[time-nuts] Simple AC mains zero-cross detector

[ed breya]

Actually, the core saturation depends on how much voltage is applied 
at a given frequency. Most power transformers are run partly into 
saturation at rated line, to get the most from the copper and iron 
available, in exchange for heat and less efficiency. The magnetizing 
current and losses will occur even with no load. The resistive loss 
will go up more with load. But, I don't think this matters in this 
application anyway.

Ed