At 10:03 PM 12/17/97 -0500, Wynn Rostek wrote:
>For US POTS, if you add a series resistor (100 ohm max) in each line, and
>then place a pair of zeners (20-30 volt) across the line (both polarities)
>you can clip the ring signal at that phone so it will not ring.  It won't
>ever ring.
>
>----------/\/\/\--------|-------|--------
>                        |       |
>                       ___      V
>                        ^      ---
>                        |       |
>                        |       |
>---------/\/\/\--------------------------
>
>By cliping the ring voltage below 30 volts, you prevent the ring detect
>circuit from being activated.

Unfortunately, the circuit drawn here will clip the voltage down to about
0.7 volts.  You have forgotten that zeners still are normal diodes in the
forward direction....  Simply place the zeners in series instead of
parallel, and your circuit should work fine, however.

 - Rick "Go with the flow" Dickinson


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