Use a MOC xxx device.
I can't remember the exact reference : it is a opto-triac (DIL 6 pins)
synchronized with the main:
-> That makes a perfect isolation from the main and not much EMC since
it opens and close when the main go to 0 volt.

Hope this helps

Jean-Yves

>----------
>De :   WILLIE W. HO[SMTP:mtl@pub.zhongshan.gd.cn]
>RŽpondre ˆ :       WILLIE W. HO
>Date : mardi 4 mai 1999 06:13
>A :    PICLIST@mitvma.mit.edu
>Objet :        TRIACS FIRING
>
>Hello,
>
>I'm using 12C508 to control a heating device, anyone can tell me how to
>firing a triacs to control the heating device on/off.
>
>Best Rgds,
>
>Willie W. HO
>