as promised in the seminar that was aired around 14:00 today, here's the material:
1) the slides - these are in PDF format, so most of you can view it.
2) the measurement data. This is a Libre Office calc file - not sure if Excel can open it, but it's worth a try. I had to pack it, otherwise this forum software doesn't accept it.
I am kinda new to presenting numbers in diagrams in Calc, so the diagrams do have the weakness that the points aren't in the exact right position. This may be improved, and I am happy to take some advice on how to do that.
What the diagram does show is that the voltage of my "Prototype #2" is most stable, and ripple is the lowest in the measurement series. Further, what I did not show in the seminar (because I didn't have the diagram finished in time) is the correlation of 12V-load and 5V drop, which is in the last sub-table. THe 5V drop is not all that high, but if you take ripple and cable/filter drop into account, it may add up to taking a 3.3V regulator into oscillation. There is really no technical necessity to compensate against the 12V-load-caused 5V drop, but I figured that while I was at "compensating" anyway, I might as well compensate that.
Another thing you'll be able to see from the measurement data is efficiency: The existing solutions - including the ones that were "made in 2019 or 2020" are in the low-to-mid 60% area, while the DC-DC converter-based approach holds up nice in the 80% area, so it's actually a money-saver (though a small one).
As soon as I have a VOD link, I'll post that here.
Another question came up in the Twitch chat, and that was about measurement errors. I believe I have addressed that by mentioning the accuracy of the multimeters: The two Uni-T meters are 6000-count, so they are really +/- one digit. Both these multimeters were bought this year, so they are in calibration. The Amprobe multimeter on the 12V rail is a 2000-count, so it's only good up to the second digit after the comma if the voltage is below 20V - which it is. So we're also talking "+/- 1 digit" for that measurement. The clamp amp meter is heavily influenced by the earth's magnetic field, so it is depending on staying in the exact position that it was in when you pressed the "zero" button. The error might be up to 10mA or 10 digits. Since the current measurement only went into efficiency calculation and not the voltage observation, it only affects the resulting accuracy of the efficiency figure.
The accuracy of the Rohde&Schwarz power analyzer is +/- 50mW, and it was last calibrated in February of this year. The Agilent mixed-signal scope is actually out of calibration, but it agrees with the Uni-T 6000-count desk mutimeter down to the third digit after the comma, which is impressive, given that the last calibration is over two years ago.
While these measurement errors do add up, the important message here is that it is actually possible to compensate for all losses with a relatively simple circuit. My criticism for "new PSU"-makers is renewed and has a solid foundation with this data.
I'm happy to add other PSUs to the measurements. Feel free to send me one, or come to an Amiga show where guests are allowed to be present (after we've beaten Covid-19), and we'll do the measurements on site (I'll have at least the resistor-load and the volt meter with me). I'm more than happy if anyone replicates these measurements, which is why I am completely open about the methods. I do want everyone with the requried skills to replicate these numbers.