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Basic questions about the pins of a cable

Discussion in 'General Electronics Discussion' started by Henol, Jul 8, 2010.

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  1. Henol


    Jul 8, 2010
    Hello everyone,

    First of all, I'm sorry for any mistake I may make, I'm not English.
    I've also never worked in electronics.

    Here is my situation: I've been told to power a particular device and to transmit its signal to a BNC, without any more information. After some research, I found that I'm gonna have to deal with a 9pin cable. I found two diagrams of this cable:

    Firt diagram:
    Pwr Rtn
    Pwr Rtn
    Sig -
    Sig +

    Second diagram:
    Sig -
    Sig +

    Here are a few questions, but feel free to give any advice for newbe:

    1) Shield, Power Rtn (Return?), Lock-, and ground all have to be grounded, have they not? Why are they called differently ?

    2) How to transmit the signal to a BNC ?
    Sig- for the outside of the BNC, Sig + for the inside ? Or should I ground the outside and transmit only sig+ to the inside, and don't use sig- ?

    3) What's Press+/Lock+ ? What do I have to do with that ?

    I will perhaps think about other questions later;

    Thank you for your help!!
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Without knowing what the device is, it is very hard to answer your question. Even knowing what the device is, we may still not be able to answer.

    There is no easy way of knowing what signal is on the coaxial cable (the one with the BNC connector)
  3. Henol


    Jul 8, 2010
    Sorry I may have not been clear enough.

    So the device is a seismometer. A cable is connected at one end to this seismometer.
    I have to create a box to which the second end of the cable will be connected.

    This box has to provide power. We will also have to be able to connect a BNC cable to this box in order to see the signal on a scope.

    Regarding the BNC : In other terms, I have a 9 pin cable as described, and I want to take the signal and put it in a BNC cable. For the moment, the BNC cable is not connected.

    To sum up, I have to understand what are 9 pins of the cable in order to wire the box the cable will be connected to.
  4. davenn

    davenn Moderator

    Sep 5, 2009
    OK thats better :) and something that I play with ... Gotta love seismology
    my original home land is New Zealand and they dont call them the "Shakey Isles" for nothing haha

    now as far as your seismometer goes ... what type is it ? a geophone, a Lehman style ? something totally different ? show us a pic of it
    MOST seismometers only have a 2 wire cable connection and the use of a screened lead like coax is common practice to cut down external electrical interference.
    I assume the signal from the seismometer is either going straight into an oscilloscope
    for easy viewing ? since you mentioned a scope
    I have used 2 different systems an analog one where the signal with into a high gain (>2000) preamp before driving an ink pen system.
    the other was a digital recorder where the output of the preamplifier was inputted into an analog to digital converter and then on to the computer.

    what are you wanting to do with the signal from the seismometer? do you want to digitise it ? do you already have a digitiser .... ie. an analog to digital converter board (ADC board) ?

    tell us a bit more about the bits you have and we can go from there :)

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