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

Charles Steinmetz csteinmetz at yandex.com
Wed Dec 17 00:39:20 EST 2014

Dave wrote:

>I'm not trying to downplay the circuit in the link above, but I want 
>to offer another possible solution to Zero-Crossing needs.
>Here's an Idea For Design from EDN magazine that I've used a couple 
>times in non-time-nut circuits, and I must say that it works 
>beautifully.  I have no measurements that would satisfy a time-nut's 
>curiosity, so if someone wants to Spice it or otherwise tear it 
>apart, please do.

That one is not ideal for this task, because (i) its output pulse is 
symmetrical about the mains zero cross, and (ii) the hysteresis zone 
is not well characterized and will drift with temperature and input 
voltage.  So, there is no edge that is well characterized in relation 
to the AC mains zero cross.

Best regards,


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