mehmet karakaya wrote:

"use LM317 adjustable power supply"

Won't work if you're downregulating from 5 V, as the old-skool 317 needs something like 3 V headroom above the output voltage in order to regulate.

The LM1117-3.3 (or izzit REG1117-3.3?) is a decent LDO but needs good decoupling at the input and output for stability.

I've been using these little Micrel MIC5202 low-noise LDOs. 5-pin SOT-23 like the TI parts someone mentioned and really pretty quiet. They do only 150 mA (the 1117 above does a lot more, I think 800 mA) so obviously it won't power a board full of fast-switching SRAMs.

-a