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Old 25th Mar 2023, 3:24 pm   #1
ms660
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Default PSUD2 versus Schade's Curves

In this example the receiver is a Ekco U353 which is a AC/DC job which uses a UY85 rectifier, the service info provides the figures and circuit info that's required.

PSUD2:

Reservoir capacitor ripple voltage percentage = 3.99%

RMS rectifier anode current = 0.1888 Amps

Rectifier anode supply VA = 45.31


Schades Curves:

Reservoir capacitor ripple voltage percentage = 4.2% (approx.)

RMS rectifier anode current = 0.198 Amps (approx.)

Rectifier anode supply VA = 47.52 (approx.)

Not a lot of difference.

Lawrence.

Last edited by ms660; 25th Mar 2023 at 3:45 pm.
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Old 25th Mar 2023, 4:03 pm   #2
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Default Re: PSUD2 versus Schade's Curves

Forgot the PSUD2 sim.

Lawrence.
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Old 29th Mar 2023, 1:03 pm   #3
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Default Re: PSUD2 versus Schade's Curves

Here's the comparison for the 5Y3GT rectifier using the analysis given for that rectifier in RDH4 Chapter 30 Section 2 starting on page 1170 using Schades curves.

VAC = 350 Volts, VDC = 350 Volts, load resistance = 2,800 Ohms, Rs (added series resistance) = 50 Ohms.

Figures without brackets = RDH4, figures within brackets = PSUD2:

VDC = 350V (357.5V)

Load current = 125mA (127.4mA)

Mean current per diode = 62.5mA (63.7mA)

RMS current per diode = 140mA (147.9mA)

Peak current per diode = 375mA (443.4mA)

Ripple voltage percentage = 5.5% (5.94%)

Link to RDH4:

http://www.tubebooks.org/books/rdh4.pdf

Not much difference apart from the peak diode current.

Lawrence.
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Last edited by ms660; 29th Mar 2023 at 1:11 pm. Reason: "using Shades curves"
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Old 29th Mar 2023, 6:13 pm   #4
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Default Re: PSUD2 versus Schade's Curves

It is good to see the good correspondance between PSU2D (which I used frequently) and Schade (whose paper I have, and blow ups of the graphs).

There is also an article in Linear Audio V8, 2014, pp 83-127 "The Otto Schade method - A practical design method for rectifier circuits" by Rudolf Moers.

He builds a flexible configuration power supply, and compares real world measurements with Schade's graphical method, other approximations, and a treatment in The Radiotron Designer's handbook Ed4.

https://www.linearaudio.net/otto-sch...ifier-circuits

And this is how you can get the articles https://www.linearaudio.net/

Craig
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Old 29th Mar 2023, 7:11 pm   #5
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Default Re: PSUD2 versus Schade's Curves

Quote:
Originally Posted by Craig Sawyers View Post
It is good to see the good correspondance between PSU2D (which I used frequently) and Schade (whose paper I have, and blow ups of the graphs).

There is also an article in Linear Audio V8, 2014, pp 83-127 "The Otto Schade method - A practical design method for rectifier circuits" by Rudolf Moers.

He builds a flexible configuration power supply, and compares real world measurements with Schade's graphical method, other approximations, and a treatment in The Radiotron Designer's handbook Ed4.

https://www.linearaudio.net/otto-sch...ifier-circuits

And this is how you can get the articles https://www.linearaudio.net/

Craig
I couldn't download the article from those links.

At least one of the valve rectifier models in PSDU2 is up the creek, at least in the PSUD2 version I have (check out the UY1N rectifier spec. in the attached screen shot) then compare to the manufactures data here:

http://www.r-type.org/pdfs/uy1n.pdf
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Old 29th Mar 2023, 8:03 pm   #6
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Default Re: PSUD2 versus Schade's Curves

Quote:
Originally Posted by ms660 View Post
PSUD2:

Reservoir capacitor ripple voltage percentage = 3.99%

RMS rectifier anode current = 0.1888 Amps

Rectifier anode supply VA = 45.31


Schades Curves:

Reservoir capacitor ripple voltage percentage = 4.2% (approx.)

RMS rectifier anode current = 0.198 Amps (approx.)

Rectifier anode supply VA = 47.52 (approx.)
It's pretty good agreement between the two!

I wanted 315V at 90mA some years ago... I decided on a 5Z4 rectifier and designed the transformer to suit, using Schade's curves, making a few assumptions such as winding resistance etc to start off.

Going round calculations at least one further time (might have been two) to refine turns, winding resistance, etc... I ended up with a transformer design.

Making it, connecting rectifier, reservoir cap, dummy load, input via Variac to set to exactly 240V, I measured DC output voltage.

318V.

Just over 1% different from desired.
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Old 29th Mar 2023, 11:49 pm   #7
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Default Re: PSUD2 versus Schade's Curves

RDH4 frequency is 60Hz, not that it makes a significant difference. Also the 50 ohm effective resistance is typically included in the PSUD2 transformer model for clarity, again not that it makes any calculated difference.

Schade curves are imho more of a mathematical approximation, and given the generalised nature of both Schade curves and PSUD2 models, it is well worth noting that calculated values have likely confidence of not much better than 5%. Meaning that any result should really be rounded to about 2 digits and at most 3, and the comparisons are effectively saying the results are the same. And then relating that to an actual measured circuit is also fraught with generalisations, including the distortion of the mains waveform and whether the valve is a good example of a bogey and the metering accuracy.

Last edited by trobbins; 29th Mar 2023 at 11:54 pm.
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Old 30th Mar 2023, 10:00 am   #8
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Default Re: PSUD2 versus Schade's Curves

And this is how you can get the articles https://www.linearaudio.net/

Craig

[/QUOTE]

I couldn't download the article from those links.

[/QUOTE]

There are instructions on the linear audio website about a USB stick with all the volumes on it on the Elektor site https://www.elektor.com/the-complete...rary-usb-stick currently about Euro80.

I have all the paper ones - I subscribed back in the day, and they just arrived. Compared to the price I paid for the originals, Euro80 is a bargain.

Craig
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Old 30th Mar 2023, 10:07 am   #9
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Default Re: PSUD2 versus Schade's Curves

I have all the elektors from 1974 to 2020 inclusive as pdf.
I took a free 6 month subscription to Elektor as a special offer from another site and had access to the back catalogue.

Peter
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Old 30th Mar 2023, 10:11 am   #10
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Default Re: PSUD2 versus Schade's Curves

I just tried to get a copy of PSUD2, unfortunately it has moved to https://groups.io/g/duncanampspsud and you have to join the group to get it.
I don't need to join yet another group.

Peter
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Old 30th Mar 2023, 10:15 am   #11
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Default Re: PSUD2 versus Schade's Curves

80 Euro's

Lawrence.
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Old 30th Mar 2023, 10:40 am   #12
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Default Re: PSUD2 versus Schade's Curves

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Originally Posted by ms660 View Post
80 Euro's

Lawrence.
Well you don't have to buy it.

The paper version was around 15 a copy while it was being published. So over 200 all told. I refer to each volume frequently.

Then there is the 300 page additional volume on Audio Power Amplifiers, and a special edition of correspondence between Douglas Self and Peter Baxandall on audio power amplifiers. I think they are also on the memory stick.

Craig
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Old 30th Mar 2023, 10:58 am   #13
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Default Re: PSUD2 versus Schade's Curves

Quote:
Originally Posted by Craig Sawyers View Post
Quote:
Originally Posted by ms660 View Post
80 Euro's

Lawrence.
Well you don't have to buy it.

The paper version was around 15 a copy while it was being published. So over 200 all told. I refer to each volume frequently.

Then there is the 300 page additional volume on Audio Power Amplifiers, and a special edition of correspondence between Douglas Self and Peter Baxandall on audio power amplifiers. I think they are also on the memory stick.
Yes, but I got Schades for free and also some comparisons to real world power supplies for free, eg: in Post#6.

Lawrence.
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Old 30th Mar 2023, 12:13 pm   #14
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Default Re: PSUD2 versus Schade's Curves

Referring back to the UY1N in Post#5, according to that screen shot it shows a PIV of 500V, a IFSM of 400mA and a IFRM of 400mA, something's wrong there to me, looking at the Philips valve data the max. Vfk is shown as 500V which might be where they got the PIV figure from.

The figures in the table in the attached screen shot shown below are the results of figures I inputted that were from the manufactures manual for the Tesla Talisman 305U receiver which uses a UY1N rectifier.

With a mains input voltage of 220 VAC, the warning box shown in the screen shot pops up when the simulation is started stating that the rectifiers PIV has been exceeded, and if the load resistance is changed to reflect a load current of 130mA with the same mains input voltage and surge limiter of 125 Ohms the simulation says that the IFSM has been exceeded...

http://www.r-type.org/pdfs/uy1n.pdf

Lawrence.
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Old 30th Mar 2023, 11:16 pm   #15
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Default Re: PSUD2 versus Schade's Curves

You may find that a few diode models in PSUD2 are custom, as they are input by users and appended to the diode lookup listing. As such, some diodes can have parameter data errors and so some caution is needed for not so common diode types.
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Old 31st Mar 2023, 10:49 am   #16
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Default Re: PSUD2 versus Schade's Curves

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Originally Posted by trobbins View Post
You may find that a few diode models in PSUD2 are custom, as they are input by users and appended to the diode lookup listing. As such, some diodes can have parameter data errors and so some caution is needed for not so common diode types.
Yes, just a bit, like the 99 Amp IFSM for the UY41

I can correct errors in the diode model file but something prevents the corrected file from being saved.

Lawrence.
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