Two 555s in one package.... Note that CMOS versiions exist. http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=3Dlm= 556&fileType=3Dpdf There's a vast literature on 555 apps - A little googling will turn up much of interest. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .