HV dc/dc...

[server]

On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.

Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

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.

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.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

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.

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.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[sea moss]

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:

On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).

 

[sea moss]

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:

On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).

 

[server]

On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
<danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).

This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

Faking in a little leakage inductance doesn\'t seem to change things.

The fet ON times are awfully short. I need to verify this by
breadboard.

I never learned c, which is just as well, since Python is the rage
now.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
<danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).

This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

Faking in a little leakage inductance doesn\'t seem to change things.

The fet ON times are awfully short. I need to verify this by
breadboard.

I never learned c, which is just as well, since Python is the rage
now.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Jasen Betts]

On 2020-07-18, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:

On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).


This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

This \"efficiency\" is so that you can keep R4 warm?

> Faking in a little leakage inductance doesn\'t seem to change things.

Leakage inductance is mostly to save money I think. if you can store
enough enegy in your chosen transformer then you can build a flyback.
A gap adds energy storage but also reduces coupling.

The fet ON times are awfully short. I need to verify this by
breadboard.

Output regulation seems poor, that\'s possibly the impedance
added by the doubler.

--
Jasen.

 

[Jasen Betts]

On 2020-07-18, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:

On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).


This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

This \"efficiency\" is so that you can keep R4 warm?

> Faking in a little leakage inductance doesn\'t seem to change things.

Leakage inductance is mostly to save money I think. if you can store
enough enegy in your chosen transformer then you can build a flyback.
A gap adds energy storage but also reduces coupling.

The fet ON times are awfully short. I need to verify this by
breadboard.

Output regulation seems poor, that\'s possibly the impedance
added by the doubler.

--
Jasen.

 

[Jasen Betts]

On 2020-07-18, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:

On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).


This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

This \"efficiency\" is so that you can keep R4 warm?

> Faking in a little leakage inductance doesn\'t seem to change things.

Leakage inductance is mostly to save money I think. if you can store
enough enegy in your chosen transformer then you can build a flyback.
A gap adds energy storage but also reduces coupling.

The fet ON times are awfully short. I need to verify this by
breadboard.

Output regulation seems poor, that\'s possibly the impedance
added by the doubler.

--
Jasen.

 

[server]

On Sat, 18 Jul 2020 23:59:17 -0000 (UTC), Jasen Betts
<jasen@xnet.co.nz> wrote:

On 2020-07-18, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:
On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).


This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

This \"efficiency\" is so that you can keep R4 warm?

The entire rackmount beast will use about two watts, and I\'m not going
to pay the electric bill. It\'s the voltage swing I didn\'t want to
waste.

Faking in a little leakage inductance doesn\'t seem to change things.

Leakage inductance is mostly to save money I think. if you can store
enough enegy in your chosen transformer then you can build a flyback.
A gap adds energy storage but also reduces coupling.

The fet ON times are awfully short. I need to verify this by
breadboard.

Output regulation seems poor, that\'s possibly the impedance
added by the doubler.

That\'s the reason to have the 150 volt regulators on the highsides.
200, even 300 volts unregulated would be fine.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sat, 18 Jul 2020 23:59:17 -0000 (UTC), Jasen Betts
<jasen@xnet.co.nz> wrote:

On 2020-07-18, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:
On Sat, 18 Jul 2020 12:47:57 -0700 (PDT), sea moss
danluster81@gmail.com> wrote:

On Saturday, July 18, 2020 at 12:32:21 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 18 Jul 2020 20:10:45 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

We use a ton of TPIC6595, a simlar part, as our universal relay and
LED driver. But I don\'t need independent control, and there will be no
uP or FPGA or anything.

You don\'t need an MCU. Just connect SER IN to VDD, SER CLK to G and have
fun.

I think one big fet can drive all 8 flyback transformers.

8*150V*1e-3A=1.2W
*Big* fet?

Bigger than SOT-23.


Use both channels of IR21531 to drive two out of phase flybacks.

We have LTC3803 in stock and they work great.

Here\'s my circuit so far:

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

It has ground-side flyback voltage feedback (D3 etc) to make the
isolated voltages about 200, so I can regulate them to 150.

Since the Coilcraft transformer has dual secondaries, I guess I could
have one transformer power two channels, with a voltage doubler in
each. That would be fun. The caps in the doubler could be current
limiters, so I could shunt regulate.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

I played around with your sim a little bit (the one you posted earlier this morning). Since the datasheet for Q4436-BL states inductance as 22uH +-15%, I drew all 8 transformers, with 4 of them at 22uH, 2 at 15% low (18.7uH) and 2 at 15% high (25.3uH), and everything else scaled accordingly. The outputs are dead on until you reduce the coupling factor K; I set it at 0.9 and all the outputs start to drift with an 8M ohm load on each output, up to 270V. I changed the loads to 1M on each output, and it looks nice; 180V for the lower inductances and 220V for the high inductances. If you want better matching, obviously for the one-off unit you can just measure the inductances first.

Anyways, that was my Saturday morning exercise. Now gonna write some C code (yuck).


This version

https://www.dropbox.com/s/lzrdedgx7ygtv76/8-chan_Doubler_1.asc?dl=0

uses half as many transformers. It uses voltage doublers in the
isolated channels and a doubler in the flyback feedback loop.

The initial swing of the flyback, when the fet turns on, is negative
24 volts, and there\'s no point in wasting that.

This \"efficiency\" is so that you can keep R4 warm?

The entire rackmount beast will use about two watts, and I\'m not going
to pay the electric bill. It\'s the voltage swing I didn\'t want to
waste.

Faking in a little leakage inductance doesn\'t seem to change things.

Leakage inductance is mostly to save money I think. if you can store
enough enegy in your chosen transformer then you can build a flyback.
A gap adds energy storage but also reduces coupling.

The fet ON times are awfully short. I need to verify this by
breadboard.

Output regulation seems poor, that\'s possibly the impedance
added by the doubler.

That\'s the reason to have the 150 volt regulators on the highsides.
200, even 300 volts unregulated would be fine.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Joerg]

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.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[server]

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?

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.







--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

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?

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.







--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[legg]

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.

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


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SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 -16 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D7
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 -16 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C5
SYMATTR Value 47n
SYMBOL res 1632 -16 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R9
SYMATTR Value 8e6
SYMBOL ind2 1264 240 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L10
SYMATTR Value 648µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 144 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D8
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 144 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D9
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 144 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C8
SYMATTR Value 47n
SYMBOL res 1632 144 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R11
SYMATTR Value 8e6
SYMBOL ind2 1264 400 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L11
SYMATTR Value 540µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 304 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D10
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 304 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D11
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 304 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C9
SYMATTR Value 47n
SYMBOL res 1632 304 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R12
SYMATTR Value 8e6
SYMBOL ind2 1264 560 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L12
SYMATTR Value 540µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 464 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D12
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 464 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D13
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 464 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C10
SYMATTR Value 47n
SYMBOL res 1632 464 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R13
SYMATTR Value 8e6
SYMBOL res 432 -192 R0
SYMATTR InstName R14
SYMATTR Value .1
SYMBOL res 560 -192 R0
SYMATTR InstName R15
SYMATTR Value .1
SYMBOL res 688 -192 R0
SYMATTR InstName R16
SYMATTR Value .1
SYMBOL res 816 -192 R0
SYMATTR InstName R17
SYMATTR Value .1
SYMBOL res 944 -192 R0
SYMATTR InstName R18
SYMATTR Value .1
SYMBOL res 1056 -192 R0
SYMATTR InstName R19
SYMATTR Value .1
TEXT 504 -368 Bottom 2 !K1 L1 L2 0.98
TEXT -64 592 Left 2 !.tran 100m startup
TEXT 248 -304 Left 2 ;8X Q4436-BL
TEXT 376 424 Left 2 ;0.8V
TEXT 712 248 Left 2 ;ZVN4424
TEXT -64 552 Left 2 !.options reltol = 0.01
TEXT 264 -264 Left 2 ;Lp = 22 uH
TEXT 280 -224 Left 2 ;1:5
TEXT 1504 -264 Left 2 ;200 uA
TEXT -72 -320 Left 2 ;200V Octal Flyback Supply
TEXT -48 -272 Left 2 ;J Larkin Jul 17 2020
TEXT 1312 616 Left 2 ;===== 6 of 8 isolated channels =====
TEXT -56 632 Left 2 ;use alternate solver
TEXT 1400 -264 Left 2 ;BAV23S
TEXT 1504 -104 Left 2 ;200 uA
TEXT 1400 -104 Left 2 ;BAV23S
TEXT 1504 56 Left 2 ;200 uA
TEXT 1400 56 Left 2 ;BAV23S
TEXT 1504 216 Left 2 ;200 uA
TEXT 1400 216 Left 2 ;BAV23S
TEXT 1504 376 Left 2 ;200 uA
TEXT 1400 376 Left 2 ;BAV23S
TEXT 1504 536 Left 2 ;200 uA
TEXT 1400 536 Left 2 ;BAV23S
TEXT 448 -352 Left 2 !K2 L3 L8 0.98
TEXT 704 -376 Left 2 !K3 L4 L9 0.98
TEXT 696 -352 Left 2 !K4 L5 L10 0.98
TEXT 952 -368 Left 2 !K5 L6 L11 0.98
TEXT 952 -344 Left 2 !K6 L7 L12 0.98

 

[legg]

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.

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


Version 4
SHEET 1 2884 916
WIRE 1296 -352 1248 -352
WIRE 1328 -352 1296 -352
WIRE 1472 -352 1392 -352
WIRE 1648 -352 1536 -352
WIRE 1728 -352 1648 -352
WIRE 1808 -352 1728 -352
WIRE 1248 -336 1248 -352
WIRE 1808 -336 1808 -352
WIRE 448 -320 416 -320
WIRE 576 -320 448 -320
WIRE 704 -320 576 -320
WIRE 832 -320 704 -320
WIRE 960 -320 832 -320
WIRE 1072 -320 960 -320
WIRE 1648 -320 1648 -352
WIRE 448 -288 448 -320
WIRE 576 -288 576 -320
WIRE 704 -288 704 -320
WIRE 832 -288 832 -320
WIRE 960 -288 960 -320
WIRE 1072 -288 1072 -320
WIRE 1808 -256 1808 -272
WIRE 1248 -240 1248 -256
WIRE 1648 -224 1648 -240
WIRE 0 -208 -96 -208
WIRE 144 -208 64 -208
WIRE 1296 -192 1248 -192
WIRE 1328 -192 1296 -192
WIRE 1472 -192 1392 -192
WIRE 1648 -192 1536 -192
WIRE 1728 -192 1648 -192
WIRE 1808 -192 1728 -192
WIRE 448 -176 448 -208
WIRE 576 -176 576 -208
WIRE 704 -176 704 -208
WIRE 832 -176 832 -208
WIRE 960 -176 960 -208
WIRE 1072 -176 1072 -208
WIRE 1248 -176 1248 -192
WIRE 1808 -176 1808 -192
WIRE 1648 -160 1648 -192
WIRE -96 -112 -96 -208
WIRE -16 -112 -96 -112
WIRE 144 -112 144 -208
WIRE 144 -112 64 -112
WIRE 368 -112 144 -112
WIRE 416 -112 416 -320
WIRE 416 -112 368 -112
WIRE 1808 -96 1808 -112
WIRE 448 -80 448 -96
WIRE 576 -80 576 -96
WIRE 576 -80 448 -80
WIRE 704 -80 704 -96
WIRE 704 -80 576 -80
WIRE 784 -80 704 -80
WIRE 832 -80 832 -96
WIRE 832 -80 784 -80
WIRE 960 -80 960 -96
WIRE 960 -80 832 -80
WIRE 1072 -80 1072 -96
WIRE 1072 -80 960 -80
WIRE 1248 -80 1248 -96
WIRE 416 -64 416 -112
WIRE 1648 -64 1648 -80
WIRE -96 -48 -96 -112
WIRE 144 -48 144 -112
WIRE 1296 -32 1248 -32
WIRE 1328 -32 1296 -32
WIRE 1472 -32 1392 -32
WIRE 1648 -32 1536 -32
WIRE 1728 -32 1648 -32
WIRE 1808 -32 1728 -32
WIRE 1248 -16 1248 -32
WIRE 1808 -16 1808 -32
WIRE 1648 0 1648 -32
WIRE -96 64 -96 32
WIRE -16 64 -96 64
WIRE 144 64 144 32
WIRE 144 64 48 64
WIRE 208 64 144 64
WIRE 256 64 208 64
WIRE 416 64 416 16
WIRE 480 64 416 64
WIRE 672 64 544 64
WIRE 736 64 672 64
WIRE 784 64 784 -80
WIRE 784 64 736 64
WIRE 816 64 784 64
WIRE 976 64 880 64
WIRE 1088 64 976 64
WIRE 1808 64 1808 48
WIRE 1248 80 1248 64
WIRE 1648 96 1648 80
WIRE -96 112 -96 64
WIRE 672 112 672 64
WIRE 1296 128 1248 128
WIRE 1328 128 1296 128
WIRE 1472 128 1392 128
WIRE 1648 128 1536 128
WIRE 1728 128 1648 128
WIRE 1808 128 1728 128
WIRE 144 144 144 64
WIRE 1088 144 1088 64
WIRE 1248 144 1248 128
WIRE 1808 144 1808 128
WIRE 1648 160 1648 128
WIRE 576 192 272 192
WIRE 624 192 576 192
WIRE 976 208 976 64
WIRE 1808 224 1808 208
WIRE 1088 240 1088 208
WIRE 1248 240 1248 224
WIRE -48 256 -96 256
WIRE 16 256 -48 256
WIRE 400 256 272 256
WIRE 576 256 480 256
WIRE 672 256 672 208
WIRE 672 256 576 256
WIRE 1648 256 1648 240
WIRE 672 288 672 256
WIRE 1296 288 1248 288
WIRE 1328 288 1296 288
WIRE 1472 288 1392 288
WIRE 1648 288 1536 288
WIRE 1728 288 1648 288
WIRE 1808 288 1728 288
WIRE -96 304 -96 256
WIRE 1248 304 1248 288
WIRE 1808 304 1808 288
WIRE 352 320 272 320
WIRE 1648 320 1648 288
WIRE 1808 384 1808 368
WIRE 672 400 672 368
WIRE 1248 400 1248 384
WIRE 1648 416 1648 400
WIRE -96 448 -96 368
WIRE -16 448 -96 448
WIRE 144 448 144 368
WIRE 144 448 64 448
WIRE 208 448 144 448
WIRE 352 448 352 320
WIRE 352 448 288 448
WIRE 480 448 352 448
WIRE 976 448 976 288
WIRE 976 448 480 448
WIRE 1296 448 1248 448
WIRE 1328 448 1296 448
WIRE 1472 448 1392 448
WIRE 1648 448 1536 448
WIRE 1728 448 1648 448
WIRE 1808 448 1728 448
WIRE 1248 464 1248 448
WIRE 1808 464 1808 448
WIRE 144 480 144 448
WIRE 1648 480 1648 448
WIRE 1808 544 1808 528
WIRE 1248 560 1248 544
WIRE 1648 576 1648 560
WIRE 608 592 608 512
FLAG 144 480 0
FLAG 672 400 0
FLAG 1728 -352 HV1
FLAG 368 -112 IN
FLAG -96 112 0
FLAG 736 64 DRAIN
FLAG 576 192 GATE
FLAG 576 256 SRC
FLAG 480 448 FB
FLAG 1248 -240 0
FLAG -48 256 COMP
FLAG 208 64 +9V
FLAG 1808 -256 0
FLAG 1296 -352 Z
FLAG 1648 -224 0
FLAG 1088 240 0
FLAG 1728 -192 HV2
FLAG 1248 -80 0
FLAG 1808 -96 0
FLAG 1296 -192 Z
FLAG 1648 -64 0
FLAG 1728 -32 HV3
FLAG 1248 80 0
FLAG 1808 64 0
FLAG 1296 -32 Z
FLAG 1648 96 0
FLAG 1728 128 HV4
FLAG 1248 240 0
FLAG 1808 224 0
FLAG 1296 128 Z
FLAG 1648 256 0
FLAG 1728 288 HV5
FLAG 1248 400 0
FLAG 1808 384 0
FLAG 1296 288 Z
FLAG 1648 416 0
FLAG 1728 448 HV6
FLAG 1248 560 0
FLAG 1808 544 0
FLAG 1296 448 Z
FLAG 1648 576 0
SYMBOL PowerProducts\\\\LTC3803 144 256 R0
SYMATTR InstName U1
SYMBOL ind2 432 -304 R0
WINDOW 0 91 29 Right 2
WINDOW 3 113 63 Right 2
SYMATTR InstName L1
SYMATTR Value 18µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=3.0 Rser=0.32 Cpar=1pF
SYMBOL ind2 1264 -240 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L2
SYMATTR Value 432µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL nmos 624 112 R0
WINDOW 0 119 67 Left 2
WINDOW 3 88 102 Left 2
SYMATTR InstName Q1
SYMATTR Value Si9420DY
SYMBOL res 656 272 R0
WINDOW 0 67 34 Left 2
WINDOW 3 60 67 Left 2
SYMATTR InstName R1
SYMATTR Value 0.33
SYMBOL res 128 -64 R0
WINDOW 0 60 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R2
SYMATTR Value 5K
SYMBOL res 80 432 R90
WINDOW 0 -8 99 VBottom 2
WINDOW 3 -35 24 VTop 2
SYMATTR InstName R5
SYMATTR Value 50k
SYMBOL cap -80 368 R180
WINDOW 0 -52 43 Left 2
WINDOW 3 -56 10 Left 2
SYMATTR InstName C2
SYMATTR Value 10n
SYMBOL voltage -96 -64 R0
WINDOW 123 -220 84 Left 2
WINDOW 0 49 44 Left 2
WINDOW 3 49 79 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName Vin
SYMATTR Value 24
SYMBOL res -32 -96 R270
WINDOW 0 -39 62 VTop 2
WINDOW 3 -46 61 VBottom 2
SYMATTR InstName Rin
SYMATTR Value 1m
SYMBOL cap 64 -224 R90
WINDOW 0 69 61 VBottom 2
WINDOW 3 41 8 VTop 2
SYMATTR InstName C4
SYMATTR Value 1
SYMBOL schottky 1328 -336 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D2
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 496 240 R90
WINDOW 0 68 52 VBottom 2
WINDOW 3 75 53 VTop 2
SYMATTR InstName R7
SYMATTR Value 2K
SYMBOL cap 48 48 R90
WINDOW 0 60 70 VBottom 2
WINDOW 3 34 -1 VTop 2
SYMATTR InstName C11
SYMATTR Value 1µ
SYMBOL schottky 1472 -336 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D1
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 -336 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C6
SYMATTR Value 47n
SYMBOL cap 544 48 R90
WINDOW 0 -49 28 VBottom 2
WINDOW 3 -38 26 VTop 2
SYMATTR InstName C7
SYMATTR Value 5n
SYMBOL res 400 -80 R0
WINDOW 0 -69 49 Left 2
WINDOW 3 -67 85 Left 2
SYMATTR InstName R10
SYMATTR Value 250
SYMBOL res 1632 -336 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R3
SYMATTR Value 8e6
SYMBOL schottky 816 80 R270
WINDOW 0 -39 35 VTop 2
WINDOW 3 -45 35 VBottom 2
SYMATTR InstName D3
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1072 144 R0
WINDOW 0 -42 29 Left 2
WINDOW 3 -50 -14 Left 2
SYMATTR InstName C1
SYMATTR Value 50n
SYMBOL res 960 192 R0
WINDOW 0 -67 38 Left 2
WINDOW 3 -75 75 Left 2
SYMATTR InstName R4
SYMATTR Value 7.6K
SYMBOL res 304 432 R90
WINDOW 0 -9 95 VBottom 2
WINDOW 3 -36 21 VTop 2
SYMATTR InstName R6
SYMATTR Value 100
SYMBOL ind2 560 -304 R0
WINDOW 0 91 29 Right 2
WINDOW 3 113 63 Right 2
SYMATTR InstName L3
SYMATTR Value 18µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=3.0 Rser=0.32 Cpar=1pF
SYMBOL ind2 688 -304 R0
WINDOW 0 91 29 Right 2
WINDOW 3 113 63 Right 2
SYMATTR InstName L4
SYMATTR Value 26µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=3.0 Rser=0.32 Cpar=1pF
SYMBOL ind2 816 -304 R0
WINDOW 0 91 29 Right 2
WINDOW 3 113 63 Right 2
SYMATTR InstName L5
SYMATTR Value 26µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=3.0 Rser=0.32 Cpar=1pF
SYMBOL ind2 944 -304 R0
WINDOW 0 91 29 Right 2
WINDOW 3 113 63 Right 2
SYMATTR InstName L6
SYMATTR Value 22µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=3.0 Rser=0.32 Cpar=1pF
SYMBOL ind2 1056 -304 R0
WINDOW 0 91 29 Right 2
WINDOW 3 113 63 Right 2
SYMATTR InstName L7
SYMATTR Value 22µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=3.0 Rser=0.32 Cpar=1pF
SYMBOL ind2 1264 -80 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L8
SYMATTR Value 432µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 -176 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D4
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 -176 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D5
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 -176 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C3
SYMATTR Value 47n
SYMBOL res 1632 -176 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R8
SYMATTR Value 8e6
SYMBOL ind2 1264 80 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L9
SYMATTR Value 648µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 -16 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D6
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 -16 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D7
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 -16 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C5
SYMATTR Value 47n
SYMBOL res 1632 -16 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R9
SYMATTR Value 8e6
SYMBOL ind2 1264 240 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L10
SYMATTR Value 648µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 144 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D8
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 144 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D9
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 144 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C8
SYMATTR Value 47n
SYMBOL res 1632 144 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R11
SYMATTR Value 8e6
SYMBOL ind2 1264 400 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L11
SYMATTR Value 540µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 304 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D10
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 304 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D11
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 304 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C9
SYMATTR Value 47n
SYMBOL res 1632 304 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R12
SYMATTR Value 8e6
SYMBOL ind2 1264 560 R180
WINDOW 0 101 76 Right 2
WINDOW 3 102 38 Right 2
SYMATTR InstName L12
SYMATTR Value 540µ
SYMATTR Type ind
SYMATTR SpiceLine Ipk=20 Rser=0.32 Cpar=2pF
SYMBOL schottky 1328 464 R270
WINDOW 0 46 35 VTop 2
WINDOW 3 -15 40 VBottom 2
SYMATTR InstName D12
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 1472 464 R270
WINDOW 0 45 32 VTop 2
WINDOW 3 -14 38 VBottom 2
SYMATTR InstName D13
SYMATTR Value BAT46WJ
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 1792 464 R0
WINDOW 0 55 17 Left 2
WINDOW 3 55 52 Left 2
SYMATTR InstName C10
SYMATTR Value 47n
SYMBOL res 1632 464 R0
WINDOW 0 62 21 Left 2
WINDOW 3 60 56 Left 2
SYMATTR InstName R13
SYMATTR Value 8e6
SYMBOL res 432 -192 R0
SYMATTR InstName R14
SYMATTR Value .1
SYMBOL res 560 -192 R0
SYMATTR InstName R15
SYMATTR Value .1
SYMBOL res 688 -192 R0
SYMATTR InstName R16
SYMATTR Value .1
SYMBOL res 816 -192 R0
SYMATTR InstName R17
SYMATTR Value .1
SYMBOL res 944 -192 R0
SYMATTR InstName R18
SYMATTR Value .1
SYMBOL res 1056 -192 R0
SYMATTR InstName R19
SYMATTR Value .1
TEXT 504 -368 Bottom 2 !K1 L1 L2 0.98
TEXT -64 592 Left 2 !.tran 100m startup
TEXT 248 -304 Left 2 ;8X Q4436-BL
TEXT 376 424 Left 2 ;0.8V
TEXT 712 248 Left 2 ;ZVN4424
TEXT -64 552 Left 2 !.options reltol = 0.01
TEXT 264 -264 Left 2 ;Lp = 22 uH
TEXT 280 -224 Left 2 ;1:5
TEXT 1504 -264 Left 2 ;200 uA
TEXT -72 -320 Left 2 ;200V Octal Flyback Supply
TEXT -48 -272 Left 2 ;J Larkin Jul 17 2020
TEXT 1312 616 Left 2 ;===== 6 of 8 isolated channels =====
TEXT -56 632 Left 2 ;use alternate solver
TEXT 1400 -264 Left 2 ;BAV23S
TEXT 1504 -104 Left 2 ;200 uA
TEXT 1400 -104 Left 2 ;BAV23S
TEXT 1504 56 Left 2 ;200 uA
TEXT 1400 56 Left 2 ;BAV23S
TEXT 1504 216 Left 2 ;200 uA
TEXT 1400 216 Left 2 ;BAV23S
TEXT 1504 376 Left 2 ;200 uA
TEXT 1400 376 Left 2 ;BAV23S
TEXT 1504 536 Left 2 ;200 uA
TEXT 1400 536 Left 2 ;BAV23S
TEXT 448 -352 Left 2 !K2 L3 L8 0.98
TEXT 704 -376 Left 2 !K3 L4 L9 0.98
TEXT 696 -352 Left 2 !K4 L5 L10 0.98
TEXT 952 -368 Left 2 !K5 L6 L11 0.98
TEXT 952 -344 Left 2 !K6 L7 L12 0.98

 

[Phil Hobbs]

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:

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?

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

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

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

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:

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?

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

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

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[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