Re: gEDA-user: OFF: triac

[Bill Sloman <bill.sloman@xxxxxxxxx>]

At 12:07 28-2-2006, you wrote:
> Leva wrote:
> > On Mon, 27 Feb 2006 18:32:32 -0500
> > DJ Delorie <dj@xxxxxxxxxxx> wrote:
> >
> > > Been there, done that.  http://www.delorie.com/house/furnace/
> > >
> > > The optos were MOC3011's, the alternacs (like triacs, but can handle
> > > inductive loads too) were digikey Q2015L6-ND's.
> > That is what I am looking for! I decided to use the MOC3063, 
> > becouse I'd like to run it from 230VAC mains.
>
> This does not make much sense to me.
> As I understand it a zero crossing opto turns on just after the 
> start of a cycle. Like a good solid state relay.   Your previous 
> mail said you want to modulate power, which assumes you are not 
> switching at zero crossing, but later.  Which do you want?

You've got two options when using triacs to control power - you 
either turn the triac on for a controllable proportion of each half 
cycle of the mains, or you turn the triac on at zero-crossing for 
some half  cycles of the mains, giving you a variable number of 
complete half-cycles. Microchip's application note spells it out.

http://ww1.microchip.com/downloads/en/appnotes/00958a.pdf

The obvious disadvantage of zero-crossing control - the rather coarse 
increments in power available over short periods of time - has to be 
balanced against the much lower electromagnetic noise generated by 
zero-crossing switching.

Bill Sloman, Nijmegen