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.LM5156 is a similar controller, but does spread-spectrum.
500 volt power supply
Started by ●September 24, 2023
Reply by ●September 24, 20232023-09-24
Reply by ●September 25, 20232023-09-25
On Sunday, September 24, 2023 at 8:10:55 PM UTC-4, John Larkin wrote:> 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. > LM5156 is a similar controller, but does spread-spectrum.Is that gimmick still in vogue? It's useful for powering up an RF synthesizer, but little else.
Reply by ●September 25, 20232023-09-25
On Mon, 25 Sep 2023 08:44:34 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:>On Sunday, September 24, 2023 at 8:10:55?PM UTC-4, John Larkin wrote: >> 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. >> LM5156 is a similar controller, but does spread-spectrum. > >Is that gimmick still in vogue? It's useful for powering up an RF synthesizer, but little else.It's for passing EMI tests. https://www.dropbox.com/sh/8nd4dibu77znh44/AAAkO6lEHy9FZ50od2-mqt0va?dl=0
Reply by ●September 26, 20232023-09-26
On Tuesday, September 26, 2023 at 2:20:56 AM UTC+10, John Larkin wrote:> On Mon, 25 Sep 2023 08:44:34 -0700 (PDT), Fred Bloggs > <bloggs.fred...@gmail.com> wrote: > >On Sunday, September 24, 2023 at 8:10:55?PM UTC-4, John Larkin wrote: > >> 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. > >> LM5156 is a similar controller, but does spread-spectrum. > > > >Is that gimmick still in vogue? It's useful for powering up an RF synthesizer, but little else. > > It's for passing EMI tests. > > https://www.dropbox.com/sh/8nd4dibu77znh44/AAAkO6lEHy9FZ50od2-mqt0va?dl=0When the pencil sketch shows the inductor a 2uH, but doesn't show it's parallel capacitance, nor a series ferrite bead (which may not add all that much inductance, but only has about 1pF of parallel capacitance) the EMI conformity isn't likely to be great. -- Bill Sloman, Sydney
Reply by ●September 26, 20232023-09-26
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? piglet
Reply by ●September 26, 20232023-09-26
On Tuesday, September 26, 2023 at 9:43:41 PM UTC+10, piglet 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?LTSpice certainly lets you simulate with parallel and inter-winding capacitances. Winding capacitance is easy enough to measure - you just need to resonate the winding with it's parallel capacitance. For 1:1 transformers like this you can put the two winding in parallel and measure the resonant frequency of the combination. The inter-winding capacitance isn't excited so it's a clean measurement. A capacitance meter can give your the interwinding capacitance, if you keep the test frequency well below the self-resonant frequency. I suppose if you excited two windings anti-parallel you would emphasis the interwinding capacitance, but I'd have to Spice it to get some feel for what you'd see. It's curious that the data sheet doesn't give parallel and interwinding capacitances. Transformers are something of a cottage industry, and not all the people who make them know as much as they might. -- Bill Sloman, Sydney
Reply by ●September 26, 20232023-09-26
On Tuesday, September 26, 2023 at 8:27:05 AM UTC-4, Anthony William Sloman wrote:> On Tuesday, September 26, 2023 at 9:43:41 PM UTC+10, piglet 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? > LTSpice certainly lets you simulate with parallel and inter-winding capacitances. > > Winding capacitance is easy enough to measure - you just need to resonate the winding with it's parallel capacitance. For 1:1 transformers like this you can put the two winding in parallel and measure the resonant frequency of the combination. The inter-winding capacitance isn't excited so it's a clean measurement. A capacitance meter can give your the interwinding capacitance, if you keep the test frequency well below the self-resonant frequency. > > I suppose if you excited two windings anti-parallel you would emphasis the interwinding capacitance, but I'd have to Spice it to get some feel for what you'd see. > > It's curious that the data sheet doesn't give parallel and interwinding capacitances. Transformers are something of a cottage industry, and not all the people who make them know as much as they might.He means what you would understand to be intrawinding capacitance, the sum total of capacitance in parallel with any specific winding. You're thinking of what would commonly be called winding coupling capacitance. Last time I measured it was by a technique of using a transistor, or any other switch, to set up a constant DC current in the winding representative of operating conditions, and then switch it off and measure the resulting resonant oscillation. Observing the decay also tells you about the Q, or lack thereof due to core and winding loss.> > -- > Bill Sloman, Sydney
Reply by ●September 26, 20232023-09-26
On Tue, 26 Sep 2023 06:14:53 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:>On Tuesday, September 26, 2023 at 8:27:05?AM UTC-4, Anthony William Sloman wrote: >> On Tuesday, September 26, 2023 at 9:43:41?PM UTC+10, piglet 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? >> LTSpice certainly lets you simulate with parallel and inter-winding capacitances. >> >> Winding capacitance is easy enough to measure - you just need to resonate the winding with it's parallel capacitance. For 1:1 transformers like this you can put the two winding in parallel and measure the resonant frequency of the combination. The inter-winding capacitance isn't excited so it's a clean measurement. A capacitance meter can give your the interwinding capacitance, if you keep the test frequency well below the self-resonant frequency. >> >> I suppose if you excited two windings anti-parallel you would emphasis the interwinding capacitance, but I'd have to Spice it to get some feel for what you'd see. >> >> It's curious that the data sheet doesn't give parallel and interwinding capacitances. Transformers are something of a cottage industry, and not all the people who make them know as much as they might. > >He means what you would understand to be intrawinding capacitance, the sum total of capacitance in parallel with any specific winding. You're thinking of what would commonly be called winding coupling capacitance. Last time I measured it was by a technique of using a transistor, or any other switch, to set up a constant DC current in the winding representative of operating conditions, and then switch it off and measure the resulting resonant oscillation. Observing the decay also tells you about the Q, or lack thereof due to core and winding loss. >Or use a capacitance meter.
Reply by ●September 26, 20232023-09-26
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? > >pigletI think those parts are bifalar wound so C between windings will be high and will vary between the many parts in the family. I don't have the 200 uH around but I'll measure a few others. I plan to breadboard the supply of course, if the customer is serious about wanting us to mke the driver. It's fast and fun to work with their engineers and scientists but the business people are glacial.
Reply by ●September 26, 20232023-09-26
On Tuesday, September 26, 2023 at 11:14:58 PM UTC+10, Fred Bloggs wrote:> On Tuesday, September 26, 2023 at 8:27:05 AM UTC-4, Anthony William Sloman wrote: > > On Tuesday, September 26, 2023 at 9:43:41 PM UTC+10, piglet 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? > > LTSpice certainly lets you simulate with parallel and inter-winding capacitances. > > > > Winding capacitance is easy enough to measure - you just need to resonate the winding with it's parallel capacitance. For 1:1 transformers like this you can put the two winding in parallel and measure the resonant frequency of the combination. The inter-winding capacitance isn't excited so it's a clean measurement. A capacitance meter can give your the interwinding capacitance, if you keep the test frequency well below the self-resonant frequency. > > > > I suppose if you excited two windings anti-parallel you would emphasis the interwinding capacitance, but I'd have to Spice it to get some feel for what you'd see. > > > > It's curious that the data sheet doesn't give parallel and interwinding capacitances. Transformers are something of a cottage industry, and not all the people who make them know as much as they might. > He means what you would understand to be intrawinding capacitance, the sum total of capacitance in parallel with any specific winding.Inter-winding capacitance is the capacitance between two windings and you measure it by setting up an alternating voltage difference between the two winding and measuring the capacitative current current flowing between them. John Larkin has made the point that if the windings are bifilar wound, as they often are in wound 1:1 transformers, you can get the interwinding capacitance from the wire and insulator properies. It ends to be high. If the windings are printed - which is what you'd expect in a mass-produced part these days - life gets a bit more complicated.> You're thinking of what would commonly be called winding coupling capacitance.Not so commonly that I've ever seen it used. > Last time I measured it was by a technique of using a transistor, or any other switch, to set up a constant DC current in the winding representative of operating conditions, and then switch it off and measure the resulting resonant oscillation. Observing the decay also tells you about the Q, or lack thereof due to core and winding loss. The resonant frequency tells you about the parallel capacitance and series inductance of the winding your have excited, and any other winding that is closely coupled to that winding. The Q tells you are about the resistance of the winding and the resistance of any parallel coupled loop (including currents induced in the core). If you are trying to pose an an expert, you aren't doing all that well. -- Bill Sloman, Sydney
