Look at the voltage on the FB pin during steady state and then change the ratio of Rupper to Rlower to change the output voltage. Note that an isolated flyback like this can accommodate a fairly wide range of output voltage without changing the turns ratio of the transformer, but at some point you will have to change it.
Also note that changing Rupper affects the frequency compensation (but so does changing the output voltage - as we Yanks say, "you can't win for losing").
Sorry for my slow answer, but I was trying to make sure that it was not me who just made a stupid mistake. But for some reason nothing helps, so I have decided to ask all of you about a different design of a power supply.
I have looked for sollutions on google and other plases but I am not sure if any of them meets these criteria:
Ac pwm flyback buck smps 220V-240V AC in 5V-10V 1A-2A DC out
I do not need the rectifier part, just the AC-DC part and the PSU do not have to be variable. All I need is the possibility to change some resistor values to change the voltage..
Please if you have or can point toward a schematic, it would be extremely helpful:-)