[sci.electronics] Interfacing a phone - need small schematic

jjoshua@topaz.rutgers.edu (Jon Joshua) (04/12/90)

I am building a hardware/software project for the MAC and I need some
help with the hardware part.

I need a small interface that hooks into a phone line and the Mac's
RS422 serial port.  When a phone is off-hook the interface should
raise the signal on the handshake line.  When the phone goes back
on-hook the interface should clear the signal.

From what I understand RS422 uses -1 and +1 and not 0 and 1 values.
Is this correct?


Thanks for any help.


JOn.
-- 
                        /\                    ?               ________________ 
jjoshua@topaz.rutgers.edu \  ____   __       fgu             |.signature under|
 Anything is possible...   \ |  |  / |     orywlut-          |  construction  |
                            ==========    gfgsdfsdfsd        |________________|
_____________________________OO_____O___hfdhksjdhfksjdfs_______||__________||__