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Messages - Mads Barnkob

Pages: [1] 2 3 ... 62
1
High Speed Filming / Re: FPS4000
« on: February 25, 2020, 11:29:58 AM »
Without the PC software, you can still transfer the internal memory to the SD card, it just takes forever! At least that is what I can do on the FPS1000HD

Please do post some pictures of the FPS4000, it is even more a myth than the FPS1000 :)

I just finished building a 250W LED flood light for high speed filming, part 3 of my video series will be a flicker test and some other measurements: https://highvoltageforum.net/index.php?topic=954.0


2
Anyways, is -30V going to kill my IGBTs or should I not worry about it?

http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/igbts/

Quote
Maximum Gate-to-Emitter Voltage (VGE)

The gate voltage is limited by the thickness and characteristics of the gate oxide layer. Though the gate dielectric rupture is typically around 80 volts, the user is normally limited to 20 or 30V to limit current under fault conditions and to ensure long term reliability.

It is normal practice to drive IGBTs at +24VDC with the Steve Ward universal driver and clones of it that most use. The reason for the gate voltage limit is not so much for protecting the gate itself, it will first break down at some 80 Volt. Higher gate voltage means higher currents can be conducted through the Collector-Emitter. We take advantage of this by pushing the gate a little over its rated voltage to allow us to conduct higher currents through the IGBT, at the cost of higher switching losses. As explained by manufacturers in the following.

It is important to note however that IGBTs exhibit relatively high gain even at high gate-emitter voltage. This is because increasing the flow of electrons by increasing the gate-emitter voltage also increases the flow of holes. The gain of a high voltage power MOSFET however is very insensitive to gate voltage once fully on.


3
Spark Gap Tesla Coils (SGTC) / Re: Tesla coil Toroid Aluminium tape benefit
« on: February 24, 2020, 02:53:13 PM »
Please attach a picture of your topload for a proper assessment of its useability.

Adding tape, if smoothed out completely, will give a more even surface and make the topload able to store higher voltages before discharging to air.

The side effect to many sharp edges is corona losses and you would most likely see shorter sparks as a result of heavy corona losses.

4
It is an interesting thought, it is well known that some manufacturers only make one base model and then the "upgrades" are either done via software if all the hardware is in place or made by adding a bit more hardware if all the software is in place.

Can you somehow check if the BIOS has any settings for the expansions? It could be that you could flash it to a T620 plus BIOS version and add the port.

I inspected a few pictures from here: https://www.servethehome.com/hp-t620-plus-thin-client-and-firewall-vpn-appliance/ and it does not seem like there is other components missing, sounds like a fun hack but a really far shot!

5
This is part 2 of my #diy #led flood light that is going to be used for high speed video filming with the FPS1000HD camera. It should be able to deliver around 20000-25000 Lumen.

Here I modify 3x HP server power supplies to deliver 36VDC, add fan controllers for the heat sinks and box it all up in a "very compact" box that can be handheld.


6
The whole idea of a gate resistor is to have it as close as possible to the gate of the IGBT/MOSFET in order to quench ringing between input capacitance and parasitic inductance in the gate drive circuit.

You can not just move it to the primary side of your GDT and expect the same function. What you have done is entirely different.

I can not quite make out from your pictures, which wires goes where, but generally you have way too long leads going everywhere, have everything as short as possible. Everything else is just asking for even more inductance and "antennas" to pick up noise from spark EMI.

Your GDT is not killing your IGBTs, your changes to the gate drive circuit and far-from-optimal wiring is killing your IGBTs

7
Voltage Multipliers / Re: Help!Capacitor that burns out after a while!
« on: February 18, 2020, 04:12:11 PM »
It sounds like you are using a capacitor beyond its voltage, current or frequency specifications. Please provide all details about the application and capacitor.

8
Solid State Tesla Coils (SSTC) / Re: How can I make my driver better
« on: February 18, 2020, 09:02:23 AM »
Search for "single MOSFET Tesla Coil" for some of the most basic circuits that can actually put out some real sparks.

I would however recommend that you look into building a Steve Ward Mini SSTC with a half-bridge: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-i/

9
Any reason you chose not to run with off the shelf LED drivers? They're cheap enough, though you wouldn't want to pick on price alone.

When I built some LED lighting for my wife's art studio I spent a long time delving into the various LED offline driver chips out there, and finally concluded I might as well buy a decent OTC driver. These were 20W lamps made with YujiLED's 98CRI LED chips. Gorgeous light - noticeably different from standard LED. Very white, looks just like sunlight.

The best offline topology appears to be a 2 stage approach, with a  boost PFC followed by a constant current buck.  Most of the combined PFC+CC chips look like they have a lot of ripple in the output as a result of the crude PFC, but they're meant for consumer lighting where BOM cost is everything.

Exactly the reason I went for building my own, all are designed for consumer lightning and those that are designed for high speed filming, well, I can not afford to throw money at that :)

10
nice setup here  :)

now let's build the power supply 
what topology will you use for PSU, knowing that there must be 0 ripple at the output to avoid flicker? :)

Something used, stable and without a doubt dangerous to the LEDs.

Server power supplies and if it all ends up in burned LEDs I will make a part 3 of 2 ;)

Ripple check, I forgot to include that in part 2, so maybe there is something for part 3, I will see if I can borrow a luxmeter somewhere as well for intensity measurements.

11
   I wonder how this would work for a short duration flash, say one microsecond (uS) ? If driven by a 1 uS current pulse would the LED illumination last for 1 uS or would it trail off giving a longer exposure ? I have tried making an air gap flash, but the energy was too low and the flash was not very bright. An LED flash would work at much lower voltages.

DIY LED flash is a thing and you are lucky them someone did a lot of hard work and documented it all :)

http://td0g.ca/2019/05/14/edgerton-a-high-speed-led-flash-diy/

12
Negative connects to the outer connector, positive to the inner connector (both are bridged as you also noticed) and resistor connects from positive to middle.

I hope this picture can help you :)


13
Light, Lasers and Optics / DIY 250W LED Flood Light for High Speed Filming
« on: February 17, 2020, 10:58:17 AM »
/>
This is part 1 of my diy led flood light that is going to be used for high speed video filming with the FPS1000HD camera.

It is being built form 5x 50W LED COBs mounted on old Pentium4 CPU coolers.

I got no affiliation with these sellers, but it is where I bought my parts:
50W LED COB chips: https://www.ebay.co.uk/itm/50-W-Watt-LED-Chip-kaltweiss-24-40-mil-4500-Lm-6000K-kw-COB-Fluter-Flutlicht/162464897645?ssPageName=STRK%3AMEBIDX%3AIT
Reflector seller1: https://www.ebay.co.uk/itm/50W-70W-100W-120W-COB-Chip-LED-Lens-Fixed-Bracket-50mm-Reflector-Collimator/112785049513?ssPageName=STRK%3AMEBIDX%3AIT
Reflector seller2: https://www.ebay.co.uk/itm/50W-70W-100W-120W-50mm-Reflector-Collimator-COB-Chip-Fixed-Bracket-LED-Lens/263468105919?ssPageName=STRK%3AMEBIDX%3AIT

14
Cool integration of a analogue instrument into sparks.

Is the sound hard for the DRSSTC to reproduce since a sax is often played with overtones, pardon me for not knowing what he really played, I am close to tone-deaf :)

Would some filtering to the piezo circuit help on the small weird sparks and plausibel also give it some more single note play to it?

Share all the circuits you want, would like to see it. On that note, could you please update you PCB pack thread with a link to this, as your drivers are now tested, which you wrote they were not, back then.

15
General Chat / Re: Help with Van De Graaff Generator Build
« on: February 13, 2020, 10:14:27 PM »
if anbody is interested they have large stainless garden orniment spheres on ebay. I found two that are about 400 mm on ebay. I also googled it to. they are a little pricy but I was able to stack 2 of them and get 3ft arcs. you can get them relitively cheap for a table top VDG

They are called "gazing balls" or "pond balls" if anyone is wondering how to find them

16
Sell / Buy / Trade / Re: WTB [EU]: Cellular Sector Antenna
« on: February 13, 2020, 08:53:14 PM »
I might have a Kathrein 900/1800 MHz antenna, 14 kg and about 1.5 meter long.

It is actually only around 50€ to ship with GLS

17
General Chat / Re: Help with Van De Graaff Generator Build
« on: February 13, 2020, 10:53:32 AM »
I am following your project and will use some of your ideas and solutions in building my own :)

I like the idea of 3D printed parts and the brushes, is the ends sharp/pointy enough to be used as spray?

To get an idea of my project, I got a large top terminal about 80 cm in diameter, spun aluminium "toroid" shaped as a mushroom.

18
This is the first upgrade for the Anet A8 3D printer. A new powersupply from a HP server will be a fire-hazard reducing upgrade compared to the original undersized and over-specified power supply that came with the printer.

12V @ 62A is of cause much more powerful that needed for the printer, but this will keep the fan spinning at minimum speed. You do not want to be in the same room as a server power supply running at full current output with maximum fan spin. It is like a jet engine.


19
Electronic Circuits / Re: Prototyp construction techniques
« on: February 07, 2020, 08:48:46 AM »
@ Weston, Wow, the amplifier looks really clean and has a very appealing symmetry to it. I'm always amazed at how well circuits like this are able to perform, if done correctly.

@ Mads, Your'e right, the prize is quite high, even when compared to most chinese PCB houses but as mentioned earlier, its kind of a lost art and just fun to do... atleast I think so.
However your home etched boards look really awesome, how do you do it, toner transfer?

@ petespaco, That sounds really interesting. However your links 404s for me, maybe I'm doing it wrong?  :-[

I also dream about building audio amplifiers in the same way as Weston, its a simple and effective method with a good ground plane.

I use toner transfer method, explained how i do it here: https://highvoltageforum.net/index.php?topic=59.0

I corrected the link to Pete's document, it was missing the [_url_] tags and since the the filename has whitespaces, the forum just cuts at first white space when auto-identifying links. Never put white spaces in filenames on the internet ;)

20
Electronic Circuits / Re: Prototyp construction techniques
« on: February 06, 2020, 02:13:55 PM »
I used protoboard/stripboard/veroboard in the beginning, but the prices on it was not appealing compared against buying 10kg of single sided PCB "scrap" from a electronics part vendor in Denmark, a promised minimum size of 100x200 and often up to A4 size made this a good deal at almost the copper content scrap price.

One of my early veroboards for a VTTC: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-vttc-i/


All my projects could be called prototypes, I never ordered factory made PCBs with silkscreen.

My first DRSSTC driver: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-i/



My second DRSSTC driver: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-ii/



My third DRSSTC driver: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-iii/



My fourth DRSSTC driver: http://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-iv/



 

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