HF switcher supply construction and voltage multiplication

This forum is for specialized infomation important to the construction and safe operation of the high voltage electrical supplies and related circuitry needed for fusor operation.
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

This is an illustration of what I'm talking about
This is an illustration of what I'm talking about
Victor Gonzalez
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Re: HF switcher supply construction and voltage multiplication

Post by Victor Gonzalez »

Pierre_Thourault wrote: Tue Mar 03, 2020 11:40 am
circuit elect.JPG
This circuit has everything, the problem will be making it work like it's idealized. You will have to face many problems. example: what type of core will you use on your inductor? Ferrite saturates easily with DC, Iron-Powder? How will you design your HF transformer? working nearly in saturation is good short circuit protection, etc....

I would use a chip like UC1825 or 3825 and IR2113 driver on the power transistors for the H-Bridge and buck
John Futter
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Re: HF switcher supply construction and voltage multiplication

Post by John Futter »

Victor is on the right track
I see that you have not provided any protection for the transistor bases or collectors.
Any transformer with a large ratio will have relatively high leakage inductance which will cause reflected high voltage artifacts into the primary this via capacitive coupling so there is no ratio reduction like the turns ratio.
all of this is known by EE's -hence this is why high voltage high power supply design is considered almost a black art.
I see your circuit is of the self oscillating type that is usually suited to output powers of up to 100 watts..
I also see that there is DC coupling to the transformer primary --this leads to early saturation due to core walk from assymetrical DC drive conditions
As already stated it is far better to use a proper driver chip and series resonate the primary with a series cap to stop core walk saturation
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Thanks a lot for your answer Victor and John,

I need to look up what you have suggested me then I will surely come back to you with an improve design.

Sum up of what you have told me ( please could you tell me if there's something I misunderstood )

- It seems like I have a problem with how to drive the H Bridge and buck so you suggest me to do it with a chip like UC1825 or 3825 and IR2113 driver on the power transistors.
- Also I need to work on the inductors I will use
- there is how to make a proper HF - HV transformer with a high turn ratio too
- and finally I need to protect the transistors

I have few questions :

- "there is DC coupling to the transformer primary " I dont get it because the H bridge outputs AC ?
- I have thought about why HF reduces the size of the components but I still don't understand so could you please explain me why I have precisely decided to do this kind of circuits xD

There is a lot of work but at least I'm helped so thanks again ;)
Pablo Llaguno
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Re: HF switcher supply construction and voltage multiplication

Post by Pablo Llaguno »

Not very familiar with electronics as advanced as what you want, but perhaps this thread can give you some ideas viewtopic.php?f=11&t=13134

Good luck
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Thank you very much Pablo for this link !

It cleary answers most of my questions and is very well structured : perfect for someone who doesn’t know a lot about electronics like me.
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Hello everyone
Since i don’t have school due to a certain viruse I can focus on this.
So i was thinking why not use a driver from a tesla coil like a DRSSTC and maybe also use the secondary rectified. Has it already been made ? Or is it stupid for some reasons ( maybe it disturbes the resonant frequency so that’s why you can’t use the secondary)
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Re: HF switcher supply construction and voltage multiplication

Post by Jon Rosenstiel »

Pierre,

Maybe this will help...

viewtopic.php?f=11&t=4569&p=29680&hilit ... ing#p29680

JonR
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Thank you Jon,
I have read the web site of steve Ward but I don’t understand the sine wave. How the LC circuit resonates if the IGBTs are off ? because the inductor and the caps are in series.
I think I’m going to build this kind of driver which can be used also in a TC since I am very interested in building a Tesla Coil ( playing music with a TC must be incredible) and as I don’t have many bucks to spend, building the same driver for the TC and the fusor will allow me to spare money.
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

I think I understand how the circuit resonates: is it thank to diodes across IGBTs ? Also I’ve read that the caps are aimed to smooth a peak of voltage but where does it come from ?
I’m gonna put a screen of the circuit so you may help me more easily
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

772A5E93-6B1B-4534-9616-7DD6C9940DCA.png
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Hello everyone,

So after many times trying to understand the Capacitor Charging Power Supply (CCPS) using the Series Load Resonant (SLR) of Mr Carl Willis. I've decided to come back to a more classic design.

However I don't give up on the CCPS as I will do my best to understand it (by the way if anyone reading this can help me or has done this cicuit, you may email me via the forum ) so I'm trying to contact Mr Carl Willis, Mr Steve Ward and Mr Marco Denicolai ( if you know them may you please inform them that I email them since I have used very old email address I'm not sure they will get my email). For me, I'll learn more and more about this circuits.

But anyway, the goal of using the same driver for my future DRSSTC ( Double Resonant Solid State Tesla Coil ) and my future fusor is achieved : I am gonna send a picture of the circuit. Please tell me if you have suggestions, remarks or if you spot a mistake.

I hope everyone is fine in this period of pandemic !
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Circuit 3.PNG
John Futter
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Re: HF switcher supply construction and voltage multiplication

Post by John Futter »

again no base or C,E protection
probably more silicon sacrifice to the gods of high voltage
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Bob Reite
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Re: HF switcher supply construction and voltage multiplication

Post by Bob Reite »

LOL! Reminds me of the very first AM solid state transmitter. No protection for the output devices. The MW-1A model got the protection diodes. I suggest that you do the same.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Hello everyone,

I have modified the circuit with diode between C and E. I have also added an inductor to smooth the ripple and limit the current. I have put a fuse too.
What do you think about these modifications ? Are there some mistakes ?

Now the next step is to finish the design completely without any errors, then find the values of all components. And after that I will try to simulate the circuit to make sure everything is OK. Then ... THE BUILD !

Pierre
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Here's the schematic of the modified design
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Circuit 3 modifie.PNG
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Hello everyone,

It’s been a long time and I’m missing time, I need to finish the fusor for the end of August so I would like to finish the circuit this week. To gain time can I do it without the buck converter ? Do I really need a variable voltage ?

Pierre T
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Edit : even if I succeed at designing the buck converter ( I think I can ), I won’t be able to design the driver for the power transistors. So I really need your help
Cai Arcos
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Re: HF switcher supply construction and voltage multiplication

Post by Cai Arcos »

Why all the hassle? Seems to me like you still don't have a solid understanding of the circuit you are trying to build, and simply copy pasting schematics in hv projects normally leads to broken components.
You also have taken the most difficult path. Might be consider start searching for a traditional 60Hz transformer, if you are in a hurry
Edit: you can scrap the buck converter and tap the output voltage from different points in the voltage multiplier. It would be mighty inconvenient (since you would have to power off the supply to change the output) though.
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

No I won’t give up but you are right I can’t finish it for september and I don’t have a fully understanding of the circuit ( because I wanted this project to motivate me at learning electronics so I’m still a newbie ) which means I understand each part of the circuit and how they are supposed to work but I have no idea how to design them.

I already thought of the solution you have proposed but my problem for the buck is to use chips to control the power transistor ( my first idea was to simply take a circuit online without understanding it but what if I have a problem ? I need to understand how it works to repair it ). And the driver for the transformer isn’t an option so anyway I have to make a driver using chips.

I’m sorry for the messages you can’t really help me except if you have advices, PDF, links, etc... or if you would like to share how you did it to learn this tricky part of electronics. Now it’s up to me !
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Dennis P Brown
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Re: HF switcher supply construction and voltage multiplication

Post by Dennis P Brown »

Don't get discouraged. Learning electronics can be very difficult. That for a voltage multiplier (V.M.) is no different but to make one that can power a fusor isn't something that many (if any) here have achieved. There is a reason those expensive power supplies that are sold are so complex when they use V.M. instead of a big transformer. High frequency circuits are not easy to design - calculating the capacitors required and final voltage are not simple procedures and EE types spend a lot of time doing that. By the way, there are many designed (with all required components listed) circuits to drive and control voltage output for V.M.'s. Just search the internet.

To get started I'd suggest you just build a simple V.M. and measure its parameters. Best to start with a low current 60 Hz supply. This way you get hands on experience with a real and simple system. Then move on to higher frequency (but low current) systems. Finally, once your calculations agree with your designs, then move up to trying the real thing. Attempting to build a full sized, high frequency fusor level power supply by a novice isn't likely to happen until one gains a great deal of real experience with such circuits.

A circuit diagram is just a map that shows the gross behavior of a given electrical circuit (does not give performance values; that requires real valued components) - that is, unless you copy someone else's system complete with their list of components. Just trying to build from a schematic isn't likely to succeed since correct caps, diodes, x-formers, and driver circuits must be selected and modeled before performance gets close to what one requires.

My two cents from someone who started that route, and built a few very high voltage systems - one with very high current (at 60 Hz so the actual power wasn't known - good for my accelerator but not likely to be a good fusor P.S.)
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Nicolas Krause
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Re: HF switcher supply construction and voltage multiplication

Post by Nicolas Krause »

Hi Pierre, I just thought I would add my two cents, I've been working on my fusor for a very long time. I think I found this site back in 2010 initially, and couldn't understand anything here. I only started buying actual parts for my device in 2015, when I went back to school for electrical engineering. With work and school and everything else, it's only now that I've got the vacuum chamber close to being done, and the pumping and pressure control well underway. I can understand more of the site now, but there's still lots left to learn! Which is great! I find it a lot more fun to look forward to all the things I'm going to learn than to get discouraged by all the things I can't do. I started learning electronics with simple kits, and then moved onto designing my own simple circuits in class and in my spare time. Designing a switch-mode power supply, especially a high voltage one, would be beyond my abilities right now. Dennis' advice of picking a simpler version to start is great, it's basically how I've learned to do anything that I couldn't do initially.
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Richard Hull
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Re: HF switcher supply construction and voltage multiplication

Post by Richard Hull »

Nicolas, you, once again, point out the proper path to the learning and knowing, be it a sprint or takes place over a long period. It is drive, study and the doing that allows us to own and function actively to good effect in all that we encounter. As we study, work and grow, we acquire skill sets. Some are for ornament and self-satisfaction. Others are of a value that can sustain us through life and result in a productive path into old age. The fusor and amateur fusion effort can teach in a way that will impact much that we do in future, even if that future has nothing to do with fusion, engineering or science. One has to learn to take on tasks and develop what skills are needed to see the task through to fruition.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Pierre_Thourault
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Re: HF switcher supply construction and voltage multiplication

Post by Pierre_Thourault »

Thank you very much for your support, your advices and your personal experience. So I’m going to break apart my circuit and learn, design and build every piece of my original circuit. I have a book for beginners about logic gates and chips so I think I’m going to start with this. Then I’ll follow Dennis’s advice and do a VM. So little by little I’ll get closer to my goal.

Again thank you guys for the support ;)
Chris Giles
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Re: HF switcher supply construction and voltage multiplication

Post by Chris Giles »

Hi Pierre, I'd recommend using a dedicated driver IC for this rather than designing it totally from scratch. Earlier in this thread the an Infineon IC is shown. Alternatively you could rip-off large parts of the circuit from a commercial design, for instance see the manual in this post. You might also be able to modify a driver circuit from a lower voltage PSU (i.e. find on eBay etc) and then use a different transformer and voltage multiplier. When constructing & testing, please bear in mind that even the low voltage side of these circuits have lethal voltages present.

Here is an explanation of how the transformer core size reduces with frequency. You also have to bear in mind that many characteristics of electronic components derate from the theoretical ideal with frequency, typically at about the frequencies used in SMPS (~50kHz), so some critical components need to be carefully chosen - specifically the capacitors.
HTH!
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