Hi
sorry for the delay. Thanks for the suggestions, David, highly appreciated!
I have tried to implement them according to my understandig and possibilities:
- replaced D2 with 22pF
- removed decoupling cap C5
unfortunately I do not understand how to combine IC3B with the current amplifier and how to move the current sense amplifier to the high side (erm, it is high side current measurement, already?!) and what you mean regarding level shifting...

I only tested this with a 4R power resistor until now so I don't know if the oscillation changes with load current (while the voltage staying the same). it certainly gets a bit worse if I allow more current to flow (by increasing the output voltage, by increasing the current limit through pin 5 of IC3B). I was testing around 1.5 - 2V so the LM334 should have kicked in. In my other PSU design I used a opamp + n-channel fet current sink which works really great. I may should have put that one in this design in as well.. my fault...
I managed to get the oscillation amplitude pk-pk down to about 30mV by increasing C13 to 100(!)nF and decreasing R11 to 1k. Diode D2 and C5 are still removed, C11 is connected to the Darlington's base again.
However there's still some nasty stuff happening (the ringing, see screenshot attached). I attached a 2200µF capacitor to the output cause I had one lying around but that did very little to the oscillation.
Oh and I'm not sure whether that's clear/obvious, the screenshot is a measurement from the PSU output terminals.
I'll have to study your attached design, I hope I can manage to squeeze something into my brain...
Any more suggestions how to get this stable (with minor bodge-compatible changes)? This is supposed to be a really cheap and easy design, BOM cost is currently around 50 EUR, incl. a 2004 character LCD from Mouser (without transformer, case and heatsink) and I'd prefer if I wouldn't have to respin the PCB immediately (also because waiting for the china shipment from jlcpcb). Downsides like slow CC mode wouldn't bother me much. I mean, slow CC mode is better than no CC mode, right? :-)