HV dc/dc...

[Bill Sloman]

On Sunday, July 19, 2020 at 12:42:42 PM UTC+10, jla...@highlandsniptechnology.com wrote:

On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-17 09:49, jlarkin@highlandsniptechnology.com wrote:


I need eight isolated 150 volt DC supplies, low current, under 1 mA
average. Commercial dc/dc converters are crazy expensive:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=&pkeyword=&sv=0&pv183=354808&pv183=354809&pv2211=i1&pv1525=100671&pv1525=114705&pv1525=140848&pv1525=157291&pv1525=182727&sf=1&FV=-8%7C922&quantity=&ColumnSort=0&page=1&pageSize=25

I guess I\'ll have to design it. Coilcraft has some nice little flyback
transformers.

I think I can use one flyback driver circuit and put all eight
primaries in parallel. Maybe regulate a little on the high sides.

The application is eight isolated high-voltage pulse outputs. My first
idea was to use grounded drivers and final pulse transformers, but the
volt-seconds get huge so the pulse transformer would be awful. Better
to float the entire output circuit.


Mostly I used CCFL inverter transformers for that. Cheap, fairly small.
Even complete modules can be had for a few dollars:

https://www.ebay.com/itm/1Pc-CCFL-inverter-board-for-LCD-screen-with-1CCFL-backlight-LCD-JN/392849295194

$3.33 with free shipping from China. We pay for that.


Yup, they\'ll make the next aircraft carrier :-(


Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

It\'s probably Baxandall Class-D oscillator. Jim Williams seems to have got the circuit from England without getting the literature reference that should have come with it - Baxandall, P.J, Proc I.E.E 106, B, 748 (1959.

http://sophia-elektronica.com/0344_001_Baxandal.pdf

From my web-site.

\"The circuit is probably best known from Jim Williams’ series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams describes the inverter as a current driven Royer inverter, referring back to the non-resonant inverter described by Bright, Pittman and George H. Royer in 1954 in a paper “Transistors as on-off switches in saturable core circuits” in Electrical Manufacturing.\"

The Baxandall inverter is handy for driving high-turns ratio step-up transformers which tend end up with rather low self-resonant frequencies.

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

The Cockroft-Walton multiplier isn\'t all that cool.

Or you could learn how to design your own special purpose transformers and find a shop that would wind them for you - it isn\'t all that difficult.

There are lots of variables to twiddle in a transformer design, so getting something close enough off the shelf isn\'t easy, even if you get downright sloppy about \"close enough\".

--
Bill Sloman, Sydney

 

[Lasse Langwadt Christensen]

søndag den 19. juli 2020 kl. 16.33.42 UTC+2 skrev Bill Sloman:

On Sunday, July 19, 2020 at 12:42:42 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-17 09:49, jlarkin@highlandsniptechnology.com wrote:


I need eight isolated 150 volt DC supplies, low current, under 1 mA
average. Commercial dc/dc converters are crazy expensive:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=&pkeyword=&sv=0&pv183=354808&pv183=354809&pv2211=i1&pv1525=100671&pv1525=114705&pv1525=140848&pv1525=157291&pv1525=182727&sf=1&FV=-8%7C922&quantity=&ColumnSort=0&page=1&pageSize=25

I guess I\'ll have to design it. Coilcraft has some nice little flyback
transformers.

I think I can use one flyback driver circuit and put all eight
primaries in parallel. Maybe regulate a little on the high sides.

The application is eight isolated high-voltage pulse outputs. My first
idea was to use grounded drivers and final pulse transformers, but the
volt-seconds get huge so the pulse transformer would be awful. Better
to float the entire output circuit.


Mostly I used CCFL inverter transformers for that. Cheap, fairly small.
Even complete modules can be had for a few dollars:

https://www.ebay.com/itm/1Pc-CCFL-inverter-board-for-LCD-screen-with-1CCFL-backlight-LCD-JN/392849295194

$3.33 with free shipping from China. We pay for that.


Yup, they\'ll make the next aircraft carrier :-(


Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

It\'s probably Baxandall Class-D oscillator. Jim Williams seems to have got the circuit from England without getting the literature reference that should have come with it - Baxandall, P.J, Proc I.E.E 106, B, 748 (1959.

http://sophia-elektronica.com/0344_001_Baxandal.pdf

From my web-site.

\"The circuit is probably best known from Jim Williams’ series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams describes the inverter as a current driven Royer inverter, referring back to the non-resonant inverter described by Bright, Pittman and George H. Royer in 1954 in a paper “Transistors as on-off switches in saturable core circuits” in Electrical Manufacturing.\"

The Baxandall inverter is handy for driving high-turns ratio step-up transformers which tend end up with rather low self-resonant frequencies.

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

The Cockroft-Walton multiplier isn\'t all that cool.

Or you could learn how to design your own special purpose transformers and find a shop that would wind them for you - it isn\'t all that difficult.

There are lots of variables to twiddle in a transformer design, so getting something close enough off the shelf isn\'t easy, even if you get downright sloppy about \"close enough\".

you are kidding right? a few 100mW at 150V for a low volume product and you
want to spend what would quickly be weeks designing/ordering/twiddling a transformer design?

 

[Lasse Langwadt Christensen]

søndag den 19. juli 2020 kl. 16.33.42 UTC+2 skrev Bill Sloman:

On Sunday, July 19, 2020 at 12:42:42 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-17 09:49, jlarkin@highlandsniptechnology.com wrote:


I need eight isolated 150 volt DC supplies, low current, under 1 mA
average. Commercial dc/dc converters are crazy expensive:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=&pkeyword=&sv=0&pv183=354808&pv183=354809&pv2211=i1&pv1525=100671&pv1525=114705&pv1525=140848&pv1525=157291&pv1525=182727&sf=1&FV=-8%7C922&quantity=&ColumnSort=0&page=1&pageSize=25

I guess I\'ll have to design it. Coilcraft has some nice little flyback
transformers.

I think I can use one flyback driver circuit and put all eight
primaries in parallel. Maybe regulate a little on the high sides.

The application is eight isolated high-voltage pulse outputs. My first
idea was to use grounded drivers and final pulse transformers, but the
volt-seconds get huge so the pulse transformer would be awful. Better
to float the entire output circuit.


Mostly I used CCFL inverter transformers for that. Cheap, fairly small.
Even complete modules can be had for a few dollars:

https://www.ebay.com/itm/1Pc-CCFL-inverter-board-for-LCD-screen-with-1CCFL-backlight-LCD-JN/392849295194

$3.33 with free shipping from China. We pay for that.


Yup, they\'ll make the next aircraft carrier :-(


Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

It\'s probably Baxandall Class-D oscillator. Jim Williams seems to have got the circuit from England without getting the literature reference that should have come with it - Baxandall, P.J, Proc I.E.E 106, B, 748 (1959.

http://sophia-elektronica.com/0344_001_Baxandal.pdf

From my web-site.

\"The circuit is probably best known from Jim Williams’ series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams describes the inverter as a current driven Royer inverter, referring back to the non-resonant inverter described by Bright, Pittman and George H. Royer in 1954 in a paper “Transistors as on-off switches in saturable core circuits” in Electrical Manufacturing.\"

The Baxandall inverter is handy for driving high-turns ratio step-up transformers which tend end up with rather low self-resonant frequencies.

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

The Cockroft-Walton multiplier isn\'t all that cool.

Or you could learn how to design your own special purpose transformers and find a shop that would wind them for you - it isn\'t all that difficult.

There are lots of variables to twiddle in a transformer design, so getting something close enough off the shelf isn\'t easy, even if you get downright sloppy about \"close enough\".

you are kidding right? a few 100mW at 150V for a low volume product and you
want to spend what would quickly be weeks designing/ordering/twiddling a transformer design?

 

[server]

On Sat, 18 Jul 2020 23:11:02 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Jul 2020 08:19:38 -0700, jlarkin@highlandsniptechnology.com
wrote:

snip

It will depend a bit on whether your circuit is
continuous-incomplete energy transfer, or not.

Pretty simple to spice it out for a first order
approximation. A bit of copying/pasting, but don\'t
expect much speed in the sim. Multiple parallel
inductors give spice the heartburn.

RL

This is pretty close:

https://www.dropbox.com/s/gnyjq9ufo34pvao/8-chan_Flyback_1.asc?dl=0

I essentially paralleled all 8 isolated channels. I don\'t think
leakage inductance will matter much. Spice runs better without it.

Loop dynamics depends on a lot of things, so might be tweaked a little
more. Or left alone.

Your fence is now white-washed.

I don\'t understand that one.

The circuit is incomplete energy transfer (and so may
be pretty noisy).

That\'s about what I expected. Different primary inductances don\'t
change the final DC voltages, and a bit of leakage inductance doesn\'t
matter either.

Sure runs slow! Efficiency is about 3%, not surprising. Just R2
dissipates more power than the loads.

The DC supply current is only about 40 mA, not enough to care about.
My pulse rate will be very low too.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sat, 18 Jul 2020 23:11:02 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Jul 2020 08:19:38 -0700, jlarkin@highlandsniptechnology.com
wrote:

snip

It will depend a bit on whether your circuit is
continuous-incomplete energy transfer, or not.

Pretty simple to spice it out for a first order
approximation. A bit of copying/pasting, but don\'t
expect much speed in the sim. Multiple parallel
inductors give spice the heartburn.

RL

This is pretty close:

https://www.dropbox.com/s/gnyjq9ufo34pvao/8-chan_Flyback_1.asc?dl=0

I essentially paralleled all 8 isolated channels. I don\'t think
leakage inductance will matter much. Spice runs better without it.

Loop dynamics depends on a lot of things, so might be tweaked a little
more. Or left alone.

Your fence is now white-washed.

I don\'t understand that one.

The circuit is incomplete energy transfer (and so may
be pretty noisy).

That\'s about what I expected. Different primary inductances don\'t
change the final DC voltages, and a bit of leakage inductance doesn\'t
matter either.

Sure runs slow! Efficiency is about 3%, not surprising. Just R2
dissipates more power than the loads.

The DC supply current is only about 40 mA, not enough to care about.
My pulse rate will be very low too.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sun, 19 Jul 2020 08:49:16 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

søndag den 19. juli 2020 kl. 16.33.42 UTC+2 skrev Bill Sloman:
On Sunday, July 19, 2020 at 12:42:42 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-17 09:49, jlarkin@highlandsniptechnology.com wrote:


I need eight isolated 150 volt DC supplies, low current, under 1 mA
average. Commercial dc/dc converters are crazy expensive:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=&pkeyword=&sv=0&pv183=354808&pv183=354809&pv2211=i1&pv1525=100671&pv1525=114705&pv1525=140848&pv1525=157291&pv1525=182727&sf=1&FV=-8%7C922&quantity=&ColumnSort=0&page=1&pageSize=25

I guess I\'ll have to design it. Coilcraft has some nice little flyback
transformers.

I think I can use one flyback driver circuit and put all eight
primaries in parallel. Maybe regulate a little on the high sides.

The application is eight isolated high-voltage pulse outputs. My first
idea was to use grounded drivers and final pulse transformers, but the
volt-seconds get huge so the pulse transformer would be awful. Better
to float the entire output circuit.


Mostly I used CCFL inverter transformers for that. Cheap, fairly small.
Even complete modules can be had for a few dollars:

https://www.ebay.com/itm/1Pc-CCFL-inverter-board-for-LCD-screen-with-1CCFL-backlight-LCD-JN/392849295194

$3.33 with free shipping from China. We pay for that.


Yup, they\'ll make the next aircraft carrier :-(


Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

It\'s probably Baxandall Class-D oscillator. Jim Williams seems to have got the circuit from England without getting the literature reference that should have come with it - Baxandall, P.J, Proc I.E.E 106, B, 748 (1959.

http://sophia-elektronica.com/0344_001_Baxandal.pdf

From my web-site.

\"The circuit is probably best known from Jim Williams’ series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams describes the inverter as a current driven Royer inverter, referring back to the non-resonant inverter described by Bright, Pittman and George H. Royer in 1954 in a paper “Transistors as on-off switches in saturable core circuits” in Electrical Manufacturing.\"

The Baxandall inverter is handy for driving high-turns ratio step-up transformers which tend end up with rather low self-resonant frequencies.

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

The Cockroft-Walton multiplier isn\'t all that cool.

Or you could learn how to design your own special purpose transformers and find a shop that would wind them for you - it isn\'t all that difficult.

There are lots of variables to twiddle in a transformer design, so getting something close enough off the shelf isn\'t easy, even if you get downright sloppy about \"close enough\".


you are kidding right? a few 100mW at 150V for a low volume product and you
want to spend what would quickly be weeks designing/ordering/twiddling a transformer design?

He has huge enthusiasm for designing custom magnetics. I have huge
enthusiasm for ordering stock parts from Coilcraft or Digikey and
shipping products. He might learn to design with standard parts - it
isn\'t all that difficult.

I wonder how his super oscillator is coming along. He ordered a custom
transformer for that, a decade or two ago.

My customer wants a proof-of-principle 150-volt pulser next week, and
I have a 10-layer PCB to release first. Really, he should just trust
us and order the real things.


--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sun, 19 Jul 2020 08:49:16 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

søndag den 19. juli 2020 kl. 16.33.42 UTC+2 skrev Bill Sloman:
On Sunday, July 19, 2020 at 12:42:42 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-17 09:49, jlarkin@highlandsniptechnology.com wrote:


I need eight isolated 150 volt DC supplies, low current, under 1 mA
average. Commercial dc/dc converters are crazy expensive:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=&pkeyword=&sv=0&pv183=354808&pv183=354809&pv2211=i1&pv1525=100671&pv1525=114705&pv1525=140848&pv1525=157291&pv1525=182727&sf=1&FV=-8%7C922&quantity=&ColumnSort=0&page=1&pageSize=25

I guess I\'ll have to design it. Coilcraft has some nice little flyback
transformers.

I think I can use one flyback driver circuit and put all eight
primaries in parallel. Maybe regulate a little on the high sides.

The application is eight isolated high-voltage pulse outputs. My first
idea was to use grounded drivers and final pulse transformers, but the
volt-seconds get huge so the pulse transformer would be awful. Better
to float the entire output circuit.


Mostly I used CCFL inverter transformers for that. Cheap, fairly small.
Even complete modules can be had for a few dollars:

https://www.ebay.com/itm/1Pc-CCFL-inverter-board-for-LCD-screen-with-1CCFL-backlight-LCD-JN/392849295194

$3.33 with free shipping from China. We pay for that.


Yup, they\'ll make the next aircraft carrier :-(


Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

It\'s probably Baxandall Class-D oscillator. Jim Williams seems to have got the circuit from England without getting the literature reference that should have come with it - Baxandall, P.J, Proc I.E.E 106, B, 748 (1959.

http://sophia-elektronica.com/0344_001_Baxandal.pdf

From my web-site.

\"The circuit is probably best known from Jim Williams’ series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams describes the inverter as a current driven Royer inverter, referring back to the non-resonant inverter described by Bright, Pittman and George H. Royer in 1954 in a paper “Transistors as on-off switches in saturable core circuits” in Electrical Manufacturing.\"

The Baxandall inverter is handy for driving high-turns ratio step-up transformers which tend end up with rather low self-resonant frequencies.

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

The Cockroft-Walton multiplier isn\'t all that cool.

Or you could learn how to design your own special purpose transformers and find a shop that would wind them for you - it isn\'t all that difficult.

There are lots of variables to twiddle in a transformer design, so getting something close enough off the shelf isn\'t easy, even if you get downright sloppy about \"close enough\".


you are kidding right? a few 100mW at 150V for a low volume product and you
want to spend what would quickly be weeks designing/ordering/twiddling a transformer design?

He has huge enthusiasm for designing custom magnetics. I have huge
enthusiasm for ordering stock parts from Coilcraft or Digikey and
shipping products. He might learn to design with standard parts - it
isn\'t all that difficult.

I wonder how his super oscillator is coming along. He ordered a custom
transformer for that, a decade or two ago.

My customer wants a proof-of-principle 150-volt pulser next week, and
I have a 10-layer PCB to release first. Really, he should just trust
us and order the real things.


--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sat, 18 Jul 2020 23:11:02 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Jul 2020 08:19:38 -0700, jlarkin@highlandsniptechnology.com
wrote:

snip

It will depend a bit on whether your circuit is
continuous-incomplete energy transfer, or not.

Pretty simple to spice it out for a first order
approximation. A bit of copying/pasting, but don\'t
expect much speed in the sim. Multiple parallel
inductors give spice the heartburn.

RL

This is pretty close:

https://www.dropbox.com/s/gnyjq9ufo34pvao/8-chan_Flyback_1.asc?dl=0

I essentially paralleled all 8 isolated channels. I don\'t think
leakage inductance will matter much. Spice runs better without it.

Loop dynamics depends on a lot of things, so might be tweaked a little
more. Or left alone.

Your fence is now white-washed.

I don\'t understand that one.

The circuit is incomplete energy transfer (and so may
be pretty noisy).

That\'s about what I expected. Different primary inductances don\'t
change the final DC voltages, and a bit of leakage inductance doesn\'t
matter either.

Sure runs slow! Efficiency is about 3%, not surprising. Just R2
dissipates more power than the loads.

The DC supply current is only about 40 mA, not enough to care about.
My pulse rate will be very low too.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Piglet]

On 19/07/2020 18:14, jlarkin@highlandsniptechnology.com wrote:

On Sun, 19 Jul 2020 08:49:16 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

søndag den 19. juli 2020 kl. 16.33.42 UTC+2 skrev Bill Sloman:
On Sunday, July 19, 2020 at 12:42:42 PM UTC+10, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-17 09:49, jlarkin@highlandsniptechnology.com wrote:


I need eight isolated 150 volt DC supplies, low current, under 1 mA
average. Commercial dc/dc converters are crazy expensive:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=&pkeyword=&sv=0&pv183=354808&pv183=354809&pv2211=i1&pv1525=100671&pv1525=114705&pv1525=140848&pv1525=157291&pv1525=182727&sf=1&FV=-8%7C922&quantity=&ColumnSort=0&page=1&pageSize=25

I guess I\'ll have to design it. Coilcraft has some nice little flyback
transformers.

I think I can use one flyback driver circuit and put all eight
primaries in parallel. Maybe regulate a little on the high sides.

The application is eight isolated high-voltage pulse outputs. My first
idea was to use grounded drivers and final pulse transformers, but the
volt-seconds get huge so the pulse transformer would be awful. Better
to float the entire output circuit.


Mostly I used CCFL inverter transformers for that. Cheap, fairly small.
Even complete modules can be had for a few dollars:

https://www.ebay.com/itm/1Pc-CCFL-inverter-board-for-LCD-screen-with-1CCFL-backlight-LCD-JN/392849295194

$3.33 with free shipping from China. We pay for that.


Yup, they\'ll make the next aircraft carrier :-(


Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

It\'s probably Baxandall Class-D oscillator. Jim Williams seems to have got the circuit from England without getting the literature reference that should have come with it - Baxandall, P.J, Proc I.E.E 106, B, 748 (1959.

http://sophia-elektronica.com/0344_001_Baxandal.pdf

From my web-site.

\"The circuit is probably best known from Jim Williams’ series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65). Jim Williams describes the inverter as a current driven Royer inverter, referring back to the non-resonant inverter described by Bright, Pittman and George H. Royer in 1954 in a paper “Transistors as on-off switches in saturable core circuits” in Electrical Manufacturing.\"

The Baxandall inverter is handy for driving high-turns ratio step-up transformers which tend end up with rather low self-resonant frequencies.

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

The Cockroft-Walton multiplier isn\'t all that cool.

Or you could learn how to design your own special purpose transformers and find a shop that would wind them for you - it isn\'t all that difficult.

There are lots of variables to twiddle in a transformer design, so getting something close enough off the shelf isn\'t easy, even if you get downright sloppy about \"close enough\".


you are kidding right? a few 100mW at 150V for a low volume product and you
want to spend what would quickly be weeks designing/ordering/twiddling a transformer design?




He has huge enthusiasm for designing custom magnetics. I have huge
enthusiasm for ordering stock parts from Coilcraft or Digikey and
shipping products. He might learn to design with standard parts - it
isn\'t all that difficult.

I wonder how his super oscillator is coming along. He ordered a custom
transformer for that, a decade or two ago.

My customer wants a proof-of-principle 150-volt pulser next week, and
I have a 10-layer PCB to release first. Really, he should just trust
us and order the real things.

You are barely touching the volt-second capability of those
transformers, clearly over-engineered :>

But seriously, what\'s the inter-winding capacitance and is that
tolerable in your app?

piglet

 

[Joerg]

On 2020-07-19 06:57, Phil Hobbs wrote:

On 2020-07-18 22:42, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

[...]

Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

Yes, and they have limits in terms of voltage.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

I also love dual-winding coils. Just make sure to vet the isolation
voltage with the manufacturer.

The ones I\'ve used have been Royers, with open-circuit outputs over a
kilovolt (so they can strike the discharge).

They can generate 1200V or more but I never used them that high. I
either drive them with an externally driven Royer (from logic on my
board) or drive them directly from a gate driver.

They come with two HV caps on the output that you can use to make
voltage doublers, which is convenient.

Mine came bare-bones, no caps. The first one I designed dutifully had
warnings in English and Spanish. Sure enough the first one it bit was
myself (German-born) and the Chinese-born engineer at my client laughed.
\"See? You should have had that warning on the board also in German and
Chinese so we are all protected\".

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2020-07-19 06:57, Phil Hobbs wrote:

On 2020-07-18 22:42, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

[...]

Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

Yes, and they have limits in terms of voltage.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

I also love dual-winding coils. Just make sure to vet the isolation
voltage with the manufacturer.

The ones I\'ve used have been Royers, with open-circuit outputs over a
kilovolt (so they can strike the discharge).

They can generate 1200V or more but I never used them that high. I
either drive them with an externally driven Royer (from logic on my
board) or drive them directly from a gate driver.

They come with two HV caps on the output that you can use to make
voltage doublers, which is convenient.

Mine came bare-bones, no caps. The first one I designed dutifully had
warnings in English and Spanish. Sure enough the first one it bit was
myself (German-born) and the Chinese-born engineer at my client laughed.
\"See? You should have had that warning on the board also in German and
Chinese so we are all protected\".

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2020-07-19 06:57, Phil Hobbs wrote:

On 2020-07-18 22:42, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 19:31:09 -0700, Joerg <news@analogconsultants.com
wrote:

On 2020-07-18 12:39, jlarkin@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 11:27:16 -0700, Joerg <news@analogconsultants.com
wrote:

[...]

Or course, with everything going LED and OLED these days it\'s only a
matter of years until the available selection starts to thin out.

I won\'t use ebay or Amazon stuff in my gear. Some of my customers care
about part traceability and anti-Chinese stuff.

Some of those things, ebay and Amazon, are OK for breadboards and lab
cables and such.

One customer recently elected to buy a bunch of $40 cables from us,
when Amazon has them for $6.


It was just meant as an example. On most projects where I needed a few
hundred volts I used the bare CCFL transformers and they cost just a few
bucks. Even from US sources they are often produced abroad, sometimes in
China.

Are the CCFL supplies flybacks or Royers or something? What sorts of
open-circuit voltages do they make?

But right, it\'s all LEDs now.

I like ISDN transformers, but they will be gone too.

Yes, and they have limits in terms of voltage.

The little DRQ-type dual inductors are great. The autotransformer
flyback and CW multiplier thing is cool.

I also love dual-winding coils. Just make sure to vet the isolation
voltage with the manufacturer.

The ones I\'ve used have been Royers, with open-circuit outputs over a
kilovolt (so they can strike the discharge).

They can generate 1200V or more but I never used them that high. I
either drive them with an externally driven Royer (from logic on my
board) or drive them directly from a gate driver.

They come with two HV caps on the output that you can use to make
voltage doublers, which is convenient.

Mine came bare-bones, no caps. The first one I designed dutifully had
warnings in English and Spanish. Sure enough the first one it bit was
myself (German-born) and the Chinese-born engineer at my client laughed.
\"See? You should have had that warning on the board also in German and
Chinese so we are all protected\".

--
Regards, Joerg

http://www.analogconsultants.com/

 

[legg]

On Sun, 19 Jul 2020 10:04:56 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 18 Jul 2020 23:11:02 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Jul 2020 08:19:38 -0700, jlarkin@highlandsniptechnology.com
wrote:

snip

It will depend a bit on whether your circuit is
continuous-incomplete energy transfer, or not.

Pretty simple to spice it out for a first order
approximation. A bit of copying/pasting, but don\'t
expect much speed in the sim. Multiple parallel
inductors give spice the heartburn.

RL

This is pretty close:

https://www.dropbox.com/s/gnyjq9ufo34pvao/8-chan_Flyback_1.asc?dl=0

I essentially paralleled all 8 isolated channels. I don\'t think
leakage inductance will matter much. Spice runs better without it.

Loop dynamics depends on a lot of things, so might be tweaked a little
more. Or left alone.

Your fence is now white-washed.

I don\'t understand that one.

.. . . at least I didn\'t pay you to do it ;-] ( Twain- Sawyer / Finn )


RL

 

[legg]

On Sun, 19 Jul 2020 10:04:56 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 18 Jul 2020 23:11:02 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Jul 2020 08:19:38 -0700, jlarkin@highlandsniptechnology.com
wrote:

snip

It will depend a bit on whether your circuit is
continuous-incomplete energy transfer, or not.

Pretty simple to spice it out for a first order
approximation. A bit of copying/pasting, but don\'t
expect much speed in the sim. Multiple parallel
inductors give spice the heartburn.

RL

This is pretty close:

https://www.dropbox.com/s/gnyjq9ufo34pvao/8-chan_Flyback_1.asc?dl=0

I essentially paralleled all 8 isolated channels. I don\'t think
leakage inductance will matter much. Spice runs better without it.

Loop dynamics depends on a lot of things, so might be tweaked a little
more. Or left alone.

Your fence is now white-washed.

I don\'t understand that one.

.. . . at least I didn\'t pay you to do it ;-] ( Twain- Sawyer / Finn )


RL

 

[legg]

On Sun, 19 Jul 2020 10:04:56 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 18 Jul 2020 23:11:02 -0400, legg <legg@nospam.magma.ca> wrote:

On Sat, 18 Jul 2020 08:19:38 -0700, jlarkin@highlandsniptechnology.com
wrote:

snip

It will depend a bit on whether your circuit is
continuous-incomplete energy transfer, or not.

Pretty simple to spice it out for a first order
approximation. A bit of copying/pasting, but don\'t
expect much speed in the sim. Multiple parallel
inductors give spice the heartburn.

RL

This is pretty close:

https://www.dropbox.com/s/gnyjq9ufo34pvao/8-chan_Flyback_1.asc?dl=0

I essentially paralleled all 8 isolated channels. I don\'t think
leakage inductance will matter much. Spice runs better without it.

Loop dynamics depends on a lot of things, so might be tweaked a little
more. Or left alone.

Your fence is now white-washed.

I don\'t understand that one.

.. . . at least I didn\'t pay you to do it ;-] ( Twain- Sawyer / Finn )


RL

 

[legg]

On Sun, 19 Jul 2020 18:42:11 +0100, Piglet <erichpwagner@hotmail.com>
wrote:

<snip>

My customer wants a proof-of-principle 150-volt pulser next week, and
I have a 10-layer PCB to release first. Really, he should just trust
us and order the real things.



You are barely touching the volt-second capability of those
transformers, clearly over-engineered :

But seriously, what\'s the inter-winding capacitance and is that
tolerable in your app?

piglet

With an even number of identical parts, driven synchronously,
it should be possible to reconfigure outputs without altering
function and ground ground appropriate points to get an
approximate null of local noise current.

Finnicky.

RL

 

[legg]

On Sun, 19 Jul 2020 18:42:11 +0100, Piglet <erichpwagner@hotmail.com>
wrote:

<snip>

My customer wants a proof-of-principle 150-volt pulser next week, and
I have a 10-layer PCB to release first. Really, he should just trust
us and order the real things.



You are barely touching the volt-second capability of those
transformers, clearly over-engineered :

But seriously, what\'s the inter-winding capacitance and is that
tolerable in your app?

piglet

With an even number of identical parts, driven synchronously,
it should be possible to reconfigure outputs without altering
function and ground ground appropriate points to get an
approximate null of local noise current.

Finnicky.

RL

 

[legg]

On Sun, 19 Jul 2020 18:42:11 +0100, Piglet <erichpwagner@hotmail.com>
wrote:

<snip>

My customer wants a proof-of-principle 150-volt pulser next week, and
I have a 10-layer PCB to release first. Really, he should just trust
us and order the real things.



You are barely touching the volt-second capability of those
transformers, clearly over-engineered :

But seriously, what\'s the inter-winding capacitance and is that
tolerable in your app?

piglet

With an even number of identical parts, driven synchronously,
it should be possible to reconfigure outputs without altering
function and ground ground appropriate points to get an
approximate null of local noise current.

Finnicky.

RL

 

[Piotr Wyderski]

jlarkin@highlandsniptechnology.com wrote:

> He has huge enthusiasm for designing custom magnetics.

I share his enthusiasm. If you depend on some non-linearities, there is
no other way but to learn the craft.

I have huge
enthusiasm for ordering stock parts from Coilcraft or Digikey and
shipping products. He might learn to design with standard parts - it
isn\'t all that difficult.

But why can\'t you have the best of both worlds and use standard parts
wherever possible and custom ones when there is a potential for blowing
the competition out of the water? Custom parts are still manufacturable,
just more expensive.

Best regards, Piotr

 

[Piotr Wyderski]

jlarkin@highlandsniptechnology.com wrote:

> He has huge enthusiasm for designing custom magnetics.

I share his enthusiasm. If you depend on some non-linearities, there is
no other way but to learn the craft.

I have huge
enthusiasm for ordering stock parts from Coilcraft or Digikey and
shipping products. He might learn to design with standard parts - it
isn\'t all that difficult.

But why can\'t you have the best of both worlds and use standard parts
wherever possible and custom ones when there is a potential for blowing
the competition out of the water? Custom parts are still manufacturable,
just more expensive.

Best regards, Piotr