I have done testing using top224 based flyback smps
for this test I did not use an oscilloscope
- Vout 15V regulated
- load : 3x 20ohm 10W resistor in parallel (6,6ohm)
result :
with 68uf elco
the voltage on the capacitor drops from 291 to 284 https://youtu.be/ojRMMRJBEOI
for me it is enough, please check attached appnote page 2 : "Typically, the DC link capacitor is selected as 2-3uF per watt of input power for universal input range (85-265Vrms) and 1uF per watt of input power for European input range (195V265Vrms)"AN-4146.pdf.pdf