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Messages - Mads Barnkob

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1
A pulse discharge with a peak current of 50,000 Ampere is send through a iPod Nano 2nd generation 4GB Pink model. This is a belonging of my back-then girlfriend, now spouse ♥. I did try to explode this on a earlier occasion in 2014, video should be somewhere on the channel in pulse power playlist :)


2
In regular automation PID we call that "gain scheduling" and is often used in process startup scenarios or to run with different settings in winter/summer.

You could also look into feed-forward PID if you want a short of "prediction" to not solely rely the process value changing, but you take into account the change of the input variable that will affect the process value.

3
The pulse discharge videos posted in this thread is a part of a series of explosive videos of old phones and electronics. The high voltage pulse capacitor bank, charger and trigger mechanism can be found with pictures, more videos and schematics here: https://kaizerpowerelectronics.dk/pulse-power/4000-joule-capacitor-bank/

A pulse discharge with a peak current of 50,000 Ampere is send through a Nokia 6230 mobile phone. A mobile phone from the era of indestructible handsets, a piece of electronics that would never let you down and yet here it is to die in a fiery explosion of hot-as-the-sun plasma discharge!


4
Sell / Buy / Trade / Re: LCR meter recommendation
« on: June 17, 2021, 08:23:57 PM »
Many years ago I just go by with one of the blue cheap Chinese LCR meters, but after Dave reviewed the DE-5000 LCR meter, I figured it was time for an upgrade. It has served me well ever since.

/>
Hi,

the best one I ever used was a HP4263B at my university.
However they are insanely overpriced even when broken.

I got myself a Deree DE5000 and I'm very happy with it.
It has proper Kelvin connections and a wide range of functionality.
I did some testing / comparing with other meters (including the HP) and was pretty surprised by its accuracy.

I tested the DE-5000 up against my broken and taped together blue Chinese LCR meter and was surprised that the cheap one was quite accurate as well!

5
I understand it now, it was just the missing link between your experiment being a replica of the subsequent experiment as A.M.Worthington describes as

Quote
"By wetting the surface of a smooth sphere we can always convert a smooth or "sheath" splash into a rough or "basket" splash. Thus when the ivory sphere (which when dry and well-polished gave, with a fall of 60 cm., the splash of Series XI, p. 97), was allowed to fall wet into the liquid, all other circumstances remaining the same, the splash of Series XIII, p. 103, was obtained, which is entirely different from the first. The wetting was effected by dipping the sphere into the bowl of milky water into which it was to fall, and then shaking off as much as possible of the adherent liquid, but in all cases the splash quickly became unsymmetrical, probably through the liquid, during the fall, drifting to one side of the sphere."

Just as Dave, I thought you replicated the hydrophilic/hydrophobic experiment, because from not knowing the papers beforehand, its counterintuitive that a wet sphere is going to act hydrophobic :)

6
I am not quite following your experiment here.

The paper you reference is talking about chemical processes to make different material spheres more hydrophilic or more hydrophobic, not the difference of a wet and dry sphere. But your experiment is to show that a wet sphere is the same as a chemically treated more hydrophilic sphere?

To improve your high speed video, you should get some 250W of LED lighting, I build one myself from 5x 50W LED COBs ( https://kaizerpowerelectronics.dk/general-electronics/250w-led-flood-light/ ), that I use for high speed video recording :) I could try to replicate your experiment with some more details on all the parts of your experiment. Its a little thin to just drop a video with no explanations...

7
Yes that is called cascaded. But that is even harder to control, due dead time from the first is likely a 2.order system and adding that to another PID will result in a 3 or 4.order system. Tuning gets harder as change on any of the PID affect the process, but its hard to evaluate on which PID parameters is optimal.

8
The video of the teardown and reverse engineering

/>
The teardown of a Fujifilm FCR XG-1 X-ray image scanner for computed radiography became the basis for this reverse engineering project. You can see the teardown of the entire Fujifilm FCR XG-1 machine here and the teardown of the polygon laser scanner module here.



A short introduction, computed radiography is based on reusable phosphor imaging plates, the plate is used instead of film. The x-ray exposed imaging plate is scanned with a red laser timed to a photomultiplier tube to read out the single pixels on the imaging plate. The returned light from the scanning laser has a different intensity dependent on the amount of absorbed x-ray energy and thus the photomultiplier tube can translate this into a 12-bit grey scale resolution.



The photomultiplier assembly is mounted on a sheet metal holder with the tube going out through a grounded layer of mu-metal for shielding the tube from electrostatic interference. The PCB has a output amplifier and power supply part on the left side of the socket and a high voltage power supply module on the right side. The Fujifilm PMT12A board has two connectors, which both went to the SCN12A card in the main computer of the Fujifilm FCR XG-1 scanner. CN1 is a 34-pin flatband pin header and CN2 is a coaxial output signal from the output amplifier.



The output amplifier is shielded, the differential amplifiers on the board is using +12/-12VDC from a LM2940CT and LM2990T regulators, as the +15/-15VDC input goes directly to the HV module. The Hamamatsu C7775 from 2007 does not have any datasheets available online, but browsing through the newest modules shows that they still make a C-series 5 pin HV module, that turns out to use the same pin layout as its earlier modules.



From the pin 5 of the C7775 comes the negative high voltage supply for the photomultiplier tube. The cathode of the tube is connected to the 4 blue capacitors that is tied to ground, to ensure a stable voltage at the start of the high voltage chain.

As more electrons are accelerated from the first dynode to the next and so on, less current is needed to drive them on, this is done with a pure resistive divider network between the dynodes, but it has its drawbacks with loss of linearity and output deviation in the region of 10-20% at high output current. A improved divider network uses capacitors to insure stable supply voltage at peaks and even individual power supplies for each dynode can be used to do the same.

From the photomultiplier tube handbooks from Hamamatsu, the requirements to a PMT high voltage power supply reveals that quality control is needed to achieve a line/load regulation at +/- 0.2% and ripple noise/temperature drift at 0.05%. The Hamamatsu R1848-07 photomultiplier tube is a 10-stage 14-pin version that can use up to -2500V dynode supply.

It took a great deal of cutting with a new sharp box cutter, to get in-between the acrylic light guide and the blue glass filter window of the photomultiplier tube. It took about an hour to free the two parts from each-other, without harming tube or light guide.



Schematic from the service manual. I marked the needed pins for the module to run without the computer/scanner analog-to-digital conversion modules.



After having seen the connection diagrams in the manual, I was confident to test the module with power on. I was using a power supply with +15 VDC, -15 VDC and GND. I shielded the window of the PMT with aluminium foil to block out any light. A powered up photomultiplier tube that is flooded with light risk burning holes in its dynodes! Protect and treat your PMT with great care.

Judging from the computer power supply of +5 VDC and the datasheet for the Hamamatsu C9619 high voltage power supply, I tried my luck with putting +5 VDC on the input pins I had located. It was also mentioned in the manual that the module has a "high voltage hardware ok" and "high voltage software ok " signal, that both had to be high for the high voltage to get active. It turns out that the input pin 5, labelled HVSH is "High Voltage Software High". When +5 VDC is applied to pin 5 the high voltage supply is generating -510 VDC.

The output signal is sine wave like waveform with 1, 2 or 3 peaks, depending on the signal strength. The highest peak was up to 70V, but I am not sure that the scaling was correct from these measurements. I unfortunately lost all my oscilloscope screenshots  to a defective USB stick :(



A photomultiplier tube can be a very sensitive instrument, depending on the negative supply voltage for the dynodes. From the PMT handbooks graphs show that common PMT behavior the amplification is highly dependent on the high voltage supply. The -510 VDC this module uses gives a mere amplification of 40.000 times. This level of amplification is sufficient for the computed radiography, but for a more interesting task like radiation detection with a scintillation crystal, it is suggested that -1 to -2 kV is needed for a amplification of 20.000.000 times and up towards 1.000.000.000 times.





9
General Chat / Re: Photonicinduction is back!
« on: June 08, 2021, 12:32:54 PM »
Its great to see him back :)

I had two videos planned to tribute his madness of overvoltage, I will do them anyway...


Mads could we ask him to join hvf? :D

Ask him all you want, but I must admit that not many of my invitations are fulfilled with people signing up :)

10
General Chat / Re: Photonicinduction is back!
« on: June 07, 2021, 08:38:05 PM »
Its great to see him back :)

I had two videos planned to tribute his madness of overvoltage, I will do them anyway...

He had some video? go viral in march/april that netted him some 500K views a month, maybe that got him motivated! https://socialblade.com/youtube/user/photonvids/monthly

Being gone for 3 years with his view numbers and if he was monetized, I guess that would have made him some 8-15k$, so it was a wise choice to get off the internet and work instead :)

11
I like the idea of making it a PCB that the Tivo plugs into, I did not think of that!

I think some of your resistor values will need tweaking when running on 5V, I had to change some of my initial design as it was too high values for my LEDs, but yeah that differs from build to build what parts are used and how bright you want something to be that sits in a dark room.

You could add a row of pin headers for external interrupters and a DIP switch row to select which is used, might not be for everyone, but I am making that on my build. Since optical outputs are money, might as well make them useful in more ways :)

My final exam was Friday two days ago, im done with studying next work, which I have been doing for 3 years, so I can finally pick up on my DRSSTC show controller again :) https://highvoltageforum.net/index.php?topic=1417.0

12
For all these questions, I wrote a very large guide on designing a DRSSTC. It is from a practical point of view with the minimum required math and a lot of best practices / experimental best results.

All at https://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/

Among the online tools is also JAVATC that I recommend using.

13
I think you can get the "best" idea from BPS.SPace on youtube or this paper I just found on google: https://project-archive.inf.ed.ac.uk/msc/20172139/msc_proj.pdf

The conclusion on the paper is that the basic PID presents the best landing performance, but highest fuel consumption. It was also my own idea that they were using some kind of model prediction or gain scheduling. I doubt a PID with 3 static settings could do the job :)

There is also a lot of speculation and interesting links to papers in this thread: https://www.reddit.com/r/spacex/comments/4ewrpq/why_classical_control_for_the_rockets_control/ f.ex. to JPL G-FOLD system descriptions: https://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4193.pdf

14
General Chat / Re: 1000:1 CT
« on: June 04, 2021, 07:59:36 AM »
It comes down to what you have available of tools, wire and time you want to spend on winding it. Using two cores is so that you can wind 2x 33 turns instead of 1000 turns on a single core, saves time at a small expense to an extra core and maybe a tad lower performance.

This is properly one of the best design guides and practical experiments on GDTs for hobby use that existed... because its gone from 4hv :( It only lives on the internet archive now: https://web.archive.org/web/20200220100634/http://thedatastream.4hv.org/gdt_practical.htm

15
Awesome Mads  :D

Just imagining what it would sound like (and look like) if we could all get together in one BIG room and get all of our various coils playing the same tracks at athe same time!

Would need some serious ear protection .... but ... what fun that would be  ;D ;D ;D

I would love to attend a Teslathon and many years ago it was discussed to arrange something in Germany, to make a European Teslathon. But time, logistics and finding enough people with large coils that want/can transport it, is a tough enough job in itself :) Unfortunately we are all too scattered around the world.

16
Example - Changed the Way You Kiss Me, on a Musical Tesla Coil


17
Beginners / Re: profdc9 ud2.7c THT question
« on: June 02, 2021, 10:57:17 PM »
I have not yet had any problems using MKT/MKP only on DRSSTC drivers, instead of ceramic capacitors, on the through-hole drivers.

Remember that many hobby designs are not based on optimum choices, but rather what you have in stock already :)

18
Very nice control panel / cabinet.

How much PF do you gain from engaging that large choke?

The big choke is to provide current limiting for the pole transformer, currently set at 26 amps. The PF correction is accomplished with a bank of capacitors contained within the black box in the back of the cabinet shown in the video. I haven't tried to compute the PF but when I engage the PFC capacitors, the current draw from the wall reduces by about 4 amps.

So 4 A reduction at 26 A, gives some 1/6'ish reduction, corresponds well with the passive PF I can get in a DRSSTC. Adding a variac can give it some 10-15% PF improvement :)

19
Electronic Circuits / Re: Magnetic spin top drive
« on: May 31, 2021, 07:51:54 PM »
This is a great little project, I will make this with my kids :) They love spinning tops in the first place, so making a circuit to help them keeping it spinning is going to be a hit.

I must have some of those fan motors around... I know they are somewhere...

20
Electronic Circuits / Re: Flyback feedback winding weirdness
« on: May 31, 2021, 07:48:21 PM »
It looks like you are charging something up with a inductive kick, that then avalanches after 400ns and then has a ringdown at 6 MHz. From the frequency it sounds like parasitic components.

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