At 08:13 PM 12/15/2013, Al Shinn wrote: >I may be wrong but it seems that to get 10 uSec and 1 Sec you need=20 >10megohm for R1, 100 ohms for R2 and .15uFd, >But I guess that gives the wrong duty cycle (1 sec on, 10 uSec off,=20 >so you would need to rig a 1 transistor inverter from the output. > >Since no one has mentioned this approach, I suspect I may be wrong.=20 >Input welcome. It would be instructive for you to actually try it. You *may* be *somewhat* successful *if* you use a CMOS version of the=20 555 timer (TLC555) but using 10M resistors with the standard bipolar=20 555 timer is pretty much out of the question. Trying what you suggested was one of my early lessons on the=20 importance of paying attention to that little term in the data=20 sheets: Input Bias Current. dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=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 .