> Chis,
>
> > The best way to unexpectedly kill a PIC through I/O that I have seen,
> > although I have not been stupid enough to try it myself - is to attempt
to
> > implement the MC ap note on triac control, where it suggests (and shows
a
> > drawing of) connecting the AC line directly to I/O for zero-cross
> > detection - relying on the pin's internal protection diodes.
>
> > That was just a ridculous idea to try and implement.
>
> I can see no problem with this, as long as the series resistor
> is large enough to limit the maximum current to the manufactures
> specification.

This is what I like to refer to as TV set engineering.  ;-D  (ducking for
cover now)  IMHO, TV set design and antenna theory (vs. reality) are
indistinguishable from black magic.  I tend to eventually "let the smoke
out" of TV's when I try to tinker with them.  So now I stick with moderately
low-voltage (120V or less) equipment with somewhat understandable
schematics.  You know.....not like TV's.  ;-)  I respect the ability of
people to connect high-voltage directly to pic by not exceeding the current
limits, but it still seems a little risky to me.  I tend to expect that
touching a pin on an IC is not going to shock me.  That hot chassis stuff
'gets' me every time.  ;-D

michael

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