12-24v to 400v DC to DC boost converter help - Page 1
Forum section: electronics / projects

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 05:38:04 am
content: I was wondering if anyone has a schematic, or project they've done that is similar. I'm designing a circuit right now and need some help, wanted to turn to the forum to see what others would say regarding best choice for my needs. I am wanting a DC to DC boost circuit that can take a variable 12-24v and turn that into around 300-400v @ 20-30mA. It doesn't matter the circuit type (flyback, flyboost, standard, etc). I just need a decent efficiency, the other thing I need is it to have as low ripple as possible. Weather it's from filtering, or component choice itself, that doesn't matter to me. Just need a fairly efficient, dead quiet circuit. If you have worked on something like this, have a schematic, or can point me in the right direction it would be amazing. I'll take any help I can get!

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 06:10:10 am
content: Jim Williams did pretty much exactly what you want in the following application note:https://www.analog.com/media/en/technical-documentation/application-notes/an118fb.pdf

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 07:07:49 am
content: It's funny I was just looking at this paper. Is there any components I can use that you know of that can achieve this? I am generally newer to Electronics on the hardware side of things (I work in offensive security) and need a bit of a hand hold with this circuit build. Admittedly, I wish I could learn it all, but there's certainly more strength in numbers. If someone could elaborate on this paper with maybe component selection, schematic starting point, something to guide me further, it would be much appreciated!! Just need more of a explanation / this is what you're going to do, here's why you are going the do that, etc. Sorry for the noob questions!

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 07:30:51 am
content: Quote from: badchardev on December 20, 2023, 07:07:49 amThis isn't for some sort of taser device is it?

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 07:53:50 am
content: Haha, actually not related to work, I'm working on this as a power supply to be a part of a high voltage mosfet audio preamp. The audio preamp circuit is figured out already just need a way to power it. Thus this post. And when I say offensive security, I mean internal network penetration testing, not really on the physical security side of things. haha.

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 08:16:05 am
content: Quote from: badchardev on December 20, 2023, 07:53:50 amGlad to hear it. The Royer circuit of the application note really only works for a relatively limited input voltage, depends on the base switching winding, by the 12V-24V input is it variable or fixed?Secondly flyback might be a much easier configuration if you could say what your noise specs are.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 08:30:41 am
content: Input would need to be variable I'd say as I intend to use it for 16vdc on this specific application, but want it to work for other applications as well if need be. I don't really have a specific noise spec, as I don't have the preamp schematic in front of me, but whatever you think would be most quiet, or if we need to add another component to the schematic, I am open to whatever direction you point me in! Also, if you wanna take it to PM we can do that as well. Whatever you are comfortable with recommending or doing is totally cool with me!

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 08:36:07 am
content: To clarify, whatever voltage is set as the input between 12-24v is what I mean, so you could set it 12v input 400v out, 16v input 400v out, etc.

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 08:50:07 am
content: Quote from: badchardev on December 20, 2023, 08:36:07 amBecause of the variable input voltage I would suggest flyback or semi resonant flyback, the semi resonant should provide lower noise but is a little more complex, also the transformer is simpler for flyback vs Royer.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 08:56:33 am
content: Let's assume standard flyback and move forward from there. I can iron out the kinks if need be, and don't want to make it too difficult for anyone contributing. So given that circuit type is chosen what would a schematic or parts list of sorts look like for this specific application?

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 08:57:59 am
content: or general next steps I suppose. hahaha

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 09:25:39 am
content: This link sounds identical to your query:https://www.reddit.com/r/AskElectronics/comments/17t8xu0/dc_to_dc_boost_converter_16v_in_to_400v_out/On it one of the posters suggested a circuit they designed, which is flyback and posted the schematic.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 09:49:34 am
content: I posted thathahaha

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 09:59:10 am
content: In the schematic shown, is there any difference to get that voltage range on vout to handle 20-30mA? Would you be able to send a schematic using those components that would fit my low noise needs? this is a great schematic to base off of but maybe we need to tweak it for low ripple? What are your thoughts?

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 10:38:12 am
content: It would need modifying, the output capacitance would need to be increased followed by an LC filter and the transformer would need to be uprated to provide the extra current, but since there are no specs for noise that is an unknown, usually it is one of those try it and see situations.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 10:45:27 am
content: If you want to help me out in regards to modifications maybe via circuit simulation, and modifying schematic accordingly, I'd gladly pay you for your time. Don't know if it's something that you'd be interested in, but you've helped me out so much! I figure it would be a breeze working with you to accomplish this goal. I can take care of real world R&D no worries, my main thing is working with someone reputable (you) and getting it there via simulation or "on paper this works". Even if it's 80% there or something. Regardless, any more help you can give either here on forum or we could take it to PM or somewhere of your choosing and turn this into a paid project, just let me know buddy! I sincerely appreciate you!!

author: Vovk_Z
author_rank: Super Contributor
timestamp: December 20, 2023, 12:42:14 pm
content: There are ready-made Chinese step-up DC-DC modules. IDK how reliable they are, but 20-30 mA seems not a large load.DC-DC V 8 ~ V 32 V to 45 ~ 390 V Adjustable high voltage boost converterI guess you may find them on Ebay on other (local?) platforms too.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 01:26:57 pm
content: Yeah, main problem with these are they are fairly noisy circuits (from what I've heard, and no schematics laying around for these so I can't tailor them in the future.

author: PSR B1257
author_rank: Frequent Contributor
timestamp: December 20, 2023, 03:25:49 pm
content: Just out of curiosity, what kind of amplifier requires a 400V rail for the pre-amp?Where is the input voltage supposed to come from?It's not intended to be mains-powered, right?

author: Martinn
author_rank: Frequent Contributor
timestamp: December 20, 2023, 06:20:54 pm
content: Of all possibilities flyback probably would be the noisiest choice. High peak currents and lots of ringing when switching off. You wrote audio preamp (don't see why one would need 400 V for an audio preamp - unless it's a tube design), which would suggest looking for low noise.You found the Jim Williams reference already, I'd also suggest going resonant current-fed Royer (or Baxandall, which would be the correct term for that type). Unfortunately JW used mainly CCFL transformers, which have gone extinct in the meantime (and would not have delivered 12 W anyway). So probably you have to wind your own. Fortunately that's quite easy as Baxandall easily deals with low coupling (high leakage inductance), where a flyback would cause huge primary spikes threatening the health of your switch.The best ressource for Baxandall design I know of is this articlehttps://www.mikrocontroller.net/articles/Royer_Converterincluding referenced forum threads. It's all German, but with some translator should be readable.You stated 400 V 30 mA as requirement, giving 12 W. For a MOSFET Baxandall ("Royer" or "ZVS") this should be easy, they go up to multiple kW for induction heaters. Not sure if one could use a small induction heater and put a transformer on the output, would save some effort.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: December 20, 2023, 07:07:53 pm
content: Quote from: badchardev on December 20, 2023, 07:53:50 amDo you want +/-200V or just +400VHow stable is the load current ? What is your preamp PSRR, over frequency - that determines how low a ripple youreallyneed.The pre-built module linked above, looks like a good place to start. That uses a good looking transformer, which helps when trying for a wide voltage change.A search finds a fuller spec of the same thing is herehttps://www.aliexpress.com/item/1005004091462517.html- says they have split rail or single rail options, 40W continual 70W peak, US $2.92Run one of those up, and measure the ripple.Do you have an oscilloscope ?

author: moffy
author_rank: Super Contributor
timestamp: December 20, 2023, 08:57:35 pm
content: Quote from: Martinn on December 20, 2023, 06:20:54 pmIf you read the whole article from page 7 Jim Williams has a whole section on low noise flyback converters, difficult I agree, but obviously not impossible.P.S. His use of very low capacitance rectifier diodes is one of the key parts of his low noise design.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 10:27:29 pm
content: +/- 16vdc is the power supplied from a 500 series lunchbox PSU.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 10:37:20 pm
content: Quote from: PCB.Wiz on December 20, 2023, 07:07:53 pmLooking for an output of a steady 400v.Getting a decent enough low ripple is fine for now, as I can tweak it later as need be, I just need a schematic that has the right components and voltages for my specific use case. Just need it to do the voltage boost for now, filtering can be chosen later but may be important to pre choose a circuit where that kind of modification isn't too difficult.I do have an oscilliscope.

author: badchardev
author_rank: Contributor
timestamp: December 20, 2023, 10:43:22 pm
content: The requirements of this circuit are very much akin to what a tube preamp would be, however it uses a high voltage mosfet in the preamp stage of the circuit to sort of "emulate" tube behavior. So we can essentially treat it as if we are powering that kind of a circuit.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: December 20, 2023, 11:18:24 pm
content: Quote from: badchardev on December 20, 2023, 10:37:20 pmThe very simplest design could use a single inductor, but the high voltage ratio here needs > 95% conduction times, and your power is not mW.Start with the AliExpress module and measure it, and look up the ICs. Their data will give a circuit, which they likely just cloned.A decent transformer is likely needed, and the Aliexpress module gives you a nice transformer and everything else essentially 'for free'.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: December 20, 2023, 11:54:01 pm
content: Quote from: badchardev on December 20, 2023, 10:43:22 pmSo that's going to be largely Class-A, which should make ripple and regulation easier.I did see this new-tech part, GAN039-650NTB, a cascode GaN with very low Crss, might be fun to play with ? Not cheap, but easy to cool.http://www.nexperia.com/ccpak

author: badchardev
author_rank: Contributor
timestamp: December 21, 2023, 12:13:00 am
content: This looks super interesting! I am gonna check this out!

author: Martinn
author_rank: Frequent Contributor
timestamp: December 23, 2023, 06:48:30 pm
content: Made a few pictures of this Chinese module. I intended to build a simple HV lab supply with this, but finally just got a real (Chinese) one.Scope shot is from switch node. Some really strange switching here, does not look as if the UC3843A does what it is supposed to do.Also as mentioned earlier not the lowest noise option one might imagine. Bipolar output with center tapped secondary is a nice bonus. Even somewhat regulated due to flyback connection.Herehttps://impulsite.ru/viewtopic.php?t=1294#p23960you can find the schematic. Googling for yh11068a will give you many more hits.Quote from: moffy on December 20, 2023, 08:57:35 pmI have not memorized all of JW's writings. These examples are a bit more low power though.I assume the TO will not need isolation. For an isolated supply, getting rid of CM noise is a whole different story (and much more difficult than filtering output ground referenced noise).I'd probably start with the yh11068a module - if it's good enough, then that is hard to beat.Next would be a current-fed resonant Royer (Baxandall), these are very easy to DIY and winding a transformer (N87 RM core, maybe RM10?) pretty easy.Or a push-pull forward, maybe even fixed duty cycle? Depends on what regulation quality is required.

author: Martinn
author_rank: Frequent Contributor
timestamp: December 23, 2023, 07:17:55 pm
content: For fun, I wired it up with my Tube load.I do have a proper electronic load, but not for 400 V.

author: Vovk_Z
author_rank: Super Contributor
timestamp: December 25, 2023, 12:14:15 pm
content: Quote from: Martinn on December 23, 2023, 06:48:30 pmLooks like it totally lacks proper snubbing and filtering. You may consider it as Lego brick where you have to add your own required parts (filters, snubbers, etc).

author: KerimF
author_rank: Frequent Contributor
timestamp: December 25, 2023, 12:56:26 pm
content: Perhaps this could be solved by a conventional low-power square wave inverter and a diode full-bridge at the transformer output.

author: Martinn
author_rank: Frequent Contributor
timestamp: December 25, 2023, 05:03:52 pm
content: Quote from: KerimF on December 25, 2023, 12:56:26 pmLike driving a 230V mains transformer backwards? If it had two say 12 V secondaries, one could make a simple push-pull with just two transistors and fixed 50% 50 Hz drive.Not sure what a mains transformer would do with square wave input. For sure it would be less noisy than a flyback.