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
500 volt power supply
Started by ●September 24, 2023
Reply by ●September 28, 20232023-09-28
Reply by ●September 28, 20232023-09-28
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.kragelund@gmail.com> wrote:>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 easierNo, 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? Some of the Zetex app notes, for their avalanche transistors, use a Marx-type circuit. Charge the caps in parallel and discharge them in series. You only have to trigger one in the string. What sort of speed and current do you need?>> >> 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?I meant parallel slabs of winding with air gaps or a coil form between. https://www.google.com/imgres?imgurl=https%3A%2F%2Fm.media-amazon.com%2Fimages%2FI%2F61zP4fPrCyL._AC_UF1000%2C1000_QL80_.jpg&tbnid=RpaiD1aRcajCoM&vet=12ahUKEwjC19et3s6BAxX7MEQIHRMLAjAQMygCegQIARBT..i&imgrefurl=https%3A%2F%2Fwww.amazon.com%2F15KV-High-Voltage-Transformer-Electronic%2Fdp%2FB073VP18C8&docid=7qz4vnbf86eSaM&w=929&h=1000&q=pie%20wound%20high%20voltage%20transformer&ved=2ahUKEwjC19et3s6BAxX7MEQIHRMLAjAQMygCegQIARBT>> >> 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.
Reply by ●September 29, 20232023-09-29
On a sunny day (Thu, 28 Sep 2023 13:49:46 -0700 (PDT)) it happened Klaus Kragelund <klaus.kragelund@gmail.com> wrote in <a643aafc-1197-4cbe-bee8-c56418ce15bbn@googlegroups.com>:>On Thursday, 28 September 2023 at 16:59:57 UTC+2, Jan Panteltje 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.. >Yeah, 768 is not bad at all. A couple of months ago I did a E13 with 200 turns, no problem at all. > >> Spreading the turns over a segmented coil former is a good idea. >Yes, that would handle the issue with large voltage differences on the secondary coil, and isolation to the primary > >> 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. >Yeah, so that's a compromise between the voltage on the primary FET during energy delivery and optimum duty-cyle. > >> 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. >I use STM32s :-) > >> 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. >Would be interesting to see the internal construction of that oneIf you go that way, a horizontal output transformer for a color TV will do about 4.5 mA DC at 25 kV so 100 W a BW TV 10 kV maybe 1 mA so about 10 W Better find a BW one for your application, some have build in rectifier, some not. The reason for about 1 V per turn goes all the way back to when they used HV rectifier tubes with 1.4 V heater voltage on single turn around the HV transformer core. https://www.radiomuseum.org/tubes/tube_dy87.html Here a cheaper one: https://www.ebay.com/p/2117756772?iid=255799552189 very old!! Data in this pdf http://bitsavers.informatik.uni-stuttgart.de/components/philips/_dataBooks/1987_C20_Philips_Wirewound_Components_for_TV_and_Monitors.pdf see page 15, it is an 11 kV version Old days!
Reply by ●September 29, 20232023-09-29
On Friday, September 29, 2023 at 4:55:18 AM UTC+10, John Larkin wrote:> On Wed, 27 Sep 2023 17:24:13 -0700 (PDT), whit3rd <whi...@gmail.com> > wrote: > >On Wednesday, September 27, 2023 at 3:57:50?PM UTC-7, John Larkin wrote: > >> On Wed, 27 Sep 2023 13:34:29 -0700 (PDT), Klaus Kragelund > >> <klaus.k...@gmail.com> wrote: > >> Potting is ugly. > > > >Yeah, but it's compact and not messy. > > It is very slow and expensive and messy. Buying the goo and a shell or mold, mixing, degassing, pouring, curing, cleanup, and then you have a thing that you can't probe or rework.But you should need to probe it it or rework it, if you design it tight in the first place> > Globbing or coating is also a pain, but not as big a pain. > > Expensive labor-intensive processes like potting and transformer winding and exotic PCB fab seem to appeal to some people for some strange reason.They can produce better performance at a lower price, which does appeal to a lot of people for a fairly obvious reason. Poseurs don't like taking the trouble to get stuff right. -- Bill Sloman, Sydney
Reply by ●September 29, 20232023-09-29
On Friday, September 29, 2023 at 6:58:46 AM UTC+10, Klaus Kragelund wrote:> 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:<snip>> > 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.I once need a 20kV pulse to start a xenon arc lamp, which drew 20A at about 20V after the arc got established. I got it by winding 20 turns of well insulated 20A wire around a gapped pair of big U-cores and hit it with with a high current 2kV impulse from a spark gap. The impulse must have saturated the core but it still rang up to 20kV on the stray capacitances - the impulse must have been dissipating in the winding resistance and core losses as ot rang up but it got high enough to start the lamp. I wish I'd been clever enough to realise that it was going to work, but in reality I'd bunged it together as a desperation move and only realised that I saturated the U-core after it had worked.> > 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?No. I call it bank winding. You break up the secondary into a series of flat sections, then stack the sections. You could do it without a former if you wound them separately with self-bonding wire then bonded each coil before you stacked them. Sort of messy, but gets the result. -- Bill Sloman, Sydney
Reply by ●September 29, 20232023-09-29
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. 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.
Reply by ●September 29, 20232023-09-29
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 thatThese are used for old style flash: https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=4itemAdapt
Reply by ●September 29, 20232023-09-29
On Fri, 29 Sep 2023 06:41:04 -0700 (PDT), Klaus Kragelund <klaus.kragelund@gmail.com> wrote:>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=4itemAdaptAmazon and ebay have zillions of similar HV and trigger transformers. Some generate 1000KV!
Reply by ●September 29, 20232023-09-29
On Saturday, September 30, 2023 at 1:04:58 AM UTC+10, John Larkin wrote:> On Fri, 29 Sep 2023 06:41:04 -0700 (PDT), Klaus Kragelund <klaus.k...@gmail.com> wrote: > >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:<snip>> >https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=4itemAdapt > Amazon and ebay have zillions of similar HV and trigger transformers. > Some generate 1000KV!Or claim to. Somebody decided to "improve" my xenon lamp power supply with a more "professional" 20kV source which contrived to blown up the power supply that delivered the 20A constant current through the arc after it had struck. Or at least the power transistors involved. You do have to know what you are doing. -- Bill Sloman, Sydney
Reply by ●September 29, 20232023-09-29
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=4itemAdaptcoilcraft 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/
