500 volt power supply...

[Anthony William Sloman]

On Thursday, October 5, 2023 at 5:20:53 PM UTC+11, Klaus Vestergaard Kragelund wrote:

On 03-10-2023 16:59, Anthony William Sloman wrote:
On Wednesday, October 4, 2023 at 1:41:37 AM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 14:37, John Larkin wrote:
On Tue, 3 Oct 2023 09:46:44 +0200, Klaus Vestergaard Kragelund <klau....@hotmail.com> wrote:
On 29-09-2023 04:09, John Larkin wrote:
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.k....@gmail.com> wrote:
On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus
Kragelund <klaus.k...@gmail.com> wrote in <903144ac-6642-4a3f...@googlegroups.com>:
On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote:
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin
j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>:
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>:
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin
j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>:
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> wrote:

snip

One can stuff a bunch of current into an inductor and then dump it into a mostly-capacitive load. That can make a high-voltage half-sine.

A transformer would work better - perhaps several of them in series.

Dump a bunch of current into the primaries in parallel - perhaps time shifted to allow the high voltage pulse to propagate through the series connected secondaries - and rely on the parallel capacitances of the secondaries to shape the pulse into a half-sine.

That\'s what I was considering doing, but still the individual
transformer needs to be able to handle the 4.5kV isolation from winding
to winding.

Multisection formers make that easy enough. A single layer of 25 micron kapton tape is good for 4kV, and several layers for rather more, so you can do it on a single section former.

--
Bill Sloman, Sydney

 

[John Larkin]

On Thu, 5 Oct 2023 08:25:19 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

On 29-09-2023 18:16, Lasse Langwadt Christensen 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=vfs9pexa0rgyxpo7pg1grqlb7&dl=0

Do you still need C11 R8 in that circuit?

It doesn\'t need them to work, but there is a big high-Q ring when the
fet turns off, and the RC damps it. It would reduce radiated EMI. And
it speeds up the simulation some.

Did you scope that?

All Spice now. I\'ll build it when the customer gets serious.

There is a load of capacitance hanging from the MOSFET drain in that flyback multiplier ciruit
I would expect it to damp RF oscillations but could be wrong...
HV diodes have capacitance too..

The real circuit will have a lot of inductances too, what with those
long strings of parts. It needs to be built and tested. Dremeled, to
start.

Here\'s an old auto-flyback C-W miltiplier prototype. I think that was
1400 volts. Worked fine.

https://www.dropbox.com/s/yd19osiwz1z74s4/HV_Proto_2.JPG?rsw=1
Yea,
I did a PMT supply this way:
http://panteltje.nl/pub/PMT_HV_supply_with_regulator_img_3175.jpg
http://panteltje.nl/pub/PMT_HV_supply_componet_side_img_3180.jpg
http://panteltje.nl/pub/PMT_regulated_power_supply_diagram_img_3182.jpg

It has been in use now for many years, sits with PMT in the cardboard tube on the right, runs on batteries:
http://panteltje.nl/pub/gamma_soectrometer_IMG_4505.JPG

Of course that is very low power, but for a bit more power, and using a real TV muliplier:
https://panteltje.nl/panteltje/pic/sc_pic/

No dremeling, boards are OK when they work..

And old TV circuits.. if you want a few kV there was / is? plenty stuff to be found on ebay.
For my case, I am working on a 5W 24V to 4.5kV converter. Right now looking to use a flyback topology, with possibly usage of
CCFL transformer bobbins.

I am thinking about staggering the windings on 2 transformers, so the voltage across the windings will be lower, but still the
individual transformer needs to handle 4.5kV insulation (functional, not safety)

Due to the limiting power, it could also be tempting to use the capacitive doublers as listed elsewhere in the thread

My worry goes beyond the design, also about corona effects, which comes into play at +kV voltages. Potting is surely needed.

For a HV transformer, old TV transformers (from the CRT times) may perhaps be an option:
https://www.google.com/search?client=firefox-b-e&q=ebay+horizonatl+TV+output+transformer
4.5 kV diodes were used for focus in color TV sets...


For a flyback, my rule of thumb (I do not use El Tea Spice), is 1 V per turn for DC input.
So 24 turns primary for 24 V DC supply.
The flyback voltage is (70/12) * 24 = 140V positive pulse if positive DC supply.
To get a 4.5 kV pulse you would then wind 4500 / 140 is about 32, multiplied by 24 makes 768 turns.
This for an EI core running at about 15 kHz (math comes from building TV output stages).
768 turns is not a big deal..
Spreading the turns over a segmented coil former is a good idea.
If you want to use a voltage multiplier then less turns are needed, use a TV multiplier, those are \'potted\'
The 70/12 factor depends on the PWM on/off ratio of the drive you feed into the switch transistor.
I use Microchip PICs for that, it has a PWM unit., hardware comparators that can directly stop the PWM drive
for cycle by cycle current limiting, and ADCs to measure voltage and currents.
Maybe an old TV horizontal output transformer with build in rectifier / multiplier would do.
https://www.ebay.com/b/flyback-transformer/bn_7024744628
to adapt use 15 kHz and add 24 turns to the core primary?
...


Maybe like this?
https://www.ebay.com/p/1692562663?iid=374326473542
plenty space for 24 turns thick wire, its a 30 kV DC out, so use less PWM ... or more primary turns
or whatever you can find... on ebay.

High turns ratios can have two problems: voltage breakdown in the
insulation, and winding capacitance limiting the flyback ratio. That\'s
where a C-W diode multiplier helps.
I am driving a UV lamp, so I need to deliver a pulse. Possible with a multiplier, but doesn\'t make it easier

Old TV flybacks were pie wound to help with both problems. That makes
a hand-wound transformer yet nastier; Sloman would love to (have
someone else) wind that.
Pie wound, so that\'s adding on layers instead of across the bobbin?

There are some cool old parts from CRT TVs but we wouldn\'t use Ebay
parts for production. Even ISDN transformers are hard to get these
days. And most of our boards have a component height limit below about
1\".
I agree, Ebay does not work for production items

I\'ve gravitated to the classic C-W layout with all series strings of
caps. That\'s driven by the poorly-or-never defined C/V behavior of
available ceramic caps, which encourages their use at a small fraction
of rated voltage.
In any case for the C-W multiplier to work properly, the charging of the caps needs to be kept low.

There are lots of cute flyback controller chips that do peak current
limiting control.

I am using a microcontroller. Microcontroller and kV design does not sound good, right?
I don\'t know how much voltage we dare generate on a regular PCB
without coating or potting. I\'m guessing that 1KV is safe and I know
that 7KV isn\'t.
Potting or conformal coating is probably needed to avoid carbonization of PCB surface.
how about something crazy, a car ignition coil? ratio about 1:100, isolation good for +20kV
coil-on-plug can be pretty small, if you need access to both ends of the secondary a dual output coil for wasted spark has that
These are used for old style flash:

https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=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-transformers/fl/

Maybe the isolation can be achieved by potting. That\'s a reasonable
cheap way to boost the isolation voltage.

Potting is an expensive mess. A C-W multiplier can be spread out to
maintain surface creepage limits. As an extreme defense against dust,
it can have a cover or be conformally coated.

My current plans are to have a single-inductor flyback and a C-W
multiplier. That will use all multi-sourced parts (except for the
control chip) and be all pick-and-place assembled, cheap parts off
reels.

Designing for production is different from personal projects.

 

[John Larkin]

On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
<utube.jocjo@xoxy.net> wrote:

On Tuesday, October 3, 2023 at 10:30:48?PM UTC-5, Anthony William Sloman wrote:
On Wednesday, October 4, 2023 at 3:00:46?AM UTC+11, John Larkin wrote:
On Tue, 3 Oct 2023 16:41:27 +0200, Klaus Vestergaard Kragelund<klau...@hotmail.com> wrote:
On 03-10-2023 14:37, John Larkin wrote:
On Tue, 3 Oct 2023 09:46:44 +0200, Klaus Vestergaard Kragelund <klau...@hotmail.com> wrote:
On 29-09-2023 04:09, John Larkin wrote:
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.k...@gmail.com> wrote:
On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus Kragelund <klaus.k...@gmail.com> wrote in <903144ac-6642-4a3f...@googlegroups.com>:
On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote:
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin <j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>:
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>:
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin <j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>:
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> wrote:
snip
I will generate a single pulse, about 5us long, shaped like a half wave sinusoid, at 100kHz repetition frequency. That\'s why I was looking at flyback, since I can control the voltage delivered simply by adjusting the primary peak current. Power seems to be less than 5W, at 4.5kV peak, duty of let\'s say 25%. probably below 10mA

One can stuff a bunch of current into an inductor and then dump it into a mostly-capacitive load. That can make a high-voltage half-sine.

This boosts 48 volts to 1400v at MHz pulse rates.

http://www.highlandtechnology.com/DSS/T850DS.shtml

by switching an inductor around. The energy is recovered and returned to the 48v supply after each pulse, which keeps the power dissipation under control.

https://www.dropbox.com/scl/fi/lkjg19hvcus9xz8aeecxy/T850_Rev_C.JPG?rlkey=0pitv0zdmb0x1tz0fkw0gj3ob&raw=1

The really tricky stuff is on the bottom of the board, dumping heat into the water-cooled baseplate.

At 5 us, you could make a 4KV DC supply and switch that into your load with a high-voltage mosfet. Brute force.

Yes, that could also be an idea. Will have some losses though, since it\'s switching into a capacitive load.

Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what
symbol failed chemists use for frequency.

 

[John Smiht]

On Thursday, October 5, 2023 at 9:22:50 AM UTC-5, John Larkin wrote:

On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what
symbol failed chemists use for frequency.

+1

 

[John Larkin]

On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
<utube.jocjo@xoxy.net> wrote:

On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what
symbol failed chemists use for frequency.

+1

I\'d respect his language skills more if he can ever learn the
difference between

its

and

it\'s.

 

[John Larkin]

On Thu, 5 Oct 2023 08:25:19 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

On 29-09-2023 18:16, Lasse Langwadt Christensen 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=vfs9pexa0rgyxpo7pg1grqlb7&dl=0

Do you still need C11 R8 in that circuit?

It doesn\'t need them to work, but there is a big high-Q ring when the
fet turns off, and the RC damps it. It would reduce radiated EMI. And
it speeds up the simulation some.

Did you scope that?

All Spice now. I\'ll build it when the customer gets serious.

There is a load of capacitance hanging from the MOSFET drain in that flyback multiplier ciruit
I would expect it to damp RF oscillations but could be wrong...
HV diodes have capacitance too..

The real circuit will have a lot of inductances too, what with those
long strings of parts. It needs to be built and tested. Dremeled, to
start.

Here\'s an old auto-flyback C-W miltiplier prototype. I think that was
1400 volts. Worked fine.

https://www.dropbox.com/s/yd19osiwz1z74s4/HV_Proto_2.JPG?rsw=1
Yea,
I did a PMT supply this way:
http://panteltje.nl/pub/PMT_HV_supply_with_regulator_img_3175.jpg
http://panteltje.nl/pub/PMT_HV_supply_componet_side_img_3180.jpg
http://panteltje.nl/pub/PMT_regulated_power_supply_diagram_img_3182.jpg

It has been in use now for many years, sits with PMT in the cardboard tube on the right, runs on batteries:
http://panteltje.nl/pub/gamma_soectrometer_IMG_4505.JPG

Of course that is very low power, but for a bit more power, and using a real TV muliplier:
https://panteltje.nl/panteltje/pic/sc_pic/

No dremeling, boards are OK when they work..

And old TV circuits.. if you want a few kV there was / is? plenty stuff to be found on ebay.
For my case, I am working on a 5W 24V to 4.5kV converter. Right now looking to use a flyback topology, with possibly usage of
CCFL transformer bobbins.

I am thinking about staggering the windings on 2 transformers, so the voltage across the windings will be lower, but still the
individual transformer needs to handle 4.5kV insulation (functional, not safety)

Due to the limiting power, it could also be tempting to use the capacitive doublers as listed elsewhere in the thread

My worry goes beyond the design, also about corona effects, which comes into play at +kV voltages. Potting is surely needed.

For a HV transformer, old TV transformers (from the CRT times) may perhaps be an option:
https://www.google.com/search?client=firefox-b-e&q=ebay+horizonatl+TV+output+transformer
4.5 kV diodes were used for focus in color TV sets...


For a flyback, my rule of thumb (I do not use El Tea Spice), is 1 V per turn for DC input.
So 24 turns primary for 24 V DC supply.
The flyback voltage is (70/12) * 24 = 140V positive pulse if positive DC supply.
To get a 4.5 kV pulse you would then wind 4500 / 140 is about 32, multiplied by 24 makes 768 turns.
This for an EI core running at about 15 kHz (math comes from building TV output stages).
768 turns is not a big deal..
Spreading the turns over a segmented coil former is a good idea.
If you want to use a voltage multiplier then less turns are needed, use a TV multiplier, those are \'potted\'
The 70/12 factor depends on the PWM on/off ratio of the drive you feed into the switch transistor.
I use Microchip PICs for that, it has a PWM unit., hardware comparators that can directly stop the PWM drive
for cycle by cycle current limiting, and ADCs to measure voltage and currents.
Maybe an old TV horizontal output transformer with build in rectifier / multiplier would do.
https://www.ebay.com/b/flyback-transformer/bn_7024744628
to adapt use 15 kHz and add 24 turns to the core primary?
...


Maybe like this?
https://www.ebay.com/p/1692562663?iid=374326473542
plenty space for 24 turns thick wire, its a 30 kV DC out, so use less PWM ... or more primary turns
or whatever you can find... on ebay.

High turns ratios can have two problems: voltage breakdown in the
insulation, and winding capacitance limiting the flyback ratio. That\'s
where a C-W diode multiplier helps.
I am driving a UV lamp, so I need to deliver a pulse. Possible with a multiplier, but doesn\'t make it easier

Old TV flybacks were pie wound to help with both problems. That makes
a hand-wound transformer yet nastier; Sloman would love to (have
someone else) wind that.
Pie wound, so that\'s adding on layers instead of across the bobbin?

There are some cool old parts from CRT TVs but we wouldn\'t use Ebay
parts for production. Even ISDN transformers are hard to get these
days. And most of our boards have a component height limit below about
1\".
I agree, Ebay does not work for production items

I\'ve gravitated to the classic C-W layout with all series strings of
caps. That\'s driven by the poorly-or-never defined C/V behavior of
available ceramic caps, which encourages their use at a small fraction
of rated voltage.
In any case for the C-W multiplier to work properly, the charging of the caps needs to be kept low.

There are lots of cute flyback controller chips that do peak current
limiting control.

I am using a microcontroller. Microcontroller and kV design does not sound good, right?
I don\'t know how much voltage we dare generate on a regular PCB
without coating or potting. I\'m guessing that 1KV is safe and I know
that 7KV isn\'t.
Potting or conformal coating is probably needed to avoid carbonization of PCB surface.
how about something crazy, a car ignition coil? ratio about 1:100, isolation good for +20kV
coil-on-plug can be pretty small, if you need access to both ends of the secondary a dual output coil for wasted spark has that
These are used for old style flash:

https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=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-transformers/fl/

Maybe the isolation can be achieved by potting. That\'s a reasonable
cheap way to boost the isolation voltage.

Seems that VMI used to have more multipliers.

https://www.voltagemultipliers.com/products/multipliers/pvm-multipliers/

Those are pretty dinky.

 

[Klaus Vestergaard Kragelund]

On 05-10-2023 19:29, John Larkin wrote:

On Thu, 5 Oct 2023 08:25:19 +0200, Klaus Vestergaard Kragelund
klauskvik@hotmail.com> wrote:

On 29-09-2023 18:16, Lasse Langwadt Christensen 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=vfs9pexa0rgyxpo7pg1grqlb7&dl=0

Do you still need C11 R8 in that circuit?

It doesn\'t need them to work, but there is a big high-Q ring when the
fet turns off, and the RC damps it. It would reduce radiated EMI. And
it speeds up the simulation some.

Did you scope that?

All Spice now. I\'ll build it when the customer gets serious.

There is a load of capacitance hanging from the MOSFET drain in that flyback multiplier ciruit
I would expect it to damp RF oscillations but could be wrong...
HV diodes have capacitance too..

The real circuit will have a lot of inductances too, what with those
long strings of parts. It needs to be built and tested. Dremeled, to
start.

Here\'s an old auto-flyback C-W miltiplier prototype. I think that was
1400 volts. Worked fine.

https://www.dropbox.com/s/yd19osiwz1z74s4/HV_Proto_2.JPG?rsw=1
Yea,
I did a PMT supply this way:
http://panteltje.nl/pub/PMT_HV_supply_with_regulator_img_3175.jpg
http://panteltje.nl/pub/PMT_HV_supply_componet_side_img_3180.jpg
http://panteltje.nl/pub/PMT_regulated_power_supply_diagram_img_3182.jpg

It has been in use now for many years, sits with PMT in the cardboard tube on the right, runs on batteries:
http://panteltje.nl/pub/gamma_soectrometer_IMG_4505.JPG

Of course that is very low power, but for a bit more power, and using a real TV muliplier:
https://panteltje.nl/panteltje/pic/sc_pic/

No dremeling, boards are OK when they work..

And old TV circuits.. if you want a few kV there was / is? plenty stuff to be found on ebay.
For my case, I am working on a 5W 24V to 4.5kV converter. Right now looking to use a flyback topology, with possibly usage of
CCFL transformer bobbins.

I am thinking about staggering the windings on 2 transformers, so the voltage across the windings will be lower, but still the
individual transformer needs to handle 4.5kV insulation (functional, not safety)

Due to the limiting power, it could also be tempting to use the capacitive doublers as listed elsewhere in the thread

My worry goes beyond the design, also about corona effects, which comes into play at +kV voltages. Potting is surely needed.

For a HV transformer, old TV transformers (from the CRT times) may perhaps be an option:
https://www.google.com/search?client=firefox-b-e&q=ebay+horizonatl+TV+output+transformer
4.5 kV diodes were used for focus in color TV sets...


For a flyback, my rule of thumb (I do not use El Tea Spice), is 1 V per turn for DC input.
So 24 turns primary for 24 V DC supply.
The flyback voltage is (70/12) * 24 = 140V positive pulse if positive DC supply.
To get a 4.5 kV pulse you would then wind 4500 / 140 is about 32, multiplied by 24 makes 768 turns.
This for an EI core running at about 15 kHz (math comes from building TV output stages).
768 turns is not a big deal..
Spreading the turns over a segmented coil former is a good idea.
If you want to use a voltage multiplier then less turns are needed, use a TV multiplier, those are \'potted\'
The 70/12 factor depends on the PWM on/off ratio of the drive you feed into the switch transistor.
I use Microchip PICs for that, it has a PWM unit., hardware comparators that can directly stop the PWM drive
for cycle by cycle current limiting, and ADCs to measure voltage and currents.
Maybe an old TV horizontal output transformer with build in rectifier / multiplier would do.
https://www.ebay.com/b/flyback-transformer/bn_7024744628
to adapt use 15 kHz and add 24 turns to the core primary?
...


Maybe like this?
https://www.ebay.com/p/1692562663?iid=374326473542
plenty space for 24 turns thick wire, its a 30 kV DC out, so use less PWM ... or more primary turns
or whatever you can find... on ebay.

High turns ratios can have two problems: voltage breakdown in the
insulation, and winding capacitance limiting the flyback ratio. That\'s
where a C-W diode multiplier helps.
I am driving a UV lamp, so I need to deliver a pulse. Possible with a multiplier, but doesn\'t make it easier

Old TV flybacks were pie wound to help with both problems. That makes
a hand-wound transformer yet nastier; Sloman would love to (have
someone else) wind that.
Pie wound, so that\'s adding on layers instead of across the bobbin?

There are some cool old parts from CRT TVs but we wouldn\'t use Ebay
parts for production. Even ISDN transformers are hard to get these
days. And most of our boards have a component height limit below about
1\".
I agree, Ebay does not work for production items

I\'ve gravitated to the classic C-W layout with all series strings of
caps. That\'s driven by the poorly-or-never defined C/V behavior of
available ceramic caps, which encourages their use at a small fraction
of rated voltage.
In any case for the C-W multiplier to work properly, the charging of the caps needs to be kept low.

There are lots of cute flyback controller chips that do peak current
limiting control.

I am using a microcontroller. Microcontroller and kV design does not sound good, right?
I don\'t know how much voltage we dare generate on a regular PCB
without coating or potting. I\'m guessing that 1KV is safe and I know
that 7KV isn\'t.
Potting or conformal coating is probably needed to avoid carbonization of PCB surface.
how about something crazy, a car ignition coil? ratio about 1:100, isolation good for +20kV
coil-on-plug can be pretty small, if you need access to both ends of the secondary a dual output coil for wasted spark has that
These are used for old style flash:

https://www.aliexpress.us/item/32521417603.html?gatewayAdapt=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-transformers/fl/

Maybe the isolation can be achieved by potting. That\'s a reasonable
cheap way to boost the isolation voltage.

Seems that VMI used to have more multipliers.

https://www.voltagemultipliers.com/products/multipliers/pvm-multipliers/

Those are pretty dinky.

Haven\'t seen them before. Sadly, Unobtanioum

 

[Klaus Vestergaard Kragelund]

On 05-10-2023 08:56, Anthony William Sloman wrote:

On Thursday, October 5, 2023 at 5:20:53 PM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 16:59, Anthony William Sloman wrote:
On Wednesday, October 4, 2023 at 1:41:37 AM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 14:37, John Larkin wrote:
On Tue, 3 Oct 2023 09:46:44 +0200, Klaus Vestergaard Kragelund <klau...@hotmail.com> wrote:
On 29-09-2023 04:09, John Larkin wrote:
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.k...@gmail.com> wrote:
On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus
Kragelund <klaus.k...@gmail.com> wrote in <903144ac-6642-4a3f...@googlegroups.com>:
On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote:
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin
j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>:
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>:
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin
j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>:
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> wrote:

snip

One can stuff a bunch of current into an inductor and then dump it into a mostly-capacitive load. That can make a high-voltage half-sine.

A transformer would work better - perhaps several of them in series.

Dump a bunch of current into the primaries in parallel - perhaps time shifted to allow the high voltage pulse to propagate through the series connected secondaries - and rely on the parallel capacitances of the secondaries to shape the pulse into a half-sine.

That\'s what I was considering doing, but still the individual
transformer needs to be able to handle the 4.5kV isolation from winding
to winding.

Multisection formers make that easy enough. A single layer of 25 micron kapton tape is good for 4kV, and several layers for rather more, so you can do it on a single section former.

Yes, possible. Then a little dirt creeps in, poluted path, ionization,
and sparks. Joerg would write \"tssss, kaboom\" etc ;-)

 

[John Smiht]

On Thursday, October 5, 2023 at 11:25:28 AM UTC-5, John Larkin wrote:

On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what
symbol failed chemists use for frequency.

+1
I\'d respect his language skills more if he can ever learn the
difference between

its

and

it\'s.

Another +1

 

[John Smiht]

On Thursday, October 5, 2023 at 12:56:58 PM UTC-5, Klaus Vestergaard Kragelund wrote:

On 05-10-2023 08:56, Anthony William Sloman wrote:
Multisection formers make that easy enough. A single layer of 25 micron kapton tape is good for 4kV, and several layers for rather more, so you can do it on a single section former.

Yes, possible. Then a little dirt creeps in, poluted path, ionization,
and sparks. Joerg would write \"tssss, kaboom\" etc ;-)

Where is Joerg? I miss him.

 

[Anthony William Sloman]

On Friday, October 6, 2023 at 1:18:20 AM UTC+11, John Larkin wrote:

On Thu, 5 Oct 2023 08:25:19 +0200, Klaus Vestergaard Kragelund <klau...@hotmail.com> wrote:
On 29-09-2023 18:16, Lasse Langwadt Christensen 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:
snip

Maybe the isolation can be achieved by potting. That\'s a reasonable cheap way to boost the isolation voltage.\\

Potting is an expensive mess.

Ham-fisted people can mess it up.

A C-W multiplier can be spread out to maintain surface creepage limits. As an extreme defense against dust, it can have a cover or be conformally coated.

My current plans are to have a single-inductor flyback and a C-W multiplier. That will use all multi-sourced parts (except for the control chip) and be all pick-and-place assembled, cheap parts of reels.

It will cost a lot more than it needs to but the customer gets stuck with the price.

> Designing for production is different from personal projects.

Not if you allow your personal prejudices to govern what you design.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Friday, October 6, 2023 at 1:22:50 AM UTC+11, John Larkin wrote:

On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:

On Tuesday, October 3, 2023 at 10:30:48?PM UTC-5, Anthony William Sloman wrote:
On Wednesday, October 4, 2023 at 3:00:46?AM UTC+11, John Larkin wrote:
On Tue, 3 Oct 2023 16:41:27 +0200, Klaus Vestergaard Kragelund<klau....@hotmail.com> wrote:
On 03-10-2023 14:37, John Larkin wrote:
On Tue, 3 Oct 2023 09:46:44 +0200, Klaus Vestergaard Kragelund <klau...@hotmail.com> wrote:
On 29-09-2023 04:09, John Larkin wrote:
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.k...@gmail.com> wrote:
On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus Kragelund <klaus.k...@gmail.com> wrote in <903144ac-6642-4a3f....@googlegroups.com>:
On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote:
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin <j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>:
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>:
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin <j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>:
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> wrote:
snip
I will generate a single pulse, about 5us long, shaped like a half wave sinusoid, at 100kHz repetition frequency. That\'s why I was looking at flyback, since I can control the voltage delivered simply by adjusting the primary peak current. Power seems to be less than 5W, at 4.5kV peak, duty of let\'s say 25%. probably below 10mA

One can stuff a bunch of current into an inductor and then dump it into a mostly-capacitive load. That can make a high-voltage half-sine.

This boosts 48 volts to 1400v at MHz pulse rates.

http://www.highlandtechnology.com/DSS/T850DS.shtml

by switching an inductor around. The energy is recovered and returned to the 48v supply after each pulse, which keeps the power dissipation under control.

https://www.dropbox.com/scl/fi/lkjg19hvcus9xz8aeecxy/T850_Rev_C.JPG?rlkey=0pitv0zdmb0x1tz0fkw0gj3ob&raw=1

The really tricky stuff is on the bottom of the board, dumping heat into the water-cooled baseplate.

At 5 us, you could make a 4KV DC supply and switch that into your load with a high-voltage mosfet. Brute force.

Yes, that could also be an idea. Will have some losses though, since it\'s switching into a capacitive load.

Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist.

John Larkin doesn\'t like coping with reality. Getting a Ph.D, in chemistry made me a successful chemist, not a failed one and getting a couple of patents as an electronic engineer is fairly convincing evidence that I did succeed as an engineer.

> I don\'t know what symbol failed chemists use for frequency.

John Larkin clearly doesn\'t know what symbol electronic engineers use for frequency. In my experience they use \"f\" not \"F\" and in that context they\'d mostly have used \"2.pi..f\".

A lower case omega would also work. Omega (uppercase Ω, lowercase ω) is the 24th and last letter of the Greek alphabet.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Friday, October 6, 2023 at 3:25:28 AM UTC+11, John Larkin wrote:

On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what
symbol failed chemists use for frequency.

I\'d respect his language skills more if he can ever learn the
difference between

its

and

it\'s.

Sadly, it\'s (a contraction of it is) a distinction that is vulnerable to typos. Flyguy, James Arthur and John Larkin do tend to be rude when other people make them. It\'s (not possessive) not an attractive habit.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Friday, October 6, 2023 at 4:56:58 AM UTC+11, Klaus Vestergaard Kragelund wrote:

On 05-10-2023 08:56, Anthony William Sloman wrote:
On Thursday, October 5, 2023 at 5:20:53 PM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 16:59, Anthony William Sloman wrote:
On Wednesday, October 4, 2023 at 1:41:37 AM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 14:37, John Larkin wrote:
On Tue, 3 Oct 2023 09:46:44 +0200, Klaus Vestergaard Kragelund <klau...@hotmail.com> wrote:
On 29-09-2023 04:09, John Larkin wrote:
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.k...@gmail.com> wrote:
On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus
Kragelund <klaus.k...@gmail.com> wrote in <903144ac-6642-4a3f....@googlegroups.com>:
On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote:
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin
j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>:
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>:
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin
j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>:
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> wrote:

snip

One can stuff a bunch of current into an inductor and then dump it into a mostly-capacitive load. That can make a high-voltage half-sine.

A transformer would work better - perhaps several of them in series.

Dump a bunch of current into the primaries in parallel - perhaps time shifted to allow the high voltage pulse to propagate through the series connected secondaries - and rely on the parallel capacitances of the secondaries to shape the pulse into a half-sine.

That\'s what I was considering doing, but still the individual
transformer needs to be able to handle the 4.5kV isolation from winding
to winding.

Multisection formers make that easy enough. A single layer of 25 micron kapton tape is good for 4kV, and several layers for rather more, so you can do it on a single section former.

Yes, possible. Then a little dirt creeps in, poluted path, ionization, and sparks. Joerg would write \"tssss, kaboom\" etc ;-)

It\'s called \"tracking\" and conformal coatings provide an answer. Cambridge Instruments made electron microscopes, typically 30kV machines. I didn\'t have much to do with the electron source, but had more to do with the photomultiplier (Everhart–Thornley) detector which we mostly ran below 1kV.. I ran one a bit higher

I wouldn\'t presume to predict what Jeorg would say. His most impressive feats were in medical ultrasound (where I\'ve also worked) which doesn\'t use high voltages).

On the subject of avoiding high voltages, could you split the drive to your electro optic modulator, so that one side went to down -2,25kV while the other side went up to +2.2.5kV?

An incidental advantage is that you balance the the stray currents driven into the ground and get quite a lot less electromagnetic interference. A carefully made balanced transfomer drive with a grounded centre tap can do that rather well.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Friday, October 6, 2023 at 11:10:49 AM UTC+11, John Smiht wrote:

On Thursday, October 5, 2023 at 11:25:28 AM UTC-5, John Larkin wrote:
On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what symbol failed chemists use for frequency.

+1

John Larkin has his preferred delusions. Getting a Ph.D. in Physical Chemistry isn\'t what most people would described as a failure in chemistry. Since he doesn\'t know the symbol most elecronic engineers use for frequency, his ignorance about what ex-chemists might do isn\'t exactly surprising. He could seem enough examples my habits here, but he long ago worked that I don\'t post the flattery he craves, so he doesn\'t bother to look at them.

I\'d respect his language skills more if he can ever learn the difference between

its

and

it\'s.

Another +1

Don\'t encourage him. It\'s not even his slur, but one he poached from James Arthur, who should have had enough sense not to confuse the occasional typo with actual ignorance.
Not that James Arthur had much sense - he confessed to being a paid shill for the Koch brothers here (back when there were still two of them) and has gone quiet ever since.

--
Bill Sloman, Sydney

 

[John Smiht]

On Friday, October 6, 2023 at 8:04:14 AM UTC-5, Anthony William Sloman wrote:

On Friday, October 6, 2023 at 11:10:49 AM UTC+11, John Smiht wrote:
On Thursday, October 5, 2023 at 11:25:28 AM UTC-5, John Larkin wrote:
On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what symbol failed chemists use for frequency.

+1
John Larkin has his preferred delusions. Getting a Ph.D. in Physical Chemistry isn\'t what most people would described as a failure in chemistry. Since he doesn\'t know the symbol most elecronic engineers use for frequency, his ignorance about what ex-chemists might do isn\'t exactly surprising. He could seem enough examples my habits here, but he long ago worked that I don\'t post the flattery he craves, so he doesn\'t bother to look at them.
I\'d respect his language skills more if he can ever learn the difference between

its

and

it\'s.

Another +1
Don\'t encourage him. It\'s not even his slur, but one he poached from James Arthur, who should have had enough sense not to confuse the occasional typo with actual ignorance.
Not that James Arthur had much sense - he confessed to being a paid shill for the Koch brothers here (back when there were still two of them) and has gone quiet ever since.

--
Bill Sloman, Sydney

Fork you. I will encourage whomever I wish to encourage.

 

[John Larkin]

On Fri, 6 Oct 2023 09:17:01 -0700 (PDT), John Smiht
<utube.jocjo@xoxy.net> wrote:

On Friday, October 6, 2023 at 8:04:14?AM UTC-5, Anthony William Sloman wrote:
On Friday, October 6, 2023 at 11:10:49?AM UTC+11, John Smiht wrote:
On Thursday, October 5, 2023 at 11:25:28?AM UTC-5, John Larkin wrote:
On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what symbol failed chemists use for frequency.

+1
John Larkin has his preferred delusions. Getting a Ph.D. in Physical Chemistry isn\'t what most people would described as a failure in chemistry. Since he doesn\'t know the symbol most elecronic engineers use for frequency, his ignorance about what ex-chemists might do isn\'t exactly surprising. He could seem enough examples my habits here, but he long ago worked that I don\'t post the flattery he craves, so he doesn\'t bother to look at them.
I\'d respect his language skills more if he can ever learn the difference between

its

and

it\'s.

Another +1
Don\'t encourage him. It\'s not even his slur, but one he poached from James Arthur, who should have had enough sense not to confuse the occasional typo with actual ignorance.
Not that James Arthur had much sense - he confessed to being a paid shill for the Koch brothers here (back when there were still two of them) and has gone quiet ever since.

--
Bill Sloman, Sydney

Fork you. I will encourage whomever I wish to encourage.

Ignore Sloman. He\'s just here to insult people. He hasn\'t designed
anything in decades.

 

[Klaus Vestergaard Kragelund]

On 06-10-2023 06:35, Anthony William Sloman wrote:

On Friday, October 6, 2023 at 4:56:58 AM UTC+11, Klaus Vestergaard Kragelund wrote:
On 05-10-2023 08:56, Anthony William Sloman wrote:
On Thursday, October 5, 2023 at 5:20:53 PM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 16:59, Anthony William Sloman wrote:
On Wednesday, October 4, 2023 at 1:41:37 AM UTC+11, Klaus Vestergaard Kragelund wrote:
On 03-10-2023 14:37, John Larkin wrote:
On Tue, 3 Oct 2023 09:46:44 +0200, Klaus Vestergaard Kragelund <klau...@hotmail.com> wrote:
On 29-09-2023 04:09, John Larkin wrote:
On Thu, 28 Sep 2023 13:58:40 -0700 (PDT), Klaus Kragelund <klaus.k...@gmail.com> wrote:
On Thursday, 28 September 2023 at 17:26:46 UTC+2, John Larkin wrote:
On Thu, 28 Sep 2023 14:59:48 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 13:34:29 -0700 (PDT)) it happened Klaus
Kragelund <klaus.k...@gmail.com> wrote in <903144ac-6642-4a3f...@googlegroups.com>:
On Wednesday, 27 September 2023 at 17:38:35 UTC+2, Jan Panteltje wrote:
On a sunny day (Wed, 27 Sep 2023 08:10:02 -0700) it happened John Larkin
j...@997arbor.com> wrote in <d3h8hitm54oie4gcl...@4ax.com>:
On Wed, 27 Sep 2023 11:44:57 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 27 Sep 2023 00:51:10 -0700) it happened John Larkin <j...@997arbor.com> wrote in <4bn7hit0n3rmcg855...@4ax.com>:
On Wed, 27 Sep 2023 05:14:49 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Tue, 26 Sep 2023 19:35:18 -0700) it happened John Larkin
j...@997arbor.com> wrote in <mf47hi15db7eq7mp2...@4ax.com>:
On Sun, 24 Sep 2023 09:18:31 -0700, John Larkin <j...@997arbor.com> wrote:

snip

One can stuff a bunch of current into an inductor and then dump it into a mostly-capacitive load. That can make a high-voltage half-sine.

A transformer would work better - perhaps several of them in series.

Dump a bunch of current into the primaries in parallel - perhaps time shifted to allow the high voltage pulse to propagate through the series connected secondaries - and rely on the parallel capacitances of the secondaries to shape the pulse into a half-sine.

That\'s what I was considering doing, but still the individual
transformer needs to be able to handle the 4.5kV isolation from winding
to winding.

Multisection formers make that easy enough. A single layer of 25 micron kapton tape is good for 4kV, and several layers for rather more, so you can do it on a single section former.

Yes, possible. Then a little dirt creeps in, poluted path, ionization, and sparks. Joerg would write \"tssss, kaboom\" etc ;-)

It\'s called \"tracking\" and conformal coatings provide an answer. Cambridge Instruments made electron microscopes, typically 30kV machines. I didn\'t have much to do with the electron source, but had more to do with the photomultiplier (Everhart–Thornley) detector which we mostly ran below 1kV. I ran one a bit higher

I wouldn\'t presume to predict what Jeorg would say. His most impressive feats were in medical ultrasound (where I\'ve also worked) which doesn\'t use high voltages).

On the subject of avoiding high voltages, could you split the drive to your electro optic modulator, so that one side went to down -2,25kV while the other side went up to +2.2.5kV?

An incidental advantage is that you balance the the stray currents driven into the ground and get quite a lot less electromagnetic interference. A carefully made balanced transfomer drive with a grounded centre tap can do that rather well.

That is a really good idea. I have done something similar when reducing
common mode voltages for a half-bridge converter, but didn\'t think to
use it in this application. Thanks for that
>

 

[ehsjr]

On 10/6/2023 12:15 AM, Anthony William Sloman wrote:

On Friday, October 6, 2023 at 3:25:28 AM UTC+11, John Larkin wrote:
On Thu, 5 Oct 2023 08:15:00 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
On Thursday, October 5, 2023 at 9:22:50?AM UTC-5, John Larkin wrote:
On Wed, 4 Oct 2023 08:24:08 -0700 (PDT), John Smiht
utube...@xoxy.net> wrote:
Switching a DC supply into a capacitive load is inherently lossy, and people usually discharge the cap and waste that energy, too.
It isn\'t, if the load hasn\'t got any resistance. Discharging the capacitor into a separate supply isn\'t clever.
So power dissipation is C*F*V^2. The inductor trick has, ideally, zero power dissipation... it just sloshes energy around. That\'s how I got 4 MHz out of a tiny Pockels Cell driver.
What on earth is \"F\"?

To an engineer it means, in this context, frequency. So to you it might mean something else in your fancy vocabulary.

Sloman isn\'t an engineer, he\'s a failed chemist. I don\'t know what
symbol failed chemists use for frequency.

I\'d respect his language skills more if he can ever learn the
difference between

its

and

it\'s.

Sadly, it\'s (a contraction of it is) a distinction that is vulnerable to typos. Flyguy, James Arthur and John Larkin do tend to be rude when other people make them. It\'s (not possessive) not an attractive habit.

Bill, you have written 252 ad hominem (what you term \"rude\") posts
on this newsgroup since 7/15/2023. On several occasions I mentioned
the (what I called negative) nature of what you posted in a reply
to it. The \"rude\" posts to which I refer sometimes had worthwhile
points in them in addition to the rude remarks, and sometimes not.
But it (the rudeness in the posts) is so frequent as to be off
putting.

I told you my thinking - that you have something to offer - so
please don\'t waste time on the negatives. Sadly it didn\'t work.
I got to the point where I thought I was your only fan after wading
through post after post where you denigrate the one to whom you
are replying.

I mention all of this because you told me it would be a kindness
you would appreciate if someone pointed out your errors to you.
You will undoubtedly think that you are without error in this,
or that the rudeness was justified.

Whatever. It\'s my loss to miss whatever good content you might
post in place of ad hominem nonsense which adds nothing of value.

Ex fan.
Ed