> how did you know that what I wanted was beyond the 555?

The 555 has two timing resistors and a cap, and normally charges the cap th=
rough both resistors, and discharges through one (or maybe the other way ar=
ound; it's been a while.)  For extremes of duty cycle, that isn't going to =
work; to get long delays you need a big cap, but to get short pulses, the r=
esistors for that big cap become impossibly small.


>>> Cost of 555:   50c
>>> Cost of PIC:    20c

Your vendor has excellent price on PICs (where?  Which?)  But is ripping yo=
u off for 555's.
Digikey says about $0.38 for a PIC10F, and about $0.10 for a 555 (in q100)
As someone else pointed out; things get more complicated when both your tri=
gger signal and your output need to be 12V, and you want 100mA=85

(That said, it seems like by now there should be a "timer generator" progra=
m where you feed in the details about the waveform you want, and it spits o=
ut microcontroller code that implements that.  No software design required.=
)  Especially if you're just talking about the sorts of waveforms a 555 can=
 generate.)

BillW


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