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 13th October 2012, 04:30 PM #1421 OnAudio diyAudio Member     Join Date: Oct 2011 Nice going __________________ onaudio.herokuapp.com
gootee
diyAudio Member

Join Date: Nov 2006
Location: Indiana
Transformer Spice Modeling and Scaling

All,

While in the process of getting ready to use the per-unitized transformer model parameters to update my spreadsheet, I had to transfer all of the equations from my LT-Spice simulation to Excel. So I first made a separate spreadsheet for just the transformer modeling and scaling.

The attached spreadsheet should be quite useful for anyone who wants to model transformers in spice or pspice.

Enjoy,

Tom
Attached Files
 Transformer_Spice_Modeling_and_Scaling-Gootee_13OCT2012.zip (66.7 KB, 8 views)

danielwritesbac
diyAudio Member

Join Date: Nov 2007
Quote:
 Originally Posted by CharlieLaub I'm not sure what you mean by the above statement. I believe that the output power is limited by the rail voltage for these cases, so the transformer VA is not going to play much of a role in output power. -Charlie
Thanks for your help on this. I did misread Tom's chart. But, the unexpectedly low ripple (I was actually aiming at less than 2v, not less than 1v) is perfectly acceptable, considering the low price of it. Nice upgrade! So, let's just go ahead and keep the "less than 1v" ripple spec. I hope that "<1.0v" was the right way to type that (if not please fix). I'm not a math expert, but the clarity of a chart is very helpful, since I am able to make comparisons.

And, here is the capacitance versus VA question in chart form.
Constraints: 800va max. 1v ripple max. 40,000u max. 1 channel.
Please fine tune the capacitance for any case that is impossible.
The resulting applicable data will show matters instantly very clearly.
Code:
```output  cap per   ripple                       secondary AC
power     rail   voltage  transformer   info     voltage
8 W     3,300u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
8 W     6,800u   0.73V    1.1a25vct   28.6VA  12.5+12.5vac
8 W    12,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

13 W     4,700u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
13 W     8,200u   0.76V    1.5a30vct   44.7VA    15+15vac
13 W    15,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

22 W     4,700u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
22 W    10,000u   0.78V    2.0a36vct   71.3VA    18+18vac
22 W    20,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

29 W     6,800u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
29 W    15,000u   0.59V    1.9a40vct   77.9VA    20+20vac
29 W    30,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

37 W    10,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
37 W    20,000u   0.50V    2.2a44vct   97.5VA    22+22vac
37 W    40,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

50 W    10,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
50 W    18,000u   0.64V    2.7a50vct  135.7VA    25+25vac
50 W    40,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

65 W    10,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
65 W    20,000u   0.65V    2.8a56vct  158.5VA    28+28vac
65 W    40,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac

95 W    10,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac
95 W    20,000u   0.76V    3.7a64vct  234.9VA    32+32vac
95 W    40,000u   <1.0V    ?.?a??vct   ??.?VA    ??+??vac```
I couldn't seem to operate your spreadsheet when approaching/passing the 100w figures, and I'd like to see a more linear behavior all the way to at least 180w, so that Tom's 125w, 150w, 180w (or so) amplifiers could be included. Here they are:
100.0W 20,000u 237.3VA
125.0W 20,000u 295.7VA
155.0W 20,000u 363.2VA
180.0W 30,000u 395.4VA

I'm sure that somebody will a power supply for the Honey Badger amplifier in this power range.

P.S.
In regards to the 0.99v or less ripple spec, I've noticed that my own power supply designs can filter 1v or 2v of ripple, but they don't always filter off 2v, in which case the audio quality may be either mid-fi or crap; so holding the ripple spec down below 1v is going to be much more compatible and consistently successful.
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Last edited by danielwritesbac; 13th October 2012 at 10:38 PM.

CharlieLaub
diyAudio Member

Join Date: Mar 2007
Location: California
Quote:
 Originally Posted by danielwritesbac Code: ```output cap per ripple secondary AC power rail voltage transformer info voltage 8 W 3,300u <1.0V ?.?a??vct ??.?VA ??+??vac 8 W 6,800u 0.73V 1.1a25vct 28.6VA 12.5+12.5vac 8 W 12,000u <1.0V ?.?a??vct ??.?VA ??+??vac 13 W 4,700u <1.0V ?.?a??vct ??.?VA ??+??vac 13 W 8,200u 0.76V 1.5a30vct 44.7VA 15+15vac 13 W 15,000u <1.0V ?.?a??vct ??.?VA ??+??vac 22 W 4,700u <1.0V ?.?a??vct ??.?VA ??+??vac 22 W 10,000u 0.78V 2.0a36vct 71.3VA 18+18vac 22 W 20,000u <1.0V ?.?a??vct ??.?VA ??+??vac 29 W 6,800u <1.0V ?.?a??vct ??.?VA ??+??vac 29 W 15,000u 0.59V 1.9a40vct 77.9VA 20+20vac 29 W 30,000u <1.0V ?.?a??vct ??.?VA ??+??vac 37 W 10,000u <1.0V ?.?a??vct ??.?VA ??+??vac 37 W 20,000u 0.50V 2.2a44vct 97.5VA 22+22vac 37 W 40,000u <1.0V ?.?a??vct ??.?VA ??+??vac 50 W 10,000u <1.0V ?.?a??vct ??.?VA ??+??vac 50 W 18,000u 0.64V 2.7a50vct 135.7VA 25+25vac 50 W 40,000u <1.0V ?.?a??vct ??.?VA ??+??vac 65 W 10,000u <1.0V ?.?a??vct ??.?VA ??+??vac 65 W 20,000u 0.65V 2.8a56vct 158.5VA 28+28vac 65 W 40,000u <1.0V ?.?a??vct ??.?VA ??+??vac 95 W 10,000u <1.0V ?.?a??vct ??.?VA ??+??vac 95 W 20,000u 0.76V 3.7a64vct 234.9VA 32+32vac 95 W 40,000u <1.0V ?.?a??vct ??.?VA ??+??vac``` I couldn't seem to operate your spreadsheet when approaching/passing the 100w figures, and I'd like to see a more linear behavior all the way to at least 180w, so that Tom's 125w, 150w, 180w (or so) amplifiers could be included. Here they are: 100.0W 20,000u 237.3VA 125.0W 20,000u 295.7VA 155.0W 20,000u 363.2VA 180.0W 30,000u 395.4VA I'm sure that somebody will a power supply for the Honey Badger amplifier in this power range.
It's not that difficult, really... Only modify cells in bold blue text... Enter what you know (e.g. transformer VA) and then manipulate what you don't know (e.g. secondary voltage, ripple voltage) until you find what you are looking for. If you want to simulate higher output power levels, the secondary transformer voltage has to be higher as well.

I hate to tell you, but I'm not going to run all of these for you These tables are inane anyway.

-Charlie

TonyTecson
diyAudio Moderator

Join Date: May 2003
Location: Palatiw, Pasig City
Quote:
 Originally Posted by AndrewT We all listen to sinewaves. Even when simulated squarewaves and sawtooth waves are inserted into digitally created music, these are composed of sinewaves.
i can assure you i don't, i use sine waves on dummy loads.....i listen to music exclusively....
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danielwritesbac
diyAudio Member

Join Date: Nov 2007
Quote:
 Originally Posted by Tony i can assure you i don't, i use sine waves on dummy loads.....i listen to music exclusively....
The picture above is the worlds most popular sine wave generator used in musical instruments. Prototypes from about 1928, patented in 1934, the Hammond Organ uses slightly dirty sine waves in an additive synthesis method of producing different tones. Newer all-digital models have recordings of mechanical tone wheel output and the most faithful of replicas pump digital tonewheel output through the same audio path as the original, including the key contacts, tubes and rotating horn speakers, thus reproducing the dynamically reactive behavior of the originals, faultlessly, along with most of the weight and cost. Even the 1-manual edition is fiercely heavy. Lighter weight options exist that subtract or supplant some of the steps in the audio chain and sound like less-authentic recordings of the real thing, but at lower cost.

All of this is tremendously popular.
Quote:
 Originally Posted by AndrewT We all listen to sinewaves. Even when simulated squarewaves and sawtooth waves are inserted into digitally created music, these are composed of sinewaves.
With the Hammond Organ as evidence, thereby, I suggest that AndrewT is correct and we have been listening to some sine waves.
In two current, relevant, and sizable industries, the Digital Hammond Organ (both authentic and off-brand) and the Digital Church Organ, are all extremely demanding of amplifier power supplies. If the power supply has either disharmonic content (ripple) or weakness (sag), these instruments would be about as fun as a flat tire. Since accurate replay is easier from the console than from a CD, I suggest that audio replay power supplies need to be even higher quality, by at least double the stiffness with half the ripple for a chance at some realism.

In related news: Due to audio quality caveats, Steinway still doesn't offer concert pianos the size of toasters. That's just another example of "no free lunch."
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Last edited by danielwritesbac; 14th October 2012 at 01:30 AM.

CharlieLaub
diyAudio Member

Join Date: Mar 2007
Location: California
Quote:
 Originally Posted by danielwritesbac ...I suggest that AndrewT is correct and we have been listening to some sine waves...
No, it's only a set of basis functions upon which you can represent a random signal. You can say the same for other functions - wavelets, for instance. So maybe THAT is what we are all listening to...

-Charlie

 14th October 2012, 02:04 AM #1428 TonyTecson   diyAudio Moderator     Join Date: May 2003 Location: Palatiw, Pasig City while music is made up from sine waves, there is no comparison with static sine waves, feed your speakers even 1 watt of 60 hz sine waves see if you can stand it.... i am talking about continuous sine wave, not the sine wave that has an envelope, attack and decay, something we call musical sounds... __________________ planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
danielwritesbac
diyAudio Member

Join Date: Nov 2007
Thank you again for editing the table. The results are high quality, practical, and definitely easy to read.
Quote:
 Originally Posted by CharlieLaub It's not that difficult, really... Only modify cells in bold blue text... Enter what you know (e.g. transformer VA) and then manipulate what you don't know (e.g. secondary voltage, ripple voltage) until you find what you are looking for. If you want to simulate higher output power levels, the secondary transformer voltage has to be higher as well. I hate to tell you, but I'm not going to run all of these for you These tables are inane anyway. I will be uploading an new version of the spreadsheet with some instructions soon, and will post here about it. -Charlie
Where do I type in the capacitance? I'm sorry, but I haven't been able to exactly correlate Tom's spreadsheet with your spreadsheet any farther than seen previously.

1). The goal of the table is to provide multiple practical examples at 1 glance as a fast (directed) place to start. In fact, it is directions. Some people will need that prefabricated guidance, for a head start. I do!
2). After having picked a practical near match example to investigate further, your spreadsheet gives excellent details on the specific behavior and the actual wattage output expected, as well as the shopping convenience of listing real transformers.

The effect of the table: In 2 seconds or less, I've been "tricked" into reading the directions. Yes, you're right that one table won't do it; however, it won't take a million either--It will take 4 to select the load:
Monobloc 8 ohms, Monobloc 4 ohms, Stereo 8 ohms, Stereo 4 ohms
But, the 4 tables can provide a practical and instant head start.
I find it necessary to narrow down the options so that I don't get stuck in simulation.
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CharlieLaub
diyAudio Member

Join Date: Mar 2007
Location: California
Quote:
 Originally Posted by danielwritesbac Where do I type in the capacitance? I'm sorry, but I haven't been able to exactly correlate Tom's spreadsheet with your spreadsheet any farther than seen previously.
As I mentioned before, you DON'T enter the capacitance. You might intuitively think along the lines of how you would build a power supply: you pick a transformer and capacitors and then you see the result. That is not how my spreadsheet is set up, however. Instead, you pick a transformer and a RIPPLE VOLTAGE and then the capacitor value is calculated. Capacitance and ripple voltage are inversely related, so one directly determines the other. Unfortunately, the way I have formulated the spreadsheet, I need to know the ripple voltage a priori since it is used in the calculations...

• use the ripple voltage to control capacitance
• reducing ripple voltage means that a larger capacitance will be required
• increasing ripple voltage means that a smaller capacitance can be used
You have to iterate around a little bit in order to home in on a particular capacitance. This seems backwards to me - I would instead specify the ripple voltage (for instance something on the order of 0.707 volts seems to be what Tom's number give) and then just list whatever capacitance results from that. You won't be using a 1%, 5% or even a 10% tolerance electrolytic anyway in this application... This would allow you to remove the ripple voltage column and just note at the top that all the capacitance numbers stated give a ripple voltage of 0.707 V (for example).

At this point, I think that should get you started.

-Charlie

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