Hello Mads and MRMILSTAR 

Thank you for your interest and kind words. After experimenting with both, halfwave and fullwave setups I have to say I would rather go the halfwave way. Fullwave didn't show as much better performance as it needed more material.

@Mads:
Power draw was just about 8kVA for the whole setup, so about 4kVA for each fullbridge/transformer. The transformers could make a lot more. 6kVA is the continuous rating for each of them. For short periods they could make much more, but I have not much more power from the line and I'm not sure what the fullbridges really can perform. They get a bit warm after each run.

Arc distance was about 70cm in the shown video. There is not much more possible, because of arcing between the diode strings. About 80cm ignition distance is the absolute maximum and this is not a safe operation anymore.

I don't know the voltage. According to measurements in the first stage of one tower I estimate about 400kV max.

Just for long arcs or got a plan like lifters and experiments?

The setups were just for fun  The material was given to me by a friend who works in the x-ray industry. I just wanted to see, what's actually possible without using oil (of course for the transformers i needed oil baths, but no oil for the multiplier setups).

Wish you all a nice week.
Best regards
kilovolt

A beautiful project! Looks very professional and neatly finished. Thank you very much for sharing!

Best regards
kilovolt 

Hello Dave

Thank you very much for your explanations and math regarding the power factor of my setup. Very interesting thoughts. I never simulated the situation on my own, because I'm not familiar with all these simulation porgrams on the market  LTSpice seems the standard tool for this, right?

The measurement with 50Ohm termination and 50Ohm shielded cable is a good idea. Maybe I'll try out some day.

Thanks for sharing your multiplier setup. Nice design and cool housing! Good that you have optimized your device for safety.  If you carry out experiments directly with people, this is certainly the right way.

Do you also build Tesla coils? I've been building a QCWDRSSTC for a few years now, but there have been a lot of setbacks. But now it seems to work slowly. Besides, I still have good material for a VTTC. Unfortunately, as a family man, I lack more and more time for new craft projects.

Best regards
kilovolt

Hello davekni

After the bridge rectifier there is a cap with 3300µF / 450V.

The diodes have to handle not only the discharge currents, but of course also the charging currents, and these will be much higher. In another forum someone had simulated the circuit, and the peak currents were quite high, several amps if I remember correctly. I also tried to measure the currents with a shunt and a battery driven scope at the lowest stage. But you couldn't tell for sure what was actually measured and what was only interference.
I am pretty sure that the diodes are the weakest link in the chain and I would definitely not save your money there. In the beginning I also had problems with internal flashovers between the stages. When that happens, the load on the diodes becomes very high. I strongly recommend to use 100mA diodes, but of course everybody has to know that for himself ;-)

250kV is a nice voltage ;-) How did you build the setup? Do you have pictures?

Best regards
kilovolt

Klugsmith:

A ballast on the transformer input is not much help until the output current is reduced well below 0.25A.  That's roughly the 50/50 lethal current at 60Hz when flowing from one hand to another (or to a leg).

You mean 0.025A, right? Because 0.25A (250mA) is really deadly, no doubt!

Best regards
kilovolt

Hello Steve

No problem, I didn't take that as a criticism. Apart from that, criticism is also very welcome, because it is helpful for improvements.

The upper capacitors are partly mounted a bit crooked. It is due to inaccuracies of the balls.

The resistor chain consists mainly of 10kOhm / 11W resistors and contains about 800kOhm. In principle you only have to make sure that the peak currents of the capacitors cannot destroy the diodes, so it is sufficient to dimension the resistors in a way that the surge currents of the diodes are never exceeded.

Best regards
kilovolt

Hello Steve

Nice specs for your multiplier circuit! Looks great. Please don't forget to share here your setup 

Best regards
kilovolt

I have worked successfully with both capacitor types. But the fact is that doorknobs can bear much higher currents than any ceramic filter capacitor. Especially in the lower stages there are sometimes massive current peaks, which can cause cheap capacitors to burst.

But doorknobs have another advantage: With the screw connections the construction is more stable and better, especially if you want to add toroids or balls for field shaping.

This is my latest bipolar Setup with doorknobs, it puts out more than 70cm arcs:


If you need some ideas, have a look at my website. I presented three cascades, one with 100kV, one with 180kV and a bipolar with up to 700kV open circuit voltage:
http://kilovolt.ch/kaskade.htm
http://kilovolt.ch/kaskade_180kv.htm
http://kilovolt.ch/kaskade_bipolar.htm

Best regards
kilovolt

Hi folks

This is my first post in this forum, so please bear with me if something doesn't quite fit the form.

I live in Switzerland, am 44 years old, married and have two children. Professionally I work as an electronics technician in a thermometry laboratory and repair measuring instruments. I have been carrying out high-voltage experiments as a hobby for almost 30 years now, but unfortunately I don't have much time left for this anymore.

Some people on youtube have asked me to present my bipolar voltage multiplier here in the forum.

The setup consists of a full bridge with two Semikron SKM200GB128D bricks, a ferrite X-ray transformer and two high multiplier towers, one for positive high voltage, one for negative high voltage. Arc ignition length is up to 75cm

Here first the electronics for the control:



The following pic shows the oscillator with bridge driver, built from a TL494, followed by a modified steve ward DRSSTC driver. Frequency is around 25kHz:



X-Ray transformer with ferrite core. It's been running in a silicon oil bath.
:


Size comparison of the X-ray transformer with an AC flyback transformer:



With the white capacitors in the picture the two cascade towers were built. They are each 1.7nF / 2.4nF with 50kV:



A first test setup of the x-ray transformer with a Jacob's ladder:



And a video of such a test:

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And here the two multiplier-towers, each consisting of 7 stages with 2.4nF and 1.7nF / 50kV caps. The brown caps at the top were replaced later with white Murata caps, same as the ones below.



The resistor chaines in the foreground of the videos (see below) are only to protect the diodes from sudden capacitor discharges. They consist of many 10kOhm / 11W and 10kOhm / 17W power resistors and they get rather warm. The setup deliversan openloop voltage of several 100kV and a short circuit current of about 35mA.

Some pics of discharges:

















A friend of mine shot a few pics with better quality:







Some videos can be found on my youtube channel:
https://www.youtube.com/user/hvpower

For example this one:

Best regards
kilovolt