Author Topic: SGTC MK1 - An Accomplishment in Progress  (Read 4857 times)

Offline John123

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #60 on: December 13, 2019, 11:00:18 PM »
It's just when I built a marx generator the UV light from the initial spark gap was used to encourage the others to spark in sync, if direct line of sight was blocked then the rest wouldn't fire reliably.

But yeah how many volts are across those prototyping board capacitors? With the prototyping boards I've used you could take a low-high voltage source of say 5-10kV and even that was enough to jump the entire boards width of gaps. Looked like an LED light show project when pulsed.

Offline jturnerkc

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #61 on: December 13, 2019, 11:19:27 PM »
It's just when I built a marx generator the UV light from the initial spark gap was used to encourage the others to spark in sync, if direct line of sight was blocked then the rest wouldn't fire reliably.

But yeah how many volts are across those prototyping board capacitors? With the prototyping boards I've used you could take a low-high voltage source of say 5-10kV and even that was enough to jump the entire boards width of gaps. Looked like an LED light show project when pulsed.

It's definitely over 10kV as this flyback is rated at 24kV max. This one does seem more current hungry, so I can certainly imagine it capable of getting angry enough to flash over. That is part of my predicament as I don't currently have a way of measuring the exact HV ouput, voltage or current. It's so hard to find specs on these flybacks that I can't even compare the rated output to the previous flyback I was using when everything ran like butter...until it didn't.

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #62 on: December 13, 2019, 11:48:12 PM »
One other thought. I see that you are using 1200 volt capacitors. What is the voltage rating of your bleed resistors? Do these have a sufficient voltage rating? I don't know what your capacitors are being charged to and it sounds like you don't either.

With regard to MMC construction technique, perf board is acceptable but not with the plated-through holes.
« Last Edit: December 13, 2019, 11:57:32 PM by MRMILSTAR »
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Offline jturnerkc

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #63 on: December 14, 2019, 12:57:15 AM »
One other thought. I see that you are using 1200 volt capacitors. What is the voltage rating of your bleed resistors? Do these have a sufficient voltage rating? I don't know what your capacitors are being charged to and it sounds like you don't either.

With regard to MMC construction technique, perf board is acceptable but not with the plated-through holes.

I'm not sure I follow regarding the bleed resistors. They don't need to be rated for "1200V" do they? I'm not sure what you're getting at.
Aren't these bleed resistors in place to, for the most part, dissipate residual charge in the capacitor after the system is powered off? They do not need to withstand the 250-300W (max) that the primary LC might see while the SGTC is operating. If there was an issue with the resistors, I would have expected to see at least one of them fail, but that's not the case. Am I wrong?
I was planning on using 1W, 1M, resistors on the new MMC.

______

Just to add to my last "update" post, as well.:
This is a run on the same circuit with the same MMC, with a different flyback and no inductors.
Until now, I've never had any issue with the MMC and DC-input-wise, I'm using nearly half the voltage I was using previously.

Video:
https://drive.google.com/open?id=1BNOaCzaXydjddC9Pn8yb6Wtv-VFpBh03

And since I'm feeling nostalgic - a nice display at 120fps:
https://drive.google.com/open?id=1CkyjDH6enRkY398ecstW0iXVxJOWfRqc
« Last Edit: December 14, 2019, 07:31:20 PM by jturnerkc »

Offline davekni

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #64 on: December 14, 2019, 05:26:41 AM »
Your existing MMC appears to use 1/4 watt resistors.  Yes, resistors almost always have a voltage rating besides a power rating.  Those 1/4 watt resistors are probably rated for 100V.  They are definitely risky at 1200V.  I've fried a number myself.  The actual carbon film band is surprisingly-short in the center, so they will arc over eventually.  The likely-100V spec. is probably limited by resistance linearity.  An ideal resistor has constant V/I.  At higher voltages, the current may increase faster or more slowly than at low voltage, making the effective resistance change.  The spec. voltage is the range where resistance tolerance is guaranteed as well as where no arc-over will occur.

You can buy high-voltage-rated resistors, which I often use.  For low-accuracy needs, I'll run resistors above rated voltage, but within limits based on my experience.  1W resistors as in your new MMC are likely fine at 1.2kV.  I've used 1W parts to 1.5kV.  The 1/4 watt resistors would probably be OK at 600V (two in series per cap).  I tend to keep 1/4 watt parts under 400V for margin (three in series per cap).

The bleed resistors do discharge the MMC after use, but they also play another important roll.  They keep the 24kV total evenly shared among the 20 caps.

The arc on your existing MMC is clearly at the left center as you said.  Here's a frame from your video:


This shows up twice, where the flash straddles two frames.  For the other flashes that fill the entire frame, the frame after shows a tiny remnant of glow at the glue.  It's hard to see without comparing to the next normal frame, but here's a capture:


The arc location is where I expected it to be after viewing the MMC layout.  With a folded zigzag, there is 80% of the total voltage across that 15mm gap, with plated holes to help bridge the distance.  If you have room, it would be better to make a long bar of side-by-side caps, 30cm total for those 15mm wide parts, with one lead at each end.  If you must fold it, add a sheet of plastic between the two folded halves to separate them.  (BTW, if your MMC was a single 30cm long bar, the plated-through holes would likely not be an issue.  There would be at most 2.4kV between adjacent wires, or only 1.2kV if the wires made all the zags as I suggested for the inductor array.)

I particularly like your 120fps video!  The good results don't mean the MMC would have continue working.  Such flash-over failures tend to build over time.  Local corona discharge slowly damages (carbonizes) the insulation, slowly making the gap shorter until eventual failure.  The same reasoning likely applied to your first flyback, failing after a period of use.

Good luck with this weekend's tests!
David Knierim

Offline Mads Barnkob

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #65 on: December 16, 2019, 10:38:43 AM »
I particularly like your 120fps video!  The good results don't mean the MMC would have continue working.  Such flash-over failures tend to build over time.  Local corona discharge slowly damages (carbonizes) the insulation, slowly making the gap shorter until eventual failure.  The same reasoning likely applied to your first flyback, failing after a period of use.

I agree on Dave's notes on the MMC, folding two high voltage ends of opposite polarity to meet like that will cause trouble.

It is not only carbon tracks from corona that is a problem, it is rather extreme to start getting burned carbon tracks from just corona, usually that takes some sparks. From corona I would say that it is the ozone that is highly corrosive and it attacks and breaks down many types of plastic materials.
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

Offline jturnerkc

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #66 on: December 17, 2019, 04:52:34 AM »
Your existing MMC appears to use 1/4 watt resistors.  Yes, resistors almost always have a voltage rating besides a power rating.  Those 1/4 watt resistors are probably rated for 100V.  They are definitely risky at 1200V.  I've fried a number myself.  The actual carbon film band is surprisingly-short in the center, so they will arc over eventually.  The likely-100V spec. is probably limited by resistance linearity.  An ideal resistor has constant V/I.  At higher voltages, the current may increase faster or more slowly than at low voltage, making the effective resistance change.  The spec. voltage is the range where resistance tolerance is guaranteed as well as where no arc-over will occur.

You can buy high-voltage-rated resistors, which I often use.  For low-accuracy needs, I'll run resistors above rated voltage, but within limits based on my experience.  1W resistors as in your new MMC are likely fine at 1.2kV.  I've used 1W parts to 1.5kV.  The 1/4 watt resistors would probably be OK at 600V (two in series per cap).  I tend to keep 1/4 watt parts under 400V for margin (three in series per cap).

The bleed resistors do discharge the MMC after use, but they also play another important roll.  They keep the 24kV total evenly shared among the 20 caps.

The arc on your existing MMC is clearly at the left center as you said.

This shows up twice, where the flash straddles two frames.  For the other flashes that fill the entire frame, the frame after shows a tiny remnant of glow at the glue. 

The arc location is where I expected it to be after viewing the MMC layout.  With a folded zigzag, there is 80% of the total voltage across that 15mm gap, with plated holes to help bridge the distance.  If you have room, it would be better to make a long bar of side-by-side caps, 30cm total for those 15mm wide parts, with one lead at each end.  If you must fold it, add a sheet of plastic between the two folded halves to separate them.  (BTW, if your MMC was a single 30cm long bar, the plated-through holes would likely not be an issue.  There would be at most 2.4kV between adjacent wires, or only 1.2kV if the wires made all the zags as I suggested for the inductor array.)

I particularly like your 120fps video!  The good results don't mean the MMC would have continue working.  Such flash-over failures tend to build over time.  Local corona discharge slowly damages (carbonizes) the insulation, slowly making the gap shorter until eventual failure.  The same reasoning likely applied to your first flyback, failing after a period of use.

Good luck with this weekend's tests!

Great observation. You were absolutely right. After separating the two halves, I've been able to run without issue for long enough that I'm confident for the time being. I've gotten back to the point where I'm encouraged by the output! I've attached some videos with observational notes.

By the end of this tinker session, I was using 35V input. That's about as hard as I want to push my ZVS or my cheap SWPS. It may be time to step up to a proper transformer...
As far as readings go - I'm really having trouble nailing down ZVS output voltage while the system is on. For some reason, even measuring the DC input proves nearly impossible with my meter as well as the digital voltmeter/ammeter I wired in to monitor the SMPS. Readings are all over the place, fluctuating wildly, except for the frequency readings which tended to average ~37-40kHz (consistent with previous tests with this particular flyback).
Unfortunately I seem to have scrambled my cheap oscilloscope, so will have to wait until i get a hold of decent one or grab another cheap kit.
I have a good assortment of cheap analog meters laying around, so I think I'll wire those in to, at least, get an average measurement on volts/amps on the 'low-voltage' side.
Is there any relatively simple way to modify one of these analog meters to monitor voltage/current on the high voltage side while the system is running?
Note: I was also reading .07A on the ZVS input negative/ground.

After 1 minute of run time, Flyback secondary and core are hot but are not of concern, yet. The ZVS inductor is very hot, as were the FETs. I did not take temperature readings, but plan to next time.
If I continue to use this ZVS driver, I should probably add a fan. You can generally just smell hot-ass electronics.
Inductors remained cool.

Specs I have for the flyback are:
Rated Output Voltage: 24.2kV/30kV (2 sources vary)
Rated Output Current: unknown
Core Dimensions: 15.46mm*41.97mm*74.11mm
HV to Return pin resistance measures: 24.35M
HV to Pin 7 resistance measures: 24.62M
I'm also reading .05nF capcitance from HV to Return.
Schematic attached in earlier post

Currently, I have the inductors split into two 6H arrays - one on the HV output, and one on the return with the spark gap in parallel. I may try swapping the MMC and spark gap and compare.
I still have the occasional fluctuation in the spark gap, which can easily be seen in the 120fps video below and still seems rather random, but short-lived,.
With the current spark gap, I do not have any airflow. Now that I have taken care of some of these variables now, I can focus on the spark gap and will refine the new one I had constructed already. I still need to solder up the new MMC, but that's coming as well.

Finally, I'm getting closer to the results I was aiming for with this build. If anyone would like, I have accurate physical measurements and schematics needed to reproduce it, and I can post them with current schematics and known specs..
After a few more tweaks I may do a proper and entire walk-through of this build process up to this point, if anyone thinks it's worth it, including the final *nice* toroid, as I've taken pics and videos all along the way.

Smaller Topload @ 35V:
/>
Larger Topload @ 35V:
/>
Larger Topload @ 35V (120fps):
« Last Edit: December 17, 2019, 04:29:26 PM by jturnerkc »

Offline davekni

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #67 on: December 18, 2019, 06:09:34 AM »
Justin,

All my cheap meters are useless with sparks around, even corona sometimes.  Placing them in a Faraday cage helps a lot (aluminum foil lined box w/o top so meter can be viewed).  Tie the foil to the meter negative lead inside the box.  A low-pass filter on the positive lead helps further, something like 10K-100K in series with a >=0.1uF cap across the meter input.  (10K if the meter input impedance is only 1M, 100K if 10M, makes 1% error in the reading.)  I made the same sort of foil/cardboard cage for my cheap Chinese scope, with a few holes for cooling air.  Besides grounding the foil to the scope ground inside the box, I also made a common-mode choke for the AC power cord (several turns of the power cord around an E55 ferrite core).  Sometimes I'll wind scope probe leads around ferrite cores as well, even on my nice Tektronix scope - to protect the scope and reduce channel crosstalk.   Add common-mode ferrites to scope probes at work as well, even without sparks to filter out.  Helps when measuring one higher-voltage signal such as an H-Bridge output and one low-voltage logic or analog signal.  (BTW, wiring for your panel meter is rather close to a HV lead, making interference worse.  Having the LV side on a ground plane as suggested previously may help with meter behavior too.)

Analog meters are great for Tesla projects.  Most list the full-scale current in fine print on the face plate.  1mA is typical.  If you can find one with 0.1mA (100uA), that would be great for measuring your HV.  200uA could be usable.  Just add a string of HV resistors from the HV flyback output to the meter, with meter - lead returning to HV return pin.  Here the resistor voltage rating does matter, as you're after linearity.  Vishay's VR68 series are good for 10kV each.  (Of course, power rating needs to fit as well.)  For measuring Tesla HV with an analog meter, dial down the ZVS input voltage until getting only 1 spark  per second.  Then you'll have some chance of seeing the firing voltage before it discharges.

You could make a small signal-diode bridge rectifier to monitor the 90Vpp-rated flyback tap with an analog meter.

I'm not clear on where you measured 70mA.  That's way to low for much on the ZVS circuit or flyback input.  It's high (but could be accurate) for the flyback secondary return pin.  If it is there, that's likely well more current than the flyback's rated for.

If you can find a PFC inductor from a good sized DC supply (PC supply or whatever), those make great ZVS inductors.

What's the diameter of the flyback ferrite core going through the potted coil?  Or, the cross-sectional area of the rectangular remaining ferrite?  That's more useful for calculating saturation than the larger dimensions.

Resistance measurements on flyback HV and focus pins is generally meaningless.  Meters don't output enough voltage for the forward drop of the HV diodes.

With two separate 6H inductor strings, is the HV return ground (to counterpoise) still at the flyback HV return pin, not after inductors?  I'd still recommend a path somewhere from HV return to the ZVS negative lead.

From the 120fps video, I think the firing variation is from remaining ionization in the spark gap, with random subtle air current changes.  A fan should get you to all louder lower-frequency sparks.  If you prefer smaller high-repetition-rate sparks, then reduce the spark gap separation, but leave air flow on for stability.

I'm presuming you re-tuned when changing toroids.  Looks like about half-way out on your primary coil in the first video.

The relatively long and separated wires running to your Tesla primary are adding inductance, which lowers coupling factor.  Not sure how beneficial higher-coupling is for this design, but I'd consider eventually shortening wires and perhaps routing them closer together with appropriate insulation in the gap.  (In my DRSSTC, even the MMC array halves are adjacent to lower inductance, but with a 10mm thick PP sheet between for insulation.)

Great to see progress!
David Knierim

Offline jturnerkc

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #68 on: December 19, 2019, 03:38:42 AM »
Instead of winding around a ferrite core for a common-mode choke, I had considered throwing on some clip-on ferrite beads for the hell of it. Would those even be worth bothering with?

As far as having the LV side on a ground plane, as suggested previously, I do have the ZVS attached to mains ground, while the flyback is still grounded to the counterpoise from the return pin along with pin 7. The inductor string is placed between that point and the spark gap.


I have a small ground bar where the HV return and TC secondary ground meet and lead to the counterpoise. Connecting the HV return to the ZVS negative would no longer keep the primary and secondary tank circuits electrically isolated from mains ground, as the ZVS negative is already grounded to mains. I had considered attaching a line from the counterpoise to a nearby pipe (granted they are likely connected to mains ground as well, but I can only assume that's better grounding directly back through the outlet) or may just suck it up and drive in a physical ground rod outside the garage…Tying all 3 to a single ground point, especially mains ground, seems to go against nearly everything I've read about Tesla Coil grounding.
I'm not sure I completely follow the reasoning, however I know the proper grounding techniques for TCs has been hotly debated, and I've certainly found evidence of at least some users tying the counterpoise to mains ground. I could give it a try. I wouldn't know where to begin trying to determine if it is for better or worse, though, unless something noticeably changes operationally that I'm able to perceive or measure with my limited equipment.

Regarding analog meters and monitoring, thank you for reminding me you had mentioned measuring the 90Vpp before. I’m not sure why that didn’t come to mind as an option. I suppose only partially because I’d like to know what the actual output voltage is of the flyback in operation. It would be worth monitoring the 90Vpp though, so at least I can have an idea of max input voltage. I have a bunch of AC analogs so may not even need to use a rectifier. I’ll have to dig and see what voltage ranges I have. I have an aluminum enclosure I can install these in as well. I had considered housing the all the LV circuitry inside, but it’s just barely too small to fit the supply and zvs both. I’ve got an eye out for a larger one.
If I were to use a bridge rectifier, what signal-diode would you suggest? Is the standard 1N4148 beefy enough to rectify 90Vpp or is there another more appropriate choice? I'll have to see what I have around. I do have a bit of an assortment that might have what I need.

Quote
What's the diameter of the flyback ferrite core going through the potted coil? Or, the cross-sectional area of the rectangular remaining ferrite? That's more useful for calculating saturation than the larger dimensions.
I'll have to get back to you on the core cross-sectional area.

You're correct about the HV and focus pin measurements - I could not get a voltage drop reading.

I would also agree with your observation of the spark gap BPS. The variations seemed different in nature to the previous issues I was having with the "new" spark gap. I'll add some airflow during my next round of tinker-time.

To answer your question about the two toroids and tuning, 'yes', I did have to re-tune when switching toroids. I moved the primary tap out about 1 1/4 turns due to the frequency change induced by the larger topload.
I’d like to try the oscilloscope method of tuning since I’m pretty much just doing "fine tuning" manually right now. Unfortunately my function generator decided to stop working since the last time I used it. Strange. I have to replace my scope anyways. Probably just get another cheap handheld since it will probably be scrambled at some point like its predecessor.

You had mentioned the length of wiring and you're right, however the wiring is really just temporary at this point and I’ve changed the orientation of some things. The longer wires were just giving me room to move things around a bit. Once I have something more finalized it will all be wired more appropriately and properly housed, etc. I’d also like to place all the LV circuitry, along with the supply in an aluminum enclosure with controls and whatnot that could be operated further away from the rest of the unit. The way you saw the MMC in that video and the other components was before I reconfigured the layout. I now have the MMC in line, essentially just fully unfolded.

I've made extremely slow progress, the last week, getting the new MMC put together and soldered. I'm actually waiting on some additional caps now, as well. I've attached an image. Every lead is separated by 1 inch and each cap is connected with a piece of 3/32" welding rod. I intend to complete wiring in the same fashion/configuration as the inductor array(s).


Considering exchanging the ZVS inductor - I do have that 0-48V SWPS I haven’t fixed yet… I could just cannibalize it. I had my eye on those big electrolytics too, for something else...maybe even a full-bridge DRSSTC later? Hmm...
I’d like to increase the operating range of my ZVS, as well, so the inductor and FETs aren’t getting so hot at 35V input. I just want everything as cool as possible. I’ve removed the ground from the caps and wired them in parallel as is more common. I had considered adding 2 more caps – 2 series strings in parallel – and adding an additional inductor in parallel with the existing to the center tap. I'm just not sure how much more the FETs can take though. I’ll need to wind my own inductors or get a hold of two matching if I go the dual inductor route.
I've also been tossing around the idea of just removing the center tap from the equation completely and just having inductors connected to both ends of the primary. It would hardly take any modification, but I've yet to investigate how the output would be affected in this actual application. More ideas to bounce around.
I'd be curious to hear your thoughts on driver usage and possible changes you might consider, yourself.
Thanks, as always!
« Last Edit: December 20, 2019, 01:16:50 AM by jturnerkc »

Offline davekni

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #69 on: December 19, 2019, 06:35:28 AM »
Yes, the clamp-on ferrite beads will help with the highest frequencies, which are often most problematic.  If the center hole is large enough and the wire long enough, wrap the wire through the bead twice or three times or whatever you can fit.  Inductance (impedance at any given frequency) goes as turns squared.  Three passes through a bead is nine times better!  There are almost no cases where common-mode inductors/beads cause trouble, and many cases where they help.

When you eventually get an aluminum box for the LV electronics, that will be even better than a ground plane.  Ferrite beads are useful where cables enter and leave the box, such as on the line cord.

Grounding of the HV return pin counterpoise would be better with a separate connection down to the counterpoise, away from where the Tesla secondary wires.  That way there isn't common wiring inductance to induce voltage spikes during arcs from the top-load.  The value of HV return grounding is to avoid enough voltage difference to arc over inside the flyback, as it's not expecting significant voltage between HV return and the primary windings.  (Perhaps I'm worrying about that too much.  If you are not connecting to any of the flyback primary windings, then your custom 10-turn primary provides additional insulation.)

If you do decide for a full HV return ground, that could be done by another wire from the line ground (or water pipe) to the counterpoise.  That keeps a bit of wiring inductance between the HV return and ZVS negative.  That bit of high-frequency isolation could be valuable especially before getting a box or ground plane for the LV electronics.

Your counterpoise on concrete is sufficient that you shouldn't experience any performance difference with grounding it.  Any difference is possibly with flyback lifetime or with interference disrupting LV circuitry.  If your copper piping includes an underground run from the water meter, that should be a great ground (unless your house is on very dry ground).  It should be tied to line ground near your breaker panel.  (BTW, if the flyback is generating 70mA, that's probably much higher risk to its survival.  An analog meter in series with the HV return pin, with a cap across the meter, would be a great addition.)

Using AC meters at 50kHz may or may not give reasonable readings.  I've never tried them above 60Hz.  AC meters also don't cover the low end of their range well.  The internal magnetic force is proportional to the square of current/voltage.  Spring and/or magnetic shaping attempts to make the response closer to linear, but that's quite limited at the low end of the range.  In general, I'd use rectifiers and DC meters for AC.  1N4148 should be fine for a 90Vpp bridge.  The peak voltage maximum is 45V, enough below1N4148's 75V rating.  For feeding a DC meter, you could include a small ~0.1uF cap across the bridge to measure peak voltage, or leave the cap off to get average voltage (2/PI times the peak for a sine wave).  Either way, add ~1.2V to the meter reading for diode drop (two diodes).  Yes, without a flyback spec for output voltage, 90Vpp (45Vpeak) just insures you aren't running the flyback over-voltage.  It doesn't directly measure output unless you can come up with a calibration scheme.

The hot ZVS inductor may be due to insufficient current capability or insufficient voltage capability.  So, parallel or series may be what helps.  (By voltage-capability, I mean volt-seconds before saturation, and losses at a given flux density and frequency.)  It's hard to figure out without a scope, so hopefully you have luck finding a new one or figuring out what's wrong with the old one.  The inductor core material makes a huge difference in heating as well.

Do you know the ZVS FET part number?  Do you have the ZVS circuit to share (or did you already)?

Don't remove the center tap!  The inductor requirements are much tougher when feeding the ends.  The signal on the center tap has twice the oscillation frequency, with the shape of a full-wave-rectified sine wave.  Peak voltage is half that of the end points.  The only reason to feed the ends is when a center-tap isn't feasible, as is often the case with induction heater coils.  Even then, it's slightly better (slightly reduced total magnetics size) to generate an artificial center tap with a separate ferrite transformer.  (Common-mode power line filter chokes work well for this artificial center-tap generation.)  All my ZVS circuits are this way - artificial or real center tap.

At the end you say: "I'd be curious to hear your thoughts on driver usage and possible changes you might consider, yourself."  I'm not certain what part(s) you are calling the "driver".  In general, ZVS can be a good fit for supplies that need to ramp from 0V to some maximum voltage on their output (as in charging your MMC).  That's very similar to my Jacob's ladder ZVS, as the output is initially at high voltage, then jumps to almost zero when the arc strikes, then rises again as the arc rises.  The key is coupling factor of the output transformer (flyback in your case).  Coupling needs to be below 86%, but not way below for reasonable efficiency.  The hand-wound flyback primary is about perfect - 81% in the quickie version I made just for this thread.  My Jacob's ladder ZVS output transformer has K = 83%.  K of 86% or higher causes the ZVS to drop out in the middle output voltage range.  Too much damping (low Q) to continue.

I'm anxious to see any flyback HV return pin current measurements, or HV output voltage and spark repetition frequency, which would allow calculating average current.  Your 70mA number, if HV return is what it referred too, is a bit scary for frying the flyback.  If that is the case, two or three flybacks in parallel is probably the best option, since you won't want to reduce current and suffer the resulting reduced spark rate.
David Knierim

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Re: SGTC MK1 - An Accomplishment in Progress
« Reply #69 on: December 19, 2019, 06:35:28 AM »

 


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post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
Today at 11:40:55 AM
post Re: Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
John123
Today at 11:32:19 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
Today at 03:48:55 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
April 01, 2020, 09:47:42 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 01, 2020, 09:31:49 PM
post Re: Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
davekni
April 01, 2020, 08:47:11 PM
post Re: Fishing for atmospheric electricity
[Static Electricity]
johnf
April 01, 2020, 08:45:14 PM
post Re: Homemade HV transformer
[Transformer (Ferrite Core)]
johnf
April 01, 2020, 08:37:29 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
April 01, 2020, 08:24:06 PM
post Re: Pt100 oddities
[Electronic Circuits]
davekni
April 01, 2020, 08:16:59 PM
post Re: Pt100 oddities
[Electronic Circuits]
johnf
April 01, 2020, 07:50:16 PM
post Re: Fishing for atmospheric electricity
[Static Electricity]
haversin
April 01, 2020, 07:42:47 PM
post Re: Homemade HV transformer
[Transformer (Ferrite Core)]
John123
April 01, 2020, 07:39:48 PM
post Re: Fishing for atmospheric electricity
[Static Electricity]
John123
April 01, 2020, 06:07:44 PM
post Photographing/filming high voltage arcs
[DSLR]
John123
April 01, 2020, 05:17:04 PM
post Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
John123
April 01, 2020, 02:01:30 PM
post Re: Pt100 oddities
[Electronic Circuits]
kamelryttarn
April 01, 2020, 01:38:47 PM
post Re: Pt100 oddities
[Electronic Circuits]
T3sl4co1l
April 01, 2020, 12:49:21 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 01, 2020, 10:29:06 AM
post Pt100 oddities
[Electronic Circuits]
kamelryttarn
April 01, 2020, 09:48:37 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
Weston
April 01, 2020, 07:01:51 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
April 01, 2020, 04:15:41 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 01, 2020, 04:05:20 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
April 01, 2020, 01:51:05 AM
post Re: A few (stupidly basic) questions
[Beginners]
davekni
April 01, 2020, 01:32:54 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
March 31, 2020, 11:03:36 PM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
Weston
March 31, 2020, 10:13:13 PM
post Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
March 31, 2020, 09:15:23 PM
post Re: Homemade HV transformer
[Transformer (Ferrite Core)]
AlexanderHun
March 31, 2020, 12:05:40 PM
post Re: A few (stupidly basic) questions
[Beginners]
Mads Barnkob
March 31, 2020, 08:54:35 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 31, 2020, 04:58:16 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
March 31, 2020, 04:44:05 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
March 31, 2020, 01:33:16 AM
post Fishing for atmospheric electricity
[Static Electricity]
haversin
March 31, 2020, 12:48:56 AM
post Re: Corona lockdown thread, tell about your situation
[General Chat]
Mads Barnkob
March 30, 2020, 08:08:54 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
March 30, 2020, 07:20:08 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 30, 2020, 06:46:02 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
March 30, 2020, 06:35:13 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 30, 2020, 05:00:11 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
March 30, 2020, 04:30:55 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
SteveN87
March 30, 2020, 01:16:47 PM
post Re: Conical pulse skip DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Acid Byte
March 30, 2020, 07:23:21 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
March 30, 2020, 06:13:52 AM
post Re: A few (stupidly basic) questions
[Beginners]
MRMILSTAR
March 30, 2020, 05:31:27 AM
post Re: synchronous motors up for bid
[General Chat]
klugesmith
March 30, 2020, 02:55:41 AM
post Re: A few (stupidly basic) questions
[Beginners]
davekni
March 30, 2020, 02:23:23 AM
post Re: Skm100 coil
[Dual Resonant Solid State Tesla coils (DRSSTC)]
oneKone
March 30, 2020, 02:22:33 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 30, 2020, 02:10:26 AM

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