CarlosFM regulated powersupply, change output voltage?

[jaste]

Ok, as said in the subject. If I would like to change the output voltage of this powersupply from 25 to 30 volts what would i do? Sure I want a good result but also a understandable answer...

THANKS!

this is the supply schematic, just scroll down to the end

http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone6.html

 

[peranders]

The best you could do is actually download the datasheet for LM338. There is all you need to know. Besides that the output voltage is set by ((R5/R3)+1)*1.25