> *>But I've used a 1uF capacitor in RM's circuit - which blinks at about 1-5 > *>Hz. This is my frequency isn't it? > > Not quite. If you refer to the core, it has to do with the switching > frequency, not with the blink frequency. I hope that I understood what you > asked ... > > Peter I think I'm wondering whether the two frequencies are the same. I went back and reread RMs comments (http://www.piclist.com/postbot.asp?id=piclist\2001\09\27\023449a ) and found the following: "When C is made large (say 1 uF range) the frequency of operation will be so low that individual output pulses will be individually distinguishable.". That says they're the same doesn't it? DS -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.