On Tue, 26 Sep 2023 12:43:30 +0100, piglet <erichpwagner@hotmail.com> wrote:>On 24/09/2023 6:59 pm, John Larkin wrote: >> On Sun, 24 Sep 2023 13:41:12 -0400, bitrex <user@example.net> wrote: >> >>> On 9/24/2023 1:25 PM, John Larkin wrote: >>>> On Sun, 24 Sep 2023 12:38:28 -0400, bitrex <user@example.net> wrote: >>>> >>>>> On 9/24/2023 12:18 PM, John Larkin 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. >>>>> >>>>> There are bunch of topologies that charge inductors in parallel and >>>>> discharge in series, helps take the stress off the switch(es) and don't >>>>> need huge duty cycles. I have one like that in my filez that's like a >>>>> Cuk, with a quasi-floating output posted at the end though haven't found >>>>> a particular use for it yet.. >>>>> >>>> >>>> I started simulating with a single 1:5 transformer, but couldn't find >>>> one for sale. >>>> >>>> 24 to 500 is sort of a black hole for flyback transformers. The >>>> "capacitor charging" flybacks are either the wrong ratio or too wimpy. >>>> >>>> The DRQ127 parts are cool and cheap (under a dollar) and multi-sourced >>>> and pick-and-place compatible, so it makes sense to use four of them. >>>> >>>> Inductors charged in parallel and discharged in series does sound >>>> cool, but I'd expect that to need a lot of parts. >>>> >>> >> >> I could also rectify each of my secondaries independently into DC, and >> stack those in series. But no big benefit, more parts. >> >> >> >>> If you have transformers with a dual secondary you can make a boosting >>> autotransformer-type topology by using the spare secondaries to couple >>> fluxes, so they act like they're all wound on the same core, sort of >>> like this somewhat silly example: >> >> The DRQ127's are 2 widings, 1:1. Handy parts. >> >> What was your 3KV for? I'm powering a Pockels Cell driver. It's only a >> moderate number of KHz so I shouldn't need a lot of power. >> >> It would be nice to spread-spectrum my supply. That LT chip is fixed >> 200 KHz. The customer can get whiney about EMI. >> > >Have you measured the inter-winding capacitance of those DRQ127s? > >My guess is many tens of pF and if you simulate with that then your >snubber requirements may be quite changed? > >pigletDRQ127, the big one in the DRQ family: 33 uH is 106 pF measuring two shorted windings 1 mH is 432 pF I'm not sure how to Spice a distributed capacitance. Maybe put half on each end?
500 volt power supply
Started by ●September 24, 2023
Reply by ●September 26, 20232023-09-26
Reply by ●September 26, 20232023-09-26
On 26/09/2023 8:22 pm, John Larkin wrote:> I'm not sure how to Spice a distributed capacitance. Maybe put half on > each end? >Yes, that is exactly what I do! piglet
Reply by ●September 26, 20232023-09-26
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.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 https://www.dropbox.com/scl/fi/kada16c6rl4kcx11pq86q/T875_HV_6.asc?rlkey=2u7nvyhxt7lgwd5dr32gpqtqo&dl=0 I like this one because it simulates fast. The MMBD5004S is a cute little dual HV diode in SOT-23. BAS21S is similar.
Reply by ●September 27, 20232023-09-27
On Wednesday, September 27, 2023 at 5:23:13 AM UTC+10, John Larkin wrote:> On Tue, 26 Sep 2023 12:43:30 +0100, piglet <erichp...@hotmail.com> > wrote: > >On 24/09/2023 6:59 pm, John Larkin wrote: > >> On Sun, 24 Sep 2023 13:41:12 -0400, bitrex <us...@example.net> wrote: > >>> On 9/24/2023 1:25 PM, John Larkin wrote: > >>>> On Sun, 24 Sep 2023 12:38:28 -0400, bitrex <us...@example.net> wrote: > >>>>> On 9/24/2023 12:18 PM, John Larkin wrote:<snip>> >Have you measured the inter-winding capacitance of those DRQ127s? > > > >My guess is many tens of pF and if you simulate with that then your > >snubber requirements may be quite changed? > > > >piglet > DRQ127, the big one in the DRQ family: > > 33 uH is 106 pF measuring two shorted windings > > 1 mH is 432 pF > > I'm not sure how to Spice a distributed capacitance. Maybe put half on each end?I got mildly obsessive about it once and split the inductor into three tightly coupled segments and divided up the stray capacitance and tied it to the new nodes.. It didn't change the behavior of the simulated circuit at all. -- Bill Sloman, Sydney
Reply by ●September 27, 20232023-09-27
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin <jl@997arbor.com> wrote in <mf47hi15db7eq7mp2nl9mdqgin7acrujdi@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. > >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=0Do you still need C11 R8 in that circuit?
Reply by ●September 27, 20232023-09-27
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin ><jl@997arbor.com> wrote in <mf47hi15db7eq7mp2nl9mdqgin7acrujdi@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. >> >>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.
Reply by ●September 27, 20232023-09-27
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <jl@997arbor.com> wrote in <4bn7hit0n3rmcg8551cskijart3cnh9ess@4ax.com>:>On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin >><jl@997arbor.com> wrote in <mf47hi15db7eq7mp2nl9mdqgin7acrujdi@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. >>> >>>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? 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..
Reply by ●September 27, 20232023-09-27
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin ><jl@997arbor.com> wrote in <4bn7hit0n3rmcg8551cskijart3cnh9ess@4ax.com>: > >>On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <alien@comet.invalid> >>wrote: >> >>>On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin >>><jl@997arbor.com> wrote in <mf47hi15db7eq7mp2nl9mdqgin7acrujdi@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. >>>> >>>>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
Reply by ●September 27, 20232023-09-27
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin <jl@997arbor.com> wrote in <d3h8hitm54oie4gclhkeetp7ked7svs5jj@4ax.com>:>On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin >><jl@997arbor.com> wrote in <4bn7hit0n3rmcg8551cskijart3cnh9ess@4ax.com>: >> >>>On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote: >>> >>>>On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin >>>><jl@997arbor.com> wrote in <mf47hi15db7eq7mp2nl9mdqgin7acrujdi@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. >>>>> >>>>>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=1Yea, 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.
Reply by ●September 27, 20232023-09-27
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.
