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all in one cable tester

Discussion in 'General Electronics Discussion' started by bungouk, Jan 10, 2012.

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  1. bungouk

    bungouk

    6
    0
    Jan 10, 2012
    Hi all

    I'm new to this forum and electronics, Does anybody know hoe to make a cable tester all d-sub cables like 25 way socket to socket or socket to plug. I would like to be able to test from 9,15 way and 25 way.
    Also i would like to be able to test LAN cables with this tester and COAX cables like BNC or N-type connectors.

    Regards

    Bungouk
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,713
    2,719
    Nov 17, 2011
    Although this may technically be possible, I don't think the effort for building such a universal tester is justifiable.

    The tester would need 2 plugs of each type to test end-to-end (or 1 plug for the tester plus a second loopback connecter for the loose end of the cable which again makes 2 connectors in sum). Since the socket only defines the mechanical pinout, the tester would need some means for setting up the expected cable configuration:
    - not all pins of the connector may be used (think 3-wire RS232 on 9-pin SDUB)
    - wires may be crossed from end-to end (think null modem)
    - wires may be shorted on purpose (e.g. RTS CTS in a modem cable)
    ...

    Plus: which properties of the cable need to be tested? Is it just correct wiring (conductance) of the cable? Is it impedance (as would be useful for BNC-connected coaxial cables)? Is it crosstalk (as would be useful for LAN cables)?

    My suggestion is: get a decent cable tester for each type of cable/requirement.

    Regards,
    Harald
     
  3. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
    Hi,

    here enclosed my favorite KISS cable tester scheme published by EDN.

    Olivier
     

    Attached Files:

  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,499
    2,839
    Jan 21, 2010
    Here is another method.

    There is a way to do this without the extra buffers so that each non-driven output becomes an effective earth return. It allows you to test cables with any (well at least up to 10) number of connections.

    I should try to dig it out... edit: here! (no reason you couldn't expand this with different ICs to test more pins).
     
    Last edited: Jan 10, 2012
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    11,713
    2,719
    Nov 17, 2011
    Nice circuit. It forgoes the problem of setting up the correct (expected) configuration of the tester for each cable under test at the cost of having to interpret the LED pattern with each test according to the expected reference pattern.

    Harald
     
  6. bungouk

    bungouk

    6
    0
    Jan 10, 2012
    Thanks for the links. I was now thinking of just making a continuity tester for just 25way d-sub connectors because they are the most common cables i have to make up where i work. Does anyone have any idea how just a 25 way d-sub tester could be made. could i use a 555 timer circuit or something else.
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    11,713
    2,719
    Nov 17, 2011
    Why would you use a timer?
    Why not use the circuit referenced by Olive? It's simple and does the job.
    For 25 wires you'd need 24 LEDs. Using red LEDs the supply voltage has to be at least 25*1.6 V = 40 V. If you don't have 40 V available, yolu can replace some or all but one LED by a short circuit in the mating connectors. Your possibilities of locating the fault position will then be limited, however.

    Harald
     
  8. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
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