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zerocross detect with H11AA1X

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dkn

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Hi.

I am using the H11AA1X optocoupler to detect zerocrossing. This is working fine, however the resistors to limit the current gets pretty hot.
I am running 230v ac and im not up for a transformer.
The resistors I use are 2 x 22k 1watts.

So any better values or ideas ?

Thank you very much for your time.

// Dennis
 

Denis,

You can use a capacitor of 100nF 400V to limit the current (it's similar to 33Kohm resistor) without power disipated.
But, the problem is that the capacitor will change the phase 90°. You must know that and correct then.
 

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    dkn

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you can use instead or resisor a current generator; the simple way is a deppletion n mosfet with a resistor.

//a
 

Hi thanks for the replies.

penrico ->
Well the condensator is ofcause a way to solve it, but I am a little unsure if the phase degree is easy enough to solve in software.

Right now I opped my resistors to 47k each, I still get the detection, and so little amps are drawn now. So it seems to be okay.


aNdreiBuuu->
Sound very interesting, would you mind telling more about this method?
 

okok

check this: **broken link removed**
in fig1 set the R1 resistor at 2K and replace the measurment instrument with your optocoupler diode!

Have Phun!

Regards,
//a
 

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    dkn

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aNdreiBuu->

Thank you very much for the clarifacation, its a really nice circuit. And it will super usefull in some future projects.
 

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