Author Topic: Tardief's DRSSTC  (Read 27044 times)

Offline Tardief

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Tardief's DRSSTC
« on: June 24, 2017, 11:07:31 PM »
Hi!
We are planning to build a DRSSTC with 4x CM600HA-24H. I have never built such a big coil, so I do not have much experience. I'm still learning and at the end of this project I want to understand everey single piece of it.  :D
I don't want to ruin a bunch of expensive things so if you could say a good/not good to my updates that would be very good.
Constructive criticism is MUCH appreciated.

#1




The  secondary diamater is fix. 315mm
What do you think?
« Last Edit: June 25, 2017, 01:48:18 PM by Tardief »

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #1 on: June 26, 2017, 12:50:19 PM »
I personally think you chose a too thin wire, thus getting many turns, higher impedance than what you really want in a huge Tesla coil like the one you are aiming for. I used 0.75 mm diameter wire for my DRSSTC3 (roughly AWG20), there are a wide range of values to use, simulate, calculate on and so on in the secondary part of my DRSSTC guide: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/secondary-coil/

4x CM600 single modules will properly give you the same performance as my DRSSTC3, so design for a max of around 2 kA peak current and you can go higher if you feel adventurous, but do not make a MMC that can not handle at least 2 kA for a prolonged time, building such a large Tesla coil is both expensive and time consuming, so do not try to cut any corners that will risk damaging expensive parts later on.

What capacitors do you have in mind for the MMC?

If you have the money ready for it, get lucky on a good deal or want to try to solder a MMC for the DC link capacitor, see if you use polypropylene/MKP capacitors for the DC link smoothing instead of the old slow electrolytic capacitors, the performance boost is incredible from the much lower time to deliver current from storage through the IGBTs to the primary circuit.

edited: to correct wrong numbers on wire size
« Last Edit: June 26, 2017, 02:37:47 PM by Mads Barnkob »
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #2 on: June 26, 2017, 01:34:29 PM »
You sure that was 0.75mm2?
http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-iii/
I thought the 0.75 is the diameter.
I choose that wire, because i cant fit enough turn with a thicker wire so the frequency would be too high.

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #3 on: June 26, 2017, 02:36:53 PM »
You sure that was 0.75mm2?
http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-iii/
I thought the 0.75 is the diameter.
I choose that wire, because i cant fit enough turn with a thicker wire so the frequency would be too high.

You are absolutely right, I am sorry for that mistake, I have edited my reply so yours with quote here will be the changelog :)

Yes I used 0.75 mm diameter wire, 1800 turns, for a 1500 mm long winding.

I still think you should use AWG20, 1700 Turns, you should get around 40 kHz.

Have you made any decisions around my other questions?
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #4 on: June 26, 2017, 03:11:51 PM »
Not yet.
Still doing some research in that topic.
Maybe we will use one from here:
http://kaizerpowerelectronics.dk/theory/good-mmc-capacitors/ <--Thanks for that  :)

How can i end up at ~40kHz with that low turn number? Even with 1800 turn it will be 45kHz according to JavaTC. The surronding capacitance has so big influence?
« Last Edit: June 26, 2017, 03:14:21 PM by Tardief »

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Re: Tardief's DRSSTC
« Reply #5 on: June 26, 2017, 03:59:34 PM »
For a MMC in a CM600 coil, look for large GTO snubber capacitors, they are in the range of 1-10uF, several kV, hundreds of ampere peak and high RMS current rating, but they will also cost you money :)

Surroundings matter a great deal to the resonant frequency, for a coil that big I calculated with 5 meter radius, that would be that I have no objects inside the strike radius of the coil.

This example with AWG20 gave me 43 kHz, I am sorry that you work in inches and I work in SI units ;)


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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #6 on: June 27, 2017, 04:14:45 PM »
Exactly, i prefer SI units. I'm from Hungary. I used inches because most of the coil builders used that and thought it would be more comfortable for them.

I thought it will be easier to find suitable capacitors. So far I have these options:

-http://hu.mouser.com/ProductDetail/Cornell-Dubilier-CDE/942C16P68K-F/?qs=sGAEpiMZZMv1cc3ydrPrF8gMTJ0uZsYN8XXe1MRhowk%3d
  10 in series and 6 in parallel. That's a lot.  :D

-http://www.tme.eu/hu/details/416.74.6030/standard-poliprop-folia-kondenzatorok/ducati-energia/

Offline futurist

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Re: Tardief's DRSSTC
« Reply #7 on: June 28, 2017, 10:52:52 AM »
Finding good and cheap MMC capacitors is the most difficult part in building DRSSTC

942Cs are not suitable for coil that big, even 10 in series may not be enough. Some coilers suggest watching only AC voltage rating of the MMC, which would be just 4600V for that MMC
Primary reactance is Xc = 1/ 2pi*f*C, multiply it by the peak current you'll be running your coil at to get your peak voltage

Second cap you posted has only 16Arms rating which is way too low for MMC use, given the large capacitance
« Last Edit: June 28, 2017, 10:56:09 AM by futurist »

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Re: Tardief's DRSSTC
« Reply #8 on: June 28, 2017, 12:50:51 PM »
I agree with Futurist.

CDE 942C is simply too expensive to use in a large DRSSTC as you get either a disproportional voltage rating or current rating to achieve the values needed in a CM600 coil.

That Ducati Energia capacitors looks like a motor run capacitor, I have no experience with using those, but given the voltage/current rating, those are properly not a viable choice as the MMC will get incredible large and expensive.

I have unfortunately not yet finished the MMC chapter of my DRSSTC design guide, it is a rather long and technical chapter to write, but you can see the 4 kinds of snubber capacitors that I would advise you to look for in the snubber capacitor part of the guide: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/snubber-capacitor/
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #9 on: June 28, 2017, 01:46:39 PM »
I really appreciate your help.  :)

What do you think about these?

http://www.zez-silko.com/en/products/capacitors-for-igbt-cylindrical-cases
For example the PVDJP 21-5/2 from the table.
2kV AC, 2uF  8 in series and 2 in parallel . That means 16kv 0.5uf. 0.5uF-->~7Ω(45kHz) -->15kV (with 2000A)

http://www.zez-silko.com/en/products/capacitors-for-scr
From here PVDJP 020-8/0,75  5 in series and 3 parallel It gives similar results.

http://www.ebay.com/itm/1PC-12000V-DC-6000V-Ac-0-22UF-MFD-80A-Resonant-Tesla-capacitor-50KHZ-G1007-XH/182177380103?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D41451%26meid%3Df556de277cb943dfa1d7761785c9c6fe%26pid%3D100033%26rk%3D3%26rkt%3D8%26sd%3D272541371882
This look pretty expensive. With this low capacity we would need a bunch of these.

I will ask them for the prices. I am pretty curious.
Irms numbers still not too high.   :-\
 
« Last Edit: June 28, 2017, 02:06:55 PM by Tardief »

Offline futurist

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Re: Tardief's DRSSTC
« Reply #10 on: June 28, 2017, 05:38:37 PM »
I suggest buying used/NOS caps or you might go bankrupt

Mine are NOS similar to these, 0.68uF 2000V, 25Arms, which allow many different MMC configurations.. and I got them for ~2$ per cap
http://www.ebay.com/itm/1-2uF-MKP-C4AS-1200VDC-HQ-Arcotronics-IGBT-Box-PCB-10-pcs-/182622703100

You can also visit your local scrapyard, maybe they could save something useful

Offline Tardief

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Re: Tardief's DRSSTC
« Reply #11 on: June 30, 2017, 11:36:04 AM »
What capacitance do you suggest for 2000Ipeak at 565Vbus?
And what about the capacitors Irms rating? I cant find any suggestion on the internet.  :-\


Quote
Primary coil conclusion: Hollow copper tubing has the best electrical and mechanical features in regard to primary coil construction. There is very little electrical difference from 10 mm to 25 mm copper tubing compared to the extra physical size.

Mads you wrote this in "Busbar and primary circuit".  That means the 10mm copper tube is enough?
« Last Edit: June 30, 2017, 02:39:58 PM by Tardief »

Offline Hydron

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Re: Tardief's DRSSTC
« Reply #12 on: July 01, 2017, 02:04:42 AM »
As current increases you're better off going for water cooled tubing than very large diameter tube. Smaller diameter is also easier to work with without kinking etc.

As for MMC capacitors:
- Capacitance should be determined by frequency and desired primary impedance. It's probably good to have a look at what people with similar sized coils have found to work well - it's not critical as long as you can adjust the primary coil to match.
- I suggest using the calculator on Mads' website to check what voltage rating is needed once you know your desired capacitance and frequency
- I strongly recommend looking on ebay etc rather than the normal parts suppliers. While Farnell, TME, RS etc can be OK for some stuff (e.g. smaller value capacitors for high frequency coils) much better bargains can be found elsewhere for large MMC caps.
- Often RMS and peak current are not directly stated in datasheets. RMS current can be determined from RMS voltage vs frequency graphs (divide RMS voltage by the capacitor impedance at the desired frequency to get RMS current), while peak current is easily determined from multiplying the dV/dt number (in V/us) by capacitance in uF.
- "Snubber" capacitors often have appropriate characteristics for MMCs if they can be found in appropriate voltage/capacitance values - they normally have good RMS current rating and low loss polypropylene dielectric (this is the only suitable dielectric for medium-large DRSSTC MMC capacitors).

I used 48 of the 2uF/1kV caps shown in the previously linked snubber capacitor guide as my MMC for my larger (~1kA peak, similar size to futurist's) coil, though the 0.68uF capacitors he used would actually be better. They were purchased at $2 USD each from a now closed US surplus dealer, though shipping overseas cost nearly as much as the capacitors.

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #13 on: July 01, 2017, 09:36:47 AM »
I only meant the physical types of polypropylene capacitors when I linked to the snubber capacitor part of the design guide, not just those manufacturers, there are hundreds of useful MKP/metallized film capacitors out there to be used.

As Hydron said, water cooling is the only solution, even 25 mm copper tubing would need water cooling, due to the proximity effect where the outer turns of the primary coil induction heats the inner turns. This is also why you should pump the cooling water in from the inner turn end.

The MMC calculator on my website that Hydron mentions: http://kaizerpowerelectronics.dk/calculators/mmc-calculator/

I would suggest that you use something like 0.75 to 1.5 uF, where 0.75 uF would be a high impedance coil that requires longer on-time but has lower peak current, thus lower peak voltage (cheaper MMC, but may not even be able to run at 2kA due to impedance limitations) 1.5 uF is the opposite, use it for a low impedance coil with higher peak currents, but also needs a more expensive MMC.

The higher capacitance in the MMC, the smaller primary coil is needed to hit the resonant frequency and thus peak current goes up UP UP!

There are many different choices to make and they are often conflicting, depending on each other, are in eachothers equations and thus changes everything once again, that is the reason why I made the MMC calculator as it is, you decide on a primary inductance, frequency and maximum primary current and then design from that.

Here are some of the best offers I could find on ebay, I shopped from Tauritronics myself, I got a lot of those 5uF snubber caps :)

http://www.ebay.co.uk/itm/5uF-1200V-MKP-Filter-Caps-GTO-LOW-ESR-HQ-arcotronics-25pcs-/172721058519?hash=item2836fa32d7:g:GWkAAOSwk5FUz9UQ

http://www.ebay.co.uk/itm/0-68uF-1600VDC-R75-MKP-HQ-Arcotronics-6Pcs-/172733208790?hash=item2837b398d6:g:2fIAAOSwk5FUsRR0

http://www.ebay.co.uk/itm/1-5uF-1000V-MKP-C4BS-HQ-Low-ESR-Arcotronics-IBGT-Tesla-2pcs-/172734282522?hash=item2837c3fb1a:g:jHoAAOSw9IpXzZTZ

http://www.ebay.co.uk/itm/0-47uF-850V-C4BS-Arcotronics-IBGT-MKP-Capacitor-Tesla-30pcs-/182642886321?hash=item2a865d46b1:g:rhMAAOSwSypY~15e

http://www.ebay.co.uk/itm/0-47uF-3000V-1-44-2-Arcotronics-IBGT-MKP-Capacitor-Tesla-12pcs-/172754315379?hash=item2838f5a873:g:IIcAAOSwHHFY~2BL
« Last Edit: July 01, 2017, 01:46:53 PM by Mads Barnkob »
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Offline Uspring

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Re: Tardief's DRSSTC
« Reply #14 on: July 01, 2017, 07:53:42 PM »
Tardief wrote:
Quote
What capacitance do you suggest for 2000Ipeak at 565Vbus?
The idea is to obtain an impedance match between the inverter and the coil. An approximate rule is:

Vmax/Imax < k  * sqrt(L/C)

Vmax is the effective input voltage. This is 4/pi of the bus voltage. This factor comes from feeding the primary with a square wave instead of a sine wave. Imax is peak primary current, k coupling and L and C primary inductance and capacitance. In effect this inequality specifies, that you shouldn't have to limit burst length in order not to exceed Imax, i.e. that secondary loading will limit primary current. An alternative way to write this equation is:

Vmax/Imax < k  / (2*pi*f*C)

f being the primary resonance frequency.

Solving for C and plugging in your values and a k of 0.2, I get a C of less than 2.2uF.
Using this value, you will probably have a hard time tuning your coil, since the right side of the inequality can become much lower if it is not perfectly tuned. So Mads recommendation is better, since it leaves some leeway in tuning. If you choose C too small you will find, that there won't flow enough current into the primary. But this can be compensated for by detuning. For a given primary current, though, a lower capacitance will be more costly.


Offline Tardief

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Re: Tardief's DRSSTC
« Reply #15 on: July 02, 2017, 11:09:44 AM »
Thanks for everyone!

http://www.ebay.co.uk/itm/5uF-1200V-MKP-Filter-Caps-GTO-LOW-ESR-HQ-arcotronics-25pcs-/172721058519?hash=item2836fa32d7:g:GWkAAOSwk5FUz9UQ
This offer sounds good.
For example in 2*10 binding. And I could change capacitance easily with adding or removing 1 from the string.
The 2 parallel string has only 2*64 Arms. The calculator says i need ~200A.

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #16 on: July 02, 2017, 01:51:35 PM »
I agree on those capacitors being the best choice, both from a ratings and economic perspective.

Irms is "only" a problem over time, so long run times would be ruled out if you do not meet these minimum figures, but with forced air cooling and as I write this I just had an idea on how to cool them even better...

From my DRSSTC guide, there you can read that 2/3 of the dissipated heat in a capacitor is radiated out axially and most through the terminal/leads, so if you made a circular heat sink to mount in between each capacitor that would properly help a lot on cooling them effectively. Just make sure that it wont be a problem insulation wise.

= a capacitor
| a flat aluminium/copper plate or heat sink

=|=|=|=|=
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #17 on: July 12, 2017, 03:55:55 PM »
We are trying to find a suitable DC Bus capacitor.
For now we have this: http://hu.mouser.com/ProductDetail/KEMET/ALS70A103NP350/?qs=sGAEpiMZZMvwFf0viD3Y3fHxNcSaiftwWEEMtbZ5fvazhnres9Q4%252bQ%3D%3D

According to the datasheet it can handle 26,2A at 10kHz.  Do you think, that 4 of these will be okay? (564Vbus)
And what about the balance resistors? We dont need them if we use brand new capacitors?

I didn't find any recomendation for the pre-charge current. I think a 220ohm 100W resistor is okay.


« Last Edit: July 12, 2017, 03:59:26 PM by Tardief »

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #18 on: July 13, 2017, 09:19:53 AM »
4 of those capacitors, 2 in series, 2 strings in parallel for 10000uF at 700VDC sounds fine, I only have 6000uF in mine, but would certainly like to have more :)

This also gives you 52,4Aripple, as I made the calculations in my DC bus capacitor chapter of the DRSSTC design guide to my large DRSSTC, its almost identical to the calculations you have to do: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/dc-bus-capacitor/

In order to keep your capacitors in good shape, you should use balance/bleeder resistors, a industry standard that I see in almost every drive/inverter/UPS I take apart is 47K across each capacitor.

I never used a pre-charge circuit, as I always had a variac at hand to ramp up the voltage slowly. 220R / 100 W is more than fine, its just for a few seconds to get the capacitors a little up in charge so that it doesn't look like a huge short circuit to the mains supply. So it is not that critical with the rating, its only going to be on for a few seconds anyway, and then bridge over by a timed relay.
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #19 on: July 15, 2017, 06:14:49 PM »
Thanks! :)

Could you tell me some more about the snubber capacitor on the IGBT?
http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/snubber-capacitor/
Here you asumed that the busbar inductance is 200nH. How should I calculate that?
Do you have some recommendation for the IGBT protection?

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #20 on: July 15, 2017, 09:59:33 PM »
Thanks! :)

Could you tell me some more about the snubber capacitor on the IGBT?
http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/snubber-capacitor/
Here you asumed that the busbar inductance is 200nH. How should I calculate that?
Do you have some recommendation for the IGBT protection?

I put this new snubber capacitor calculator online only a few weeks ago, if even that long: http://kaizerpowerelectronics.dk/calculators/snubber-capacitor-calculator/

You should ultimately measure the inductance at your resonant frequency, or similar, with a LCR meter. You could also just use the high / low estimate rules, as seen in the calculator page.:

Estimated high inductance snubber capacitance = Peak current / 100
Estimated low inductance snubber capacitance = (Peak current / 100) * 0.5

With a good clean, short, sturdy bus layout, you only need snubber capacitors to protect the IGBTs, TVS diodes are not needed then.
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #21 on: July 17, 2017, 07:59:16 PM »
It seem obvious, but i want to be sure. When you made the calculations with the result fmax=56kHz for the IGBT is it the same for half and full bridge or it concern to only 1 piece?

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #22 on: July 17, 2017, 10:50:15 PM »
I assume that you are referring to the IGBT part of the DRSSTC guide.

Since its mainly estimated around the currents through the switch, there is no difference from a half- to a full-bridge, if we adjusted the voltage to have the same current go through, each switch would see the same current. 1000A going through a IGBT, to coil to ground in a half-bridge is the same as 1000A going through a IGBT, to coil, through another IGBT.

As current is the same for components in series, the advantage of a full-bridge lies in the double voltage rating and thus also possible to lower the currents that has to be switched. So a full-bridge is vital in high frequency inverters with bricks.
« Last Edit: July 18, 2017, 11:35:54 PM by Mads Barnkob »
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #23 on: July 18, 2017, 08:15:49 PM »
I can't thank you enough.  :)
Hope we can buy the parts soon and start to build.

It semm thath we will use CM600HA-24H.
In the IGBT selection part of the guideyou use CM600DU-24H.
I have some questions about the difference.

Here there is a 0.02 multiplier. What is this number?


We didn't find this information for the CM600HA. Can we use that what you used?


Here you used 0.081. In the CM600HA that is 0.03.Can be there that much difference?

(Sorry for the big images I dont know how to make them smaller :-[ )
« Last Edit: July 18, 2017, 08:17:59 PM by Tardief »

Offline Mads Barnkob

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Re: Tardief's DRSSTC
« Reply #24 on: July 19, 2017, 07:43:26 PM »
The CM600 model I have was a custom made version that optimized for faster turn-off, I can not really recall to be honest, but overall it is very much the same as other CM600 IGBT half-bridge bricks.

As I tried to write in the guide, we make an assumption up against datasheets with hard switching specifications, but the DRSSTC is soft switching at a very low duty cycle, so at 200uS on-time and 200 BPS it corresponds to 4% duty cycle (or 0.04 in a equation) and since that is for square wave signal, we half that figure since a DRSSTC burst is a damped sine wave ocsillation, so we end up at 2% (or 0.02 in a equation)

Yes, you can use the same switching loss energy curves, we are already assuming so much and extrapolating curves that it will do just fine :)

0.081 is the thermal impedance Zth(j-c) read out from the curve showing this against the on-time, you have to find the value that fits your duty cycle from that curve. This coefficient is highly dependant on the package the IGBT comes in, so this is important to get from the right datasheet. But this is always in the datasheets.

There is a thread about my DRSSTC guide, I would really love if you replied to that with parts of the guide that is hard to understand or need futher explanation. https://highvoltageforum.net/index.php?topic=38.0
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #25 on: July 31, 2017, 09:51:33 AM »
Hi,
We found a really cheap seller on ebay who sells a CM600 for 25$.
What dou you think? It seems to cheap for me? Maybe its used or fake?

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Re: Tardief's DRSSTC
« Reply #26 on: July 31, 2017, 12:56:52 PM »
Probably used, exactly what you should look for :)
I'd go for it

edit:
Just check if it's 600V version, not all are rated for 1200V
For example http://www.ebay.com/itm/IGBT-Modul-MITSUBISHI-CM600DY-12NF-High-Power-Switching-Use-600V-600A-/263115142944
« Last Edit: July 31, 2017, 12:59:01 PM by futurist »

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Re: Tardief's DRSSTC
« Reply #27 on: July 31, 2017, 01:04:45 PM »

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Re: Tardief's DRSSTC
« Reply #28 on: July 31, 2017, 02:56:22 PM »
It's a single IGBT module, you'll need 4 of those for fullbridge

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Re: Tardief's DRSSTC
« Reply #29 on: August 01, 2017, 10:08:21 AM »
I only see them at 50$/piece, so that is 200$ for a full-bridge, that is about what I payed for the used bricks I have.

They do write that they are new, it is from Malaysia, company called IGBT wholesale, feedback on ebay looks fine... its hard to say, but they are much cheaper than competition.

Import taxes might also add to the total price.
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Re: Tardief's DRSSTC
« Reply #30 on: August 02, 2017, 02:05:21 PM »
It's worth a try. Hope it will be good.

We are planning to buy the driver and the midi controller from Eastern Voltage.
Here are the ones we thought:

Driver:  http://www.easternvoltageresearch.com/universal_drsstc.html 
Controller: http://www.easternvoltageresearch.com/plasmasonic_mod.html
They are pretty expensive but seems good. These two items are enough to controll the coil?



We will make the secondary coil tomorrow. ;D

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Re: Tardief's DRSSTC
« Reply #31 on: August 02, 2017, 06:16:28 PM »
Nice winding rig!

I would suggest you build your own driver, that one is really expensive
For start, use interrupter from oneTesla, you just need 2 pots, arduino nano and optic transmitter - total cost 20$ at most

If you really don't want to bother with soldering and testing driver PM me, I have one spare board

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Re: Tardief's DRSSTC
« Reply #32 on: August 02, 2017, 06:22:57 PM »
Winding/varnishing rig and pipe looks good!

I would not advise anyone, except if you are in a hurry and money is not a issue, to buy a EVR product, which is 99% based on the Steve Ward universal drivers which was further developed by Finn Hammer and Gao Guang, among others.

Gao got both MIDI controller and UD2.7 for sale on his website, as kits, so prices are also completely different.

UD2.7: http://loneoceans.com/labs/sales/ud27/
Midi: http://loneoceans.com/labs/sales/midi2/

there is also the onetesla midi interrupter: http://onetesla.com/products/kits/interrupters-all.html

I got both Gao's and onetesla, except I did not put Gao together yet :o

There are also other alternatives around on other forums/websites, heck, if you want you can have the ExpressPCB files to etch a single sided(all DIP) UD2.1 that I did a layout for. Still has some issues like components doesn't fit completely and needs a little "compacting" or "strecting" :)
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Offline Tardief

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Re: Tardief's DRSSTC
« Reply #33 on: August 02, 2017, 07:37:21 PM »
Thanks both of you.
 Eventually we decided at Loneocean's driver.

We already have some questions.

We have a disagreement in the team.
   -Put the rectifier, precharger, voltmeters etc. in a box away from the coil near to us. In this case we would need  about 10m cable in the DC side.
    -Put all these things under the coil. No unnecessarily long DC cable, but we will need a buch of cable for the feedbacks(Voltage, relay status etc.).

What dou you think?

The other question is about the ferrit in the feedback circuit. What we need to pay attention? High permeability and that's all?



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Re: Tardief's DRSSTC
« Reply #34 on: August 02, 2017, 08:47:56 PM »
I made all my coils to be supplied by AC, most of the time from a variac.

I got two different ways of measuring the input current / voltage, I got my large variac with a 3 phase voltage/current meter in ( http://kaizerpowerelectronics.dk/power-supplies/3-phase-13a-variac/ ) and a Merlin Gerin PM700 3 phase power analyzer instrument ( http://kaizerpowerelectronics.dk/power-supplies/merlin-gerin-pm700-power-meter/ ) that I can use for power factor readout, so I know the DC voltage / current from calculations, so I never ran any wires back for instruments. There is only the AC cable and fibre optic cable.

I usually just used the same cores as I used for the GDT, they do however only need to be physically big if its needed because of the conductor you have to get through it or insulation to the inverter voltage is a problem. You properly already know the datastream GDT guide? http://thedatastream.4hv.org/gdt_index.htm
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Re: Tardief's DRSSTC
« Reply #35 on: August 03, 2017, 10:43:56 PM »
We almos done with the winding.


We had a little accident. :D
We wantedf a second layer, so we put the epoxi into to fridge. It became so hot that the frige melted.  :o Stupid idea...
So no second layer now.



How did you attached the secondary coil to the base?
And what is you experience about bus voltage 564V vs 680V?

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Re: Tardief's DRSSTC
« Reply #36 on: August 04, 2017, 10:19:43 AM »
A few notes:

- 564V vs 680V is not critical if you are running 1200V IGBTs. Assuming you have some control over the bus voltage up to that point (variac? SCR rectifier?) then I'd go for the configuration that gives you the highest possible voltage, as you'll have more adjustment room. If you do not have control, then I'd start off with tests using a DC power supply, then the lowest mains voltage possible (rectified 230V AC is approx 325V DC), and finally move to the full voltage once everything works well. A SCR controlled rectifier for voltage adjustment would be extremely useful, and will not add significant cost/size to the project, so I would strongly suggest building one if you don't have a variac.

- I also would suggest a loneoceans driver, or (even better), a UD+ driver from Philip Slawinski (see http://classictesla.com/pslawinski/udplus.html )

- Ferrite choice for current transformer is not critical, most will work, including anything suitable for a GDT. Gate drive transformer requires more design effort, but is not difficult, and Mads' link is very useful.

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Re: Tardief's DRSSTC
« Reply #37 on: August 04, 2017, 02:45:18 PM »
I have only been using 564VDC from 3x400VAC, but I would switch to up to 800VDC any day if I could :) Most of the components are already rated for the higher voltage, its simply the problem of making/finding a 3 phase PFC power supply for that voltage range.

We made a large diameter nylon bolt with split pin, this mounts through a hole in the primary base plate, the split is inserted on the under side. It is loose and attached to a string, so that the bolt can disappear into the secondary coil in order for it so stand flat on ground when not mounted on the base plate.

Takes two people to mount the coil on the plate, but that has more to do with the weight of the secondary coil itself, it is very close to 40-50 kg.
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Offline DanniL

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Re: Tardief's DRSSTC
« Reply #38 on: August 04, 2017, 05:11:37 PM »
This rectification how can 680VDC?

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Re: Tardief's DRSSTC
« Reply #39 on: August 06, 2017, 09:47:16 PM »
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Offline Hydron

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Re: Tardief's DRSSTC
« Reply #40 on: August 07, 2017, 02:18:54 PM »
It is basically 3 parallel single phase voltage doublers. Instead of having 400VAC fullwave rectified to 564VDC, you have the midpoint/neutral to get 2x 325VDC ~ 650VDC across the capacitors.

I am unsure about how this balances in regard to load on each phase or neutral.
I imagine the load sharing would also depend on interactions between the coil BPS and line frequency. The DRSSTC is not a nice constant load; it will take big chunks of energy out of the bus capacitors at a low frequency. At lower BPS, especially close to multiples of line frequency, there may be significant mismatch between phase currents just because the bus caps get emptied just before the peak of a particular phase. I have not done any simulations however, though they would not be difficult (I suggest LTSPICE as a more powerful tool than online simulators - it's easy to model most of the coil in it).

Offline Tardief

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Re: Tardief's DRSSTC
« Reply #41 on: August 12, 2017, 10:06:07 PM »
Hi,
The topload is under construction.  :) I will make some photos when its done.

We still have some wuestions about the primary coil.
We will make it from 12mm copper tube.
What is the suggested distance between the turns? We thought about 1cm.
And what about the distance between the primary and the secondary?
The last question is about the coupling. It has to be an exact value or it's enough that is about 0.15?

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Re: Tardief's DRSSTC
« Reply #42 on: August 12, 2017, 11:19:16 PM »
There is very little benefit from 10 mm to 20 mm copper tubing, for coil of your size I wouldn't go anything higher than 10 mm if you didn't already bought the tube
Also 12 mm tubing will be more difficult to bend in shape than 10 mm

I suggest coupling k ~ 0.16 so you can lower it by raising secondary, for example with wood disc

Offline Tardief

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Re: Tardief's DRSSTC
« Reply #43 on: August 14, 2017, 11:09:23 AM »
We wanted to use 12mm because we can pump through more air/water.

How did you choose the size of the heatsink?

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Re: Tardief's DRSSTC
« Reply #44 on: August 14, 2017, 01:52:43 PM »
Hi,
The topload is under construction.  :) I will make some photos when its done.

We still have some wuestions about the primary coil.
We will make it from 12mm copper tube.
What is the suggested distance between the turns? We thought about 1cm.
And what about the distance between the primary and the secondary?
The last question is about the coupling. It has to be an exact value or it's enough that is about 0.15?

12 mm copper tube is fine for a primary, 10 mm is a very common size in Denmark, so that is what I always use.
I have 20 mm between turns on my large DRSSTC, less would make it harder to mount a heavy tap contraption on, simply from risk of short-circuiting two turns.
I think its about 20-30 mm from secondary to most inner turn of the primary coil
Coupling is a very interesting parameter, the higher the better, but you have to take measures against flash-over, tuning can be more tricky etc. Somewhere between 0.15 to 0.20, as futurist mentions, its much easier to lower the coupling with a few disks that making it higher later (like in, good luck sawing a hole in the middle and lowered the coil down through it)
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Re: Tardief's DRSSTC
« Reply #45 on: August 30, 2017, 07:22:59 PM »
Hi,
We are still alive. :D

What ferrit core do you suggest for the GDT and feedback?
I found that the AL should be big enough, but nothing about the physical size.

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Re: Tardief's DRSSTC
« Reply #46 on: September 04, 2017, 09:41:54 AM »
Hi,
We are still alive. :D

What ferrit core do you suggest for the GDT and feedback?
I found that the AL should be big enough, but nothing about the physical size.

For the GDT I calculated it for my DRSSTC1, but just doubled the physical size for the DRSSTC3 :o  ( http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-i/ scrol down to 25th September 2009 )

For feedback, just use the same core type as for the GDT, but here the physical size is more dependant on where you want it to sit in the circuit, it simply has to be large enough to make the primary cable/busbar go through, have enough distance for isolation from the inverter voltage and not be a source for a possible short circuit from inverter into control circuit. I made a nylon bobbin for them to be mounted on, with a piece of brass rod going through for the DRSSTC3.

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Re: Tardief's DRSSTC
« Reply #47 on: November 03, 2017, 06:03:45 PM »
Hi,
We disappeared a little. Unfortunately the university ruined our scheduel.
We had some problem with the GDT.


Here is what we got.
It should be a perfect square wave, doesnt it?
The blue one is the input. The yellow is the output.
The function generator makes a perfect square wave until i connect the GDT.

Offline futurist

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Re: Tardief's DRSSTC
« Reply #48 on: November 03, 2017, 07:05:56 PM »
The signal looks completely fine :)

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Re: Tardief's DRSSTC
« Reply #49 on: November 03, 2017, 10:11:36 PM »
You only have minimal overshoot/ringing and some droop, you could try 2-3 more windings on the GDT to counter this, but there is really no need to, as futurist says, it looks just fine :)
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Re: Tardief's DRSSTC
« Reply #50 on: November 04, 2017, 09:26:41 AM »
Thank you.
I thought I need a  squre wave without any deformation.

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Re: Tardief's DRSSTC
« Reply #51 on: November 07, 2017, 11:39:25 PM »
Unfortunately I am still not sure about the best GDT option.
We made some new measurements.

This was made with 15 turns.



The other with 20 turns.


The waveform looks better with 20 turns, but if I am right than the more turns will reduce the current and that can be a problem.
Should we stick with the 15 turns to avoid that?

Which is the better?
Using one core for driving all of the IGBTs or using two of them?


« Last Edit: November 07, 2017, 11:42:49 PM by Tardief »

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Re: Tardief's DRSSTC
« Reply #52 on: November 08, 2017, 10:46:21 AM »
From my DRSSTC1: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-i/
Code: [Select]
Its a Epcos ring core, material: N30, good up to 5MHz, Aemm^2: 95,89, AL: 5750nH

Inductance with 10 turns: L = AL * N^2 = 5750 * 10^2 = 575 uH

Peak current: Ipeak = (Vin * t * D) / Lmag = (24 * (70000/1000000) * 0,5) / (575 * 10^-6) = 1460 mA

Irms = Ipeak * 0,577 = 842 mA

Minimum number of turns needed to avoid saturation

t, 50% duty cycle = (1 / 70000) / 2 = 7,3*10^-6

Nmin = ( V x t ) / ( B x Ae ) = (12 * (7,3*10^-6)) / (0,2 * (95,89*10^-6)) = 4,6 turns

Current needed to drive a single 60N60 IGBT gate

I = Qc / t = (146*10^-9) / (1/70000) = 10,22 mA, including magnetising current, double this figure.

So with more turns you will lower your peak current, but also have less voltage drop, but remember that a few Volt droop is not a problem. It is better to have a fast turn-on without too much ringing, than a nice looking too slow turn-on with too high switching losses.

There is also the IGBT gate drive calculator, I do not recall if we talked about that: http://kaizerpowerelectronics.dk/calculators/igbt-gate-drive-calculator/
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Re: Tardief's DRSSTC
« Reply #53 on: December 06, 2017, 03:27:42 PM »
Hi,
We are currently testing the driver with some capacitor(instead of the IGBTs).
What should be the open time for a CM600 H-bridge?
The capacitor was 68nF. The GDT had 13 turns with a core from Eastern Voltage.
We got more than 700ns rise time.  We used a driver from Gao. Without load the rise time was 40ns.
« Last Edit: December 06, 2017, 03:40:03 PM by Tardief »

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Re: Tardief's DRSSTC
« Reply #54 on: December 07, 2017, 07:27:45 PM »
If you scroll down to "Soft switching and zero current switching" on this page: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/igbts/

You can see that Kizmo has switched a CM600 on in just 100 ns, but that is due to resonant switching, so it seems good with the rule of thumb of 10 times faster in resonant switching, that you have 700 ns in a simulated hard switching setup.
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Re: Tardief's DRSSTC
« Reply #55 on: February 03, 2018, 08:05:18 PM »
Hi,
After the exams we had some time to work on the coil.  :D



We have already made some tests but we are not sure in some things.
The current limit was ~300A. The IGBTs stayes cool.
The load was resistive at the firs image. A 4kW halogen light bulb.











Cyan = Vce, Blue = primary current.
On the Vce we measured  ~15V drop.  :o

We tested the IGBTs with a welding transformer. Here are the results:
At 17A the Uce was 1,06V
30A - 1.19V
40A - 1.27
50A - 1.35
60A - 1.41
70A - 1.46
80A - 1.5
90A - 1.55
100A - 1.59
It seems good, but then what did we measure?

And what do you think about the spikes?  (we used UD2.7 from Loneoceans) We tried to reduce them with phase lead.

I hope we can show you huge sparks soon.
« Last Edit: February 04, 2018, 12:31:29 PM by Tardief »

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Re: Tardief's DRSSTC
« Reply #56 on: February 04, 2018, 10:53:35 AM »
First I would like to say, really nice job on the topload, secondary and inverter box, it all looks very professional!

Let me guess, you have been testing at low input voltage?

I have described the problems with low voltage testing IGBTs here: https://highvoltageforum.net/index.php?topic=184.msg1203#msg1203
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Re: Tardief's DRSSTC
« Reply #57 on: February 04, 2018, 12:29:14 PM »
You are right. The Bus voltage did not go beyond 100V. Thank you!  :)

What do you think about the voltage drop?

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Re: Tardief's DRSSTC
« Reply #57 on: February 04, 2018, 12:29:14 PM »

 


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[General Chat]
davekni
Today at 03:59:27 AM
post Re: Kaizer VTTC 1
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
March 28, 2024, 09:15:11 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 28, 2024, 01:01:12 PM
post Re: Big Coil Build Log
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 28, 2024, 05:47:34 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
davekni
March 28, 2024, 04:45:07 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 28, 2024, 04:18:27 AM
post Push Pull VTTC
[Vacuum Tube Tesla Coils (VTTC)]
janno288
March 28, 2024, 01:10:08 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 27, 2024, 10:54:52 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
March 27, 2024, 11:53:42 AM
post Re: OCD Triggering Early + Low Output
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 05:14:36 AM
post Re: Is the UD2.7C under voltage lock out basically worthless?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 04:47:48 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 04:41:59 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 27, 2024, 12:04:34 AM
post Re: Super flat QCW simulation (does this look reasonable?)
[Dual Resonant Solid State Tesla coils (DRSSTC)]
toooldforthis
March 26, 2024, 11:08:14 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 11:07:20 PM
post Re: Is the UD2.7C under voltage lock out basically worthless?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 10:46:29 PM
post OCD Triggering Early + Low Output
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 26, 2024, 09:03:43 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 26, 2024, 08:46:59 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 26, 2024, 05:02:18 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 26, 2024, 03:16:03 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
Anders Mikkelsen
March 26, 2024, 01:41:49 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 04:48:22 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
March 26, 2024, 04:16:37 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 26, 2024, 04:16:24 AM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
davekni
March 26, 2024, 04:13:02 AM
post Re: CM400 Induction Heater
[Electronic Circuits]
davekni
March 26, 2024, 04:00:43 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
davekni
March 26, 2024, 03:19:18 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
March 26, 2024, 01:50:42 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 25, 2024, 08:05:02 PM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
Mads Barnkob
March 25, 2024, 07:41:29 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 25, 2024, 06:45:46 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 25, 2024, 05:44:25 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
Anders Mikkelsen
March 25, 2024, 04:47:17 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 25, 2024, 04:27:22 PM
post Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
March 25, 2024, 03:57:34 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
March 25, 2024, 02:06:41 PM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
KrisPringle
March 25, 2024, 04:43:25 AM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
davekni
March 25, 2024, 02:39:40 AM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
KrisPringle
March 25, 2024, 12:47:09 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 24, 2024, 07:36:32 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
Alberto
March 24, 2024, 07:27:24 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 24, 2024, 04:25:23 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 10:47:35 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 09:30:21 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 04:34:31 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 03:04:25 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 01:38:34 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 04:20:03 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
davekni
March 23, 2024, 12:54:30 AM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
davekni
March 23, 2024, 12:05:57 AM
post capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 22, 2024, 11:45:03 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
OmGigaTron
March 22, 2024, 11:30:09 PM
post Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
Mads Barnkob
March 22, 2024, 10:20:35 PM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Benbmw
March 22, 2024, 09:21:13 PM
post Re: What actually kills MOSFETs?
[Beginners]
AstRii
March 22, 2024, 03:37:11 PM
post What actually kills MOSFETs?
[Beginners]
FPS
March 22, 2024, 05:09:20 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 22, 2024, 03:57:54 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 22, 2024, 02:59:25 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 21, 2024, 06:31:42 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
rikkitikkitavi
March 21, 2024, 03:08:01 PM
post Re: [WTS] IGBT, Ferrite, Capacitors, Tools, PSU, Industrial components and parts
[Sell / Buy / Trade]
Mads Barnkob
March 21, 2024, 01:37:32 PM
post Re: Difference between these transformers
[Transformer (Ferrite Core)]
Alberto
March 21, 2024, 11:42:07 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 21, 2024, 04:09:14 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 21, 2024, 02:15:31 AM
post My Homemade Structural Analysis X-Ray Machine
[X-ray]
Luca c.
March 21, 2024, 01:35:40 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 20, 2024, 10:40:00 PM
post Re: Difference between these transformers
[Transformer (Ferrite Core)]
Mads Barnkob
March 20, 2024, 08:03:41 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Mads Barnkob
March 20, 2024, 07:51:57 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 20, 2024, 10:39:47 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 20, 2024, 04:09:59 AM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 20, 2024, 01:13:23 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Keybored
March 20, 2024, 12:45:16 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 20, 2024, 12:30:30 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 19, 2024, 11:12:24 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 19, 2024, 09:47:49 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 19, 2024, 09:44:19 PM
post Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 19, 2024, 06:52:09 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 19, 2024, 05:02:44 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
March 19, 2024, 05:01:41 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 19, 2024, 04:31:02 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 19, 2024, 03:59:54 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 19, 2024, 06:41:39 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
davekni
March 19, 2024, 04:05:49 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
OmGigaTron
March 18, 2024, 09:08:35 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
2020-Man
March 18, 2024, 09:07:35 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
Twospoons
March 18, 2024, 08:57:06 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
MRMILSTAR
March 18, 2024, 03:51:33 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 18, 2024, 02:59:46 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 18, 2024, 02:33:25 PM
post Can I Trust This Super Cheap Site?
[General Chat]
2020-Man
March 18, 2024, 11:02:12 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Twospoons
March 18, 2024, 02:36:11 AM
post Re: Best forum for vacuum tube amplifiers?
[General Chat]
Mads Barnkob
March 17, 2024, 07:42:55 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:15:14 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 05:05:04 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
davekni
March 17, 2024, 04:50:51 AM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Twospoons
March 17, 2024, 04:45:17 AM

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