At 08:39 AM 5/9/2003 -0300, Eduardo Garcia wrote:
>  Well, I am using now a simple circuit. I have connected to the tip and
>ring
>   a diodes bridge to fix the positive and negative references.
>   For obtain the isolated signal corresponding to line presence have a 68K
>   resistor in a diode of a opto-isolator.

You need a larger resistor, like 10M, and a better opto with higher current
transfer ratio.

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