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

[ed breya]

It seems to me that a low voltage secondary should be OK by using a 
fast comparator IC rather than a transistor to decide - the gain of 
the IC allows for much smaller detection levels, so the equivalent 
zero-crossing velocity could be the same. An IC tripping in a 10 mV 
band should provide the same effective ZC velocity at 12 V input as a 
transistor working around 100 mV with 120 V input. Or am I missing something?

Ed