• magnetics question

    From jlarkin@highlandsniptechnology.com@21:1/5 to All on Wed Apr 6 08:53:22 2022
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.



    --

    I yam what I yam - Popeye

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  • From Arie de Muijnck@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Apr 6 18:24:49 2022
    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I
    ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX
    with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz
    dynamo in the basement to get 400 Hz).

    Arie

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to eternal.september@ademu.com on Wed Apr 6 09:33:49 2022
    On Wed, 6 Apr 2022 18:24:49 +0200, Arie de Muijnck <eternal.september@ademu.com> wrote:

    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I >ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier >module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX
    with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz >dynamo in the basement to get 400 Hz).

    Arie

    I think so... for a given core, power scales linearly with frequency.
    A simple scribble with a 4-winding transformer suggests that.

    Thanks

    John


    --

    I yam what I yam - Popeye

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  • From Tauno Voipio@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Apr 6 19:44:04 2022
    On 6.4.22 19.33, jlarkin@highlandsniptechnology.com wrote:
    On Wed, 6 Apr 2022 18:24:49 +0200, Arie de Muijnck <eternal.september@ademu.com> wrote:

    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I
    ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier
    module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX
    with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz
    dynamo in the basement to get 400 Hz).

    Arie

    I think so... for a given core, power scales linearly with frequency.
    A simple scribble with a 4-winding transformer suggests that.

    Thanks

    John


    You have to be prepared for larger core losses due to the
    higher frequency if you use the same core material.

    The higher frequency core materials are bulkier
    for the same power due to the smaller permeability.

    I'd use a 400 Hz transformer.

    --

    -TV

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  • From Arie de Muijnck@21:1/5 to Tauno Voipio on Wed Apr 6 18:47:39 2022
    On 2022-04-06 18:44, Tauno Voipio wrote:
    On 6.4.22 19.33, jlarkin@highlandsniptechnology.com wrote:
    On Wed, 6 Apr 2022 18:24:49 +0200, Arie de Muijnck
    <eternal.september@ademu.com> wrote:

    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I
    ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier >>> module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX >>> with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz >>> dynamo in the basement to get 400 Hz).

    Arie

    I think so... for a given core, power scales linearly with frequency.
    A simple scribble with a 4-winding transformer suggests that.

    Thanks

    John


    You have to be prepared for larger core losses due to the
    higher frequency if you use the same core material.

    The higher frequency core materials are bulkier
    for the same power due to the smaller permeability.

    I'd use a 400 Hz transformer.


    Which is why I used (Amplimo) toroids - they are good until several kHz.

    Arie

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  • From Arie de Muijnck@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Apr 6 18:45:43 2022
    On 2022-04-06 18:33, jlarkin@highlandsniptechnology.com wrote:
    On Wed, 6 Apr 2022 18:24:49 +0200, Arie de Muijnck <eternal.september@ademu.com> wrote:

    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I
    ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier
    module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX
    with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz
    dynamo in the basement to get 400 Hz).

    Arie

    I think so... for a given core, power scales linearly with frequency.
    A simple scribble with a 4-winding transformer suggests that.

    Thanks

    John

    Yes, which is exactly why switching PSU's are now the standard. The cost
    saving in iron (ferrite) and copper and capacitors, and all transport
    costs, far outweighs (pun intended) the cost of the semiconductors.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz versions.

    Arie

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to eternal.september@ademu.com on Wed Apr 6 17:21:51 2022
    On a sunny day (Wed, 6 Apr 2022 18:24:49 +0200) it happened Arie de Muijnck <eternal.september@ademu.com> wrote in <t2kesh$3t5$1@dont-email.me>:

    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I >ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier >module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX
    with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz >dynamo in the basement to get 400 Hz).

    Arie

    Yes, that is how I make 60 Hz here in 50 Hz land,
    100 W audio amp 60 Hz from PC signal generator
    in 50 Hz mains transformer connected the other way around.
    Not very efficient, but nice sinewave and no harmonics.
    A simple raspberry followed by a low pass could drive that
    (raspi audio out is some PWM I think, sure has RF on it).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Apr 6 17:14:59 2022
    On a sunny day (Wed, 06 Apr 2022 08:53:22 -0700) it happened jlarkin@highlandsniptechnology.com wrote in <2fdr4hdk4ni4l5ds6vb97hkgtvbiufs47u@4ax.com>:

    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    When I wind some transformer I usulally look at the no load primary inductance so it is high eneough not to drain power,
    Then for that L and the given Core material I get number of turns
    Many of thsoe core sellers specify a core size for a given power.
    The load current, number of turns and wire diameter will give you weight of the coils.
    That weight is to be added to the core material for total 'mass' if that is what you mean.



    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.


    Why not balanced with 2 transistors and a transformer 48 to 120 V
    ___________
    T1 ______ ||(
    )||(
    48 V +--- ||( 120 V
    ______)||(
    T2 ||(__________


    Dunno how accurate it needs to be, replace the T1 T2 with thyristors, tune it with a big cap and make it self-oscillating?
    ___________
    T1________________ ||(
    | )||(
    === 48 V +--- ||( 120 V
    _|______________)||(
    T2 ____ ||(__________
    feedback ____) ||


    Or use the almost all knowing google:
    https://www.google.com/search?q=48V+DC+to+120V+AC+400Hz++circuit+diagram
    select 'images' for circuits.


    I'll have lots of air flow, so maybe I can push things some too.

    Yes was storm here too

    --- SoupGate-Win32 v1.05
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  • From Dave Platt@21:1/5 to pNaonStpealmtje@yahoo.com on Wed Apr 6 11:17:32 2022
    In article <t2ki95$afi$1@dont-email.me>,
    Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

    Yes, that is how I make 60 Hz here in 50 Hz land,
    100 W audio amp 60 Hz from PC signal generator
    in 50 Hz mains transformer connected the other way around.
    Not very efficient, but nice sinewave and no harmonics.
    A simple raspberry followed by a low pass could drive that
    (raspi audio out is some PWM I think, sure has RF on it).

    It's pretty easy to connect a $10-or-so I2S audio DAC board to a Pi,
    rather than using the on-board audio DAC. The ones I've been using
    (based on Ti/Burr-Brown PCM-series DAC chips) put out a pretty clean
    waveform - one can add a very simple low-pass to block noise up
    above a few hundred kHz if necessary.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to Arie de Muijnck on Wed Apr 6 23:00:32 2022
    Arie de Muijnck wrote:

    Yes, which is exactly why switching PSU's are now the standard. The cost saving in iron (ferrite) and copper and capacitors, and all transport
    costs, far outweighs (pun intended) the cost of the semiconductors.

    Their regulation capability is far better than that of the more
    conventional PSUs.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz versions.

    But why 400 then? A typical scaling factor would be 10, so 500Hz should
    be expected. Instead, they have selected the odd value of 8. Backward compatibility with an arbitrarily selected frequency back in the
    medieval times?

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to eternal.september@ademu.com on Wed Apr 6 17:00:14 2022
    On Wed, 6 Apr 2022 18:45:43 +0200, Arie de Muijnck <eternal.september@ademu.com> wrote:

    On 2022-04-06 18:33, jlarkin@highlandsniptechnology.com wrote:
    On Wed, 6 Apr 2022 18:24:49 +0200, Arie de Muijnck
    <eternal.september@ademu.com> wrote:

    On 2022-04-06 17:53, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.

    Weight is almost linear with power, and inversely with frequency.

    When I needed a 115V 400Hz for DO-160 aviation equipment development, I
    ordered a 100W amplifier set from Amplimo (https://www.amplimo.nl/):
    Mains transformer (toroid 115/230V in), rectifier, capacitors, amplifier >>> module, and an extra mains transformer (used in reverse) for the 115V
    output.
    Added a 400 Hz oscillator with a timer controlled gain control (4051 MUX >>> with some resistors) to create the required brownout and dropout
    profiles. The customer was so amused they ordered some for their
    production and test line (until then, they used a gigantic motor + 400Hz >>> dynamo in the basement to get 400 Hz).

    Arie

    I think so... for a given core, power scales linearly with frequency.
    A simple scribble with a 4-winding transformer suggests that.

    Thanks

    John

    Yes, which is exactly why switching PSU's are now the standard. The cost >saving in iron (ferrite) and copper and capacitors, and all transport
    costs, far outweighs (pun intended) the cost of the semiconductors.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz versions.

    Arie

    I think you're living in the past. 60-400Hz magnetics are
    routinely shipped around the world for local cost reduction,
    making 'iron' transport costs irrelevent.

    Only end-use weight and volume remain signifigant.

    RL

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  • From Mike Monett@21:1/5 to Piotr Wyderski on Wed Apr 6 21:19:49 2022
    Piotr Wyderski <bombald@protonmail.com> wrote:

    Arie de Muijnck wrote:

    Yes, which is exactly why switching PSU's are now the standard. The
    cost saving in iron (ferrite) and copper and capacitors, and all
    transport costs, far outweighs (pun intended) the cost of the
    semiconductors.

    Their regulation capability is far better than that of the more
    conventional PSUs.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz
    versions.

    But why 400 then? A typical scaling factor would be 10, so 500Hz should
    be expected. Instead, they have selected the odd value of 8. Backward compatibility with an arbitrarily selected frequency back in the
    medieval times?

    Best regards, Piotr

    Aircraft are moving away from the fixed 400Hz frequency to variable
    360-800Hz.

    "On the other hand, the innovation of power supply system in aircraft performance in the system of power supply: 360~800Hz large capacity
    variable frequency AC power system is using gradually instead of the
    constant frequency of 400Hz power supply on most of the aircraft[3,4]"

    https://www.atlantis-press.com/article/25862618.pdf




    --
    MRM

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  • From Piotr Wyderski@21:1/5 to Mike Monett on Wed Apr 6 23:25:40 2022
    Mike Monett wrote:

    Aircraft are moving away from the fixed 400Hz frequency to variable 360-800Hz.

    "On the other hand, the innovation of power supply system in aircraft performance in the system of power supply: 360~800Hz large capacity
    variable frequency AC power system is using gradually instead of the
    constant frequency of 400Hz power supply on most of the aircraft[3,4]"

    Interesting. Why not DC then? It is going to be consumed by a switcher
    of some sort anyway, be it a PSU or motor controller.

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mike Monett@21:1/5 to Piotr Wyderski on Wed Apr 6 21:31:51 2022
    Piotr Wyderski <bombald@protonmail.com> wrote:

    Mike Monett wrote:

    Aircraft are moving away from the fixed 400Hz frequency to variable
    360-800Hz.

    "On the other hand, the innovation of power supply system in aircraft
    performance in the system of power supply: 360~800Hz large capacity
    variable frequency AC power system is using gradually instead of the
    constant frequency of 400Hz power supply on most of the aircraft[3,4]"

    Interesting. Why not DC then? It is going to be consumed by a switcher
    of some sort anyway, be it a PSU or motor controller.

    Best regards, Piotr

    My Piper Malibu distributed power in DC. Various instruments either used DC
    as is, or changed it to 400Hz. I believe larger A/C generate 3-phase.

    A possible reason for limiting the frequency may be skin effect. When you
    have to run power from the engines under the wings all over the plane, the losses could become serious.



    --
    MRM

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  • From Lasse Langwadt Christensen@21:1/5 to All on Wed Apr 6 14:34:36 2022
    onsdag den 6. april 2022 kl. 23.26.01 UTC+2 skrev Piotr Wyderski:
    Mike Monett wrote:

    Aircraft are moving away from the fixed 400Hz frequency to variable 360-800Hz.

    "On the other hand, the innovation of power supply system in aircraft performance in the system of power supply: 360~800Hz large capacity variable frequency AC power system is using gradually instead of the constant frequency of 400Hz power supply on most of the aircraft[3,4]"
    Interesting. Why not DC then? It is going to be consumed by a switcher
    of some sort anyway, be it a PSU or motor controller.

    does relays and switches used for ~400Hz AC need to be beefed up like for DC?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to jla...@highlandsniptechnology.com on Wed Apr 6 14:36:59 2022
    On Wednesday, April 6, 2022 at 8:53:36 AM UTC-7, jla...@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    That's an interesting, and difficult, question. I'm assuming power transformer with
    unknown load on the secondary, there's current-transformer assumptions which are 'way different.

    Firstly, you need the core not to saturate at rated input voltage and
    no load; that means the core material's B-H curve has to be considered to set core size.
    This is about the magnetic flux distribution in the area (cross-section) of its path.

    Second, you need the primary and secondary wire resistances to be low enough for
    acceptable heat losses (usually, primary and secondary will have same loss, but that'll
    have steps at available gage sizes...) which means every core shape will have differing
    size according to the throat available for windings. Variacs will have different
    rules, because there's no separate primary and secondary wire gage, This affects
    the magnetic path length, not the area.

    Third, you need the whole assembly to stay cool; we don't usually see heatsinks on
    transformers, but every pole pig IS certainly a kind of keep-it-cool problem, and
    for high frequency, core losses (and maybe even skin effect in conductors) will have to
    be considered even for small items.

    With only the first item considered, cross sectional area is constant for peak current-turns
    at no load, so expect V /f proportional to area, thus weight roughly scale by f**(-1.5).
    It's a project that'll benefit from log-log and/or semilog graph paper.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Wed Apr 6 14:51:46 2022
    onsdag den 6. april 2022 kl. 23.37.03 UTC+2 skrev whit3rd:
    On Wednesday, April 6, 2022 at 8:53:36 AM UTC-7, jla...@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?
    That's an interesting, and difficult, question. I'm assuming power transformer with
    unknown load on the secondary, there's current-transformer assumptions which are 'way different.

    Firstly, you need the core not to saturate at rated input voltage and
    no load; that means the core material's B-H curve has to be considered to set core size.
    This is about the magnetic flux distribution in the area (cross-section) of its path.

    Second, you need the primary and secondary wire resistances to be low enough for
    acceptable heat losses (usually, primary and secondary will have same loss, but that'll
    have steps at available gage sizes...) which means every core shape will have differing
    size according to the throat available for windings. Variacs will have different
    rules, because there's no separate primary and secondary wire gage, This affects
    the magnetic path length, not the area.

    Third, you need the whole assembly to stay cool; we don't usually see heatsinks on
    transformers, but every pole pig IS certainly a kind of keep-it-cool problem, and
    for high frequency, core losses (and maybe even skin effect in conductors) will have to
    be considered even for small items.

    With only the first item considered, cross sectional area is constant for peak current-turns
    at no load, so expect V /f proportional to area, thus weight roughly scale by f**(-1.5).
    It's a project that'll benefit from log-log and/or semilog graph paper.

    can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency you can also
    increase the voltage 8 times, and thus get 8 times the power

    --- SoupGate-Win32 v1.05
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  • From Clifford Heath@21:1/5 to Piotr Wyderski on Thu Apr 7 08:27:54 2022
    On 7/4/22 7:00 am, Piotr Wyderski wrote:
    Arie de Muijnck wrote:
    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz
    versions.

    But why 400 then?

    Probably to do with still using rotating converters and other
    synchronous things. 24000RPM is feasible in 1950s technology, but much
    more gets hard.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Wed Apr 6 16:22:36 2022
    On Wed, 6 Apr 2022 21:19:49 -0000 (UTC), Mike Monett <spamme@not.com>
    wrote:

    Piotr Wyderski <bombald@protonmail.com> wrote:

    Arie de Muijnck wrote:

    Yes, which is exactly why switching PSU's are now the standard. The
    cost saving in iron (ferrite) and copper and capacitors, and all
    transport costs, far outweighs (pun intended) the cost of the
    semiconductors.

    Their regulation capability is far better than that of the more
    conventional PSUs.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz
    versions.

    But why 400 then? A typical scaling factor would be 10, so 500Hz should
    be expected. Instead, they have selected the odd value of 8. Backward
    compatibility with an arbitrarily selected frequency back in the
    medieval times?

    Best regards, Piotr

    Aircraft are moving away from the fixed 400Hz frequency to variable >360-800Hz.

    "On the other hand, the innovation of power supply system in aircraft >performance in the system of power supply: 360~800Hz large capacity
    variable frequency AC power system is using gradually instead of the
    constant frequency of 400Hz power supply on most of the aircraft[3,4]"

    https://www.atlantis-press.com/article/25862618.pdf

    There are constant-frequency generators that always make 400 Hz. I
    don't know how they work.

    360 (sometimes 250) to 800 Hz is "Wild power", what you can get from
    anywhere to stay alive. A ram air turbine is "the thing you never want
    to see used."

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to lang...@fonz.dk on Wed Apr 6 16:49:05 2022
    On Wednesday, April 6, 2022 at 2:51:50 PM UTC-7, lang...@fonz.dk wrote:
    onsdag den 6. april 2022 kl. 23.37.03 UTC+2 skrev whit3rd:
    On Wednesday, April 6, 2022 at 8:53:36 AM UTC-7, jla...@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?
    That's an interesting, and difficult, question. I'm assuming power transformer with
    unknown load on the secondary, there's current-transformer assumptions which are 'way different.

    Firstly, you need the core not to saturate at rated input voltage and
    no load; that means...

    With only the first item considered, cross sectional area is constant for peak current-turns
    at no load, so expect V /f proportional to area, thus weight roughly scale by f**(-1.5).
    It's a project that'll benefit from log-log and/or semilog graph paper.

    can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency you can also
    increase the voltage 8 times, and thus get 8 times the power

    Yes, that's correct. I was thinking, though, of resizing the core which would shorten
    the wire length required, thus allow thinner wire with similar resistance; a redesign of
    the transformer for the higher frequency is different from using the same transformer.
    So, my scaling assumes a transformer reconfiguration in shape. It doesn't get into
    the correct way to do that wire re-dimensioning, because that includes dissipation of heat
    changing with size... and heat can be shed by conduction, or convection, with different
    power laws.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Leo Smith@21:1/5 to All on Wed Apr 6 19:51:54 2022
    You can see if there is any transformer you are looking for https://www.easybom.com/c/transformers

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mike Monett@21:1/5 to Lasse Langwadt Christensen on Thu Apr 7 05:46:32 2022
    Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:

    [...]

    Can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency
    you can also increase the voltage 8 times, and thus get 8 times the
    power

    P = E^2 / R
    8^2 = 64



    --
    MRM

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to bombald@protonmail.com on Thu Apr 7 06:17:41 2022
    On a sunny day (Wed, 6 Apr 2022 23:00:32 +0200) it happened Piotr Wyderski <bombald@protonmail.com> wrote in <t2kv1u$2c98k$1@portraits.wsisiz.edu.pl>:

    Arie de Muijnck wrote:

    Yes, which is exactly why switching PSU's are now the standard. The cost
    saving in iron (ferrite) and copper and capacitors, and all transport
    costs, far outweighs (pun intended) the cost of the semiconductors.

    Their regulation capability is far better than that of the more
    conventional PSUs.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz versions.

    But why 400 then? A typical scaling factor would be 10, so 500Hz should
    be expected. Instead, they have selected the odd value of 8. Backward >compatibility with an arbitrarily selected frequency back in the
    medieval times?

    Railroad here also uses 400 Hz.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Dave Platt on Thu Apr 7 06:15:53 2022
    On a sunny day (Wed, 6 Apr 2022 11:17:32 -0700) it happened dplatt@coop.radagast.org (Dave Platt) wrote in <s221ii-pqmv2.ln1@coop.radagast.org>:

    In article <t2ki95$afi$1@dont-email.me>,
    Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

    Yes, that is how I make 60 Hz here in 50 Hz land,
    100 W audio amp 60 Hz from PC signal generator
    in 50 Hz mains transformer connected the other way around.
    Not very efficient, but nice sinewave and no harmonics.
    A simple raspberry followed by a low pass could drive that
    (raspi audio out is some PWM I think, sure has RF on it).

    It's pretty easy to connect a $10-or-so I2S audio DAC board to a Pi,
    rather than using the on-board audio DAC. The ones I've been using
    (based on Ti/Burr-Brown PCM-series DAC chips) put out a pretty clean
    waveform - one can add a very simple low-pass to block noise up
    above a few hundred kHz if necessary.

    I have a couple of those USB audio sticks,
    adds a clean output and also a mike input.
    Also has auto-gain for the mike
    alsmixer -c 1
    http://panteltje.com/pub/alsamixer_c_1.gif
    show just an other USB device

    Those sticks are about 3 USD on ebay with free shipping, something like this:
    https://www.ebay.com/itm/144291219756
    Sounds a bit like 'expanded' audio....must be the '3D' part...

    For the original Pi output I made a cable with a simple RC lowpass in it,
    that goes to my audio amp for background music in the room.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Mike Monett on Wed Apr 6 23:25:06 2022
    Mike Monett wrote:
    ================

    Can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency
    you can also increase the voltage 8 times, and thus get 8 times the
    power

    ** That is too simple.

    At 8 times the frequency, core losses go up by the same ratio dramatically increasing the heat that must be dissipated.
    But more importantly, there are strict limits on the voltages that can be safely tolerated by insulation.
    High voltage transformers groups windings into insulated sub sections consuming much available window space.
    Destructive corona discharge becomes a big issue between layers and even turns.


    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to Lasse Langwadt Christensen on Thu Apr 7 09:15:49 2022
    Lasse Langwadt Christensen wrote:

    can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency you can also
    increase the voltage 8 times, and thus get 8 times the power

    Core losses in ferrite/powder materials do not obey simple rules and the exponents in the approximate equations have fancy values like f^2.8. So
    these are not exactly equivalent.

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to Phil Allison on Thu Apr 7 09:26:56 2022
    On 2022-04-07 08:25, Phil Allison wrote:

    At 8 times the frequency, core losses go up by the same ratio dramatically increasing the heat that must be dissipated.

    One can see here how complex the formula is e.g. here:

    https://www.tme.eu/Document/a26e91abd72e59c56f207dc94b9eb235/ARNOLD-MS-184026-2.pdf

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From piglet@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Apr 7 08:46:43 2022
    On 06/04/2022 4:53 pm, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.




    Your first option eliminates an output transformer and means you could
    make AC out as low a frequency as you want, even DC. Only problem could
    be if customer wants to see a DC winding resistance but perhaps even
    that could be synthesiesed?

    piglet

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to All on Thu Apr 7 09:22:31 2022
    whit3rd wrote:

    Yes, that's correct. I was thinking, though, of resizing the core which would shorten
    the wire length required, thus allow thinner wire with similar resistance; a redesign of
    the transformer for the higher frequency is different from using the same transformer.
    So, my scaling assumes a transformer reconfiguration in shape. It doesn't get into
    the correct way to do that wire re-dimensioning, because that includes dissipation of heat
    changing with size... and heat can be shed by conduction, or convection, with different
    power laws.

    I used to have a copy of an article from the ETH I believe, where they
    ran global optimisation on power transformers and simulated them with
    FEM solvers. The conclusion was that 200kHz is the optimal switching
    frequency given the current state of the art. Switching faster to get
    smaller size makes other parameters worse, switching slower makes things unnecessarily bulky.

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Thu Apr 7 07:48:13 2022
    torsdag den 7. april 2022 kl. 07.46.39 UTC+2 skrev Mike Monett:
    Lasse Langwadt Christensen <lang...@fonz.dk> wrote:

    [...]

    Can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency
    you can also increase the voltage 8 times, and thus get 8 times the
    power
    P = E^2 / R
    8^2 = 64


    current must stay the same it is limited by the wire sizes

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Thu Apr 7 07:50:22 2022
    On Thu, 7 Apr 2022 08:46:43 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 06/04/2022 4:53 pm, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.




    Your first option eliminates an output transformer and means you could
    make AC out as low a frequency as you want, even DC. Only problem could
    be if customer wants to see a DC winding resistance but perhaps even
    that could be synthesiesed?

    piglet

    Yeah, I guess we'll do a high frequency inverter to 200 volts dc or
    so, and then a floating h-bridge. That can output bipolar dc, ac,
    anything. May as well have ferrite custom magnetics, than steel.

    The Coilcraft PL300 transformers are fabulous, 300 watts in a
    surface-mount package. Their Spice coupling coefficient is 0.9996.

    I bet we could push some more watts if we blow some air through the
    planar kapton windings.




    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Thu Apr 7 07:55:13 2022
    On Thu, 7 Apr 2022 05:46:32 -0000 (UTC), Mike Monett <spamme@not.com>
    wrote:

    Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:

    [...]

    Can't it be more or less simplified to:
    if you take a suitable transformer and run it at 8 times the frequency
    you can also increase the voltage 8 times, and thus get 8 times the
    power

    P = E^2 / R
    8^2 = 64

    Transformer power is usually limited by heating from copper loss. 64x
    power implies 8x current, which won't work.

    It might be worse than 8x power at 8x frequency, if skin and proximity
    effects increase copper loss.



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Apr 7 16:01:12 2022
    On a sunny day (Thu, 07 Apr 2022 07:50:22 -0700) it happened jlarkin@highlandsniptechnology.com wrote in <50ut4hlsh2r8u2ev6b4n8ja1gm1icf4k9p@4ax.com>:

    On Thu, 7 Apr 2022 08:46:43 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 06/04/2022 4:53 pm, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.




    Your first option eliminates an output transformer and means you could
    make AC out as low a frequency as you want, even DC. Only problem could
    be if customer wants to see a DC winding resistance but perhaps even
    that could be synthesiesed?

    piglet

    Yeah, I guess we'll do a high frequency inverter to 200 volts dc or
    so, and then a floating h-bridge. That can output bipolar dc, ac,
    anything. May as well have ferrite custom magnetics, than steel.

    The Coilcraft PL300 transformers are fabulous, 300 watts in a
    surface-mount package. Their Spice coupling coefficient is 0.9996.

    I bet we could push some more watts if we blow some air through the
    planar kapton windings.

    How will a H bridge like that without transformers react to inductive peaks from loads?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Arie de Muijnck@21:1/5 to legg on Thu Apr 7 18:12:25 2022
    On 2022-04-06 23:00, legg wrote:
    On Wed, 6 Apr 2022 18:45:43 +0200, Arie de Muijnck <eternal.september@ademu.com> wrote:
    Yes, which is exactly why switching PSU's are now the standard. The cost
    saving in iron (ferrite) and copper and capacitors, and all transport
    costs, far outweighs (pun intended) the cost of the semiconductors.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz versions. >>
    Arie

    I think you're living in the past. 60-400Hz magnetics are
    routinely shipped around the world for local cost reduction,
    making 'iron' transport costs irrelevant.

    Only end-use weight and volume remain significant.

    RL

    In the past? Could be, I designed it more than 30 years ago.

    But airplane equipment should still be as light-weight as possible.
    Nowadays of course even those 400 Hz transformers will have been
    replaced by switchers.

    Arie

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pNaonStpealmtje@yahoo.com on Thu Apr 7 09:12:47 2022
    On Thu, 07 Apr 2022 16:01:12 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:

    On a sunny day (Thu, 07 Apr 2022 07:50:22 -0700) it happened >jlarkin@highlandsniptechnology.com wrote in ><50ut4hlsh2r8u2ev6b4n8ja1gm1icf4k9p@4ax.com>:

    On Thu, 7 Apr 2022 08:46:43 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 06/04/2022 4:53 pm, jlarkin@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.




    Your first option eliminates an output transformer and means you could >>>make AC out as low a frequency as you want, even DC. Only problem could >>>be if customer wants to see a DC winding resistance but perhaps even
    that could be synthesiesed?

    piglet

    Yeah, I guess we'll do a high frequency inverter to 200 volts dc or
    so, and then a floating h-bridge. That can output bipolar dc, ac,
    anything. May as well have ferrite custom magnetics, than steel.

    The Coilcraft PL300 transformers are fabulous, 300 watts in a
    surface-mount package. Their Spice coupling coefficient is 0.9996.

    I bet we could push some more watts if we blow some air through the
    planar kapton windings.

    How will a H bridge like that without transformers react to inductive peaks >from loads?

    Inductive peaks? Like saturation? It would current limit.

    Our PM alternator simulator is similar, uses a full-bridge output
    stage, and can drive a dead short. Regulators for PM alternators
    usually short the alternator to limit voltage. That blew up our
    first-gen design that used a TI audio output chip.



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Thu Apr 7 09:18:49 2022
    torsdag den 7. april 2022 kl. 16.50.35 UTC+2 skrev jla...@highlandsniptechnology.com:
    On Thu, 7 Apr 2022 08:46:43 +0100, piglet <erichp...@hotmail.com>
    wrote:
    On 06/04/2022 4:53 pm, jla...@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.




    Your first option eliminates an output transformer and means you could
    make AC out as low a frequency as you want, even DC. Only problem could
    be if customer wants to see a DC winding resistance but perhaps even
    that could be synthesiesed?

    piglet
    Yeah, I guess we'll do a high frequency inverter to 200 volts dc or
    so, and then a floating h-bridge.

    https://www.hobbielektronika.hu/forum/getfile.php?id=125378

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Thu Apr 7 09:31:16 2022
    torsdag den 7. april 2022 kl. 01.22.48 UTC+2 skrev John Larkin:
    On Wed, 6 Apr 2022 21:19:49 -0000 (UTC), Mike Monett <spa...@not.com>
    wrote:
    Piotr Wyderski <bom...@protonmail.com> wrote:

    Arie de Muijnck wrote:

    Yes, which is exactly why switching PSU's are now the standard. The
    cost saving in iron (ferrite) and copper and capacitors, and all
    transport costs, far outweighs (pun intended) the cost of the
    semiconductors.

    Their regulation capability is far better than that of the more
    conventional PSUs.

    And why airplanes use 400 Hz - the tiny transformers I had designed in >>> in the product were amusing, 8 times smaller than the usual 50 hz
    versions.

    But why 400 then? A typical scaling factor would be 10, so 500Hz should
    be expected. Instead, they have selected the odd value of 8. Backward
    compatibility with an arbitrarily selected frequency back in the
    medieval times?

    Best regards, Piotr

    Aircraft are moving away from the fixed 400Hz frequency to variable >360-800Hz.

    "On the other hand, the innovation of power supply system in aircraft >performance in the system of power supply: 360~800Hz large capacity >variable frequency AC power system is using gradually instead of the >constant frequency of 400Hz power supply on most of the aircraft[3,4]"

    https://www.atlantis-press.com/article/25862618.pdf
    There are constant-frequency generators that always make 400 Hz. I
    don't know how they work.

    https://en.wikipedia.org/wiki/Doubly-fed_electric_machine#Double_fed_induction_generator ?

    360 (sometimes 250) to 800 Hz is "Wild power", what you can get from
    anywhere to stay alive. A ram air turbine is "the thing you never want
    to see used."

    afaiu some newer airplanes have power that varies in frequency
    because it is simpler and lighter to do than a fixed output frequency
    as engine rpm varies from idle to takeoff

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to Piotr Wyderski on Thu Apr 7 17:03:28 2022
    Piotr Wyderski <bombald@protonmail.com> wrote in news:t2m3g2$38tt4$1@portraits.wsisiz.edu.pl:

    whit3rd wrote:

    Yes, that's correct. I was thinking, though, of resizing the
    core which would shorten the wire length required, thus allow
    thinner wire with similar resistance; a redesign of the
    transformer for the higher frequency is different from using the
    same transformer. So, my scaling assumes a transformer
    reconfiguration in shape. It doesn't get into the correct way to
    do that wire re-dimensioning, because that includes dissipation
    of heat changing with size... and heat can be shed by conduction,
    or convection, with different power laws.

    I used to have a copy of an article from the ETH I believe, where
    they ran global optimisation on power transformers and simulated
    them with FEM solvers. The conclusion was that 200kHz is the
    optimal switching frequency given the current state of the art.
    Switching faster to get smaller size makes other parameters worse,
    switching slower makes things unnecessarily bulky.

    Best regards, Piotr


    Ferrite core miniature transformers we used for HVPS design ran best
    at around 56kHz. It varies too depending on the ferrite formulation
    and finished product functional characteristics. But you should know
    that.

    Essentially, you are off the mark on this too.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Apr 7 17:15:50 2022
    On a sunny day (Thu, 07 Apr 2022 09:12:47 -0700) it happened jlarkin@highlandsniptechnology.com wrote in <v23u4hhn9o712gkobu1nenkf63k6i28s3v@4ax.com>:

    On Thu, 07 Apr 2022 16:01:12 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:
    How will a H bridge like that without transformers react to inductive peaks >>from loads?

    Inductive peaks? Like saturation? It would current limit.

    I actually meant flyback pulses

    Our PM alternator simulator is similar, uses a full-bridge output
    stage, and can drive a dead short. Regulators for PM alternators
    usually short the alternator to limit voltage. That blew up our
    first-gen design that used a TI audio output chip.

    I have this one:
    https://www.bol.com/nl/nl/p/green-cell-12v-voltage-auto-omvormer-12v-naar-220v-230v-2000w-zuivere-sinus-golf/9200000122523930/#product_specifications
    12 V DC to 230V AC 50 Hz
    It is heavy, 4.7 kg

    Works great so far, so have not opened it yet :-)
    was 200 Euro
    No idea of the circuit.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to langwadt@fonz.dk on Thu Apr 7 10:40:52 2022
    On Thu, 7 Apr 2022 09:18:49 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:

    torsdag den 7. april 2022 kl. 16.50.35 UTC+2 skrev jla...@highlandsniptechnology.com:
    On Thu, 7 Apr 2022 08:46:43 +0100, piglet <erichp...@hotmail.com>
    wrote:
    On 06/04/2022 4:53 pm, jla...@highlandsniptechnology.com wrote:
    https://www.dropbox.com/s/jnb3jmw8rcmdeir/XfmrScatter.JPG?raw=1

    How does the mass of a transformer scale with frequency?

    I want to make a 120v 400 Hz power supply. I might boost my 48v up to
    200DC and use an isolated h-bridge out to the load, or we could put
    the bridge down at 48v and boost with a biggish transformer.

    I'll have lots of air flow, so maybe I can push things some too.




    Your first option eliminates an output transformer and means you could
    make AC out as low a frequency as you want, even DC. Only problem could
    be if customer wants to see a DC winding resistance but perhaps even
    that could be synthesiesed?

    piglet
    Yeah, I guess we'll do a high frequency inverter to 200 volts dc or
    so, and then a floating h-bridge.

    https://www.hobbielektronika.hu/forum/getfile.php?id=125378


    I'm leaning towards a full h-bridge in the first stage. It uses the
    copper better and doesn't need snubbing.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From Piotr Wyderski@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Apr 7 21:00:22 2022
    jlarkin@highlandsniptechnology.com wrote:

    The Coilcraft PL300 transformers are fabulous, 300 watts in a
    surface-mount package. Their Spice coupling coefficient is 0.9996.

    And pretty cheap, as I can see. But the 1500 Vrms is a bit low.

    Best regards, Piotr

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  • From legg@21:1/5 to eternal.september@ademu.com on Thu Apr 7 16:13:38 2022
    On Thu, 7 Apr 2022 18:12:25 +0200, Arie de Muijnck <eternal.september@ademu.com> wrote:

    On 2022-04-06 23:00, legg wrote:
    On Wed, 6 Apr 2022 18:45:43 +0200, Arie de Muijnck
    <eternal.september@ademu.com> wrote:
    Yes, which is exactly why switching PSU's are now the standard. The cost >>> saving in iron (ferrite) and copper and capacitors, and all transport
    costs, far outweighs (pun intended) the cost of the semiconductors.

    And why airplanes use 400 Hz - the tiny transformers I had designed in
    in the product were amusing, 8 times smaller than the usual 50 hz versions. >>>
    Arie

    I think you're living in the past. 60-400Hz magnetics are
    routinely shipped around the world for local cost reduction,
    making 'iron' transport costs irrelevant.

    Only end-use weight and volume remain significant.

    RL

    In the past? Could be, I designed it more than 30 years ago.

    But airplane equipment should still be as light-weight as possible.
    Nowadays of course even those 400 Hz transformers will have been
    replaced by switchers.

    Arie

    I was refering to transport costs of matl. In the past, this
    also encouraged local mfr of LF magnetics.

    RL

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