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GPS power control

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  • scott@opentrac.org
    I think I m going to do a small run of another board revision to test out a few ideas, including the motion sensor. I m also looking at adding another switch
    Message 1 of 5 , Oct 9, 2006
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      I think I'm going to do a small run of another board revision to test out a
      few ideas, including the motion sensor. I'm also looking at adding another
      switch to control power to the GPS receiver. Another VN820 would be
      overkill, though - it shouldn't really have to drive more than about 100 mA.
      I'm thinking a PNP transistor as a high side switch might do it. Some of
      the MCU I/O pins can sink up to 25 mA, should be fine even with a low Hfe.

      Hmm.. maybe that's not such a good idea if there's a possibility that it
      might need to switch 12 volts for GPS power. But then, maybe it's not worth
      supporting 12 volt GPS power control anyway. Getting a little too tired
      tonight to think clearly on this.

      Suggestions?

      Scott
    • Wes Johnston, AI4PX
      I think many folks would like 5v switched power for a GPS, but myself, since I smoked a tripmate years ago by hooking it to 12v accidentally, I always put a
      Message 2 of 5 , Oct 10, 2006
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        I think many folks would like 5v switched power for a GPS, but myself, since I smoked a tripmate years ago by hooking it to 12v accidentally, I always put a regulator into the GPS and run them on 12v.  Personally, I can see using the motion sensor to turn on the GPS and radio at the same time.  Only the most miserly power application would require powering on the GPS separate from the radio.  Of course this excludes applications where the high current switch is used in a balloon cutdown... but in that application you'd run the GPS all the time anyway.
         
        Another use I could think of for power control on a tracker would be either door locks or engine kill. 
         
        Wes

         
        On 10/10/06, scott@... <scott@...> wrote:

        I think I'm going to do a small run of another board revision to test out a
        few ideas, including the motion sensor. I'm also looking at adding another
        switch to control power to the GPS receiver. Another VN820 would be
        overkill, though - it shouldn't really have to drive more than about 100 mA.
        I'm thinking a PNP transistor as a high side switch might do it. Some of
        the MCU I/O pins can sink up to 25 mA, should be fine even with a low Hfe.

        Hmm.. maybe that's not such a good idea if there's a possibility that it
        might need to switch 12 volts for GPS power. But then, maybe it's not worth
        supporting 12 volt GPS power control anyway. Getting a little too tired
        tonight to think clearly on this.

        Suggestions?

        Scott


      • Wes Johnston, AI4PX
        Ohh, and also a high current switch to activate an ejection seat.... muhhh hahhh haaaaa haaaahhh!!!
        Message 3 of 5 , Oct 10, 2006
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          Ohh, and also a high current switch to activate an ejection seat.... muhhh hahhh haaaaa haaaahhh!!!

          On 10/10/06, Wes Johnston, AI4PX <wes@...> wrote:
          I think many folks would like 5v switched power for a GPS, but myself, since I smoked a tripmate years ago by hooking it to 12v accidentally, I always put a regulator into the GPS and run them on 12v.  Personally, I can see using the motion sensor to turn on the GPS and radio at the same time.  Only the most miserly power application would require powering on the GPS separate from the radio.  Of course this excludes applications where the high current switch is used in a balloon cutdown... but in that application you'd run the GPS all the time anyway.
           
          Another use I could think of for power control on a tracker would be either door locks or engine kill. 
           
          Wes

           
          On 10/10/06, scott@... < scott@...> wrote:

          I think I'm going to do a small run of another board revision to test out a
          few ideas, including the motion sensor. I'm also looking at adding another
          switch to control power to the GPS receiver. Another VN820 would be
          overkill, though - it shouldn't really have to drive more than about 100 mA.
          I'm thinking a PNP transistor as a high side switch might do it. Some of
          the MCU I/O pins can sink up to 25 mA, should be fine even with a low Hfe.

          Hmm.. maybe that's not such a good idea if there's a possibility that it
          might need to switch 12 volts for GPS power. But then, maybe it's not worth
          supporting 12 volt GPS power control anyway. Getting a little too tired
          tonight to think clearly on this.

          Suggestions?

          Scott



        • Curt, WE7U
          ... Ever see the anti-theft system which consisted of pipes right below the doors of the car on the outside with nozzles pointing up? If the alarm was
          Message 4 of 5 , Oct 11, 2006
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            On Tue, 10 Oct 2006, Wes Johnston, AI4PX wrote:

            > Ohh, and also a high current switch to activate an ejection seat.... muhhh
            > hahhh haaaaa haaaahhh!!!

            Ever see the anti-theft system which consisted of pipes right below
            the doors of the car on the outside with nozzles pointing up? If
            the alarm was triggered it instantly caused flames to shoot upwards
            on both sides of the car about 6 feet or so. I think that was in
            Africa. We can't do that here.

            But I digress... What was it Scott asked again?

            --
            Curt, WE7U. APRS Client Comparisons: http://www.eskimo.com/~archer
            "Lotto: A tax on people who are bad at math." -- unknown
            "Windows: Microsoft's tax on computer illiterates." -- WE7U
            "The world DOES revolve around me: I picked the coordinate system!"
          • Keri Morgret
            No, but I have seen (a website of) a street legal jet powered VW Beetle. http://www.ronpatrickstuff.com/ I know it s off topic, but this is the OT list, right?
            Message 5 of 5 , Oct 11, 2006
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              No, but I have seen (a website of) a street legal jet powered VW Beetle.

              http://www.ronpatrickstuff.com/

              I know it's off topic, but this is the OT list, right? :) And it does
              feel like a Friday.

              Hmm..maybe we could get this guy licensed and on APRS so we can see
              where he is and check out his car?

              N6TME

              >Ever see the anti-theft system which consisted of pipes right below
              >the doors of the car on the outside with nozzles pointing up? If
              >the alarm was triggered it instantly caused flames to shoot upwards
              >on both sides of the car about 6 feet or so. I think that was in
              >Africa. We can't do that here.
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