>
> To save the troubles of zero crossing detection just use a opto-coupler
> with zero-crossing detection built in. Toshiba make some that are
> surprisingly cheap.

I know. I just happen to have all the MOC3010's I need for this project.
And as the app note points out all that's really needed is a single
high valued resistor. Now Tech Brief 008 on the web site points out
that the best way to be sure that you don't slag anything is to fuse the
ground and neutral lines together. That way if you get an incorrectly
wired socket such that hot is on the wrong line, then the fuse will
immediately blow saving both the house circuitry and the project.

> The one I have used is a TLP3063 (this is more or less an industry standard
> number).
> It will directly fire a TRIAC.
> If you don't need to turn on for less than one half cycle then this is the
> easy way.
> You could then easily run your project off a battery as the opto-coupler
> only needs about 5mA.

Power was never ever the issue. It was gravy to learn how to design and
use transformerless power supplies.

BAJ
>
> This has turned out to be a long interesting thread...

Most definitely.

BAJ