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
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
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 ??+??vac100.0W 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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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
i can assure you i don't, i use sine waves on dummy loads.....i listen to music exclusively....
i can assure you i don't, i use sine waves on dummy loads.....i listen to music exclusively....
All of this is tremendously popular.
With the Hammond Organ as evidence, thereby, I suggest that AndrewT is correct and we have been listening to some sine waves.AndrewT said:
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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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
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...
i am talking about continuous sine wave, not the sine wave that has an envelope, attack and decay, something we call musical sounds...
Thank you again for editing the table. The results are high quality, practical, and definitely easy to read.
This is not "instead of" your spreadsheet. It is 2 steps.
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.
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.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
-Charlie
This is not "instead of" your spreadsheet. It is 2 steps.
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.
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...
So, back to your question about capacitance:
- 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
I can understand your confusion about this.
At this point, I think that should get you started.
-Charlie
I see it, finally.
Multiple simultaneous sine waves is a lot more demanding on the power supply than one sine wave.
Thanks!
it would be interesting to compare actual energy content of music versus static sine waves....
static sine waves are used in analysis for lack of a better alternative....this issue have been discussed at length here many many years ago...
to keep out feet firmly on the ground, it would be best to know the difference, it has an impact(economic) on our choices as well....
Am doin it. THANKS!!
Yes, now that you mention it, specify desired ripple target at the start, totally makes sense, being that it IS the quality control dial that will directly affect realism for LTP or noise for singleton. THANKS AGAIN!!!
EDIT!
I'm stuck.
Entering dramatically different transformer VA doesn't change capacitance like indicated in Tom's spreadsheet. I cannot synchronize the data to reflect (per same ripple figure) what happens to required transformer VA if you either remove half of the capacitance or double it.
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Unless the power level is being changed somewhat significantly, changing VA won't change capacitance all that much. That's because power output is tied to RMS current which is tied to ripple voltage and capacitance. I'm not sure what numbers you are running, but for instance let's investigate a 25+25 transformer and fix ripple voltage at 1 V:
Code:
VA power capacitance
300VA 48 36,177
200VA 45 35,173
150VA 43 34,251
100VA 38 32,382
80VA 34 30,943
60VA 29 28,560What is happening is that, as the VA rating falls, the amount of sag increases. The ripple is being caused by the amplifier draining the caps, and I include both the current delivered to the load as output power and the current that is dissipated power (as waste heat) in this calculation. The total current only falls from 6.04 to 4.79 amps when the VA rating is falling from 300VA to 60VA. That ratio of 6.04 to 4.79 is 1.26 times, the same as the ratio 36,177 uF to 28,560 uF. The capacitance is just not going to go down by half if the ripple voltage is fixed at 1 V.
Personally I think that it is more instructive to see what happens when ripple voltage is allowed to vary (increase). As ripple increases, the available power will decrease and so will capacitance. For instance, let's stick with the 150VA 25+25 transformer:
Code:
Vripple power capacitance
1 43 34,251
2 40 16,662
3 37 10,813
4 34 7,898
5 32 6,157I seem to be envisioning the problem in a backwards (or reverse) fashion compared to how others are envisioning it. Maybe that is why we are having trouble getting on the same wavelength...
-Charlie
OK, the next revision of my spreadsheet is now available. I've changed some names and titles and improved some of the graphs, but the guts are the same. I've also added a worksheet containing info on the model, its assumptions, and some basic usage instructions.
Get it here:
Power_Supply_capability_calculations_VER2.2.xls
Here is a screen shot of one of the plots:
-Charlie
Get it here:
Power_Supply_capability_calculations_VER2.2.xls
Here is a screen shot of one of the plots:
-Charlie
i can assure you i don't, i use sine waves on dummy loads.....i listen to music exclusively....
Thanks for confirming that your statement was wrong and that your defense of that wrong statement was also wrong.
Guys, stick to the technical arguments.Yes, provided that the frequency, amplitude and phase of these sine waves are such that they add up to some approximation to a low frequency square wave. I thought we established much earlier in the thread that an LF square wave is the hardest thing for a PSU to cope with, in terms of current delivery and hence required reservoir capacitor value. Anything else is easier.danielwritesbac said:
There may be a separate issue with things like IM caused by capacitor nonlinearity, but that is for another thread.
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