component identification question

Discussion in 'General Electronics Chat' started by lokeycmos, Jan 8, 2013.

  1. lokeycmos

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  2. tracecom

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    I was wrong, so I deleted my stupid answer.
     
    Last edited: Jan 8, 2013
  3. bertus

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  5. lokeycmos

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  6. praondevou

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    According to WIKI the voltage on the telephone line "on-hook" is -50VDC and +90VAC superimposed on that -50V when it's ringing.

    90VAC --» 127Vp

    That would be 177V maximum voltage between ring and tip. So I would choose a transorb value not less than 200V, e.g. the 1.5KE220CA.

    The transorb is always connected to the phone line so it has to support these high voltages. Eventhough I don't know if it would be effective for every imaginable phone line voltage disturbance when S1 is closed (off-hook).
     
  7. lokeycmos

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    In the link you posted, what is the difference between "reverse standoff voltage" and "breakdown voltage min/max"? Also how much current is expected in a phone line?
     
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