[Asterisk-Users] OLD PA system.

[Jerry Jones]

Unless you pruchae an exteral zone page adapter which accepts FXS  
coonections, use an ata with fxo connection

I have never had to 'add' loop current, although I have not used all  
fxo adapters. I can verify Adit and other channel bank fxo  
connections do not require any voltage, the just give the analog  
audio out


On Jun 12, 2006, at 9:24 AM, Bob Chiodini wrote:

> Thomas Kenyon wrote:
>> John Novack wrote:
>>
>>> Bob Chiodini wrote:
>>>
>>>
>>>> You might put 600 ohm/600 ohm matching transformer to isolate the
>>>> port and the amp.  Should also maintain loop current if needed.
>>>>
>>>> Bob...
>>>>
>>>>
>>> FXO ports do not  generate loop current, they detect loop current  
>>> from
>>> the Central office.
>>> Think of an FXO as  a controllable switch and matching transformer.
>>> An FXO port will give Asterisk/Zaptel a red alarm without loop
>>> current, so that probably won't work for a PA system that doesn't
>>> supply battery.
>>> What's wrong with using the (usually) unused sound card built into
>>> many machines?
>>>
>>> John Novack
>>>
>> Mostly it uses the wrong impedance, and I know I can probably get an
>> impedance matching transformer, but I'm not allowed to spend any  
>> money
>> that I don't need to.
>> (Otherwise I'd have replaced the amp in the first place with one that
>> didn't fall from the arc).
>>
>>
> Won't you still need to maintain the loop current to make the PAP2  
> look
> like the port is off-hook?  (FXS BTW)
>
> I would think the impedance matching xformer falls int the "need to"
> category.
>
> Bob...
>
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