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.

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..

> What's strange is that adding the two snubbers increases the LT spice
> sim speed radically, about 10:1.

High dv/dt stiffens the system, maybe.

Version 4
SHEET 1 2640 1316
WIRE 16 -768 -912 -768
WIRE 448 -768 16 -768
WIRE 672 -768 448 -768
WIRE 16 -624 16 -768
WIRE 448 -624 448 -768
WIRE 672 -400 672 -768
WIRE 224 -384 -624 -384
WIRE 448 -384 448 -544
WIRE 448 -384 304 -384
WIRE 512 -384 448 -384
WIRE 624 -384 576 -384
WIRE 16 -208 16 -544
WIRE 976 -208 16 -208
WIRE 1200 -208 976 -208
WIRE 1488 -208 1264 -208
WIRE 1728 -208 1488 -208
WIRE 2032 -208 1808 -208
WIRE 2432 -208 2032 -208
WIRE 2528 -208 2432 -208
WIRE -624 -80 -624 -384
WIRE 976 -64 976 -208
WIRE 1488 -64 1488 -208
WIRE 2432 64 2432 -208
WIRE -912 80 -912 -768
WIRE 976 80 976 0
WIRE 1488 80 1488 0
WIRE 2032 80 2032 -208
WIRE 16 288 16 -208
WIRE -624 368 -624 -16
WIRE -528 368 -624 368
WIRE -384 368 -448 368
WIRE -144 368 -384 368
WIRE -32 368 -80 368
WIRE 672 368 672 -304
WIRE 976 368 1488 80
WIRE 976 368 672 368
WIRE 1216 368 976 368
WIRE 1504 368 976 80
WIRE 1504 368 1280 368
WIRE 2032 368 2032 144
WIRE 2032 368 1504 368
WIRE 2432 368 2432 144
WIRE 2432 368 2032 368
WIRE 2512 368 2432 368
WIRE 2432 480 2432 368
WIRE -384 512 -384 368
WIRE 672 608 672 368
WIRE 2432 624 2432 560
WIRE -912 800 -912 160
WIRE -384 800 -384 592
WIRE -384 800 -912 800
WIRE 16 800 16 384
WIRE 16 800 -384 800
WIRE 672 800 672 688
WIRE 672 800 16 800
WIRE 16 880 16 800
WIRE -624 912 -624 368
WIRE -624 1120 -624 992
FLAG 16 880 0
FLAG -624 1120 0
FLAG 2432 624 0
FLAG 2528 -208 Out-
IOPIN 2528 -208 Out
FLAG 2512 368 Out+
IOPIN 2512 368 Out
SYMBOL voltage -912 64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL nmos -32 288 R0
SYMATTR InstName M1
SYMATTR Value Si3440DV
SYMBOL cap 1264 -224 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 40 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 0.47µ
SYMBOL cap 1280 352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 0.47µ
SYMBOL ind2 1712 -192 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 4 56 VBottom 2
SYMATTR InstName L3
SYMATTR Value 220µ
SYMBOL schottky 960 -64 R0
SYMATTR InstName D2
SYMATTR Value RB168LAM150
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL voltage -624 896 R0
WINDOW 3 52 50 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 5 0 10n 10n 0.0000122 0.0000142)
SYMATTR InstName V2
SYMBOL cap 2016 80 R0
SYMATTR InstName C4
SYMATTR Value 4.7µ
SYMBOL ind2 32 -528 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L1
SYMATTR Value 220µ
SYMBOL ind2 688 704 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L2
SYMATTR Value 220µ
SYMBOL res 2416 464 R0
SYMATTR InstName R1
SYMATTR Value 1Meg
SYMBOL Digital\\inv -688 -16 R270
SYMATTR InstName A1
SYMATTR SpiceLine Vhigh=5V,Td=5e-9,Trise=100n
SYMBOL pmos 624 -304 M180
SYMATTR InstName M2
SYMATTR Value QS8M51_P
SYMBOL ind2 208 -368 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 4 56 VBottom 2
SYMATTR InstName L6
SYMATTR Value 2.2µ
SYMBOL ind2 -544 384 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 4 56 VBottom 2
SYMATTR InstName L7
SYMATTR Value 2.2µ
SYMBOL res -400 496 R0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL res 432 -640 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL FerriteBead 544 -384 R90
WINDOW 0 -16 0 VBottom 2
SYMATTR InstName L4
SYMATTR Value 1.542µ
SYMATTR SpiceLine Ipk=2 Rser=0.045 Rpar=587 Cpar=1.216p mfg="Würth
Elektronik" pn="74279218 WE-CBF 1206"
SYMBOL res 2416 48 R0
SYMATTR InstName Rload
SYMATTR Value 10k
SYMBOL FerriteBead -112 368 R90
WINDOW 0 -16 0 VBottom 2
SYMATTR InstName L5
SYMATTR Value 1.542µ
SYMATTR SpiceLine Ipk=2 Rser=0.045 Rpar=587 Cpar=1.216p mfg="Würth
Elektronik" pn="74279218 WE-CBF 1206"
SYMBOL schottky 1472 -64 R0
SYMATTR InstName D1
SYMATTR Value RB168LAM150
SYMATTR Description Diode
SYMATTR Type diode
TEXT -872 560 Left 2 !.tran 0.1
TEXT 200 -568 Left 2 !K1 L1 L6 0.99
TEXT 256 464 Left 2 !K2 L7 L2 0.99

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.

>> What's strange is that adding the two snubbers increases the LT spice
>> sim speed radically, about 10:1.
>
>High dv/dt stiffens the system, maybe.
>
>
>
>Version 4
>SHEET 1 2640 1316
>WIRE 16 -768 -912 -768
>WIRE 448 -768 16 -768
>WIRE 672 -768 448 -768
>WIRE 16 -624 16 -768
>WIRE 448 -624 448 -768
>WIRE 672 -400 672 -768
>WIRE 224 -384 -624 -384
>WIRE 448 -384 448 -544
>WIRE 448 -384 304 -384
>WIRE 512 -384 448 -384
>WIRE 624 -384 576 -384
>WIRE 16 -208 16 -544
>WIRE 976 -208 16 -208
>WIRE 1200 -208 976 -208
>WIRE 1488 -208 1264 -208
>WIRE 1728 -208 1488 -208
>WIRE 2032 -208 1808 -208
>WIRE 2432 -208 2032 -208
>WIRE 2528 -208 2432 -208
>WIRE -624 -80 -624 -384
>WIRE 976 -64 976 -208
>WIRE 1488 -64 1488 -208
>WIRE 2432 64 2432 -208
>WIRE -912 80 -912 -768
>WIRE 976 80 976 0
>WIRE 1488 80 1488 0
>WIRE 2032 80 2032 -208
>WIRE 16 288 16 -208
>WIRE -624 368 -624 -16
>WIRE -528 368 -624 368
>WIRE -384 368 -448 368
>WIRE -144 368 -384 368
>WIRE -32 368 -80 368
>WIRE 672 368 672 -304
>WIRE 976 368 1488 80
>WIRE 976 368 672 368
>WIRE 1216 368 976 368
>WIRE 1504 368 976 80
>WIRE 1504 368 1280 368
>WIRE 2032 368 2032 144
>WIRE 2032 368 1504 368
>WIRE 2432 368 2432 144
>WIRE 2432 368 2032 368
>WIRE 2512 368 2432 368
>WIRE 2432 480 2432 368
>WIRE -384 512 -384 368
>WIRE 672 608 672 368
>WIRE 2432 624 2432 560
>WIRE -912 800 -912 160
>WIRE -384 800 -384 592
>WIRE -384 800 -912 800
>WIRE 16 800 16 384
>WIRE 16 800 -384 800
>WIRE 672 800 672 688
>WIRE 672 800 16 800
>WIRE 16 880 16 800
>WIRE -624 912 -624 368
>WIRE -624 1120 -624 992
>FLAG 16 880 0
>FLAG -624 1120 0
>FLAG 2432 624 0
>FLAG 2528 -208 Out-
>IOPIN 2528 -208 Out
>FLAG 2512 368 Out+
>IOPIN 2512 368 Out
>SYMBOL voltage -912 64 R0
>WINDOW 123 0 0 Left 0
>WINDOW 39 0 0 Left 0
>SYMATTR InstName V1
>SYMATTR Value 5
>SYMBOL nmos -32 288 R0
>SYMATTR InstName M1
>SYMATTR Value Si3440DV
>SYMBOL cap 1264 -224 R90
>WINDOW 0 0 32 VBottom 2
>WINDOW 3 40 32 VTop 2
>SYMATTR InstName C1
>SYMATTR Value 0.47µ
>SYMBOL cap 1280 352 R90
>WINDOW 0 0 32 VBottom 2
>WINDOW 3 32 32 VTop 2
>SYMATTR InstName C2
>SYMATTR Value 0.47µ
>SYMBOL ind2 1712 -192 R270
>WINDOW 0 32 56 VTop 2
>WINDOW 3 4 56 VBottom 2
>SYMATTR InstName L3
>SYMATTR Value 220µ
>SYMBOL schottky 960 -64 R0
>SYMATTR InstName D2
>SYMATTR Value RB168LAM150
>SYMATTR Description Diode
>SYMATTR Type diode
>SYMBOL voltage -624 896 R0
>WINDOW 3 52 50 Left 2
>WINDOW 123 0 0 Left 0
>WINDOW 39 0 0 Left 0
>SYMATTR Value PULSE(0 5 0 10n 10n 0.0000122 0.0000142)
>SYMATTR InstName V2
>SYMBOL cap 2016 80 R0
>SYMATTR InstName C4
>SYMATTR Value 4.7µ
>SYMBOL ind2 32 -528 R180
>WINDOW 0 36 80 Left 2
>WINDOW 3 36 40 Left 2
>SYMATTR InstName L1
>SYMATTR Value 220µ
>SYMBOL ind2 688 704 R180
>WINDOW 0 36 80 Left 2
>WINDOW 3 36 40 Left 2
>SYMATTR InstName L2
>SYMATTR Value 220µ
>SYMBOL res 2416 464 R0
>SYMATTR InstName R1
>SYMATTR Value 1Meg
>SYMBOL Digital\\inv -688 -16 R270
>SYMATTR InstName A1
>SYMATTR SpiceLine Vhigh=5V,Td=5e-9,Trise=100n
>SYMBOL pmos 624 -304 M180
>SYMATTR InstName M2
>SYMATTR Value QS8M51_P
>SYMBOL ind2 208 -368 R270
>WINDOW 0 32 56 VTop 2
>WINDOW 3 4 56 VBottom 2
>SYMATTR InstName L6
>SYMATTR Value 2.2µ
>SYMBOL ind2 -544 384 R270
>WINDOW 0 32 56 VTop 2
>WINDOW 3 4 56 VBottom 2
>SYMATTR InstName L7
>SYMATTR Value 2.2µ
>SYMBOL res -400 496 R0
>SYMATTR InstName R3
>SYMATTR Value 10k
>SYMBOL res 432 -640 R0
>SYMATTR InstName R4
>SYMATTR Value 10k
>SYMBOL FerriteBead 544 -384 R90
>WINDOW 0 -16 0 VBottom 2
>SYMATTR InstName L4
>SYMATTR Value 1.542µ
>SYMATTR SpiceLine Ipk=2 Rser=0.045 Rpar=587 Cpar=1.216p mfg="Würth
>Elektronik" pn="74279218 WE-CBF 1206"
>SYMBOL res 2416 48 R0
>SYMATTR InstName Rload
>SYMATTR Value 10k
>SYMBOL FerriteBead -112 368 R90
>WINDOW 0 -16 0 VBottom 2
>SYMATTR InstName L5
>SYMATTR Value 1.542µ
>SYMATTR SpiceLine Ipk=2 Rser=0.045 Rpar=587 Cpar=1.216p mfg="Würth
>Elektronik" pn="74279218 WE-CBF 1206"
>SYMBOL schottky 1472 -64 R0
>SYMATTR InstName D1
>SYMATTR Value RB168LAM150
>SYMATTR Description Diode
>SYMATTR Type diode
>TEXT -872 560 Left 2 !.tran 0.1
>TEXT 200 -568 Left 2 !K1 L1 L6 0.99
>TEXT 256 464 Left 2 !K2 L7 L2 0.99

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.
>

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:

Version 4
SHEET 1 2652 1076
WIRE 880 -144 240 -144
WIRE 1040 -144 880 -144
WIRE 1280 -144 1104 -144
WIRE 1472 -144 1280 -144
WIRE 1664 -144 1536 -144
WIRE 1840 -144 1728 -144
WIRE 2272 -144 1840 -144
WIRE 2496 -144 2272 -144
WIRE 0 -80 -80 -80
WIRE 144 -80 80 -80
WIRE 624 -64 240 -64
WIRE 1280 -64 1280 -144
WIRE 288 -16 240 -16
WIRE 544 -16 368 -16
WIRE -80 16 -80 0
WIRE 144 16 144 0
WIRE 144 16 -80 16
WIRE -80 32 -80 16
WIRE 480 64 240 64
WIRE 1280 112 1280 0
WIRE 880 128 880 -144
WIRE 1840 128 1840 -144
WIRE -80 144 -80 112
WIRE 304 240 240 240
WIRE 480 240 480 64
WIRE 480 240 384 240
WIRE 544 320 544 -16
WIRE 544 320 240 320
WIRE 2272 320 2272 -144
WIRE 192 352 16 352
WIRE 1280 352 1280 176
WIRE 1280 352 768 352
WIRE 1840 352 1840 192
WIRE 1840 352 1280 352
WIRE 192 432 64 432
WIRE 624 448 624 -64
WIRE 624 448 240 448
WIRE 1840 496 1840 352
WIRE 1280 512 1280 352
WIRE 352 528 240 528
WIRE 1280 656 1280 576
WIRE 16 672 16 352
WIRE 352 672 352 528
WIRE 352 672 16 672
WIRE 480 704 480 240
WIRE 480 704 240 704
WIRE 544 784 544 320
WIRE 544 784 240 784
WIRE 880 784 880 192
WIRE 1280 784 1280 720
WIRE 1280 784 880 784
WIRE 1488 784 1280 784
WIRE 1680 784 1552 784
WIRE 1840 784 1840 560
WIRE 1840 784 1744 784
WIRE 2272 784 2272 400
WIRE 2272 784 1840 784
WIRE 64 800 64 432
WIRE 192 800 64 800
WIRE 192 880 16 880
WIRE 768 880 768 352
WIRE 768 880 240 880
WIRE 240 896 240 880
WIRE 1840 912 1840 784
WIRE 464 976 240 976
WIRE 16 1040 16 880
WIRE 464 1040 464 976
WIRE 464 1040 16 1040
FLAG 1840 912 0
FLAG -80 144 0
FLAG 2496 -144 ~3kVDC
IOPIN 2496 -144 Out
SYMBOL ind2 128 16 M180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L1
SYMATTR Value 10
SYMBOL ind2 256 -48 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L2
SYMATTR Value 10
SYMBOL ind2 256 80 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L3
SYMATTR Value 10
SYMBOL ind2 256 224 M0
SYMATTR InstName L4
SYMATTR Value 10
SYMBOL ind2 176 448 M180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L5
SYMATTR Value 10
SYMBOL ind2 256 544 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L6
SYMATTR Value 10
SYMBOL voltage -80 -96 R0
WINDOW 3 -219 77 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value SINE(0 170 60)
SYMATTR InstName V1
SYMBOL cap 1824 496 R0
SYMATTR InstName C1
SYMATTR Value 4.7µ
SYMBOL cap 1824 128 R0
SYMATTR InstName C2
SYMATTR Value 4.7µ
SYMBOL diode 1472 -128 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value VS-E5TX0812
SYMBOL res -96 16 R0
SYMATTR InstName R1
SYMATTR Value 1Meg
SYMBOL res 384 -32 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 1
SYMBOL res 96 -96 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 0.0001
SYMBOL diode 1296 176 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D3
SYMATTR Value VS-E5TX0812
SYMBOL cap 1104 -160 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 4.7µ
SYMBOL diode 1296 576 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D4
SYMATTR Value VS-E5TX0812
SYMBOL diode 1552 768 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D5
SYMATTR Value VS-E5TX0812
SYMBOL cap 896 192 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C4
SYMATTR Value 4.7µ
SYMBOL res 2256 304 R0
SYMATTR InstName R4
SYMATTR Value 470k
SYMBOL ind2 256 688 M0
SYMATTR InstName L7
SYMATTR Value 10
SYMBOL ind2 176 896 M180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L8
SYMATTR Value 10
SYMBOL ind2 256 880 M0
SYMATTR InstName L9
SYMATTR Value 10
SYMBOL res 400 224 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 1
SYMBOL diode 1664 -128 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D2
SYMATTR Value VS-E5TX0812
SYMBOL diode 1296 0 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D6
SYMATTR Value VS-E5TX0812
SYMBOL diode 1296 720 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D7
SYMATTR Value VS-E5TX0812
SYMBOL diode 1744 768 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D8
SYMATTR Value VS-E5TX0812
TEXT -32 -144 Left 2 !K1 L1 L2 L3 0.99
TEXT -40 272 Left 2 !K2 L4 L5 L6 0.99
TEXT -296 -48 Left 2 !.tran 10
TEXT -168 752 Left 2 !K3 L7 L8 L9 0.99

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.

søndag den 24. september 2023 kl. 19.25.43 UTC+2 skrev John Larkin:
> On Sun, 24 Sep 2023 12:38:28 -0400, bitrex <us...@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.

wouldn't plenty of off-line smps transformers be in that range run in reverse?
like f.eks. https://www.digikey.dk/da/products/detail/w%C3%BCrth-elektronik/750871030/2208831

On Sun, 24 Sep 2023 11:33:01 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Sunday, September 24, 2023 at 12:18:49?PM UTC-4, 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.
>
>It's an instance of a 25 year old (minimum) idea usually called a tapped inductor boost.
>
>https://www.microsemi.com/document-portal/doc_view/124899-ips401-application-note
>
>There are others, these people did the grunge work:
>
>https://www.researchgate.net/figure/High-boost-topologies-a-Boost-flyback-topology-b-Tapped-inductor-boost-converter-c_fig2_273517256
>
>You don't have to actually "join" to see the paper, they let you view/download.
>
>
>
>>
>> What's strange is that adding the two snubbers increases the LT spice
>> sim speed radically, about 10:1.
>
>That's because they're linearizing nodes that are difficult to handle with too much ideality like pure capacitances, inductances. How many times has LTS flipped out because it wants a finite conductance in parallel with a pure capacitance, usually to a source node.

The latest version seems to allow open caps and floating parts.

>
>I'm getting an efficiency of 66% from your graphs., meaning circuit is okay for low power. Where is all that loss coming from? Or going to more appropriately?

Resistors in the snubbers are burning watts. I'm seeing 90% without
the snubbers. They need tweaking. Their current virtue is to speed up
the sim time. Saveral other part values are there to do that, and will
be changed on the real thing.

At under 5 watts out, and megawatts available, I don't really need
efficiency.

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.

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.

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

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=0

When 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

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

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

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

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.

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?
>
>piglet

I 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.

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

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?
>
>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?

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

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.

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

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?

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.

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..

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