Mains Line voltage detection

[ZeleC]

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

 

[leotim]

You can use the attached circuit:

 

[stefano.delfiore]

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

if you need galvanic isolation you could use this circuit.

stefano

 

[ZeleC]

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.

 

[artem]

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 ).

 

[Davood Amerion]

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.

 

[stefano.delfiore]

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