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3.5 mm jack internal connections

Discussion in 'General Electronics Discussion' started by at89atbits, Sep 29, 2014.

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  1. at89atbits

    at89atbits

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    Sep 20, 2014
    What are the internal connections of a typical 3.5 mm jack supposed to be?

    3.5mm jack.jpg

    Like where are we supposed to connect these pins?
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Stereo jacks (2.5 mm, 3.5 mm and 1/4") have three conductors: tip (at the end of the plug), ring, and sleeve (body). These connectors are therefore called tip-ring-sleeve or TRS connectors.

    When they are used for audio applications, the tip is the left channel audio, the ring is the right channel audio, and the sleeve is the common, return, or 0V connection.

    If that doesn't answer your question, you'll need to explain what you're asking.
     
  3. at89atbits

    at89atbits

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    Sep 20, 2014
    I am designing the circuit for taking ECG signal via audio jack
    and then processing the signal
    So when i design the PCB layout for the circuit, i'll use the footprint of the audio 3.5 mm jack for this

    So i am confused as to how are the connections around this jack to be made..
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    That's still very vague.

    The connections should be made with copper tracks.

    If you're asking which pin of the jack socket connects to which contact, that information should be in the data sheet fo the jack socket. If you can't find it, post a link to the data sheet and I'll have a look at it.

    If you're asking which signal will come in on which contact, then you need documentation on the device that will be plugged into it.

    If that doesn't answer your questions then you need to explain your question better.
     
  5. at89atbits

    at89atbits

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    Sep 20, 2014
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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  7. davenn

    davenn Moderator

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    Sep 5, 2009
    OK so they are all mono sockets do you really want a mono or do you want a stereo as you hinted at earlier ??
    oops I didn't scroll far enough ;)

    do you want the smaller or larger style ?

    did you think of using your multimeter in continuity mode to find out which pin is which ?
    Plug in a plug to the socket and from one connection on the plug and see where it goes on the socket



    Dave
     
    Last edited: Sep 29, 2014
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    The stereo ones are on the second page.
     
  9. davenn

    davenn Moderator

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    yeah I saws that and edited ;)
     
  10. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Right. That was going to be my next suggestion... assuming he actually has a socket in his hands. If he doesn't, I guess a careful web search would be appropriate, for that specific part number first. (There seem to be two numbers associated with each part.) If he can find a clear enough photo he may be able to make out the arrangement of the contacts inside under the transparent cover. Also there may be other compatible sockets made by other manufacturers; he could lay out the board assuming they would be the same, and add some positions for track cuts and solder blobs to swap the tip and ring connections over if necessary.

    at89atbits you haven't given us much information to work from.
     
  11. at89atbits

    at89atbits

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    Sep 20, 2014
    Sir,
    I have to take the input from the audio jack and provide it to the inverting and non inverting inputs of an amplifier
    So I am unsure which of the TRS to be connected to where
     
  12. davenn

    davenn Moderator

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    so did you do as I suggested and meter it out ?
    you would have you answer in a couple of minutes :)

    Dave
     
  13. at89atbits

    at89atbits

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    Sep 20, 2014
    Can you please explain more about the test that you suggested
     
  14. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Please answer these questions.

    1. What is the part number of the jack socket you intend to use?
    2. Do you have one of these in your possession? Or do you just have a data sheet?
    3. Do you have a stereo jack plug to suit that socket? And do you have a multimeter?
     
  15. at89atbits

    at89atbits

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    Sep 20, 2014
    i found the mistake i was doing in the interpretation.
    Thank you so much for the help :)
     
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