400Hz 115V ac power testing - Matlab/simulink to the rescue

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required.. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled.. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

 

On Saturday, October 26, 2019 at 6:32:49 AM UTC-4, Phil Allison wrote:

blo...@columbus.rr.com wrote:

------------------------------


I have a gradient amplifier which is a high power op amp that is DC coupled.
It turns out this is a high powered audio amp that is dc coupled
(it was made by crown audio and relabeled by picker ).


** One of these:

https://www.ebay.com/c/21030870708

Crown M600s were never sold as audio amps, cos it's mono

- so always a lab thing.



... Phil

Those are exactly what I am using. It is an incredible unit. We had always used it for our DC testing.

 

[Phil Allison]

blo...@columbus.rr.com wrote:

------------------------------

I have a gradient amplifier which is a high power op amp that is DC coupled.
It turns out this is a high powered audio amp that is dc coupled
(it was made by crown audio and relabeled by picker ).

** One of these:

https://www.ebay.com/c/21030870708

Crown M600s were never sold as audio amps, cos it's mono

- so always a lab thing.



.... Phil

 

On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.





--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Sat, 26 Oct 2019 08:42:10 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

I think I'll just tie-wrap the fan to the board and solder its leads
to a couple of vias.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[bitrex]

On 10/26/19 11:42 AM, jlarkin@highlandsniptechnology.com wrote:

On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.

If it's just for the audio band you could also use a digital
synthesizer. Like the kind for making music with. like:

<https://en.audiofanzine.com/synth-rack/access-music/Virus-Rack-XL/>

the digital units are accurate to fractions of a Hz and you can define
your own tunings and tone sequences. A lot of modern pop music is all
"frequency sweeps" and "abrupt frequency changes" anyway.

Matlab/Simulink is over 2 grand for a commercial license, that rack box
above cost about 500 bucks second-hand probably

 

[Jan Panteltje]

On a sunny day (Sun, 27 Oct 2019 01:30:55 -0400) it happened bitrex
<user@example.net> wrote in <jY9tF.82882$hB2.34075@fx42.iad>:

On 10/26/19 11:42 AM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the
design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and
down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not
even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp
that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of
it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at
the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency
and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of
the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800
Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.




If it's just for the audio band you could also use a digital
synthesizer. Like the kind for making music with. like:

https://en.audiofanzine.com/synth-rack/access-music/Virus-Rack-XL/

the digital units are accurate to fractions of a Hz and you can define
your own tunings and tone sequences. A lot of modern pop music is all
"frequency sweeps" and "abrupt frequency changes" anyway.

Matlab/Simulink is over 2 grand for a commercial license, that rack box
above cost about 500 bucks second-hand probably

It is not so hard to write some C code and write samples to a wave file.

 

On Sunday, October 27, 2019 at 1:31:00 AM UTC-4, bitrex wrote:

On 10/26/19 11:42 AM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.




If it's just for the audio band you could also use a digital
synthesizer. Like the kind for making music with. like:

https://en.audiofanzine.com/synth-rack/access-music/Virus-Rack-XL/

the digital units are accurate to fractions of a Hz and you can define
your own tunings and tone sequences. A lot of modern pop music is all
"frequency sweeps" and "abrupt frequency changes" anyway.

Matlab/Simulink is over 2 grand for a commercial license, that rack box
above cost about 500 bucks second-hand probably

Here is an example of a signal to generate:
The signal free runs at 360Hz. at a moment of you choosing the signal ramps down to zero volts in 20 msec and stays at 0V for 80 msec. The signal then ramps up to 115V in 20 msec at 800 Hz. Afterwords the signal continues to play at 800 Hz. wave files can sort of work but you do not get to time when to introduce the transient, which is much better.

 

On Saturday, October 26, 2019 at 11:42:18 AM UTC-4, jla...@highlandsniptechnology.com wrote:

On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio..

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.





--

John Larkin Highland Technology, Inc

lunatic fringe electronics

Are you designing a 3 phase supply that can also impose the various DO-160 perturbations on the signal?

 

[Jan Panteltje]

On a sunny day (Sun, 27 Oct 2019 02:59:44 -0700 (PDT)) it happened
blocher@columbus.rr.com wrote in
<be6a5056-0da4-4de0-9361-f3f54598823a@googlegroups.com>:

Here is an example of a signal to generate:
The signal free runs at 360Hz. at a moment of you choosing the signal ramps
down to zero volts in 20 msec and stays at 0V for 80 msec. The signal then
ramps up to 115V in 20 msec at 800 Hz. Afterwords the signal continues to
play at 800 Hz. wave files can sort of work but you do not get to time when
to introduce the transient, which is much better.

Bull, you can switch amplitude at 1/fsample.

 

On Sun, 27 Oct 2019 02:55:15 -0700 (PDT), blocher@columbus.rr.com
wrote:

On Saturday, October 26, 2019 at 11:42:18 AM UTC-4, jla...@highlandsniptechnology.com wrote:
On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.





--

John Larkin Highland Technology, Inc

lunatic fringe electronics

Are you designing a 3 phase supply that can also impose the various DO-160 perturbations on the signal?

The immediate application is simulating a 3-phase PM alternator that
powers a FADEC. If I can make the box more general, I should, and
maybe sell some more. The key to simulating the alternator is to be
able to program complex impedances as well as voltage and frequency.

I don't think we'll try to do the full DO-160 thing, with transients
and such.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[bitrex]

On 10/27/19 4:50 AM, Jan Panteltje wrote:

On a sunny day (Sun, 27 Oct 2019 01:30:55 -0400) it happened bitrex
user@example.net> wrote in <jY9tF.82882$hB2.34075@fx42.iad>:

On 10/26/19 11:42 AM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the
design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and
down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not
even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp
that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of
it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at
the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency
and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of
the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800
Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.




If it's just for the audio band you could also use a digital
synthesizer. Like the kind for making music with. like:

https://en.audiofanzine.com/synth-rack/access-music/Virus-Rack-XL/

the digital units are accurate to fractions of a Hz and you can define
your own tunings and tone sequences. A lot of modern pop music is all
"frequency sweeps" and "abrupt frequency changes" anyway.

Matlab/Simulink is over 2 grand for a commercial license, that rack box
above cost about 500 bucks second-hand probably

It is not so hard to write some C code and write samples to a wave file.

Yeah that's not hard to do. WAV-file writing though is one of those
exercises that proves a point about C or perhaps coding in general - Ask
any average programmer to write a C program that can write some
arbitrary data in an array to a .wav format file in C it's a
less-than-one-afternoon job.

however ask a programmer to write an API that opens _all_ common .wav
file formats (the data can be e.g. floating point or signed int, mono or
stereo, interleaved or not, 16 bit, 24 bit, etc.), allows the sample
data to be easily dumped to an appropriately-sized array or arrays in
memory for manipulating, and then easily allows arbitrary edited data to
be written out to a new file of the same format you started with, or
perhaps a different format. And performs this task correctly with any
..wav file you throw at it in the usual they often come in.

This isn't an unreasonable task to want to do, and superficially the
..wav file format isn't particularly complex it's just a text header and
some formatted PCM data afterwards, it's not even compressed. If you
wanted to even say start to write an audio-editing application in C and
didn't have a library to do this off-the-shelf you'd have to do it yourself.

How long would you estimate that job would take and make sure the result
is bug-free, in C, for the "average programmer"?

 

On Sun, 27 Oct 2019 01:30:55 -0400, bitrex <user@example.net> wrote:

On 10/26/19 11:42 AM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.




If it's just for the audio band you could also use a digital
synthesizer. Like the kind for making music with. like:

https://en.audiofanzine.com/synth-rack/access-music/Virus-Rack-XL/

the digital units are accurate to fractions of a Hz and you can define
your own tunings and tone sequences. A lot of modern pop music is all
"frequency sweeps" and "abrupt frequency changes" anyway.

Matlab/Simulink is over 2 grand for a commercial license, that rack box
above cost about 500 bucks second-hand probably

We plan to do polyphase DDS waveform generation in an FPGA. We have
done that many times before and this will be routine. The analog
outputs will be from a quad 16-bit SPI DAC. Again routine.

Most of our problems here are mechanical/packaging/cooling. And
getting the customer to give us the info we need, which is why this is
going so slow.

This air flow looks pretty good, small fans tie-wrapped to the bottoms
of the amp boards and one overall inlet fan on the side.

https://www.dropbox.com/s/bqeg2948c4w0gt4/P900_Box_7.pdf?raw=1

When my SolidWorks guy gets back, he can make it all work.






--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[bitrex]

On 10/27/19 5:59 AM, blocher@columbus.rr.com wrote:

On Sunday, October 27, 2019 at 1:31:00 AM UTC-4, bitrex wrote:
On 10/26/19 11:42 AM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 26 Oct 2019 03:15:19 -0700 (PDT), blocher@columbus.rr.com
wrote:

My latest assignment requires me to evaluate a power supply design that operates off of 400Hz ac power. To validate the design I have to apply lots of signal fluctuations. These fluctuations include frequency sweeps and various voltage ramps up and down. Abrupt frequency changes are also required. Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)

I have a gradient amplifier which is a high power op amp that is DC coupled. It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this problem I have come to think of it as driving the unit with high power audio.

As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.

Anyhow, I have matlab with simulink and using I/Q modulation against a freeruning audio source I can run my base frequency and apply various signal transformations and create nearly every specified waveform. I then play them out of the audio port of the computer and into a simple op amp then to my gradient amplifier.

I ran into one small problem....my audio output was not good. There was probably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought one of these for 10$:

https://www.amazon.com/gp/product/B07L56C28R/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

And guess what.... flat as a pancake. Absolutely perfect response (at lease where I need it).

You can use matlab and simulink as a very powerful laboratory waveform generator.

We have a rackmount Peavey 800 watt amp and some transformers to
generate 120/240 VAC and high current/low voltages (to drive CTs) at
various frequencies. Works fine. The Peavey had a lot of phase shift
at 60 Hz, so we beefed up some coupling caps.

I'm now designing a 3-phase AC power source to simulate aircraft
power. We're using 500 watt TI h-bridge chips and custom toroidal
transfomers.

We were talking here about cooling the class-D chips. I think we'll
put them on the bottom of the board, with a heat sink and a fan real
close.

https://www.dropbox.com/s/pnghjixvnxy0f3m/DSC04171.JPG?raw=1

https://www.dropbox.com/s/gz6hux8y55gs37x/DSC04173.JPG?raw=1

My mechanical designer is on vacation in the Azores, so I had to hack
the box layout in Visio.

https://www.dropbox.com/s/411d7sg06s6vs62/Visio-P900_Box_6.pdf?raw=1

Visio is terrible for things like this. I'm going to force myself to
learn Fusion.

You have made me think about hanging some DRAM on the FPGA and
allowing complex waveforms to be stored and generated, not just sine
waves. Premium ver$ion.




If it's just for the audio band you could also use a digital
synthesizer. Like the kind for making music with. like:

https://en.audiofanzine.com/synth-rack/access-music/Virus-Rack-XL/

the digital units are accurate to fractions of a Hz and you can define
your own tunings and tone sequences. A lot of modern pop music is all
"frequency sweeps" and "abrupt frequency changes" anyway.

Matlab/Simulink is over 2 grand for a commercial license, that rack box
above cost about 500 bucks second-hand probably

Here is an example of a signal to generate:
The signal free runs at 360Hz. at a moment of you choosing the signal ramps down to zero volts in 20 msec and stays at 0V for 80 msec. The signal then ramps up to 115V in 20 msec at 800 Hz. Afterwords the signal continues to play at 800 Hz. wave files can sort of work but you do not get to time when to introduce the transient, which is much better.

Can you show a screencap of how that's set up in Simulink?

It could likely be done with some kind of audio production
hardware/software, or a .wav editing suite, but from your description it
does sound like it's faster to put together the test suite in Simulink
than either of those. Surely than writing C code oneself to do it!

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

The immediate application is simulating a 3-phase
PM alternator that powers a FADEC.

I watched a few videos about FADEC, fascinating! John,
I will say this, you are having entirely too much fun.


--
Thanks,
- Win

 

[bitrex]

On 10/27/19 12:42 PM, Winfield Hill wrote:

jlarkin@highlandsniptechnology.com wrote...

The immediate application is simulating a 3-phase
PM alternator that powers a FADEC.

I watched a few videos about FADEC, fascinating! John,
I will say this, you are having entirely too much fun.

"Full authority analogue control was used in the 1960s and introduced as
a component of the Rolls-Royce/Snecma Olympus 593 engine of the
supersonic transport aircraft Concorde."

I hope it used like 500 LM324s.

 

[Jan Panteltje]

On a sunny day (Sun, 27 Oct 2019 11:30:12 -0400) it happened bitrex
<user@example.net> wrote in <9KitF.341257$LG2.316861@fx48.iad>:

On 10/27/19 4:50 AM, Jan Panteltje wrote:
On a sunny day (Sun, 27 Oct 2019 01:30:55 -0400) it happened bitrex
user@example.net> wrote in <jY9tF.82882$hB2.34075@fx42.iad>:
It is not so hard to write some C code and write samples to a wave file.


Yeah that's not hard to do. WAV-file writing though is one of those
exercises that proves a point about C or perhaps coding in general - Ask
any average programmer to write a C program that can write some
arbitrary data in an array to a .wav format file in C it's a
less-than-one-afternoon job.

Most programming is not a less than 1 afternoon job.
As I have done all that stuff in C and soem of it is actually on my website
and then I am also going back to the eighties about doing it.
I do not see the problem.
The problem arises when you start tinkering with a lot of bloated libraries
that may or may not do what you want and shield you from basic hardware.
I did sound for the IBM PC when most never even heard about an IBM PC.
Was part of my job (announcement system, spoke from wave tables).
Even worse some did it in X86 asm.

You do know that 'hello world' in asm is only a few bytes?

To isolate so called programmers from the hardware is evil,
leads to bloat, and avoids them understanding what really happens.
The total learning time of all the bloated programs and libraries is then greater
than you reading up on the wave format and writing some simple code
to do whatyouwannado.

That said I have been coding 12 hours a day at least for the last few days rewriting Raspberry Pi4 code
now I have a media system, satellite receiver, new desktop, networked video,
several browsers, extra storage etc..
its is hard work in a way, but also rewarding one it all works.

however ask a programmer to write an API that opens _all_ common .wav
file formats (the data can be e.g. floating point or signed int, mono or
stereo, interleaved or not, 16 bit, 24 bit, etc.), allows the sample
data to be easily dumped to an appropriately-sized array or arrays in
memory for manipulating, and then easily allows arbitrary edited data to
be written out to a new file of the same format you started with, or
perhaps a different format. And performs this task correctly with any
.wav file you throw at it in the usual they often come in.

The man wants signals to his amplifier to test things.
Stay with what is needed and get it done.
Write it in any language you want, but C is the best for those things IMO.

 

[bitrex]

On 10/27/19 2:34 PM, Jan Panteltje wrote:

On a sunny day (Sun, 27 Oct 2019 11:30:12 -0400) it happened bitrex
user@example.net> wrote in <9KitF.341257$LG2.316861@fx48.iad>:

On 10/27/19 4:50 AM, Jan Panteltje wrote:
On a sunny day (Sun, 27 Oct 2019 01:30:55 -0400) it happened bitrex
user@example.net> wrote in <jY9tF.82882$hB2.34075@fx42.iad>:
It is not so hard to write some C code and write samples to a wave file.


Yeah that's not hard to do. WAV-file writing though is one of those
exercises that proves a point about C or perhaps coding in general - Ask
any average programmer to write a C program that can write some
arbitrary data in an array to a .wav format file in C it's a
less-than-one-afternoon job.

Most programming is not a less than 1 afternoon job.
As I have done all that stuff in C and soem of it is actually on my website
and then I am also going back to the eighties about doing it.
I do not see the problem.
The problem arises when you start tinkering with a lot of bloated libraries
that may or may not do what you want and shield you from basic hardware.
I did sound for the IBM PC when most never even heard about an IBM PC.
Was part of my job (announcement system, spoke from wave tables).
Even worse some did it in X86 asm.

You do know that 'hello world' in asm is only a few bytes?

To isolate so called programmers from the hardware is evil,
leads to bloat, and avoids them understanding what really happens.
The total learning time of all the bloated programs and libraries is then greater
than you reading up on the wave format and writing some simple code
to do whatyouwannado.

An 8 bit AVR or PIC one guy can fully understand. A modern x86 processor
system is too complex for any one person to understand all of, not even
the teams that built them.

That said I have been coding 12 hours a day at least for the last few days rewriting Raspberry Pi4 code
now I have a media system, satellite receiver, new desktop, networked video,
several browsers, extra storage etc..
its is hard work in a way, but also rewarding one it all works.




however ask a programmer to write an API that opens _all_ common .wav
file formats (the data can be e.g. floating point or signed int, mono or
stereo, interleaved or not, 16 bit, 24 bit, etc.), allows the sample
data to be easily dumped to an appropriately-sized array or arrays in
memory for manipulating, and then easily allows arbitrary edited data to
be written out to a new file of the same format you started with, or
perhaps a different format. And performs this task correctly with any
.wav file you throw at it in the usual they often come in.

The man wants signals to his amplifier to test things.
Stay with what is needed and get it done.
Write it in any language you want, but C is the best for those things IMO.

A data structure that wraps a dynamic array like a std::vector sure
makes life easier.

 

On 27 Oct 2019 09:42:02 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...

The immediate application is simulating a 3-phase
PM alternator that powers a FADEC.

I watched a few videos about FADEC, fascinating! John,
I will say this, you are having entirely too much fun.

Both of us are fortunate to be electronic dilettantes. We get to play
with all sorts of science and technology for a while, see wild stuff
and design electronics for it and be heroes, and move on in a few
months without making any of that our careers.

My customer is threatening to send me a FADEC, which I have no use
for. What I really want is an alternator. I want to chuck it into a
milling machine and spin it up and measure things. I have tried to buy
a used/junker alternator from aircraft repair companies, no luck so
far. The ones on small planes are usually modified excited-field car
types.

The FADECs initially power up off aircraft 24 volts DC. Once the
engine fires up, they get their power off a private PM alternator
geared to one of the fans.

Alternators are often shunt regulated, ie shorted, so my source has to
tolerate that, and present about the right impedances and load line.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Winfield Hill]

bitrex wrote...

"Full authority analogue control was used in the 1960s and
introduced as a component of the Rolls-Royce/Snecma Olympus
593 engine of the supersonic transport aircraft Concorde."

FAAEC ?


--
Thanks,
- Win