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Modular connector snafu

Discussion in 'Electronic Design' started by Oppie, Dec 6, 2012.

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  1. Oppie

    Oppie Guest

    Is there any standard for modular phone connectors? I suspect not since was
    looking up the 4p4c headset jack (referred to as RJ9, RJ10 and RJ22), I
    don't recall that any of the manufacturers indicated pin numbers. Of course,
    it also is complicated by whether the connecting cable is 1:1 or cross-over.
    RJ11 is often confused as it is wider and though has also 4 circuits
    connected, is actually spaced for 6 circuits.

    Was connecting up a demo board this morning that used the 4p4c modular
    connector for the CAN bus. Cannibalized a connector and cord from an old
    telset. Became a smoke generator inadvertently. Luckily, no damage and all
    worked after I mirrored one of the sockets. The telco handset cord was
    cross-over type and luckily had enough impedance to get hot rather than
    killing anything else (5V and ground in it).
     
  2. These any help?

    http://en.wikipedia.org/wiki/4P4C#4P4C

    "However, if the wire pair for the handset transducer and the wire
    pair for the handset microphone are each wired in a crossover
    arrangement, then both the transducer and microphone will function
    correctly; even if the handset has an electret microphone. Most
    telephone handset cords (cable assemblies) are wired this way."

    As the Wiki article points out, the handset connectors have nothing to
    do (directly) with the PSTN so they are not registered.

    http://www.belfuse.com/Data/UploadedFiles/MN300018.pdf
     
  3. Also, you can just look into the ends of the clear polycarbonate
    plugs- you can see the wire color codes.

    As Jeff points out, the tools are available from all sorts of places
    and can be very inexpensive (starting at under $10, up to a few
    hundred or more for production hand tools).

    Modular jacks are great- cheap, pretty reliable, positive retention,
    built in strain relief, easily and cheaply field-terminated. Too bad
    the female connectors are so enormous.
     
  4. Oppie

    Oppie Guest

    Thank you Jeff and Spehro for your input.
     
  5. Nico Coesel

    Nico Coesel Guest

    And yet Motorola had the numbering reversed on all their radio
    communication equipment.
     
  6. josephkk

    josephkk Guest


    Check out TIA-561

    also:

    http://www.dcbnet.com/notes/eia561.html

    There it is.

    ?-)
     
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