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Messages - Mads Barnkob

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1
Hi donnersm and welcome to HVF

dexter pretty much hit all the nails right on the head, I also want to chime in on the onetesla driver should be avoided due to their low-component-count-design that for reasons of only selling more replacement kits was made without basic important protective circuits, like the OCD which is crucial for any DRSSTC.

I wrote a long DRSSTC design guide with many different topics, also about grounding: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/grounding-circuit-protection-and-emi/

I would advise you to start over with Steve Wards UD1.3 ( https://www.stevehv.4hv.org/new_driver.html ) or UD2.1b ( https://www.stevehv.4hv.org/leadcomp/UD2_1revB/ )

2
Solid state Tesla coils / Re: SSTC interruptor not working
« on: Today at 11:46:44 AM »
Do you have any unused IC input pins? You should tie all these unused inputs to ground, else you risk cross-talk inside the IC from EMI.

I assume you already double-checked your traces for errors etc.

3
Welcome to all new members on HVF, good to see you pop inhere and give a word or two about yourself.

@Johnf, I hope we get a share of your huge experience, that is a serious business end you are in where high voltage/current/frequency is actual in commercial use.

@Coupling, A portable handheld QCW is no easy task, looking forward to see how you execute that project!

@Twospoons, do you have any projects going on that we will get to see?

@Jeff B, the induction heater threads have really taken off with experiments with the, now so cheap, Chinese units, so good to see another chime in with more experience on using these.

4
Vacuum tube Tesla coils / Re: "LightningStorm" VTTC project
« on: Today at 11:40:18 AM »
Looks very good, but how is the creepage distance on the inside of that feed-through? The outer part looks to be fairly long and will be fine for 30kV, this is your tank capacitor rating, but not likely your circulating tank voltage, however it does look like its much smaller distance from the copper band to the mounting screws on the inside.

5
X-ray / Re: Siemens Polyphos 30 xray machine
« on: June 21, 2019, 09:08:16 AM »
Teardown of the Siemens Polyphos 30 X-ray head which contains step-up transformers, voltage multipliers and a rotating plate x-ray tube and a lot of oil!


6
Hi Shrad and welcome to HVF

Got any high voltage projects going on for the hobby or professionally?

7
Dual Resonant Solid State Tesla coils / Re: A dynamical arc model v2
« on: June 19, 2019, 10:43:32 AM »
Mads wrote:
Quote
...is there however any pitfalls or common causes in all 3 sets?
I'm not sure, what you mean here. Can you explain?

I was just wondering if there was something too much in common for the coils, so as the model is limited to coils generating 1-2 meter sparks and everything below and above gets more and more out of alignment with reality. I know you got no clear answer as you have no available data for this, but what is your gut feel about it?

I will take the model for a spin one of the coming evenings :)

8
Electronic circuits / Re: CRT hacking ideas....
« on: June 18, 2019, 08:22:23 PM »
I always loved the oscilloscope clocks, build a large version of it and hang it on your wall! http://oscilloscopeclocknixiecrt.com/

Not even hackday has something you didn't mention https://hackaday.io/projects?tag=crt

I seem to recall that someone, long ago, used CRTs as giant capacitors for pulse discharges, just be sure to put the damn thing in a enclosure if it decides to implode :)

9
Dual Resonant Solid State Tesla coils / Re: A dynamical arc model v2
« on: June 17, 2019, 08:54:41 PM »
Thank you for sharing your model data, looks very promising that you have it fit over 3 datasets, is there however any pitfalls or common causes in all 3 sets?

An arc simulation can be extremely useful. It can serve as a tool to choose primary and secondary tank parameters, will give a hint at achievable arc lengths, allows a guess at primary currents in a DRSSTC, can answer questions like "Are bigger top loads better than smaller ones", are higher or lower operating frequencies better, is there a choice between long and thin versus short and fat sparks, what is the effect of shorter or longer bursts, how does upper pole perform in comparison to lower pole operation etc.

Can the simulation do some calculations as well, depending on maybe some more input data, so it automatically calculates some parameters from the model you set up for a specific spark appearance? I know this sounds a bit the wrong way around, but could be a confirmation of the model.

The arcs temperature plays a big role in the calculation. At higher temperatures, the heat causes ionisation by fast air molecules bumping into each other. That begins at 3000-4000K. But also at lower temperatures, there is an effect, because the air expands, making it thinner and causing breakdown voltages to drop. There is also a time dependency there, since the expansion is not immediate but takes a few us. Short, but possibly not negligible. So to sum up, QCW data would be quite interesting.

This was something we discussed many years ago on 4hv, the differences between Kizmo's 1uF, Dalus' 1.5uF and mine 0.8uF, but only at a surface level of calling it low vs. high impedance and compare spark brightness/thickness. So while the low impedance also have lower losses in the primary circuit, shorter ring up time it might still be the preferable choice due to higher arc temperature from the start? Or is the "few us", more than a few, so a high impedance coil with long on-time gets in the same range anyway?

10
Dual Resonant Solid State Tesla coils / Re: Next Gen DRSSTC
« on: June 17, 2019, 11:13:33 AM »
Good job on the continued development of the software, looks real good with a debugging system and as Hydron says, we look forward to video from the show, hopefully you can get on a distance this time to capture how big it really is :)

11
Spark gap Tesla coils / Re: Where to buy Tesla coil capacitors?
« on: June 17, 2019, 10:46:56 AM »
I used to participate in group-buys directly from digikay, so we all could get a better price when buying a total of 500 caps: https://www.digikey.dk/product-detail/en/cornell-dubilier-electronics-cde/942C20S15K-F/338-3958-ND/1929493

I have a spare MMC, made from 942C capacitors that I would be willing to sell, depends on your location if it is worth shipping, it is the original for my large DRSSTC, but I never used it before upgrading to large GTO snubber caps. You can see if you scroll down to "14th May 2012" here: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-iii/

12
If 50 Hz is an absolute priority, which I assume it is as many electrical properties change effect as frequency goes up. I think you should look into getting a neon sign transformer, iron core and then use a range of resistors to limit the current to the level you need and you could use a variac on the input side to vary the output voltage.
 

13
YouTubes change from subscription to notification bell has had a huge impact on all channels, as they only themself estimate a average of maximum 30% of subscribers will actually get a notification due to people not updating their notification settings for all previously subscribed channels.

I myself have run through my entire subscription list and turned on notifications for all channels, as that was the reason I subscribed to them in the first place, I want to see the videos :) I know it can be used differently by browsing the subscription page and then only get notifications from a few select channels.

I made a little video about @Veritasium's algorithm analysis, @YouTubeHelp's notification system and analytics compared up against my own analytics.


14
VNTC, while I unfortunately does not have much to add, I just wanted to say I follow your discussions of theoretic operation with great interest. Uspring is sharp as usual :)

15
Capacitor banks / Re: Bought huge capacitors
« on: June 12, 2019, 09:48:22 PM »
One of my other concerns is that my neighbors would get mad at me (it'll probably sound like an explosion)

More in the region of gun shot, it does not get that deep boom from a huge displacement of a lot of air, it is a sharp metallic snapping from the intense and short lived short circuit energy discharge.

With some soft materials around, which can also act as blast shields, you can absorb a lot of sound. Even just a closed door to a garage will take most of it.

Also, take safety serious as Hydron says, these energy levels can remove your hand or any other flesh that becomes a conductor.

16
Electronic circuits / Re: Offgrid 48V solar to 24V battery setup
« on: June 12, 2019, 07:33:16 PM »
/>
 In part 3 I test the setup with all 3 panels connected and look at the performance over the last 8 days.

It all consists of:

3x 250W solar panels

1x Victron SmartSolar 100|30 MPPT battery charger

2x Norbatt 12V 150Ah batteries

1x 750W 24VDC to 230VAC inverter


17
Capacitor banks / Re: Bought huge capacitors
« on: June 12, 2019, 10:56:39 AM »
First, congratulations on a bargain buy there! I will buy them off you if shipping isn't a killer!

I got some good papers collected on high current discharges, especially the one on erosion is interesting when it comes to designing spark gaps: http://kaizerpowerelectronics.dk/tools/file-archive/?drawer=application_notes*pulse_power

One of these capacitors is obvious choice as DC bus capacitor in a large DRSSTC, as in serisouly large, multiply 600-1200A IGBTs in parallel, 5-6 meters tall, so might not be the project you are looking for. Or build your own electric car.

Ring launchers, can crushers etc. utilizes lower voltage better as you have less flash-over of the work coil, so there is always that.

18
You should visit the websites of ferrite core manufacturers, many of them have excelent guides on choosing the right core for your application. F.ex. here is a short guide from mag-inc.com: https://www.mag-inc.com/Design/Design-Guides/Transformer-Design-with-Magnetics-Ferrite-Cores

19
Solid state Tesla coils / Re: Flat Secondary Coil on PCB?
« on: June 04, 2019, 09:04:46 AM »
You could stack multiply PCBs as its done with planar transformers where the PCB are connected with VIA and the primary/secondary are interleaved for highest possible coupling.

I know this might not work as well with a high voltage output like this, but at least it is a common used practise to make these electronic layer cakes.

20
Solid state Tesla coils / Re: SSTC Design Questions
« on: June 04, 2019, 09:00:11 AM »
You show insight, you can use the available tools and you ask specific questions to your design. This is the right approach to get help on a forum like this!

Do not worry about being 15, I wish I started with electronics that young and not first at 25, different age, different problems :) Money is always an issue, spend some time on setting up search agents / saved searches on ebay so you get emails for new listed items that you look for. Specific IGBT, MOSFETs, Capacitors, etc. makes it easier to catch a good deal.

I am glad you found help from my website, also be sure to check out loneoceans website, he wrote some good SSTC guides.

Overall your design looks fine, you can omit the primary capacitor in JavaTC as it has no purpose for a SSTC. You can experiment with more primary turns and higher coupling, if you want to lower the primary peak current.

Looking forward to see your building process.


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