On Fri, 29 Sep 2023 09:16:40 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>fredag den 29. september 2023 kl. 15.41.10 UTC+2 skrev Klaus Kragelund: >> On Thursday, 28 September 2023 at 23:09:44 UTC+2, Lasse Langwadt Christensen wrote: >> > torsdag den 28. september 2023 kl. 22.58.46 UTC+2 skrev Klaus Kragelund: >> > > On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote: >> > > > On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> >> > > > wrote: >> > > > >> > > > >On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus >> > > > >Kragelund <klaus.k...@gmail.com> wrote in >> > > > ><903144ac-6642-4a3f...@googlegroups.com>: >> > > > > >> > > > >>On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote: >> > > > >>> On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin >> > > > >>> <j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>: >> > > > >>> >On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> >> > > > >>> >wrote: >> > > > >>> > >> > > > >>> >>On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin >> > > > >>> >><j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>: >> > > > >>> >> >> > > > >>> >>>On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> >> > > > >>> >>>wrote: >> > > > >>> >>> >> > > > >>> >>>>On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin >> > > > >>> >>>><j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>: >> > > > >>> >>>> >> > > > >>> >>>>>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> >> > > > >>> >>>>>wrote: >> > > > >>> >>>>> >> > > > >>> >>>>>> >> > > > >>> >>>>>>This is pleasingly weird. >> > > > >>> >>>>>> >> > > > >>> >>>>>>https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 >> > > > >>> >>>>>> >> > > > >>> >>>>>>Sort of a baseline-boosted multi-auto-transformer voltage-doubler >> > > > >>> >>>>>>flyback. >> > > > >>> >>>>>> >> > > > >>> >>>>>>What's strange is that adding the two snubbers increases the LT spice >> > > > >>> >>>>>>sim speed radically, about 10:1. >> > > > >>> >>>>> >> > > > >>> >>>>>Since I couldn't find a suitable flyback transformer, and I only need >> > > > >>> >>>>>500 volts at 10 mA, a flyback/C-W multiplier makes sense. >> > > > >>> >>>>> >> > > > >>> >>>>>https://www.dropbox.com/scl/fi/aquzpawfn8mfmfsnx70ra/T875_HV_6.jpg?rlkey=vfs9pexa0rgyxpo7pg1grqlb7&dl=0 >> > > > >>> >>>> >> > > > >>> >>>>Do you still need C11 R8 in that circuit? >> > > > >>> >>> >> > > > >>> >>>It doesn't need them to work, but there is a big high-Q ring when the >> > > > >>> >>>fet turns off, and the RC damps it. It would reduce radiated EMI. And >> > > > >>> >>>it speeds up the simulation some. >> > > > >>> >> >> > > > >>> >>Did you scope that? >> > > > >>> > >> > > > >>> >All Spice now. I'll build it when the customer gets serious. >> > > > >>> > >> > > > >>> >>There is a load of capacitance hanging from the MOSFET drain in that flyback multiplier ciruit >> > > > >>> >>I would expect it to damp RF oscillations but could be wrong... >> > > > >>> >>HV diodes have capacitance too.. >> > > > >>> > >> > > > >>> >The real circuit will have a lot of inductances too, what with those >> > > > >>> >long strings of parts. It needs to be built and tested. Dremeled, to >> > > > >>> >start. >> > > > >>> > >> > > > >>> >Here's an old auto-flyback C-W miltiplier prototype. I think that was >> > > > >>> >1400 volts. Worked fine. >> > > > >>> > >> > > > >>> >https://www.dropbox.com/s/yd19osiwz1z74s4/HV_Proto_2.JPG?rsw=1 >> > > > >>> Yea, >> > > > >>> I did a PMT supply this way: >> > > > >>> http://panteltje.nl/pub/PMT_HV_supply_with_regulator_img_3175.jpg >> > > > >>> http://panteltje.nl/pub/PMT_HV_supply_componet_side_img_3180.jpg >> > > > >>> http://panteltje.nl/pub/PMT_regulated_power_supply_diagram_img_3182.jpg >> > > > >>> >> > > > >>> It has been in use now for many years, sits with PMT in the cardboard tube on the right, runs on batteries: >> > > > >>> http://panteltje.nl/pub/gamma_soectrometer_IMG_4505.JPG >> > > > >>> >> > > > >>> Of course that is very low power, but for a bit more power, and using a real TV muliplier: >> > > > >>> https://panteltje.nl/panteltje/pic/sc_pic/ >> > > > >>> >> > > > >>> No dremeling, boards are OK when they work.. >> > > > >>> >> > > > >>> And old TV circuits.. if you want a few kV there was / is? plenty stuff to be found on ebay. >> > > > >>For my case, I am working on a 5W 24V to 4.5kV converter. Right now looking to use a flyback topology, with possibly usage of >> > > > >>CCFL transformer bobbins. >> > > > >> >> > > > >>I am thinking about staggering the windings on 2 transformers, so the voltage across the windings will be lower, but still the >> > > > >>individual transformer needs to handle 4.5kV insulation (functional, not safety) >> > > > >> >> > > > >>Due to the limiting power, it could also be tempting to use the capacitive doublers as listed elsewhere in the thread >> > > > >> >> > > > >>My worry goes beyond the design, also about corona effects, which comes into play at +kV voltages. Potting is surely needed. >> > > > > >> > > > >For a HV transformer, old TV transformers (from the CRT times) may perhaps be an option: >> > > > > https://www.google.com/search?client=firefox-b-e&q=ebay+horizonatl+TV+output+transformer >> > > > >4.5 kV diodes were used for focus in color TV sets... >> > > > > >> > > > > >> > > > >For a flyback, my rule of thumb (I do not use El Tea Spice), is 1 V per turn for DC input. >> > > > >So 24 turns primary for 24 V DC supply. >> > > > >The flyback voltage is (70/12) * 24 = 140V positive pulse if positive DC supply. >> > > > >To get a 4.5 kV pulse you would then wind 4500 / 140 is about 32, multiplied by 24 makes 768 turns. >> > > > >This for an EI core running at about 15 kHz (math comes from building TV output stages). >> > > > >768 turns is not a big deal.. >> > > > >Spreading the turns over a segmented coil former is a good idea. >> > > > >If you want to use a voltage multiplier then less turns are needed, use a TV multiplier, those are 'potted' >> > > > >The 70/12 factor depends on the PWM on/off ratio of the drive you feed into the switch transistor. >> > > > >I use Microchip PICs for that, it has a PWM unit., hardware comparators that can directly stop the PWM drive >> > > > >for cycle by cycle current limiting, and ADCs to measure voltage and currents. >> > > > >Maybe an old TV horizontal output transformer with build in rectifier / multiplier would do. >> > > > > https://www.ebay.com/b/flyback-transformer/bn_7024744628 >> > > > > to adapt use 15 kHz and add 24 turns to the core primary? >> > > > >... >> > > > >:-) >> > > > > >> > > > >Maybe like this? >> > > > > https://www.ebay.com/p/1692562663?iid=374326473542 >> > > > >plenty space for 24 turns thick wire, its a 30 kV DC out, so use less PWM ... or more primary turns >> > > > >or whatever you can find... on ebay. >> > > > > >> > > > High turns ratios can have two problems: voltage breakdown in the >> > > > insulation, and winding capacitance limiting the flyback ratio. That's >> > > > where a C-W diode multiplier helps. >> > > I am driving a UV lamp, so I need to deliver a pulse. Possible with a multiplier, but doesn't make it easier >> > > > >> > > > Old TV flybacks were pie wound to help with both problems. That makes >> > > > a hand-wound transformer yet nastier; Sloman would love to (have >> > > > someone else) wind that. >> > > Pie wound, so that's adding on layers instead of across the bobbin? >> > > > >> > > > There are some cool old parts from CRT TVs but we wouldn't use Ebay >> > > > parts for production. Even ISDN transformers are hard to get these >> > > > days. And most of our boards have a component height limit below about >> > > > 1". >> > > I agree, Ebay does not work for production items :-) >> > > > >> > > > I've gravitated to the classic C-W layout with all series strings of >> > > > caps. That's driven by the poorly-or-never defined C/V behavior of >> > > > available ceramic caps, which encourages their use at a small fraction >> > > > of rated voltage. >> > > In any case for the C-W multiplier to work properly, the charging of the caps needs to be kept low. >> > > > >> > > > There are lots of cute flyback controller chips that do peak current >> > > > limiting control. >> > > > >> > > I am using a microcontroller. Microcontroller and kV design does not sound good, right? >> > > > I don't know how much voltage we dare generate on a regular PCB >> > > > without coating or potting. I'm guessing that 1KV is safe and I know >> > > > that 7KV isn't. >> > > Potting or conformal coating is probably needed to avoid carbonization of PCB surface. >> > how about something crazy, a car ignition coil? ratio about 1:100, isolation good for +20kV >> > coil-on-plug can be pretty small, if you need access to both ends of the secondary a dual output coil for wasted spark has that >> These are used for old style flash: >> >> https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=4itemAdapt > >coilcraft have some ccfl transformers, but the isolation rating is quite a bit lower than your 4.5kV > >https://www.coilcraft.com/en-us/products/transformers/power-transformers/ccfl-transformers/fl/NRND, another dying technology.
500 volt power supply
Started by ●September 24, 2023
Reply by ●September 29, 20232023-09-29
Reply by ●September 29, 20232023-09-29
On Fri, 29 Sep 2023 01:53:09 -0700 (PDT), whit3rd <whit3rd@gmail.com> wrote:>On Thursday, September 28, 2023 at 7:09:27?PM UTC-7, John Larkin wrote: >> On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund >> <klaus.k...@gmail.com> wrote: > >> >I am driving a UV lamp, so I need to deliver a pulse. Possible with a multiplier, but doesn't make it easier >> No, the C-W multiplier isn't good for pulsing. Ixys has a 4700 volt >> mosfet. A C-W multiplier could make the HV. >> >> Maybe use a Marx generator? With medium-high voltage mos or SiC fets? > >Not usually a great idea; at HV, the best switch is photo-SCR.Should work, but might be too slow for some applications. It is a nice idea to make high-current HV pulses. Six of these maybe: https://www.digikey.com/en/products/detail/vishay-semiconductor-opto-division/VOT8125AB-V/9843471 One can use SSRs to make a Marx generator, but they are slow. The Zetex avalanche transistors are cool but expensive. A C-W multiplier followed by some switch makes more sense.>It takes a while to turn off, which limits your pulse rate somewhat. >Turn-ON and HV tolerance is spectacularly good, though. >Triggered spark gaps (krytron, anyone?) work a treat, too.I have a Krytron, a beautiful piece of glass. Los Alamos sold it from their surplus outlet by mistake. https://www.dropbox.com/s/mdqw9pod98zjutd/Kry_Box.jpg?raw=1 https://www.dropbox.com/s/7vkdemdk48k3myd/Kry_Danger.jpg?raw=1 https://www.dropbox.com/s/i2hhyvouro59c6l/Kry_Guts.jpg?raw=1 That will switch 4KV and 500 amps, 2 megawatts. And it's the tiniest of Krytrons. I don't think they are used in gadgets these days.
Reply by ●September 30, 20232023-09-30
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <jl@997arbor.com> wrote:> >This is pleasingly weird. > >https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 > >Sort of a baseline-boosted multi-auto-transformer voltage-doubler >flyback. > >What's strange is that adding the two snubbers increases the LT spice >sim speed radically, about 10:1.OK, this has become sort of a background hobby, waiting on the customer to get serious. https://www.dropbox.com/scl/fi/60nb1pcrnl17c07tk8xeu/T875_HV_9.jpg?rlkey=9uv466edcuvddmjldgepcyi0u&raw=1 All the caps are a part that we have, 100nF 630 volts 1812. Of course the capacitance plummets as voltage goes up, so the Spice values have to be adjusted appropriately. C is only 20nF at 500 volts. The RCD snubber is nice. It softens the rise at the fet drain and dissipates less power than a simple RC that damps ringing about the same. 10 ms of sim runs in about 30 seconds on a wimpy laptop, which is tolerable. I just got four new monster Win11 machines which should be blinding fast with Spice. We're setting up one to look and behave sensibly (ie, like Win7 did) and will clone the other three when I'm happy with that. We did manage to get the PADS pcb programs to install. That's always an adventure. Windows keeps getting worse. It has become an ad+annoy vehicle for Microsoft. At boot time, the home screen is a full-screen ad for Edge that won't go away. Explorer drag-and-drop is insane. Screen capture is insane. I can't make Irfanview the default image viewer. Another annoyance.
Reply by ●October 1, 20232023-10-01
On a sunny day (Sat, 30 Sep 2023 12:10:06 -0700) it happened John Larkin <jl@997arbor.com> wrote in <2grghi1vnnsmrkbclipkjceu9r8t70c28l@4ax.com>:>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <jl@997arbor.com> >wrote: > >> >>This is pleasingly weird. >> >>https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 >> >>Sort of a baseline-boosted multi-auto-transformer voltage-doubler >>flyback. >> >>What's strange is that adding the two snubbers increases the LT spice >>sim speed radically, about 10:1. > >OK, this has become sort of a background hobby, waiting on the >customer to get serious. > >https://www.dropbox.com/scl/fi/60nb1pcrnl17c07tk8xeu/T875_HV_9.jpg?rlkey=9uv466edcuvddmjldgepcyi0u&raw=1 > >All the caps are a part that we have, 100nF 630 volts 1812. Of course >the capacitance plummets as voltage goes up, so the Spice values have >to be adjusted appropriately. C is only 20nF at 500 volts.That much really? Th big caps I use do not change at all I think?>The RCD snubber is nice. It softens the rise at the fet drain and >dissipates less power than a simple RC that damps ringing about the >same.Nice, it delivers power back to the supply line :-)>10 ms of sim runs in about 30 seconds on a wimpy laptop, which is >tolerable. > >I just got four new monster Win11 machines which should be blinding >fast with Spice. We're setting up one to look and behave sensibly (ie, >like Win7 did) and will clone the other three when I'm happy with >that. > >We did manage to get the PADS pcb programs to install. That's always >an adventure. > >Windows keeps getting worse.I have double glass windows :-) Linux, even on a small computah like Raspberry Pi4 8 GB is simple and OK, posting this from one. Network access? Just 1 Huawei 4G USB stick, I pay 32 Euro (about the same in dollies) a month for 10 GB limited 4G internet. Works everywhere in Europe?, plug USB stick in my laptop and I am online. Much safer than WiFi from some place. As to Raspberries.. in the upcoming version Pi5 removing he analog audio output jack they did was a bad idea, not enough USB sockets, now you always need an USB hub if you want to do anything? changing the I/O chip requires you to re-write all your I/O based stuff? (not the first time they did that). Maybe China can come up with a better small computah. It has become an ad+annoy vehicle for>Microsoft. At boot time, the home screen is a full-screen ad for Edge >that won't go away. Explorer drag-and-drop is insane. Screen capture >is insane. > >I can't make Irfanview the default image viewer. Another annoyance. > > >
Reply by ●October 1, 20232023-10-01
On Sun, 01 Oct 2023 05:31:31 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Sat, 30 Sep 2023 12:10:06 -0700) it happened John Larkin ><jl@997arbor.com> wrote in <2grghi1vnnsmrkbclipkjceu9r8t70c28l@4ax.com>: > >>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <jl@997arbor.com> >>wrote: >> >>> >>>This is pleasingly weird. >>> >>>https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 >>> >>>Sort of a baseline-boosted multi-auto-transformer voltage-doubler >>>flyback. >>> >>>What's strange is that adding the two snubbers increases the LT spice >>>sim speed radically, about 10:1. >> >>OK, this has become sort of a background hobby, waiting on the >>customer to get serious. >> >>https://www.dropbox.com/scl/fi/60nb1pcrnl17c07tk8xeu/T875_HV_9.jpg?rlkey=9uv466edcuvddmjldgepcyi0u&raw=1 >> >>All the caps are a part that we have, 100nF 630 volts 1812. Of course >>the capacitance plummets as voltage goes up, so the Spice values have >>to be adjusted appropriately. C is only 20nF at 500 volts. > >That much really? Th big caps I use do not change at all I think?I measured one. https://www.dropbox.com/scl/fi/zrrount2a5s7k5bmqh4bu/C-V.jpg?rlkey=3so16njq8md4ccnm610a8mf49&raw=1 There are some big C0G caps around these days, but in this case I may as well use the X7R in stock and let it do what it does. It's fun to make an RC timing ramp from a Z5U or something. The exponential curves UP.> >>The RCD snubber is nice. It softens the rise at the fet drain and >>dissipates less power than a simple RC that damps ringing about the >>same. > >Nice, it delivers power back to the supply line :-)I didn't invent that, got that from a switcher textbook. There are actually "lossless" snubbers that store the snub energy in an inductor or a transformer and return it to the supply, but that's overkill in a 5 watt supply. The C-W multiplier actually clamps the mosfet drain to safe voltages; an inductor doesn't have leakage inductance! (Or it has 100% leakage inductance?) The snubber is there to damp the HF ringing and reduce radiated EMI.> > >>10 ms of sim runs in about 30 seconds on a wimpy laptop, which is >>tolerable. >> >>I just got four new monster Win11 machines which should be blinding >>fast with Spice. We're setting up one to look and behave sensibly (ie, >>like Win7 did) and will clone the other three when I'm happy with >>that. >> >>We did manage to get the PADS pcb programs to install. That's always >>an adventure. >> >>Windows keeps getting worse. > >I have double glass windows :-)I have to have two giant windows replaced; they fog up from failed double-pane window seals. That seems to be chronic. They have some internal coating that gets ugly once it gets wet. Planned obsolescence. Absent that, they can usually be drilled to fix the condensation problem.>Linux, even on a small computah like Raspberry Pi4 8 GB is simple and OK, posting this from one. >Network access? Just 1 Huawei 4G USB stick, I pay 32 Euro (about the same in dollies) a month for 10 GB limited 4G internet. >Works everywhere in Europe?, plug USB stick in my laptop and I am online. >Much safer than WiFi from some place. >As to Raspberries.. in the upcoming version Pi5 removing he analog audio output jack they did >was a bad idea, not enough USB sockets, now you always need an USB hub if you want to do anything? >changing the I/O chip requires you to re-write all your I/O based stuff? (not the first time they did that). >Maybe China can come up with a better small computah. > > > > >It has become an ad+annoy vehicle for >>Microsoft. At boot time, the home screen is a full-screen ad for Edge >>that won't go away. Explorer drag-and-drop is insane. Screen capture >>is insane. >> >>I can't make Irfanview the default image viewer. Another annoyance. >> >> >>
Reply by ●October 1, 20232023-10-01
On a sunny day (Sun, 01 Oct 2023 07:08:02 -0700) it happened John Larkin <jl@997arbor.com> wrote in <4cuihitefaok29ca02dt12cdd0085og2f7@4ax.com>:>On Sun, 01 Oct 2023 05:31:31 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Sat, 30 Sep 2023 12:10:06 -0700) it happened John Larkin >><jl@997arbor.com> wrote in <2grghi1vnnsmrkbclipkjceu9r8t70c28l@4ax.com>: >> >>>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <jl@997arbor.com> >>>wrote: >>> >>>> >>>>This is pleasingly weird. >>>> >>>>https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 >>>> >>>>Sort of a baseline-boosted multi-auto-transformer voltage-doubler >>>>flyback. >>>> >>>>What's strange is that adding the two snubbers increases the LT spice >>>>sim speed radically, about 10:1. >>> >>>OK, this has become sort of a background hobby, waiting on the >>>customer to get serious. >>> >>>https://www.dropbox.com/scl/fi/60nb1pcrnl17c07tk8xeu/T875_HV_9.jpg?rlkey=9uv466edcuvddmjldgepcyi0u&raw=1 >>> >>>All the caps are a part that we have, 100nF 630 volts 1812. Of course >>>the capacitance plummets as voltage goes up, so the Spice values have >>>to be adjusted appropriately. C is only 20nF at 500 volts. >> >>That much really? Th big caps I use do not change at all I think? > >I measured one. > >https://www.dropbox.com/scl/fi/zrrount2a5s7k5bmqh4bu/C-V.jpg?rlkey=3so16njq8md4ccnm610a8mf49&raw=1That is realy awfull! Tt will likely create more ripple and less output.>There are some big C0G caps around these days, but in this case I may >as well use the X7R in stock and let it do what it does.If the output stays in spec OK...>It's fun to make an RC timing ramp from a Z5U or something. The >exponential curves UP.You could use that for frequency modulation, sort of a very big varicap... Not very linear...>> >>>The RCD snubber is nice. It softens the rise at the fet drain and >>>dissipates less power than a simple RC that damps ringing about the >>>same. >> >>Nice, it delivers power back to the supply line :-) > >I didn't invent that, got that from a switcher textbook. > >There are actually "lossless" snubbers that store the snub energy in >an inductor or a transformer and return it to the supply, but that's >overkill in a 5 watt supply. > >The C-W multiplier actually clamps the mosfet drain to safe voltages; >an inductor doesn't have leakage inductance! (Or it has 100% leakage >inductance?) The snubber is there to damp the HF ringing and reduce >radiated EMI.CRT TV horizontal output stages are interesting, also have a 'tuning capacitor' so the flyback is tuned to some harmonic (third harmonic Fred?) of the drive frequency, I experimented with winding several transformers for TVs I build. This goes a bit into that, so no snubbers needed. http://www.broadcaststore.com/pdf/model/793699/TT207%20-%205080.pdf tv_horizontal_output_stage_operating__TT207-5080.pdf see figure 6: --------- -------- | | | | -- --- --- . / \ ----------- ------------ flyback tuned
Reply by ●October 1, 20232023-10-01
On Sun, 01 Oct 2023 16:07:30 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Sun, 01 Oct 2023 07:08:02 -0700) it happened John Larkin ><jl@997arbor.com> wrote in <4cuihitefaok29ca02dt12cdd0085og2f7@4ax.com>: > >>On Sun, 01 Oct 2023 05:31:31 GMT, Jan Panteltje <alien@comet.invalid> >>wrote: >> >>>On a sunny day (Sat, 30 Sep 2023 12:10:06 -0700) it happened John Larkin >>><jl@997arbor.com> wrote in <2grghi1vnnsmrkbclipkjceu9r8t70c28l@4ax.com>: >>> >>>>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <jl@997arbor.com> >>>>wrote: >>>> >>>>> >>>>>This is pleasingly weird. >>>>> >>>>>https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 >>>>> >>>>>Sort of a baseline-boosted multi-auto-transformer voltage-doubler >>>>>flyback. >>>>> >>>>>What's strange is that adding the two snubbers increases the LT spice >>>>>sim speed radically, about 10:1. >>>> >>>>OK, this has become sort of a background hobby, waiting on the >>>>customer to get serious. >>>> >>>>https://www.dropbox.com/scl/fi/60nb1pcrnl17c07tk8xeu/T875_HV_9.jpg?rlkey=9uv466edcuvddmjldgepcyi0u&raw=1 >>>> >>>>All the caps are a part that we have, 100nF 630 volts 1812. Of course >>>>the capacitance plummets as voltage goes up, so the Spice values have >>>>to be adjusted appropriately. C is only 20nF at 500 volts. >>> >>>That much really? Th big caps I use do not change at all I think? >> >>I measured one. >> >>https://www.dropbox.com/scl/fi/zrrount2a5s7k5bmqh4bu/C-V.jpg?rlkey=3so16njq8md4ccnm610a8mf49&raw=1 > >That is realy awfull!It's what ceramic caps do. Z5 types are worse. C0Gs are linear but don't come in big values.>Tt will likely create more ripple and less output.I put in enough derated caps to do what I want.> > >>There are some big C0G caps around these days, but in this case I may >>as well use the X7R in stock and let it do what it does. > >If the output stays in spec OK... > > >>It's fun to make an RC timing ramp from a Z5U or something. The >>exponential curves UP. > >You could use that for frequency modulation, sort of a very big varicap... >Not very linear...There are ceramic things that behave like varicaps. Some are three-terminal, with the c-modulation pin being separate. Varicaps are nonlinear too. I think the nonlinearity of ceramic caps could be used to make a power amplifier and maybe even an oscillator. Just for fun, probably not practical. Certainly make a frequency multiplier. High power NLTLs, shock lines, can use ceramic nonlinearity. Somebody made a single slab transmission line like that.> > >>> >>>>The RCD snubber is nice. It softens the rise at the fet drain and >>>>dissipates less power than a simple RC that damps ringing about the >>>>same. >>> >>>Nice, it delivers power back to the supply line :-) >> >>I didn't invent that, got that from a switcher textbook. >> >>There are actually "lossless" snubbers that store the snub energy in >>an inductor or a transformer and return it to the supply, but that's >>overkill in a 5 watt supply. >> >>The C-W multiplier actually clamps the mosfet drain to safe voltages; >>an inductor doesn't have leakage inductance! (Or it has 100% leakage >>inductance?) The snubber is there to damp the HF ringing and reduce >>radiated EMI. > >CRT TV horizontal output stages are interesting, also have a 'tuning capacitor' >so the flyback is tuned to some harmonic (third harmonic Fred?) of the drive frequency, >I experimented with winding several transformers for TVs I build. > >This goes a bit into that, so no snubbers needed. > http://www.broadcaststore.com/pdf/model/793699/TT207%20-%205080.pdf > tv_horizontal_output_stage_operating__TT207-5080.pdf > see figure 6: > --------- -------- > | | | | >-- --- --- > . > / \ >----------- ------------ flyback tuned > >The horizontal output transistors are mostly obsolete. Some had interesting properties. I used the c-b junction of one as a drift step-recovery diode.
Reply by ●October 1, 20232023-10-01
On Sunday, October 1, 2023 at 9:08:19 AM UTC-5, John Larkin wrote:> On Sun, 01 Oct 2023 05:31:31 GMT, Jan Panteltje <al...@comet.invalid> > wrote: > >On a sunny day (Sat, 30 Sep 2023 12:10:06 -0700) it happened John Larkin > ><j...@997arbor.com> wrote in <2grghi1vnnsmrkbcl...@4ax.com>: > > > >>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> > >>wrote: > >> > >>> > >>>This is pleasingly weird. > >>> > >>>https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0 > >>> > >>>Sort of a baseline-boosted multi-auto-transformer voltage-doubler > >>>flyback. > >>> > >>>What's strange is that adding the two snubbers increases the LT spice > >>>sim speed radically, about 10:1. > >> > >>OK, this has become sort of a background hobby, waiting on the > >>customer to get serious. > >> > >>https://www.dropbox.com/scl/fi/60nb1pcrnl17c07tk8xeu/T875_HV_9.jpg?rlkey=9uv466edcuvddmjldgepcyi0u&raw=1 > >> > >>All the caps are a part that we have, 100nF 630 volts 1812. Of course > >>the capacitance plummets as voltage goes up, so the Spice values have > >>to be adjusted appropriately. C is only 20nF at 500 volts. > > > >That much really? Th big caps I use do not change at all I think? > I measured one. > > https://www.dropbox.com/scl/fi/zrrount2a5s7k5bmqh4bu/C-V.jpg?rlkey=3so16njq8md4ccnm610a8mf49&raw=1John, I have worked quite extensively with CW multipliers. Both series and parallel ones. The nice thing about series multipliers is that the capacitors will see no more than the p-p input voltage. So I don't think you high voltage ones except to use them at a lower voltage to improve capacitance. Parallel multipliers are more efficient but do require the higher voltage ( at least on the final stage). Good luck with your project and please post its progress here.Thanks.> There are some big C0G caps around these days, but in this case I may > as well use the X7R in stock and let it do what it does.> It's fun to make an RC timing ramp from a Z5U or something. The > exponential curves UP. > > > >>The RCD snubber is nice. It softens the rise at the fet drain and > >>dissipates less power than a simple RC that damps ringing about the > >>same. > > > >Nice, it delivers power back to the supply line :-) > I didn't invent that, got that from a switcher textbook. > > There are actually "lossless" snubbers that store the snub energy in > an inductor or a transformer and return it to the supply, but that's > overkill in a 5 watt supply. > > The C-W multiplier actually clamps the mosfet drain to safe voltages; > an inductor doesn't have leakage inductance! (Or it has 100% leakage > inductance?) The snubber is there to damp the HF ringing and reduce > radiated EMI. > > > > > >>10 ms of sim runs in about 30 seconds on a wimpy laptop, which is > >>tolerable. > >> > >>I just got four new monster Win11 machines which should be blinding > >>fast with Spice. We're setting up one to look and behave sensibly (ie, > >>like Win7 did) and will clone the other three when I'm happy with > >>that. > >> > >>We did manage to get the PADS pcb programs to install. That's always > >>an adventure. > >> > >>Windows keeps getting worse. > > > >I have double glass windows :-) > I have to have two giant windows replaced; they fog up from failed > double-pane window seals. That seems to be chronic. > > They have some internal coating that gets ugly once it gets wet. > Planned obsolescence. Absent that, they can usually be drilled to fix > the condensation problem. > >Linux, even on a small computah like Raspberry Pi4 8 GB is simple and OK, posting this from one. > >Network access? Just 1 Huawei 4G USB stick, I pay 32 Euro (about the same in dollies) a month for 10 GB limited 4G internet. > >Works everywhere in Europe?, plug USB stick in my laptop and I am online. > >Much safer than WiFi from some place. > >As to Raspberries.. in the upcoming version Pi5 removing he analog audio output jack they did > >was a bad idea, not enough USB sockets, now you always need an USB hub if you want to do anything? > >changing the I/O chip requires you to re-write all your I/O based stuff? (not the first time they did that). > >Maybe China can come up with a better small computah. > > > > > > > > > >It has become an ad+annoy vehicle for > >>Microsoft. At boot time, the home screen is a full-screen ad for Edge > >>that won't go away. Explorer drag-and-drop is insane. Screen capture > >>is insane. > >> > >>I can't make Irfanview the default image viewer. Another annoyance. > >> > >> > >>
Reply by ●October 2, 20232023-10-02
On Friday, September 29, 2023 at 12:07:37 PM UTC-7, John Larkin wrote:> On Fri, 29 Sep 2023 01:53:09 -0700 (PDT), whit3rd <whi...@gmail.com> > wrote: > >On Thursday, September 28, 2023 at 7:09:27?PM UTC-7, John Larkin wrote: > >> On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund > >> <klaus.k...@gmail.com> wrote: > > > >> >I am driving a UV lamp, so I need to deliver a pulse. Possible with a multiplier, but doesn't make it easier > >> No, the C-W multiplier isn't good for pulsing. Ixys has a 4700 volt > >> mosfet. A C-W multiplier could make the HV. > >> > >> Maybe use a Marx generator? With medium-high voltage mos or SiC fets? > > > >Not usually a great idea; at HV, the best switch is photo-SCR.> Should work, but might be too slow for some applications. It is a nice > idea to make high-current HV pulses. Six of these maybe: > > https://www.digikey.com/en/products/detail/vishay-semiconductor-opto-division/VOT8125AB-V/9843471Ick; triacs, not SCRs, and you'd have to wire-connect those input pins... I was thinking more of fibers to a receiver with phototransistor, use PNP and NPN phototransistor to make an SCR, bias it with a 9V battery at each node, so a single lamp flash can light up all the nodes at once. That 9V pulse, of course, just goes to the gate of a REAL SCR. This one seems thrifty, and does over a kilovolt <https://www.digikey.com/en/products/detail/vishay-general-semiconductor-diodes-division/VS-25TTS16SLHM3/9467407> The real advantage, though, of photoSCR is in the turnon dI/dt limit; it doesn't have any, because it turns on full-area when lit. That takes more light than you'd likely push through a fiber, however. 150 A/us is the limit you get for your $2.86
Reply by ●October 2, 20232023-10-02
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