[Asterisk-Users] Ring Voltage Supplied by Wildcard TDM400P REV E/F& AUTO FXS/DPO

[Rich Adamson]

> > I'm trying to connect a TDM400P with an FXS module to a Valcom V-9940
> > Paging adaptor. This port on the TDM400P was connected to a 2500 Set
> > and was working I just re-connected it to the Valcom (which
> > is known to
> > work on a Telco POTS line) and its not picking up.  The
> > Valcom docs say
> > it need a minimum of 75 Volts at 20-30 Hz to recognize a
> > call... So the
> > question is what ring voltage does the FXS modules on a TDM400P put
> > out? 
> 
> Ultimately, that depends on how much current is being drawn, but my
> multimeter reports about 70V on a 6 foot line cord. Generally, I'd
> expect an FXS to put out more like 90-110V (that's what my TalkSwitch
> supplies).

According to the Silicon Labs spec sheet, the 3210 chip can supply
"ringing signals of up to 88v peak or more, enabling the ProSLIC
to drive a 5 REN ringer load across loop lengths of 2000 feet or
more."

The multimeter will be measuring rms voltage, not peak.