Michael Welter wrote: > Jason A. Pattie wrote: >> Robert Hajime Lanning wrote: >> >>> Echo echo ech ech ec ec e e . . >>> >>> :) >>> >>> <quote who="[EMAIL PROTECTED]"> >>> >>>> What's the importance of the impedance matching in a FXO interface >>>> ? >> >> >> > My experience is with excessive buzz and hum on the line. When I > plug a vintage Western Electric phone into the line, there is no buzz > or hum because the phone has its own impedance matching circuitry. > When I plug my AT&T 954 set into the line, I hear a lot of hum. I'm > told the X100P does not have impedance matching. > > Rich Adamson is the fellow to talk with about impedance. Apparently > the hum on my lines is caused by a partial ground on either the tip > or ring (or both) wire. If both leads have the same resistance to > ground (matched) then there is no hum. > > I don't experience echo with the buzz and hum. I've been told that > echo is caused when the circuit goes from four wire to two wire. > > I'm trying to locate a schematic of an impedance matching circuit so I > can breadboard a device but haven't found one so far. I anyone has > experience with this I invite him to reply. > > Mike
If you KNOW the impedances of the two lines, a simple impedance matching transformer available at any electronics distributer (Mouser, Digi-Key, etc) carries many differdnt types, that are just for this purpose. Nik _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
