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Messages - davekni

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1
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I have to ask what diodes could i put into the voltage doubler tho because i could not find any info about it anywere really for the 230V (maybe my googleing skills are giveing up on me agin.. idk...) i had some ideas but they seemed stoopid so i prefeared to not put anything and kindly ask directly instead of posting something totally wrong that somebody could have followed and done wrong too.
230V RMS has a peak voltage of 230 * sqrt(2) = 325V.  Doubler will produce 2 * 325V = 650V (at no load).  Diodes need to be rated above 650V, so 800V or 1000V.  Generally easiest and cheapest to buy full-wave rectifiers (four-diode bridges) and parallel the diodes for higher current capability (wire two "AC" terminals together).

Another option is to use thyristors instead of diodes.  Thyristors become part of inrush current limiting by phase control (like a light dimmer turning on instead of a Variac).  Some people here on the forum have implemented such inrush current limiting circuits, but not me.  I don't know of any specific circuits or designs available to copy.

2
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in my opinion che black one sould be henaf but i might be wrongy.
Probably fine.  Measure temperature eventually when running at high power.

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So, i spent a lot of time into the schematics too! And i finally came up with something that seems decent.
Could you please check everything and tell me if i did all righty and if not what and why? Would be amazing!
This voltage doubler would be a perfect simple circuit to use for learning analog simulation.  If you really want, I'll give you a direct answer.  However, you will learn much more if you learn by simulation.  Or, try a small low-voltage version.  Use small signal diodes and a white plastic breadboard or other temporary interconnection method and a low-voltage AC source (small transformer such as for doorbell...).  Measure voltage and waveforms with your scope.  Learning will take time now, but the understanding will help you understand more subtle details debugging the finished DRSSTC build.

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I have to ask what diodes could i put into the voltage doubler tho because i could not find any info about it anywere really for the 230V (maybe my googleing skills are giveing up on me agin.. idk...) i had some ideas but they seemed stoopid so i prefeared to not put anything and kindly ask directly instead of posting something totally wrong that somebody could have followed and done wrong too.
Simulation and/or breadboarding will allow you to measure voltage across diodes, so know what voltage rating is necessary.  Same for current, though that is easier in simulation than with breadboarding.

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I did everything as it seemed right to me but i'm totally not an electronic engeneer or something. So i could have messed up everything or i could have putted some non oky components on it.
An ECB is great for gate drive components.  As with GDT wiring, placement of parts and shape of copper interconnect is important to minimize inductance.  Same general rule:  Keep the emitter return copper close to the gate drive parts and copper, such as emitter copper on the bottom side of ECB and gate parts and copper on the top side.  That minimizes loop area, so minimizes inductance.

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Is if i have to use mika insulator for the IGBT plate and heatsink before applaying the therml paste even if its Half Bridge or not.
IGBT bricks include internal insulators.  Do not add mica.  (If you ever work with TO247 parts and need insulation, there are much better materials now.  Mica was common 50 years ago.  Thermal conductivity is low, however, so not a good choice.)  Do use thermal paste.

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This question is maybe stoopid but i did not consider this before... i have a single phase 230V at home with around 3kW, so would my coil be able to stay into that range of power or will my house shut down because of contract limitations?
I presume 230V 3kW is for one outlet, not the rating of electrical service to your entire house.  If so, then you should be fine.  If you draw too much power, the circuit breaker for that one circuit will trip.

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And lastly, i tryed to look up for some soft start electronics to put into the coil to avoid useing my variac (i would like the coil to be as plug & play as possible...) but that thing was really hard for me to understand, like i got the components but i totally didnt get where to hook it up. So if you could put me on the right path... agin... it would be so amazing!
Soft start is generally necessary.  Variac is the most common soft-start method for DRSSTC.  Commercial supplies typically use a resistor (usually NTC thermistor) in series with the line, shorted by relay contacts after bulk capacitors charge.  I'd suggest getting your coil working with a Variac first before tackling a soft-start circuit.

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And i also had problems finding materials for my primary coil since reading from Mads amazing guide the primary can really heat up AF. So i would like you to suggest me a cheap but good material so that i can start doing my primary coil this week or next week too!
I used polycarbonate.  However, my primary coil is a bit warped now after running at 10kW this summer.

3
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The winding method with a network cable that is described, is how I did in on my first DRSSTC: https://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-i/
This is a great finished GDT image.  Very neatly constructed.

I made a little step-by-step tutorial of how to wind such GDTs, using a half-bridge version for simplicity:
https://highvoltageforum.net/index.php?topic=1854.msg13949#msg13949

4
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If thats it and i understood it currectly i will do it then you could judge it maybe!
Yes, I think you understand correctly.  Electrons don't pay attention to wire color, so just mark appropriately.  (May be a bit harder to verify correctness from pictures, however.)  If you look at any of my projects posted here, you will see that I'm entirely into the science, with almost no attention paid to aesthetics :).

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FeedBack & OCD CT as suggested i did 23 turns per each core then i set two on top of each other and i passed one single wire of the front single one inside them and then i soldered and with an heat shrinking thingy i got it insulated, if you tell me is oky, i will proceed to hot glue or with some zipties to lock the cores in place thogether:
Looks good!

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I saw on the amazing Mads DRSSTC guide that i sould keep everything metallic far from the primary (for heating problems), but i have planned and already bought the pices for the coil box frame in aluminum. and i planned to ground it all so that i could have a "faraday cage" already protecting the components without the need of strange wires or stuff going all around the box. i planned to leave it all open or to cover the sides with dark plexiglass (or normal transparent plexiglass with a black film behind to make it dark).
Not sure I have a picture of the frame, but aluminum close to the primary is likely to be a problem.


5
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About the Interrupter Switch, I attached some images, indicating where it is.
During the initial tests I turn the two potentiometers position. But now I'm going to leave the duty cycle at very low (2M).
Thank you for the schematic.  When the switch is open, the driver is continuously enabled.  UCC27425 enable inputs have internal pull-up resisters.  Open is enabled.  If you want a switch to disable the coil, short enable to ground after the 5k series resistor.  If you leave the existing switch in place, make sure it is always closed during testing.  Yes, low duty cycle (2M) is good.  Of course, you won't get long sparks at low duty cycle.  It is still better for experimenting with primary coil polarity and antenna placement without frying transistors.  Then carefully increase power.

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I'm going to add the light bulb. What is the capacitor specification?
To first order, whatever you have around that can handle 170Vdc and be mounted at the ECB.  (Not a small electrolytic, however, as that will have problems with RMS current being too high.)  I was thinking of a 1uF to 10uF film capacitor.  Or, a larger electrolytic.  The large electrolytic will support higher performance during testing with the light bulb, supplying peak current during the infrequent enable pulses.  However, that also increases risk of frying FETs/IGBTs.  So, at least initially, a film capacitor is lower risk to your FETs/IGBTs.

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About the changes in the antenna circuit, I drew a picture of what I understood. Is it correct?
Yes, exactly.  The two resistors need to be the same value.  (Actually, the upper resistor to +5V could be ~20% higher value than the resistor to ground, since HC14 input thresholds are typically a bit below half supply voltage.)

Edit:  I forgot to mention an alternative to these two resistors.  You can instead add a single resistor, ~1Mohm, between 74HC14 pins 1 and 2.  This is actually better than the two separate resistors.  It will make the 74HC14 oscillate at a low frequency even without antenna feedback, which will kick-start the feedback.  You can experiment with lower resistor values to make the kick-start frequency close to coil operating frequency for even more certain startup.  BTW, likely easiest to add the resistor to ECB back-side, from 74HC14 pins 2/3 to one lead of the 1k resistor.

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Other information: When I turn on the system only with the low voltage circuit, I hear a noise like a vibration, but when I turn the potentiometers, nothing changes.
Perhaps makes sense if that is with your existing enable switch open, so driver continuously enabled.  Might be line-frequency hum being picked up by the antenna.  If it still occurs with the 555 connected to enable and the 2M resistor set to 2M, then I'd be a bit concerned.

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I also attached some images of the board without the components and the GDT.
Based on a quick review, layout looks reasonable.

Good luck!

6
Two GDTs is necessary for running pulse-skip mode with drivers such as UD2.9.  If not running pulse-skip mode, there is generally no reason to use two GDTs.  Only slight advantage of two GDTs would be lower leakage inductance IF the single-GDT alternative used only a single primary winding wire.  If the single GDT is wound with four twisted pairs, with one wire of each pair paralleled to form the primary, that is ideal for low leakage inductance.

7
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I guess i will buy both if i can get a nice deal out of it but mainly i will start useing directly the silver one, so that at least i dont waste time haha.
If you haven't purchased the black one yet, don't.  Buy only the silver one.

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Also i will try to do the GDT like you suggested, but i need to understant that message a bit better before (i saw that quickly i admit, but i didnt get it at least at first reading) so if you would be a bit more clear on how to wind it and how to make the connections would be amazing! I really want this coil to be as much perfect as possible!
Since I've tried to describe this winding several times before, with limited success, I finally made a little tutorial post showing how:
https://highvoltageforum.net/index.php?topic=1854.msg13949#msg13949
This design isn't uniquely mine.  It shows up in many builds here, usually in the full-bridge version.  I haven't been able to find any specific instructions, so made the above-linked post.

You are welcome for the help.  It is a good challenge for me to figure out how to explain things without presuming specific prior knowledge.

Thank you to Mads for the compliment.

8
Spark Gap Tesla Coils (SGTC) / Re: 60hz synchronous motor on 50hz?
« on: November 29, 2021, 12:07:30 AM »
Yes, phase-locked control is possible.  I built two motor drives for my SRSGTC.  First used a standard synchronous motor.  The second used a DC motor with a home-built speed controller locked to line frequency.  That allows simple remote phase adjustment with a potentiometer.  For both motors/drives, I found it necessary to use a separate outlet for the motor, not shared with the outlets used for SRSGTC power.  (Coil power came from two 120V outlets to get more power, one MOT per outlet, series connected secondaries.)  If the motor ran on one of the power outlets, voltage drop induced by the main coil power changed motor phase, which changed power drawn, etc.  Caused unstable feedback.

9
Transformer (Ferrite Core) / Re: SG3525 push pull snubber calculation
« on: November 28, 2021, 11:58:24 PM »
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Trying to google FET gate resistor calculations, found that most people trying different values to find right one.
Found some formulas, but it's useless - no needed values in datasheet.
So It's worth to replace 10R with 4.7R, turn on time will be little faster, less switch losses ?
For your particular case, gate waveforms look fine, so I'd leave it as is.  Your switching losses are dominated by power transformer leakage inductance and the resulting avalanche breakdown clamping of turn-off voltage spikes.  Switching speed related losses will be comparatively insignificant.

In general, optimal gate resistance depends on many tradeoffs, so is difficult to calculate in advance.  For GDT-driven gates, damping the ring (overshoot and undershoot) caused by GDT leakage inductance is usually the key consideration.  A good low-leakage-inductance GDT and wiring allows lower gate resistance and therefore faster switching.  Even without a GDT, long gate wires can have enough inductance to need damping with gate resistance.

The second common consideration is intentional slowing of switching times.  For bridge designs, parasitic inductance causes voltage spikes that otherwise are theoretically clamped by the opposing FET/IGBT's internal diode.  Slowing switch-off speed reduces such voltage spikes.  Slowing switch-on speed reduces diode reverse-recovery current spikes when switching after zero-current.

Third, in typical hobby bridge designs, dead-time (cross-conduction prevention) time is provided by gate resistors paralleled with diodes to speed-up turn-off relative to turn-on.  Here the value is determined by the needed dead-time (how slow the IGBT's turn-off is relative to turn-on).

10
Beginners / GDT (Gate Drive Transformer) tutorial
« on: November 28, 2021, 11:40:56 PM »
Hopefully this isn't wasted redundant work.  I've seen many builds with good GDT construction, using both halves of each twisted pair.  However, all the GDT construction guides I've found use a single primary wire.  Below is construction of a half-bridge GDT using two twisted pairs from CAT5 cable.  This is easier to see in pictures.  Extension to full-bridge isn't difficult.  Use four pairs, with four paralleled windings for primary, one wire from each pair.  (BTW, CAT5 isn't necessary.  If starting with single wires, twist pairs together, and use those pairs exactly as you would with pairs extracted from CAT5 cable.)

Start with a suitable high-permeability ferrite core.  (Some options listed at the end.)  The core I'm using here works, although the shape is not typical.  Pay attention to winding technique, not so much to core shape.

Wind two (for half-bridge) twisted pairs around the core.  More discussion about the number of turns to follow.  I'm using 4 turns here.  Mark the starting end of all four wires for later identification.  Here I've "marked" starting ends by length (short), with the tail ends left longer.  Other (preferred) options are to add bits of tape to the starting ends or strip insulation from the starting ends only.





Untwist the pairs almost to the core:



Twist each wire (each winding) with itself all the way back to where the pair twisting starts.  Don't leave any significant loop area of untwisted wire:



Pair one winding of each pair together for the primary.  I've chosen the lighter-color wire of each pair for simplicity, white and light-blue.  Most important: connect the two starting ends (short ends or stripped ends or however you marked them) together, then the two tail ends together.  If pairing is swapped, driver can be damaged by the shorted load.  (Test at very-low duty cycle initially just in case of error.)  The remaining winding of each pair is for an IGBT.  Starting end of one IGBT winding is gate.  Starting end of other IGBT winding is emitter of other IGBT.



Since I hadn't used tape to identify starting ends at the beginning, I added tape now.  Then cut the tail ends to length and strip.  Connect the two primary tail ends together:



The reason for the twisting is to minimize leakage inductance.  Leakage inductance slows down gate waveforms and causes overshoot and undershoot and generally-sloppy gate drive.  Twisting forces the wires to remain close together with little loop area between wires for magnetic field to slip through.  Best to maintain this pairing all the way to the driver for primary and all the way to gate and emitter terminals of IGBTs (or FETs) for the secondaries.  Avoid excess loop area when adding gate series resistors.  Keep the emitter wire adjacent the resistor to minimize loop area.

Now for a bit about cores and turns.  I'll add a second post on measuring cores and finished GDTs, a bit more advanced topic.
Toroid shape is generally preferred, but E-cores work if ungapped (no air gap or spacer between the two halves).
Most important two parameters are:
     Core material (reasonably-high permeability and saturation flux density).
     Core cross-sectional area.  Picture the area of a core slice inside one turn of the GDT winding.
Iron and other compressed-powder cores never work well.  Most (but not all) ferrite materials are OK.
Low-frequency EMI suppression cores are reasonable.  That is what I used above.  Most larger EMI cores are low-frequency, so workable.  This includes common-mode chokes found in power supplies.  (Remove existing windings.)  Such EMI materials include:
3C11, 3E6, 3E12, 3E10, 3E15, 3E25, 3E26, 3E27, 3E65
More ideal ferrite materials are generally designed for switching power supply transformers etc.  These include:
PC40, PC200
N27, N30, N35, N41, N49, N51, N72, N87, N88, N92, N95, N96, N97
T35, T37, T37, T38, T46, T57, T65, T66
3C90 through 3C97

Concerning cross-sectional area, more is better, within constraints of fitting the GDT mechanically into the build.  The core I used above is 28mm long, 14mm ID, 28mm OD.  The ring is 7mm thick (0.5 * (OD - ID)).  So cross-sectional area is 7mm thick * 28mm long = 196mm^2.  If using a more-typical ring toroid, the formula includes a factor of PI/4:  Area = length * 0.5 * (OD - ID) * PI / 4.

In general, look for cross-sectional area to be at 50mm^2 or more.  A bit smaller is fine for high-frequency Tesla coils.  Larger for low-frequency coils.  10 turns is usually plenty.  Excess turns increases wire length and therefore leakage inductance.  The above example is 4 turns.

(All my GDTs have either 2 turns or 3 turns.  That works with large area cores and careful measurement to make sure its enough.  A few more turns is generally safer.  Too many turns causes subtle issues due to leakage inductance.  Too few turns is more catastrophic, possibly damaging the driver and/or IGBTs when the core saturates.)

Here's a great picture from Mads of a full H-Bridge GDT constructed this way:
https://highvoltageforum.net/index.php?topic=1856.msg13969#msg13969

A couple other posts with images that aren't quite as obvious.  For this first, look at the upper GDT wound with CAT5 cable including jacket:
https://highvoltageforum.net/index.php?topic=588.msg3779#msg3779
And this 3-turn GDT from my bridge tutorial:
https://highvoltageforum.net/index.php?topic=1324.msg9886#msg9886

11
Yes, that one should be much better for forced-air (fan) cooling.  As I said, you could try your existing one initially.  Or get this one to avoid any need to rebuild later.

12
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i came out with this windings for the OCD and FeedBack CT, 23x23x23 on the tree cores and i will pass one white around two of them from the other one
Yes, I think you understand correctly.  A picture after construction will verify.  Yes, that is for 529:1 final ratio, which should be good for 5.1 ohm OCD burden resistor and for the 51 ohm feedback burden resistor.  (Higher voltage is expected on the feedback input.)

Both GDT pictures look great.  There's no need to keep the wires all together once they leave the core.  Twist the two primary wires together to head one direction (to UD2.7).  Twist each secondary winding lead with itself to head to the two gate-emitter terminals.

BTW, GDT leakage inductance can be even a bit lower if wound with two twisted pairs (four wires total).  One half of each pair is secondary, one for each IGBT gate-emitter connection.  The other half of each pair are wired in parallel to UD2.7 output.  (This is just me being a perfectionist.  Your 3-wire construction will work fine for this relatively-low-frequency coil.)

That heatsink may suffice, but it is not great.  It was designed for passive air cooling (natural convection).  Heatsinks designed for forced-air cooling (fans) have many more fins tightly packed together, often with a thicker base.  Since you have it already, I'd start with that heatsink.  Should work fine for low-duty-cycle testing.  As you increase interrupter duty cycle (increase total power consumption), measure temperature.  If excess temperature limits the power you want to run, then buy a better heatsink.

13
Solid State Tesla Coils (SSTC) / Re: Driverless SSTC
« on: November 28, 2021, 12:32:09 AM »
Slayer oscillators like this are simple, but also finicky.

As with most electronic circuits, wire length causes problems.  Wires have inductance.  Tight layout and construction is required.  Especially the 1.5ke12 diode needs to be soldered directly to the FET.  1.5ke400 should also be fairly close.

There are plenty of counterfeit IRFP460 parts available.  I have no experience with "Bojack".  Their FETs may or may not have the robustness of normal industry vendors such as Vishay/Siliconix.

If you have access to a variac or other way to reduce voltage, I'd start below 120V.

14
I'd keep your later secondary for lower frequency.  Wind a new smaller-diameter primary to get coupling high as Mads suggested.  Do double-check circuit implementation too as per Mads.

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From there I try to turn the interrupter switch on and off but nothing different has occurred.
The circuit you posted doesn't show an "interrupter switch".  If you are setting UCC27425 enable continuously high with a switch, failure is likely.  This circuit is designed to run at limited duty cycle controlled by the 555 timer chip.  Test at very low duty cycle (0-2M variable resistor set to 2M) until everything is working correctly.

For further protection during initial testing, I'd run at lower voltage or current.  If no variac is available, add a power resistor (incandescent light bulb) in series with the +IN power terminal.

An additional capacitor between +IN and -IN at the ECB may help with any voltage transients there, caused by long wiring inductance back to bulk capacitors.

I've seen this circuit variation several times, but it isn't quite as good as Steve's original versions.  See these links:
https://www.instructables.com/Building-a-solid-state-tesla-coil/
or with additional startup aid:
https://www.stevehv.4hv.org/SSTC5/miniSSTCsch.JPG
The key difference is around the antenna input.  The original versions use 1N60 germanium diodes directly on HC14 input.  The new circuit's added 1k resistor is good, but the added 0.1uF capacitor and change to 1N4148 diodes causes issues.  The 1N60 diodes have enough leakage current to bias HC14 input to roughly center-supply voltage, making it more sensitive to antenna signals.  1N4148 diodes have very low leakage current, and the 0.1uF capacitor isolates any bias voltage from getting to HC14.

There's an even better fix than changing diodes:  Add two identical resistors (1Meg to 10Meg) across the two 1N4148 diodes and replace the 0.1uF capacitor with a piece of wire.

My guess is that the primary connection polarity that "explodes transistors" is the correct polarity.

15
Transformer (Ferrite Core) / Re: SG3525 push pull snubber calculation
« on: November 27, 2021, 08:51:05 PM »
Looks good!

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For this run used 1uF film capacitor.
New L = 1 / (4 * PI * PI * 500kHz * 500kHz * 1) = 0.10uH
This 0.10uH includes inductance of the 1uF capacitor and its leads.  Inductance to bulk caps will be slightly under 0.10uH.  Perhaps 0.08uH to bulk caps and 0.02uH for 1uF cap and leads as a guess.

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DC bus near FETs.
Seeing this plot allows one more calculation.  Switching pulse goes from ~36V up to ~63V, for a 27V delta.  Since this is the transformer primary center tap, 27V pulse here corresponds to 54V pulse on FET drain.  The measured FET drain pulse is ~72V baseline (with FET off) to ~235V peak, for a ~163V delta.  Of this 163V delta, 54V is from DC bus, leaving 109V due to transformer primary leakage inductance.  So, roughly, your switching losses are now 1/3rd due to remaining DC bus inductance and 2/3rds due to transformer leakage inductance.

Transformer leakage inductance can also be estimated from above.  DC bus inductance is transformed by 4x due to 2x turns ratio, so about 0.08uH * 4 = 0.32uH.  Leakage inductance is (109V / 54V) * 0.32uH = 0.65uH.  Of course, this is somewhat rough estimate, as I'm presuming 0.02uH for inductance of 1uF cap/leads.

BTW, the FET DS pulse voltage is lower now (235V rather than previous 270V) due to FETs running cooler.  The parasitic inductance reductions reduce pulse width, but not amplitude directly.  Amplitude is based on FET avalanche breakdown voltage, which increases with temperature.  Pulse voltage is one way to monitor FET internal die temperature.

How is performance with your clean upgrades?

16
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What i get was that i need to run my UD2.7 Rev. C with 2A at least and max around 3A (im in the 3A range on my current power supply so i am super oky on this) but the part that gets me the most is the windings, im totally not understanding the rateo between windings on it.. and even how to use only 3 of my EPCOS ones to do it all (if is possible OFC), im really confused on this  :/ .
I was referring to current into the UD2.7 OCD input, not the power supply to UD2.7.

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I didnt get there is this resistor, maybe im just stoopid but i didnt see it in the UD2.7 Rev. C board :/ ...
R17 and R28 in the lower left corner of UD2.7 schematic are the OCD CT burden resistors, 5.1 ohms each.  The current transformer (CT for short) transforms primary current from 500A for example down to 2A to feed the UD2.7 OCD input.  This 2A current is rectified by bridge rectifier D4-D7, then to resistors R17 and R28.  The resulting voltage across R17 and R28 feeds comparitor IC7.  If one of R17 or R28 is removed, resistance becomes 5.1 ohms total instead of half that (2.55 ohms), so less current is required from OCD CT to trip OCD and end the burst.

There are many DRSSTC builds documented on this forum and other sites.  Look at their OCD and feedback CT construction, and GDT construction.

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Since i dont want to just build a coil from other persons heads but i whant to actually understand my coil and how it works and what i need to care about when i build it.. and following some guides and haveing help and doing my research on this forum to possibly get it working and relaiable running for even long periods of time. could you please explain me or guide me to a site or something that really explains everything super detalied and even for a nooby like me pls? :3
I appreciate your desire to make your own design.  That is the fun part.  However, DRSSTC design isn't a good place to start learning basic electronics concepts.  If you have a signal generator and oscilloscope, use those to explore how inductors and transformers work.  Wind a single coil of a few turns around your N30 toroid core.  Connect to signal generator and scope voltage as you change frequency.  If you don't have a signal generator, make a simple one from a 555 timer or schmitt trigger inverter.  Once those results start to make sense, feed the signal generator into UD2.7 feedback input.  Then experiment with GDT variations on UD2.7 output.

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Also... i know that this might be a stoopid question. but. do i need to make the turns all the same? so its 1:1:1 ? i guess yes.. but... agin.. i want to know why even if i know its right so that i understand this better agin.
There are some designs using other GDT ratios.  UD2.7 is designed for 1:1:1.  That simple ratio is generally best, allowing winding with twisted pairs for low leakage inductance.

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So my question is.. knowind from Mads and his amazing work, and from the mmt user on 4hv, that the coil with this igbt is running around 75khz (from the mmt user "f0: 65-85kHz")
with an 11cm pvc pipe and AWG 30 wire, i would have to do a wiers 1:7 ratio to only get around 70-80khz with a huge topload. But since the coil would likely do aroud 1.5-2Mt of sparks i guess would be oky to have it high even if the ratio is not the one Mads suggested in his guide of around 1:4 to 1:5 ... or am i wrong?
Are you discussing the ratio of secondary height to secondary diameter?  (Ratios can be of any two numbers, most often here referring to transformer turns ratios, the number of secondary turns / number of primary turns.)  For secondary diameter/height, my DRSSTC is about 1:7.  However, 1:4 or 1:5 would be better.  My 1:7 limits coupling factor before racing sparks occur on the secondary.

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Lastly i would like you to check out my post about the strange IGBT that is giveing me headake.. I think you would find it interesting haha..
Yes, I did see your other post.  I had looked for data before posting my first answer to you.  Didn't find any.

17
Spark Gap Tesla Coils (SGTC) / Re: 60hz synchronous motor on 50hz?
« on: November 26, 2021, 06:58:16 PM »
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Here is a couple of pictures of a teletype motor my father and I have.
It was a little hard to get a good picture of nameplate info stamped direct into round motor body, I think it is readable zoomed in...hope this helps some...
The nameplate lists 50Hz and 60Hz operation, along with the corresponding 3000RPM and 3600RPM.  Should work fine.

18
I have some very-similar looking DC motors w/o gears, that turn at similarly slow speeds.  They were for tape players.  Some have internal mechanical speed regulation by centrifugal-force actuated contact points.

19
Quote
The simple way of auto-starting the discharge is to insert a ~1" piece of ~26-30awg bare copper wire into a small hole drilled into the top of the carbon electrode.  The sharp tip will initiate even a tiny discharge and then the copper will simply melt down to a small ball that resides in the hole for the duration of the experiment while the carbon electrode takes over.  Of course, you have to reload the wire each time.
Thank you for confirming my "cheat" solution.  That is exactly what I used in Reply#6 above.

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Thanks for sharing, very nice to see it works so well with fixed driving frequency.  I notice the freq is pretty constant despite arc load on my self-oscillating types. I find the controlled gate drive appealing, and lack of high speed PLL also appealing.
I think the arc ends up being so low-Q that it adds more loss than detuning.

20
Voltage Multipliers / Re: Practical limitations in size for Marx or CW
« on: November 25, 2021, 07:22:32 PM »
Make a simulation model (LTSpice or other free tool).  Include parasitic capacitance between the two capacitor stacks.

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post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
Today at 07:54:59 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
Today at 06:44:04 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 12:31:43 AM
post Re: MidiStick V2.0: Next gen tesla coil interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
dbach
December 06, 2021, 11:51:07 PM
post Re: profdc9 ud2.7c tht question
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
December 06, 2021, 07:48:31 PM
post Re: MidiStick V2.0: Next gen tesla coil interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
TMaxElectronics
December 06, 2021, 03:32:15 PM
post profdc9 ud2.7c tht question
[Dual Resonant Solid State Tesla coils (DRSSTC)]
costas_p
December 06, 2021, 01:57:36 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
December 06, 2021, 11:07:28 AM
post Re: What driver to use for first DRSSTC build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 06, 2021, 04:17:35 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Maju
December 05, 2021, 11:58:51 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
December 05, 2021, 11:21:11 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Maju
December 05, 2021, 08:53:57 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
December 05, 2021, 08:27:13 PM
post Go Big or Go Home
[Static Electricity]
abstruse1
December 05, 2021, 06:06:28 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
December 05, 2021, 12:35:17 PM
post Re: Nokia Siemens 3G Flexi 2100MHz 50W Amplifier Teardown
[Radio Frequency]
Mads Barnkob
December 05, 2021, 12:02:05 PM
post Re: MidiStick V2.0: Next gen tesla coil interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
dbach
December 05, 2021, 12:20:13 AM
post [Ebay find]: 6x Infineon Fast IGBT Modul FZ400R12KE4 1200V 400A Semitrans
[Sell / Buy / Trade]
Mads Barnkob
December 04, 2021, 11:35:01 PM
post Re: MidiStick V2.0: Next gen tesla coil interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
TMaxElectronics
December 04, 2021, 11:02:35 PM
post Re: Nokia Siemens 3G Flexi 2100MHz 50W Amplifier Teardown
[Radio Frequency]
Da_Stier
December 04, 2021, 01:16:47 PM
post Nokia Siemens 3G Flexi 2100MHz 50W Amplifier Teardown
[Radio Frequency]
Mads Barnkob
December 04, 2021, 09:03:55 AM
post Re: Dissimilar caps for Marx or CW?
[Voltage Multipliers]
Mads Barnkob
December 04, 2021, 08:42:26 AM
post Dissimilar caps for Marx or CW?
[Voltage Multipliers]
abstruse1
December 04, 2021, 05:39:32 AM
post Re: Looking to build by first DRSSTC as a high voltage beginner
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
December 03, 2021, 07:27:09 PM
post Re: help with finding resonant frequency
[Beginners]
HVuser
December 03, 2021, 04:43:39 AM
post Re: Looking to build by first DRSSTC as a high voltage beginner
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
December 03, 2021, 01:37:46 AM
post Re: Practical limitations in size for Marx or CW
[Voltage Multipliers]
abstruse1
December 02, 2021, 11:35:39 PM
post Re: Practical limitations in size for Marx or CW
[Voltage Multipliers]
MRMILSTAR
December 02, 2021, 09:53:13 PM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 02, 2021, 05:10:30 AM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
December 02, 2021, 04:58:53 AM
post Re: Syntherrupter - A Feature-rich, Polyphonic Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
December 02, 2021, 12:47:10 AM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 01, 2021, 10:30:50 PM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
December 01, 2021, 09:10:11 PM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 01, 2021, 06:36:14 AM
post Re: DRSSTC build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
November 30, 2021, 08:10:17 PM
post DRSSTC build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
balazs
November 30, 2021, 06:55:58 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 30, 2021, 06:23:03 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
davekni
November 30, 2021, 05:58:42 AM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 30, 2021, 05:35:58 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 30, 2021, 01:50:18 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
November 30, 2021, 01:19:18 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 30, 2021, 12:07:59 AM
post gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
November 29, 2021, 11:45:44 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 29, 2021, 10:52:43 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Intra
November 29, 2021, 03:15:23 PM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
TiagoBS
November 29, 2021, 03:08:58 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Netzpfuscher
November 29, 2021, 12:15:12 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 29, 2021, 12:26:28 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
davekni
November 29, 2021, 12:07:30 AM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
davekni
November 28, 2021, 11:58:24 PM
post GDT (Gate Drive Transformer) tutorial
[Beginners]
davekni
November 28, 2021, 11:40:56 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 28, 2021, 10:21:11 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
johnnyzoo
November 28, 2021, 10:05:40 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
November 28, 2021, 08:13:08 PM
post Re: Infrastructure and Architecture
[General Chat]
futurist
November 28, 2021, 06:12:44 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 28, 2021, 04:48:04 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
PowerTech
November 28, 2021, 03:16:11 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 28, 2021, 09:36:10 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
plasma
November 28, 2021, 05:32:16 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 28, 2021, 04:28:33 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 28, 2021, 02:19:00 AM
post Re: Where to buy DIY or home made capacitor book(s)?
[Capacitor Banks]
huntergroundmind
November 28, 2021, 01:58:12 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 28, 2021, 12:53:27 AM
post Re: Driverless SSTC
[Solid State Tesla Coils (SSTC)]
davekni
November 28, 2021, 12:32:09 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
davekni
November 28, 2021, 12:16:04 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 27, 2021, 11:42:08 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
304er
November 27, 2021, 11:32:12 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
jpvvv123
November 27, 2021, 11:09:43 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
paulj
November 27, 2021, 10:06:41 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
PowerTech
November 27, 2021, 09:40:34 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
davekni
November 27, 2021, 08:51:05 PM
post Re: Infrastructure and Architecture
[General Chat]
Da_Stier
November 27, 2021, 08:09:50 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
PowerTech
November 27, 2021, 06:00:42 PM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 27, 2021, 05:04:46 PM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 04:45:14 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
November 27, 2021, 07:59:37 AM
post Re: Contest of motor slowness, or lowness of voltage?
[Science, Research and News In Other Fields Than Electronics]
Mads Barnkob
November 27, 2021, 07:52:59 AM
post Re: FPS1000HD unboxing and first impression
[High Speed Filming]
Mads Barnkob
November 27, 2021, 07:51:01 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
November 27, 2021, 07:47:23 AM
post Re: Infrastructure and Architecture
[General Chat]
Mads Barnkob
November 27, 2021, 07:37:57 AM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
Mads Barnkob
November 27, 2021, 07:21:43 AM
post Re: BrOdin coil - High power Big sparks!
[Dual Resonant Solid State Tesla coils (DRSSTC)]
patracy
November 27, 2021, 06:06:59 AM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 05:27:27 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 03:19:55 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 02:31:46 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 02:22:20 AM
post Driverless SSTC
[Solid State Tesla Coils (SSTC)]
bismallah
November 26, 2021, 11:59:27 PM
post Infrastructure and Architecture
[General Chat]
Da_Stier
November 26, 2021, 11:27:47 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
klugesmith
November 26, 2021, 11:17:55 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 26, 2021, 08:24:39 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 26, 2021, 07:48:07 PM
post Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
TiagoBS
November 26, 2021, 07:44:25 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
davekni
November 26, 2021, 06:58:16 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
plasma
November 26, 2021, 05:40:37 PM
post Re: "Exploding" water
[Capacitor Banks]
MRMILSTAR
November 26, 2021, 04:39:07 PM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 26, 2021, 04:31:20 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Intra
November 26, 2021, 03:52:08 PM
post Re: "Exploding" water
[Capacitor Banks]
johnf
November 26, 2021, 09:17:07 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
paulj
November 26, 2021, 08:45:34 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 26, 2021, 06:31:56 AM

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