>         Uhm, lets see, you are using a PIC computing device to fire a
triac
> at zero crossing but can't put a delay/advance on top of the zero crossing
> you detect to get the firing exactly at the zero crossing.  Are you sure
you
> understand what PICs do?

    I am quite sure I understand what PIC's do. I have been working with
microprocessors for more than 15 years :-) What I meant is that the
detection would not be exactly at the zero crossing because you would always
have some difference induced by inductive loads and noise. I guess it would
happen in any one of the circuits. That could not be compensated in software
because it would not be constant.

>         There are things out there called logic level triacs that only
need
> a small resistor between the PIC and the triac.  But you think they are
too
> small (bet you that some company out there is making just what you want),
so
> you need to use a resistor and a transistor to switch about 10V to gate a
> power triac.

    The problem with logic level triacs is the price. They are nice for a
hobby project but not for production where price is a major problem.


>         What happens if I am using 220v
>         with 2 phases instead of a phase and a neutral connection ?
>
>         Nothing - just treat both lines as active to earth and insulate
> accordingly

    I do not have a earth connection !!! Is is not mandatory to have earth
connections in houses installations in Brazil !! The outlet output may have
just 2 connections with 2 power phases. I hate it but it is true.

>         My power supply
>         will be a capacitor coupled supply, without a transformer.
>
>         Now you could have problems if the power supply is drawn from a
> different pair in the 3 phase cable (like 225V instead of 5V).

     That is not going to be the problem. It is going to be connected to the
same phases of the load always.

Thanks for the fast answer.

Best regards,
Alexandre Guimaraes
alexg@iis.com.br