Mains Line voltage detection

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ZeleC

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Hi
I want to build a small interface circuit that detects the presence of a the mains 230V AC,I want to feed the signal to a uC (0 =no line voltage, 1 line voltage present)
I have a couple of ideas just want to c yours
thanks
 

You can use the attached circuit:
 

ZeleC said:
Hi
I want to build a small interface circuit that detects the presence of a the mains 230V AC,I want to feed the signal to a uC (0 =no line voltage, 1 line voltage present)
I have a couple of ideas just want to c yours
thanks
Click to expand...

if you need galvanic isolation you could use this circuit.

stefano
 

it seems that these circuits will give a square wave image of the AC line ??
well Im looking for a logic 1 for presence and logic 0 absence.
 
ZeleC - the possibitlies are infinite (c) :
Put another capacitor parallel to R3 in second schematics, increase R3 value and and choose newly inserted capacitor value as R3 (Ohm) * Cnew (Farad) = Seconds delay before mains disappeared (rough estimation ).
 

ZeleC,
output of stefano.delfiore's circuit isnt square wave!
if you check optocoupler you see that it use 2 LED and each LED light in one half cycle.
I think you can use this circuit.
if any pulse appeared in output, increase C1 value to 1uF or 2.2uF.

Regards,
Davood.
 


to whom it may interest, I acquired by oscilloscope some waveforms from the circuit that I have posted.

stefano
 

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