To my knowledge clamping diodes are not standard on all i/o ports on the
PICs...  I believe they interfere with some applications.  ALWAYS chck
the data sheet.  I do remember using the internal diode on the A port of
a 16c84 for clamping rs-232 voltages, so I'm sure it's common, but I
don't think it is always the case.

-Adam

Darren King wrote:
>
> 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
> >