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@REPLYADDR John Larkin <jl@997PotHill.com>
@REPLYTO 2:5075/128 John Larkin
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@TID: FIDOGATE-5.12-ge4e8b94
On Fri, 29 Sep 2023 09:16:40 -0700 (PDT), Lasse Langwadt Christensen
<
langwadt@fonz.dk> wrote:
>fredag den 29. september 2023 kl. 15.41.10 UTC+2 skrev Klaus Kragelund:
>> On Thursday, 28 September 2023 at 23:09:44 UTC+2, Lasse Langwadt
Christensen wrote:
>> > torsdag den 28. september 2023 kl. 22.58.46 UTC+2 skrev Klaus Kragelund:
>> > > On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
>> > > > On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <
al...@comet.invalid>
>> > > > wrote:
>> > > >
>> > > > >On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT))
it happened Klaus
>> > > > >Kragelund <
klaus.k...@gmail.com> wrote in
>> > > > ><
903144ac-6642-4a3f...@googlegroups.com>:
>> > > > >
>> > > > >>On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan
Panteltje wrote:
>> > > > >>> On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700)
it happened John Larkin
>> > > > >>> <
j...@997arbor.com> wrote in <
d3h8hitm54oie4gcl...@4ax.com>:
>> > > > >>> >On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje
<
al...@comet.invalid>
>> > > > >>> >wrote:
>> > > > >>> >
>> > > > >>> >>On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700)
it happened John Larkin
>> > > > >>> >><
j...@997arbor.com> wrote in <
4bn7hit0n3rmcg855...@4ax.com>:
>> > > > >>> >>
>> > > > >>> >>>On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje
<
al...@comet.invalid>
>> > > > >>> >>>wrote:
>> > > > >>> >>>
>> > > > >>> >>>>On a sunny day (Tue, 26 Sep 2023 19:35:18
-0700) it happened John Larkin
>> > > > >>> >>>><
j...@997arbor.com> wrote in <
mf47hi15db7eq7mp2...@4ax.com>:
>> > > > >>> >>>>
>> > > > >>> >>>>>On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin
<
j...@997arbor.com>
>> > > > >>> >>>>>wrote:
>> > > > >>> >>>>>
>> > > > >>> >>>>>>
>> > > > >>> >>>>>>This is pleasingly weird.
>> > > > >>> >>>>>>
>> > > > >>>
>>>>>>
https://www.dropbox.com/sh/sif3efs69dxe1mg/AACY0RJGXl4k8CVvauUbJtYFa?dl=0
>> > > > >>> >>>>>>
>> > > > >>> >>>>>>Sort of a baseline-boosted multi-auto-transformer
voltage-doubler
>> > > > >>> >>>>>>flyback.
>> > > > >>> >>>>>>
>> > > > >>> >>>>>>What`s strange is that adding the two snubbers
increases the LT spice
>> > > > >>> >>>>>>sim speed radically, about 10:1.
>> > > > >>> >>>>>
>> > > > >>> >>>>>Since I couldn`t find a suitable flyback
transformer, and I only need
>> > > > >>> >>>>>500 volts at 10 mA, a flyback/C-W multiplier makes sense.
>> > > > >>> >>>>>
>>>>>https://www.dropbox.com/scl/fi/aquzpawfn8mfmfsnx70ra/T875_HV_6.jpg?rlkey=vf
s9pexa0rgyxpo7pg1grqlb7&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+tra
nsformer
>> > > > >4.5 kV diodes were used for focus in color TV sets...
>> > > > >
>> > > > >
>> > > > >For a flyback, my rule of thumb (I do not use El Tea
Spice), is 1 V per turn for DC input.
>> > > > >So 24 turns primary for 24 V DC supply.
>> > > > >The flyback voltage is (70/12) * 24 = 140V positive
pulse if positive DC supply.
>> > > > >To get a 4.5 kV pulse you would then wind 4500 / 140
is about 32, multiplied by 24 makes 768 turns.
>> > > > >This for an EI core running at about 15 kHz (math
comes from building TV output stages).
>> > > > >768 turns is not a big deal..
>> > > > >Spreading the turns over a segmented coil former is a good idea.
>> > > > >If you want to use a voltage multiplier then less
turns are needed, use a TV multiplier, those are `potted`
>> > > > >The 70/12 factor depends on the PWM on/off ratio of
the drive you feed into the switch transistor.
>> > > > >I use Microchip PICs for that, it has a PWM unit.,
hardware comparators that can directly stop the PWM drive
>> > > > >for cycle by cycle current limiting, and ADCs to
measure voltage and currents.
>> > > > >Maybe an old TV horizontal output transformer with build
in rectifier / multiplier would do.
>> > > > >
https://www.ebay.com/b/flyback-transformer/bn_7024744628
>> > > > > to adapt use 15 kHz and add 24 turns to the core primary?
>> > > > >...
>> > > > >:-)
>> > > > >
>> > > > >Maybe like this?
>> > > > >
https://www.ebay.com/p/1692562663?iid=374326473542
>> > > > >plenty space for 24 turns thick wire, its a 30 kV DC
out, so use less PWM ... or more primary turns
>> > > > >or whatever you can find... on ebay.
>> > > > >
>> > > > High turns ratios can have two problems: voltage breakdown in the
>> > > > insulation, and winding capacitance limiting the flyback ratio. That`s
>> > > > where a C-W diode multiplier helps.
>> > > I am driving a UV lamp, so I need to deliver a pulse.
Possible with a multiplier, but doesn`t make it easier
>> > > >
>> > > > Old TV flybacks were pie wound to help with both problems. That makes
>> > > > a hand-wound transformer yet nastier; Sloman would love to (have
>> > > > someone else) wind that.
>> > > Pie wound, so that`s adding on layers instead of across the bobbin?
>> > > >
>> > > > There are some cool old parts from CRT TVs but we wouldn`t use Ebay
>> > > > parts for production. Even ISDN transformers are hard to get these
>> > > > days. And most of our boards have a component height limit below about
>> > > > 1".
>> > > I agree, Ebay does not work for production items :-)
>> > > >
>> > > > I`ve gravitated to the classic C-W layout with all series strings of
>> > > > caps. That`s driven by the poorly-or-never defined C/V behavior of
>> > > > available ceramic caps, which encourages their use at a small fraction
>> > > > of rated voltage.
>> > > In any case for the C-W multiplier to work properly, the
charging of the caps needs to be kept low.
>> > > >
>> > > > There are lots of cute flyback controller chips that do peak current
>> > > > limiting control.
>> > > >
>> > > I am using a microcontroller. Microcontroller and kV design
does not sound good, right?
>> > > > I don`t know how much voltage we dare generate on a regular PCB
>> > > > without coating or potting. I`m guessing that 1KV is safe and I know
>> > > > that 7KV isn`t.
>> > > Potting or conformal coating is probably needed to avoid
carbonization of PCB surface.
>> > how about something crazy, a car ignition coil? ratio about
1:100, isolation good for +20kV
>> > coil-on-plug can be pretty small, if you need access to both
ends of the secondary a dual output coil for wasted spark has that
>> These are used for old style flash:
>>
>>
https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=4itemAdapt
>
>coilcraft have some ccfl transformers, but the isolation rating is
quite a bit lower than your 4.5kV
>
>https://www.coilcraft.com/en-us/products/transformers/power-transformers/ccfl-t
ransformers/fl/
NRND, another dying technology.
--- Forte Agent 3.1/32.783
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