., only 2 total gaps). This will allow you
>> to maintain adequate mechanical clearance while also allowing the gaps
>> to initially fire at the reduced starting voltage in your LTR system.
>>
>> I don't recommend an inductive kick LTR approach since its benefits may
>> not justify the added setup complexity and gap firing difficulties.
>>
>> Hope this helps and good luck!
>>
>> Bert
>>
>>
>> Daniel Kunkel wrote:
>>> Thank you all for the input so far!
>>>
>>> 1) Bert:
>>> In your opinion, with a SRSG/NST setup, how often should a safety gap
>> pop?
>>> 10% of the time, or less? Based on what you are saying, I'd say the
>>> resonant rise symptoms match my situation. I can see the safety gap
>>> preventing things from 'rise' escalating, but that doesn't seem like a
>>> permanent fix? I like your previous suggestion of removing the PFC caps
>> and
>>> starting over...but I am guessing the BPS and capacitance are not
>>> happy...so ultimately do I need to re-size the MMC? What do you suggest
>> on
>>> sizing?
>>>
>>> 2) Gary:
>>> I am glad you brought this up. I had initially removed the MMC and
>> swapped
>>> in my Maxwell .06 uF cap, but no amount of fiddling could get the gap to
>>> reliably fire, let alone produce streamers. I have seen situations like
>>> this before, and it was always due to the tank cap being too large. I
>> have
>>> no idea how your 15/60 is charging and firing a .04 uF cap! For my NST
>>> setup with 120 BPS, JavaTC suggests a .0553 uF cap. For you, it suggests
>> a
>>> mere .0277 uF.
>>>
>>> To answer your question, 'I suspect that
>>> you were unable to stop the safety gap from firing so you opened it up to
>>> where it stopped?', the answer is YES, you are correct.
>>>
>>> My cap options are MMC (100 caps of .068 @ 2,000 VDC) or Maxwell pulse
>> cap,
>>> .06 uF @ 50,000 volts)...what do you suggest I try?
>>>
>>> 3) Phil:
>>> Thanks for digging that out of the archives! I always love reading
>> material
>>> from Richie. I can't wait get a real transformer one day (it WILL happen)
>>> and then I can leave the NST's behind. I think this all confirms what
>>> everyone is saying...my tank cap needs to be altered.
>>>
>>> 4) To anyone else still reading...
>>>
>>> Here is a pic of coil running...I did manage to take a quick video and
>> here
>>> is a single frame. By scaling on the photo (secondary is 26.5" inches of
>>> winding), the lower streamer alone is 62+" from the breakout point to the
>>> end of the frame. It is 72" from the break out straight down to the
>> ground,
>>> and this streamer ALMOST hit the ground at an angle, so I'd say it was
>>> right around the the 6 foot mark. The amp meter was showing 40 amps...4.8
>>> kVA YIKES!
>>> https://imgur.com/a/xQKOpbx
>>>
>>> ~Dan
>>> Kansas City area
>> <snip>
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>> https://www.pupman.com/mailman/listinfo/tesla
>>
>
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