Is PSUD II trust-worthy or not? - diyAudio
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Old 31st March 2012, 02:02 AM   #1
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Default Is PSUD II trust-worthy or not?

I was just trying out for the first time the PSUD II and try to make as perfect as possible PS for a tube amplifier i'm making. I was able to find the right combination of caps and resistors and later on added a choke...up to that point no problems at all...the graphic drawing showed me a perfect result. The thing is that when i make an exact replica of already existing and working PS, it gives me totally different readings of voltage on various points in the circuit.
Now, my question is: can i trust PSUD or go for the already proven designs no matter what PSUD shows? Has anyone had positive/negative experience with this PSUD II?

matej888
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Old 31st March 2012, 02:10 AM   #2
Zen Mod is offline Zen Mod  Serbia
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did you use F1 ?
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Old 31st March 2012, 11:58 AM   #3
DF96 is offline DF96  England
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'Exact replica' means you have carefully measured transformer and choke winding resistances and put these in the PSUD2 model, as well as capacitor ESR. You have also adjusted your mains voltage to match the model.

Is 'totally different' an exaggeration?
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Old 31st March 2012, 12:41 PM   #4
AndrewT is online now AndrewT  Scotland
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The software user must understand the software workings and be able to check the accuracy of any model predictions.

Looks like you are not safe to be let loose on PSUDII.
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Old 31st March 2012, 04:49 PM   #5
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First of all i want to thank you guys for help (seriuosly, not trying to be sarcastic), but as i said i'm new with this software and sure i am doing something wrong, there's no doubt....

I've put as many data available regarding the power transformer, and chokes letting out the ESR of the caps (i will try to get that info too) and by exact replica i ment copying the schematics i have and comparing the results. My question was only (not having any experience with PSUD) if the software was reliable and could be taken as reference...

But i'm not stopping here, i will do further research and eventually find out (i'm actually reading all posts regarding the PSUD) what is the
right way to do it or better what am i doing wrong or missing out!


p.s.: if somebody is interested i can send the copied PSUD file for a check...


Thanx
matej888
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Old 31st March 2012, 07:12 PM   #6
DF96 is offline DF96  England
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No simulator is perfect, but PSUD2 is reckoned to be quite good. Have you given time for the voltages to stabilise?
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Old 31st March 2012, 07:31 PM   #7
Pano is offline Pano  United States
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Quote:
Originally Posted by DF96 View Post
Have you given time for the voltages to stabilise?
That's a major mis-step when first learning the software, for sure.
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Old 31st March 2012, 09:31 PM   #8
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@DF96: yes, i've let the voltage to stabilize for 25 seconds (which should be more than enough) and the characteristics on the graphic displayed as flat as a flat can be...with the software i defenitely got the psu right, which to me was too suspicious...you know..get it to work perfectly the first time.... and that's the reason why i tested the software with already proven schematics.
But ok, i'm a lot closer to understand it now, than i was before...
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Old 31st March 2012, 11:09 PM   #9
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You may be best off posting your data file and having us look at it. The software has proven itself to be very accurate time and time again. Typically the issue is either misuse of the features or incorrect input data
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Old 31st March 2012, 11:20 PM   #10
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To get accurate results first you must measure the open circuit voltage of your transformer, always higher than the advertised voltage. Also, you need the winding resistance of primary and secondary. You must also set the Mains frequency under options. There is one gray area. When you are using the FWCT configuration, IIRC you need to use half the end to end secondary resistance. I could be wrong on this.

To get accurate results for RMS current, the simulation needs to run an integral number of cycles. 100mS is good because it's 5 cycles at 50Hz, 6 cycles at 60Hz. Use a nice long delay as mentioned above.
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