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Messages - Steve Ward

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1
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Steve:  Interesting to know that you use external drain-source capacitance.  I'd wondered about that and ran many simulations both with and without external capacitance.  In simulation, I could get a little more power with the external capacitor.  It lowered primary resonant impedance, reducing how far out-of-tune it became as the secondary arc load increased.  However, I liked the simplicity and cleanliness of using internal FET Cds only.  FET current is close to sine wave.  No sudden changes in current at zero Vds.  Even though this FET has dual source leads, I liked the idea of no sudden current transfer, avoiding the resulting ring in the parasitic inductance loop from FET to external drain-source capacitor.

I had the same line of thought (about snubber current vs fet channel current), and for a period of time I suspected the added D-S capacitance was causing my circuit to self-oscillate in a worse way due to the interrupted current through the common source inductance (it blew up once and there was unusual ringing observed at the gate). However, in practice it seems to work fine despite a little extra ringing.  I try to keep the extra Cds about equal in charge to the fet's Qoss, effectively doubling the charge of the fet alone, all else being equal this should allow for twice the input current for the same peak voltage.  For the SiC JFET cascode that i use, the extra Cds should help reduce switch-off losses which are the dominant source of energy loss, i think, for most class E.  Other SiC Fet technology might not be as limited in switch-off speed, so perhaps you wouldn't see much gain from the extra Cds.  Also, i use the 4-lead package for lower source inductance.

Noticing a few things about your design - the secondary Fres is significantly higher than the operating frequency, and so I think this mode of operation, primary-resonant, is what provides graceful operation over wide power range with a fixed frequency.  Perhaps, like my HFSSTCs, once the arc capacitance is big enough to bring the secondary Fres to the actual operating frequency, the ZVS turn-on is lost.

Thanks for the waveforms, I also see similar higher frequency ringing in mine but not as pronounced on the drain voltage like that. I assumed in my case it might be ringing of the Cds internal vs snubber with any inductance between them, but you dont have that circuit... hmmm

2
General Chat / Re: Why are SGT50T65FD1PN soo cheap on lcsc?
« on: June 09, 2021, 09:15:22 PM »
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Does it really matter, considering thermal transfer package to heatsink is limited , especially if you use some form of insulation and not just grease the surfaces?Even the attachment of the capsule has significance. Making the heatsink slightly larger so that the sum of thermal resistance stays the same is easy.

Especially some manufacturers states ridicuosly high power capabilites based on theoretical calculations. I mean, 350W in a TO-220? Seriously?

This dissipation rating or Rth j-c is mostly indicative of how large the actual semiconductor is, so one with half the Rth (or 2X the Pdiss) is indeed about twice the area and consequently will have more volume to absorb the high power losses in pulsed applications.  The dissipation rating is obtained by assuming 25*C tab/interface temperature with Tjmax (150 or 175*C typically) applied to the junction and measuring the power flow from the chip, so its not a "practical use" rating, but still a reasonable metric to compare by. 

So even though the Rth of the device itself is only a small portion of the total thermal resistance stackup (typical TO-247 insulator might be ~1*C/W) the fact that its a bigger chip inside means it has lower transient thermal impedance and will handle greater pulse power.  Even for non-pulse power designs, it can really help to pick the biggest chip size for a given package to increase the power density of a design, and some designs really can appreciate the .2 to .5 *C/W reduction of going from a wimpy device to a strong one.

3
Looking to offload some ferrites!  Perfect for that HV transformer, induction heater or power conversion project!  A few of the cores have cracked in my care (whoops!) and have been superglued back together, these will be discounted.  Many transformer designs will easily tolerate the extra air gap caused by the glue, but I digress...  The type of ferrite on these is generally not known, but for power ferrites, there's not a huge variation in types anyway.

Buyer pays shipping, USPS, UPS, FEDEX.  I accept paypal.  PM me if interested, willing to make a deal! 

Dimensions are per half-core section.

Large U: 93.5 wide x 76 tall x 30 deep(mm).  28mm x 30mm cross section with 36mm window between ferrite legs. 
I have 4 matched sets (plus 1 cracked set) and 1 of a different type of ferrite.  $15/set, $10/set for the cracked-leg one.


Large U/I: same large U above, I is 27mm wide, 30mm deep and 94mm long. Only have 1  $10/set


Wide U: 102 wide x 57 tall x 25 deep(mm).  25 x 25mm cross section with 51.5mm window between legs.  Only 1 set and one of the cores is broken/glued.  $10/set.


Long E: 70 wide x 54 tall x 32 deep(mm).  22x32mm cross section in the center and 11x32 cross section at the outside legs.  13mm window between legs. 5 sets available,  $10/set


Wide E: 80 wide, 39 tall, 20 deep (mm).  20x20 cross section with 20mm window between legs.  50ALL material (TSC ferrite),  4 sets available at $5/set.



4
Trying to thin out the collection before I move out of state!  Buyer pays shipping, UPS, USPS, FEDEX.  I accept paypal, PM me if interested! 

I'm currently "reforming" all units listed below, if any show high leakage i'll remove them from the listing.  I suspect, however, that they still have good life left in them for experimental use.  I set the price, hopefully, low enough to entice buyers as I'm moving out of state next month.  I'd entertain offers if someone wants them all for a deal or is broke but really wants caps for their coil.  I have too many caps and these need to go!

43 types available (from left to right in picture, dimensions do not include terminal post):

Nippon Chemi-con 10,000uF 400VDC, 1620grams, 3.5" x 6.75", QTY 4 available at $20 each (Ive used these within the last few years, light duty filter applications)

AEG 12,000uF 350VDC, 1480grams, 3" x 8.7", QTY 2 available at $10 each (these might be from my DRSSTC2, or they were spares, i cant recall, but they're old-ish).

ADz (?) 22,000uF 200VDC, 985grams, 3" x 5.6", QTY 2 available at $5 each (these might be from my DRSSTC1, could be good for 120VAC doubler for powerful coil).

Nippon ChemiCon 15,000uF 350VDC, 1620grams, 3.375" x 7.4", QTY 2 available at $10 each, one has a dent but still seems to hold a charge fine. (oldish, backups for my big QCW FAT coil). 

5
Voltage Multipliers / Re: New High Voltage Mutliplier Setup
« on: May 23, 2021, 06:08:33 PM »
Thanks for sharing this project!  Those long, ghostly, soft arcs are very nice for indoor demonstration!  Are you feeling the hair raise on your body, yet?  I put together a 5-stage (10X input multiplication) tower that could make 200kV and jump some 16" air gap, which agrees well with your 80cm for 400kV.  Even with 200kV, the ion streams could be intense, causing discharges several feet from the machine as "static" charge builds up on items nearby.

Is there any chance for recombining the parts from full-wave to half-wave to achieve higher voltages still? The high voltage DC corona plumes are fascinating, but very difficult to capture well on camera compared to the arcs, but at extremely high voltage it may be more interesting.

6
Thanks for making this and sharing it!

I'm impressed that it works well with fixed freq.  Could you share some waveforms during the operation?**  Seeing no extra snubber capacitance from D-S suggests you're likely seeing short, but relatively high amplitude, voltage pulses?  Usually the drain voltage is clamped from going negative by the body diode.  I add extra D-S capacitance when possible (usually about the same energy as Coss), to widen but shorten the drain voltage pulse, but its limited by the Q of the load, if too low, ZVS switching is lost. This is how my HFSSTC works over its limits in range, but i could imagine how fixed frequency would further hinder safe switching under different load conditions.

**You may already be aware, but for those who aren't, its good to realize that probing high frequency and high voltage can destroy probes at less than their rated AC voltage.  I use passive 100X probes rated for 2 or 5kV, and even they will not spec them to handle the ~1kV at 10MHZ that i subject them to, however they do seem to manage (maybe not so much long term). 
...
However, my Micsig differential probe promptly burned out part of its compensation network (which includes resistors in series with capacitors to fine tune the response).  I tried to alert them of this issue as they do not include a frequency de-rating for their probe, but it fell on deaf ears of their support people who insisted its 1300V rating was fine to 100MHZ!  Anyway, a typical probe with 20pF load capacitance probing an 800V peak-peak signal would see just about 1amp peak to peak, which is quite a lot for a probe!  The higher voltage probes can get down to just a few pF which seems to be key to their surviving, is my bet.  However, the micsig probe is only 2pF in single ended mode (one side of the probe at a stable voltage), and it still failed.  On the other hand, the relatively low cost P2301C is only rated for 50VAC at 10MHz despite its 5kVDC rating.  And even with 6.5pF input capacitance, its not looking great, but so far it's held up OK with ~1kVpk at ~9MHz.

Quote
I used that on my lower power ~200 watt HFSSTC. I tried other electrodes including carbon and like the
tungsten best. An iridium spark plug conductor also worked and didn't appear to erode like the tungsten.
It was wild watching some of the higher melting point metals melt in that arc.

With higher power levels, tungsten begins to flash a blinding white light.  I've melted a spot on a 1/4" tungsten rod with a ~1kW HFSSTC, during the event the rod was emitting incredible sounds like a tea kettle boiling over.  I wore a welding mask and sucked the gases out of the area with overhead hood. 

I know there's a lot of folks that really adore tungsten, but from a practical sense, carbon rod wins by a lot in terms of utility/cost.

7
Sell / Buy / Trade / Re: Huge IGBTs (looking for a home)
« on: May 17, 2021, 12:34:04 AM »
Thanks for all the interest, everyone.  I think the IGBTs have found new homes, my condolences to anyone who I could not supply with free IGBTs this time :-).


8
Sell / Buy / Trade / Huge IGBTs (looking for a home)
« on: May 15, 2021, 10:20:31 PM »
I'm looking to see if anyone has a good home for these parts, preferably within the US, recipient pays shipping - I'm just looking to give these away.

I have 4 of each of these giant IGBTs from electric trains:

1MBI2400U4D-170

http://www.farnell.com/datasheets/1676909.pdf

DIM1200ESM33

https://www.dynexsemi.com/Portals/0/assets/downloads/DNX_DIM1200ESM33-F000.pdf

Also have some gate driver boards that could be reverse-engineered, which use the large plastic fiber optic cables (R-2551Z and T-1551Z) and have some kind of isolating power supply input.  Whoever takes IGBTs will get gate drivers, too, as i try to reduce my collection.

9
Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Jimmy drsstc
« on: May 02, 2021, 05:15:38 AM »
Hah! that website still exists!

I think Jimmy was the first to exploit double resonance h-bridge drive in a "transient" mode to make big sparks at high peak power, and thus the first recognizable DRSSTC.  That first machine ended up making up to 8 foot sparks with over 1kA from CM150s, really, quite groundbreaking for a first go. 

At around the time he was working on that first coil we were trading notes a lot.  That first DRSSTC used a microcontroller to generate gate pulses at a fixed frequency.  I was experimenting with "interrupted SSTCs" at that time where I began to stumble into near double resonance as my DC blocking capacitor started to resonate with some very low primary inductance, but it was Jimmy that helped me realize that and push it further.  I don't really think I invented anything in particular, but I did put out a number of decent designs that seemed to become standard. 

Like some sort of weird "high voltage forum fairytale", I actually work (remotely) with Jimmy, doing motor/inverter research and design. 


10
Those are some crazy sparks!  Might i suggest carbon "gouging" rod for breakout point?  I'd rate it as "bright, but much less bright than tungsten" and doesn't melt like metals.

Since its already a LF coil, could you try a bigger toroid to push the sparks up?  That seems to be my impression of how to control the spark direction.

Congrats on no transistor explosions, that's a tremendous energy reserve!

11
General Chat / Re: Tesla coil records and extremes
« on: March 01, 2021, 02:04:44 AM »
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the largest drsstc
https://pbs.twimg.com/media/DrdddwEV4AARtqv.jpg

Not even DR, but yes, very big.  Lightning on Demand (Greg) can comment since he's the builder, but that machine has no resonant primary cap so its basically a huge SSTC.   

12
Solid State Tesla Coils (SSTC) / Re: Self Oscillating Half Bridge Wonder
« on: February 09, 2021, 06:33:20 PM »
Quote
Sounds like SiC enabled some serious performance.

I got very similar performance with a FDH44N50 Si MOSFET, so it's not just "use SiC and you'll get huge arcs".  I recommend learning on low cost Si, like IRFP460, before trying SiC.  I have a few P460A's in my collection, so maybe i'll demo what can be done with that fet sometime, but i think 6" flame is probably well within range.  I would not waste time with lower voltage devices, save the P260N's for a bus modulator or something useful ;-).

The real performance enhancement is in the tuning, my setup runs almost constant primary current over the range of 20-120V input with slightly declining primary current at higher input voltage (i've gone to 140V so far, but loss of ZVS was becoming apparent). 

Previous secondary coils which had more inductance and capacitance had required about double the primary current to reach similar flame size, and then i realized its probably better to just minimize Csec as much as possible, and that double resonance isn't required for such a low voltage machine.  Instead, the output coil just provides voltage gain via induction, and with its Fres being significantly higher than operating freq, there is not much phase shift between primary voltage and secondary output, so primary voltage directly contributes.

I do most of my tuning exploration in ltspice before trying on the real thing, though i have to use the real thing to capture the plasma loading effect to run a realistc sim, so its an iterative process.  Max power level so far was around 1 to 1.2kW, but it looks like it could do 1500W with the 650V fet i have now, and ~3kW with 1200V, and *much care* given to the tuning.  It's a fine balancing act, but fortunately with this "detuned" approach the plasma load seems to nicely match the class-E requirements over a wide operating range, enabling the self-oscillator to run reliably at high power.

In fact, since using the de-tuned approach i have not lost a single FET, even when pushing the drain voltage beyond device spec by some 25V-50V.  And for those wondering, yes, i did break a few (4) SiC devices, i believe each time caused by loss of ZVS due to mode-hopping when the flame became too big, or simply overloading them thermally, as the old secondary ran with double the primary current!

I'm writing a paper that details the theory and design of my HFSSTC and the various ways I worked to optimize it, hope to publish it to a new website within the next weeks.

13
Nice switching there!

That looks like its ready to run with more space around it. 

Also, i noticed the mains line inductance was significant enough to require some decent bus , especially if your OCD just stops the oscillation at peak line current. 

14
Solid State Tesla Coils (SSTC) / Re: SSTC or DRSSTC with GaN Transistors
« on: December 01, 2020, 04:59:28 AM »
On an "academic" level, GaN is still superior to SiC in terms of junction charge loss vs on-state resistance, so in theory you can make the *most* efficient switchers with GaN, and in fact, that's what I do for work lately. However, you'd better ditch any kind of "through hole" packaging and stick with laminated multi-layer designs with very low total inductance (<10nH for a half-bridge/de-coupling cap loop).  Even considering resonant loads that can charge the output junctions for "free", it still costs VARs which have a cost via the circuit resistance, so GaN wins by reducing junction charging time/current.

However, the downsides of GaN are indeed smaller voltage tolerances and possibly higher thermal resistance, and well, it costs a lot more than Si or even SiC.  I've used GaN to drive Tesla coils, but only because I have the parts on hand for work projects, the cost/performance ratio applicable to TCs is not very compelling.  Perhaps for a small coil aiming for minimal heatsinking and the cost isnt too high, it would be handy.

 

15
Litz wire is often made from "solderable" magnet wire, which with a little abrasion while applying the iron will often succeed at wetting into the whole bundle of wires producing tap points which should only have a minor effect on the litz performance.

However, I'd agree with others that tuning the primary cap is a very practical way to avoid primary taps if you're careful about knowing your secondary parameters.  JavaTC is my go-to tool for designs. 

Ive built several QCWs with litz wire, and i will say it can make a significant difference in wire temperature (provided the litz is really spec'd for the high freq, your cooktop stuff might only be sized for 20-50khz, so its not as effective as the super fine stuff i used rated for 300-500khz), but generally the primary coil loss is relatively small compared to total energy, so you probably wont see any real boost in spark performance. 


16
Solid State Tesla Coils (SSTC) / Re: Fun with wireless power
« on: August 08, 2020, 10:22:04 PM »
Nice video and demo.  Good to see you here, Greg!

I have to wonder how much more power you might receive if one of those sparks grabbed a hold of your aerial :-).

Maybe you can get crowd-funded to build a bumper car arena with intermittent lightning on demand!

On a more serious note... One question that comes to mind is whether it makes sense to operate as an "interrupted" or "pulsing" type coil, or go for lower peak fields with a continuous-wave type drive?  I haven't thought much about how efficiency changes with field strength. But maybe there's some reason the efficiency goes up with more voltage, so higher pulsed levels make more sense.  The rectification losses are non-linear, working in favor of pulsing i think, but all the IIR losses would rather go for a CW setup.  At least that's my take on it.

17
I'm also building an IH (well, ive built a few now...) aimed at higher freq's in this range.  I'd be happy to share details, but its still in the works.  Also, as you already know, building these kinds of things are a steep learning curve with plenty of ways to go wrong. 

I'm using CREE SiC devices with a boot-strap type gate driver.  I have a post called "a three phase "tree phase" tesla coil" that has schematics attached for my half-bridge design, which im using the same design for the IH project.  I'm gonna try the C3M0065100K in full-bridge as im limited to about 12KW, which at 600VDC is only 20A or so (the switches might see 30A peak).   

The topology of the heater is a series resonant tank circuit fed by a step-down ferrite transformer with litz wire primary and water cooled secondary and a ratio of 35:1.  The bridge switching will happen strictly at or above the resonance frequency as this offers lower switching losses for the mosfets.  Power can also be controlled in this manner by operating off-resonance to control the boost that the resonance offers.

Alternatively, if the switching losses are too great, i will use a pulse-skipping method where the full-bridge can alternate between supply voltage at resonance, versus connecting both sides of the bridge to the same voltage, essentially putting zero voltage into the resonant circuit, letting the resonant current decay, before pumping it back up again.

I would say the SiC stuff is relatively easy to use if you are aware of a few things, like keeping gate drive parasitic inductances to an absolute minimum, and also watching the loop inductance of the half-bridge itself, because the higher switching rates available can more easily generate voltage transients.  The gate drive can oscillate and self-destruct if its sloppy (too much stray inductance).  I highly recommend the mosfets with a 4th "kelvin source" connection which eases the gate drive issues.

I've scored many CELEM capacitors on ebay recently, for pretty low prices.  Im using a pair of CSM150's of the .66uF type in parallel for this latest iteration. I do worry that some of them might be worn out, but the cost was small enough to take the risk.  The capacitance checks out OK on the 6 of them that i bought so far (i also got a pair of CP100, and a pair of CHF3 type 6). 

With all that being said, if you are in a hurry i would consider other options first as developing something like this is very challenging and likely to have a lot of hurdles.

I guess its worth saying why I want to build another IH, particularly with higher frequency capacity.  This heater is aimed at heating small copper pieces for purposes of selectively soldering them together as they are stacked with insulators and solder paste to form high-fill-factor motor windings.  The higher frequency will drive up the losses in my copper work pieces, getting it to soldering temperature even faster than my 210khz induction heater can now, which can take up to 60 seconds to achieve soldering temp, even with 500Apk circulating in my work coil.  Shorter heat time should limit the heat flow into neighboring coils and the stator core.   

18
Voltage Multipliers / Re: Different styles of HV electrodes
« on: July 25, 2020, 09:44:37 PM »
I'd agree with your original thoughts that it mostly comes down to manufacturing cost or other practical considerations.

The more perfectly smooth the surface is, the more stress it can stand before breakdown, but only marginally.  In my FEMM simulation, the breakdown voltage was reduced by maybe 20% when going from ideal toroid to a "ring" or skeleton toroid as you call it, and this was acceptable.  It depends on the radius of the conductors and how they are grouped, as they will partially shield eachother, reducing the e-field.  That is to say, a single ring would have a far lower breakdown voltage than a group of rings approximating the shape of a toroid with larger cross section.  Similarly, grouping a cluster of spheres together would raise the breakdown potential compared to a single sphere of the same diameter.   

19
General Chat / Re: Little Bee B Field / Current Probe
« on: July 11, 2020, 10:23:24 PM »
This looks like a great tool to have, even if the relative amplitude of the signal isn't too accurate.  A lot of use cases would allow for an extra "cored" sensor, usually at some other point in the circuit, to be used as a reference for the amplitude of the current.  One particular use case would be measuring switching losses, but im not sure the bandwidth is there for fast switches.

Im curious, what would be roughly the upper limit on current it can measure before saturating?  Assuming the wire size is comparable width as the sensor.

20
Heatsinks: I don't have any measurements to back my predictions, just going off of what the insulator manufacturers claims are for conductivity.  I do agree that at ~10mS the transient die heat is starting to become dependent on the tab-heatsink resistance,  It matters more and more the longer the "pulse" duration, of course.

Quote
As for the gate drive, I'm surprised that bootstrap works so well - I was expecting separate supplies for each high-side device, which is a major pain once you have lots of them (and the main reason why I'm still using a GDT, albeit with somewhat heroic efforts to reduce leakage inductance). Have you got a separate 12V supply to each half bridge, or is everything running off a single supply?

Originally, all gate drive power came from a single supply.  The problem with this is when you have high current on the negative bus rail, and some inductance/resistance due to some wire length, so that the negative rail of the PFC was different potential than the negative rail of the half-bridges.  The result can be loss in gate drive voltage depending on bus current, as well as some current passing through the wires supplying gate drive power to the modules.  For good margin, i decided to use independent 12V (really 16V i think) supplies for each of the 3 half-bridges and the PFC gate drive power and completely avoid this power loop issue.

Quote
Thank you for sharing such a complete design walk-through, when I first saw the videos back from your first tests, I was not sure if it was a new topology, so interesting to see its a SSTC driven much like a modern X-Ray transformer with a large dc block capacitor and variable frequency to determine the output voltage.

Yeah, its a pretty common scheme found in high voltage supplies because usually any transformer capable of generating high voltages will have a resonance near the practical range of operating frequencies, so you may as well use it to your advantage for power control.

Quote
So the ramp generated for the PFC is sinusoidal for it to work in quasi-resonant mode?

I should have explained that the PFC just charges up the large 400V 12mF (x2 in series) bus caps that the 3 phase RF inverter runs from.  The PFC just does the best it can to maintain a set DC voltage, but the power demand from the 3p inverter can greatly exceed the capability of the PFC, and so the DC bus voltage rapidly drops down, in fact, during the "QCW ramp".  Far from ideal, but it does "work".  This is part of the motivation to switch to battery power, and perhaps even keep the PFC's boost section only, since it can handle about 50A RMS, at 450V.  Or i can ditch the boost and the battery can supply >150A, but only at 400V or so.

Quote
Is there some advantage in controlling the switching frequency instead of the phase to control power?
Ehh, I'd have to think about what the difference is here, i think it comes down to stability. I wondered the same thing about controlling phase instead of freq. maybe it would be better to try a phase regulator, making it more like a classic 4046 PLL chip (phase comparator drives operational frequency).  However, the real machine produces primary currents that are far from simple sinusoids at times, so phase comparison can be corrupted.  In particular there is a strong 3rd harmonic present.

Quote
Due to the coupling between the coils does the power drawn by each inverter remain matched despite mismatches in spark loading? Does it matter which primary you monitor the phase from?

There's some "funny stuff" going on that tends to throw the 3 phase system out of balance (probably different spark loads).  Sometimes 2 coils will have 180* phase between primary currents, and the 3rd phase is somewhere inbetween.  You cannot count on them being 120* phase shifted, at all.  So my controller watches all 3 primary currents for zero crossing events, compared with all 3 switching commands.  This means, if one coil has a higher resonance frequency than the others, it will cause the inverter to switch faster, holding back performance.  I can generate much longer sparks with just 1 coil running instead of 3, i think due to this compromise. 

In fact, when i first built this thing my quality control was poor and my coils were not exactly tuned.  The resulting current waveforms were really something, especially because this early iteration had the 3 coils very closely coupled.  Since then, ive burned up the original coils, giving me opportunity to re-do with my new winding machine i got from ebay with a turn counter built in. Once i actually tried, the coils match rather nicely.

Despite this, there is still a "power struggle" between coils.  Over time there is a tendency for primary currents to oscillate between the 3 phases, in magnitude. 

RF envelope 1 and 2 show some examples of what can happen.  Definitely no guarantees of balance or phase relationship that i can see.

One experiment i have in mind is to tie all 3 primary returns together (in a "star" or "wye" or "Y"), rather than returning them to the DC bus as i have now (which keeps them more isolated).  This essentially gives a floating "neutral" point, which may serve to balance the power to the 3 coils?  It might actually make balancing worse, if the coil with the weakest spark has the highest Q and lowest imepdance.  I haven't made up my mind on how this could work out, yet :P.

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[Voltage Multipliers]
MRMILSTAR
September 21, 2021, 10:33:34 PM
post Re: Futurist's DRSSTC 0.5
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
September 21, 2021, 07:21:50 PM
post Re: Load resistance and discharge terminal for my 14-stage CW multiplier
[Voltage Multipliers]
klugesmith
September 21, 2021, 05:24:35 PM
post Re: BrOdin coil - High power Big sparks!
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
September 21, 2021, 04:18:47 PM
post Load resistance and discharge terminal for my 14-stage CW multiplier
[Voltage Multipliers]
MRMILSTAR
September 21, 2021, 06:30:44 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
davekni
September 21, 2021, 06:04:52 AM
post Re: BrOdin coil - High power Big sparks!
[Dual Resonant Solid State Tesla coils (DRSSTC)]
fh89
September 21, 2021, 03:56:28 AM
post Re: Idea for QCW DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
johnnyzoo
September 20, 2021, 09:24:10 PM
post Re: BrOdin coil - High power Big sparks!
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Uspring
September 20, 2021, 05:07:43 PM
post Re: Large Rectifier Tube
[General Chat]
Benbmw
September 20, 2021, 04:12:27 PM
post Re: Proper phase lead adjustment at the input
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Chrisader
September 20, 2021, 10:40:33 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 20, 2021, 10:39:59 AM
post Re: BrOdin coil - High power Big sparks!
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
September 20, 2021, 10:38:31 AM
post Re: Large Rectifier Tube
[General Chat]
klugesmith
September 20, 2021, 07:07:55 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 20, 2021, 06:03:57 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
davekni
September 20, 2021, 05:31:57 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 20, 2021, 04:59:17 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 20, 2021, 04:28:03 AM
post Re: Idea for QCW DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
September 20, 2021, 12:53:39 AM
post Re: Idea for QCW DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
johnnyzoo
September 19, 2021, 11:09:37 PM
post Re: Idea for QCW DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
AstRii
September 19, 2021, 09:47:14 PM
post Re: Idea for QCW DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
September 19, 2021, 08:28:05 PM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
davekni
September 19, 2021, 08:19:01 PM
post Idea for QCW DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
AstRii
September 19, 2021, 07:58:09 PM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 19, 2021, 03:16:40 PM
post Re: Driverless MOSFET SSTC
[Beginners]
AstRii
September 19, 2021, 01:32:47 PM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 19, 2021, 10:15:24 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
Magneticitist
September 19, 2021, 06:32:18 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
davekni
September 19, 2021, 06:06:44 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
September 19, 2021, 04:14:18 AM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
Magneticitist
September 18, 2021, 11:33:37 PM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AstRii
September 18, 2021, 10:42:45 PM

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