I need to monitor 480vac 3 phase by using SFH628A-4 (Nglect PC817D) so i have one phase(L1) and another phase L2, if i did use this my output will be DC or will be ac with 120HZ
in this circuit , i need output of opto high as long i have the 2 phases but when i lose one phase it will be high
in case of i have 2 phases , is the output will be dc?

 

Why not just use a small bridge rectifier across the two phases with appropriate resistors for the opto?
Max..

 

Why not just use a small bridge rectifier across the two phases with appropriate resistors for the opto?
Max..

Thanks Max , so if i use bridge and capacitor after the bridge i will fix the issues of turning on and off of the opto(120hz)?

 

To eliminate the ripple, use a capacitor after the bridge.
Max.