Loading ...
Sorry, an error occurred while loading the content.

GPS & Aux 232 port

Expand Messages
  • Mark Huffman
    When using the Garmin GPS 18LVC on the aux232 port of the TNC-X, do I have to provide an external power to the GPS reciever or can I use the middle connection
    Message 1 of 2 , Jun 7 9:03 AM
    • 0 Attachment
      When using the Garmin GPS 18LVC on the aux232 port of the TNC-X, do I
      have to provide an external power to the GPS reciever or can I use the
      middle connection of the jack, which is connected to pin 14 of the
      max232a chip. I am going to probably answer my own question, but it
      looks like I will have to provide an external power source for the GPS,
      because the pin 11 on the max232a is the input for pin 14, but I want
      to make sure I am correct.

      My TNC-X has the Xtracker board installed.

      Any help would be appreciated.

      Mark N5OTD
    • John Hansen
      External power would work well. Here s another option. I m not sure what the current drain of a Garmin 18LVC is, but my guess is that if you tried to draw
      Message 2 of 2 , Jun 8 7:35 AM
      • 0 Attachment
        External power would work well. Here's another option. I'm not sure
        what the current drain of a Garmin 18LVC is, but my guess is that if you
        tried to draw current from the TNC-X, it would overwhelm the 78L05
        regulator. However, I designed the PC Board for TNC-X so it could
        accommodate a 7805 regulator instead of a 78L05. Then you would be able
        to use it to supply up to 1 amp (it might require a heatsink, though).
        So if you wanted to, you could disconnect the unused pin from the AUX232
        phone jack and connect it instead to any convenient +5 volt source on
        the TNC-X. You could then draw the GPS power from the TNC-X power
        supply. However, you should look up the docs on the GPS to check it's
        current requirements before doing this.

        John Hansen W2FS
        Coastal ChipWorks

        Mark Huffman wrote:
        >
        > When using the Garmin GPS 18LVC on the aux232 port of the TNC-X, do I
        > have to provide an external power to the GPS reciever or can I use the
        > middle connection of the jack, which is connected to pin 14 of the
        > max232a chip. I am going to probably answer my own question, but it
        > looks like I will have to provide an external power source for the GPS,
        > because the pin 11 on the max232a is the input for pin 14, but I want
        > to make sure I am correct.
        >
        > My TNC-X has the Xtracker board installed.
        >
        > Any help would be appreciated.
        >
        > Mark N5OTD
        >
        >
      Your message has been successfully submitted and would be delivered to recipients shortly.