I believe that you are correct in your deductions.  I did not read the app
note close enough to see they stated that the diodes on the port were
internal - I THINK (therefore I am not sure) this is common for cmos parts.

David V. Fansler
Network Administrator
TriPath Imaging, Inc. (Formerly AutoCyte, Inc)
336-222-9707 Ext. 261
dfansler@autocyte.com <mailto:dfansler@autocyte.com>
Now Showing! www.mindspring.com/~dfansler
<http://www.mindspring.com/~dfansler>   Updated September 23, 1999


                -----Original Message-----
                From:   Darren King [mailto:darren.king@SYMPATICO.CA]
                Sent:   Wednesday, December 08, 1999 4:56 PM
                To:     PICLIST@MITVMA.MIT.EDU
                Subject:        Re: Microchip Appnote Dimmer Problem.

                Hmm..  OK this is what I thought kind of.  I was confused by
the White
                (return) after the triac.  However I guess thats pretty
simple it just goes
                back to the WHITE on JP2 and the only reason for that is
that the Vcc
                Circuit requires it to produce the +5V for the MCU to run.

                Sound right?

                The diode network that this appnote talks about inside the
12C508 that
                protects it from the large AC Current which gives it
Vdd+0.7v that kind of
                thing.  Does this exist in all PicMicros?

                Darren King

                ----- Original Message -----
                From: Fansler, David <DFANSLER@AUTOCYTE.COM>
                To: <PICLIST@MITVMA.MIT.EDU>
                Sent: Wednesday, December 08, 1999 10:06 AM
                Subject: Re: Microchip Appnote Dimmer Problem.


                > Darren - I do not pretend to be an expert - but here is
what I see.
                >     1.  The schematic does not totally match the article
                >     2.  The load would go between Hot Out and Hot In.
                >     3.  You would supply a Neutral (white wire) to Return.
                >     4.  You would supply Hot (balck wirefrom power
company) to Hot In
                >     5.  Ground (green) is a good idea.  It can be tied to
Neutral (which
                is
                > done in US breaker boxes).
                >     6.  Vcc is generated by the circuit above the PIC
(RV1, R1,2, C1-3,
                > D1-3)
                >     7.  I would take JP1 to be an external input to allow
control of the
                > circuit by an outside source (another PIC, automation
system, etc.)
                >     8.  While simple, a fair warning is given in the
article that this
                > circuit has no isolation from the AC main and therefore
can bite you!
                >     9.  If used for lighting purposes, this circuit will
produce filament
                > hum at low light levels (larger filaments hum more)  A
large choke in line
                > with the load will kill the hum.
                >
                > David
                >
                > -----Original Message-----
                > From: Darren King [mailto:darren.king@SYMPATICO.CA]
                > Sent: Wednesday, December 08, 1999 2:44 PM
                > To: PICLIST@MITVMA.MIT.EDU
                > Subject: Microchip Appnote Dimmer Problem.
                >
                >
                >
http://www.microchip.com/Download/Appnote/Category/rDesigns/40171a.pdf
                >
<http://www.microchip.com/Download/Appnote/Category/rDesigns/40171a.pdf>
                >
                > I have looked at the above 100 times and I'm still
confused.  I don't
                really
                > want to build this circuit without understanding it.  I
really hope
                somebody
                > could help with this one.  I'm not familar with the Hot in
- Hot
                Out -Return
                > (White).  When I see White I know what that means.  So
which of the hot in
                > and hot out is  supposed to be the black?  Is the green
wire used?  Does
                the
                > load hook up between the Hot Out and the Return?  What is
Vcc supposed to
                > be?  Is this where I hook up the load?  What is RV1?  As
you can seem I'm
                > not an electronics wiz, but understanding this would help
out greatly.  As
                > you can read, I'm really lost.
                >
                > Darren King
                >