[General] How To Detect AC 230V 50Hz supply using EL817 Optocoupler?? circuit please

[shaha2014]

hello friends i am designing a ckt which will detect presence of mains (230V ac) is it possible to desing using EL817 optocoupler?? what all components to be attached at input of optocoupler for safety?
can any1 show e a ckt for this??
at the output side i am going to use 8051 uC

 

[jayanth.devarayanadurga]

Drop down 230 V to say 5V and use a diode to convert this to DC. Now using a resistor in series connect it to input of opto. When AC is present opto output will keep 8051 pin high. If AC is absent then 8051 will sense low. Use External interrupt of 8051 to sense the presence.

 

[shaha2014]

will this ckt work??

R1=R2=22k 2 watt..

whether it will blow the optocoupler ??
please help...
because agin i will need transformer and rectifier ckt to covert 230V to 5v, i want to avoid it.

 

[Knife]

I used this circuit with PC817 opto before, it will solve your problem. I think it will work. But if any problem, only you need to change 1.5M resistor according your opto's LED current limits.

 

[paulfjujo]

hello,

will this ckt work??
R1=R2=22k 2 watt..
whether it will blow the optocoupler ??
please help... .

Reverse diode is usually not included into the photocoupler and must be added..
this could be work ...
without transform this output as DC average...

I suppose you will send the square 50Hz signal into a timer ,
with a timeout of 20mS to detect missing AC Power suplly

 

[alexan_e]

Do you want to be able to detect under voltage situations? If do then check https://www.edaboard.com/threads/272112/#post1166225

If just want to get pulses from the mains then you can use https://www.edaboard.com/threads/222774/#post948702

In either case calculate the input side resistance according to your application requirements.