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RE: [tracker2] Power From Laptop

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  • Fred Hillhouse
    100mA is usually no problem and possibly up to 400mA. But there is no guarantee above 100mA. _____ From: tracker2@yahoogroups.com
    Message 1 of 9 , Feb 2, 2009
      100mA is usually no problem and possibly up to 400mA. But there is no guarantee above 100mA.
       


      From: tracker2@yahoogroups.com [mailto:tracker2@yahoogroups.com] On Behalf Of Tyson S.
      Sent: Monday, February 02, 2009 13:58
      To: tracker2@yahoogroups.com
      Subject: Re: [tracker2] Power From Laptop

      You can try the USB, I think it's 5 Volts. They make coffee cup warmers powered by them.


      From: Scott Miller <scott@opentrac. org>
      To: tracker2@yahoogroup s.com
      Sent: Monday, February 2, 2009 10:43:38 AM
      Subject: Re: [tracker2] Power From Laptop

      Nope, not to any useful degree. You can sometimes steal a few mA, but
      that's about it.

      Scott

      Adam Sherman wrote:
      >
      >
      > Is it possible to get power via the serial port on a laptop?
      >
      > Thanks,
      >
      > A.
      >
      > --
      > Adam Sherman
      > me@... <mailto:me%40va3shr .ca>
      > VA3SHR
      >
      >


    • Wes Johnston, AI4PX
      If I recall correctly, the rs232 spec says there is a 300ohm resistor in series with each output pin. It s a current limiter by default. Should give about
      Message 2 of 9 , Feb 2, 2009
        If I recall correctly, the rs232 spec says there is a 300ohm resistor in series with each output pin.  It's a current limiter by default.    Should give about 40mA.   Very often, you can rewire an output pin to put 12v on it... the good news is that +/-12v is safe on rs232 due to a 3k ohm input impedance on any device you would plug in... so it won't fry your TNC or serial mouse. 
         
        I have to agree with another poster... safer bet is to leech power from USB.
         
        Wes

        On Mon, Feb 2, 2009 at 1:39 PM, Adam Sherman <adam@...> wrote:

        Is it possible to get power via the serial port on a laptop?

        Thanks,

        A.

        --
        Adam Sherman
        me@...
        VA3SHR




        --
        Wes
        ---
        You can't get rid of poverty by giving people money.

        It may be necessary temporarily to accept a lesser evil, but one must never label a necessary evil as good.
      • Jason KG4WSV
        ... The USB spec says any peripheral gets 100mA by default. Up to 500mA may be available, but it requires some negotiation to get more than 100mA. In reality,
        Message 3 of 9 , Feb 2, 2009
          On Mon, Feb 2, 2009 at 1:30 PM, Fred Hillhouse <fmhillhouse@...> wrote:
          > 100mA is usually no problem and possibly up to 400mA. But there is no
          > guarantee above 100mA.

          The USB spec says any peripheral gets 100mA by default. Up to 500mA
          may be available, but it requires some negotiation to get more than
          100mA.

          In reality, I think some ports just give you 500mA.

          -Jason
          kg4wsv
        • Adam Sherman
          ... Thanks for the overwhelming amount of replies! The end conclusion is that a serial-USB adapter than would power the Tracker should be possible. I m going
          Message 4 of 9 , Feb 2, 2009
            On 2-Feb-09, at 13:39 , Adam Sherman wrote:
            > Is it possible to get power via the serial port on a laptop?


            Thanks for the overwhelming amount of replies!

            The end conclusion is that a serial-USB adapter than would power the
            Tracker should be possible. I'm going to investigate.

            A.

            --
            Adam Sherman
            me@...
            VA3SHR
          • P. Suryono Adisoemarta
              I made a pigtail on the null-modem cable for OT+, with a short cable to plug to the USB port of the laptop, to tap the 5V line (leftmost pin) and deliver
            Message 5 of 9 , Feb 3, 2009
               
              I made a pigtail on the null-modem cable for OT+, with a short cable to plug to the USB port of the laptop, to tap the 5V line (leftmost pin) and deliver it to Pin 4 on the DB9 to OT1 series (or OT2m).
              73 de Paulus N5SNN / YD0NXX
               

              --- On Mon, 2/2/09, Adam Sherman <adam@...> wrote:
              From: Adam Sherman <adam@...>
              Subject: [tracker2] Power From Laptop
              To: tracker2@yahoogroups.com
              Date: Monday, February 2, 2009, 12:39 PM

              Is it possible to get power via the serial port on a laptop?
              
              Thanks,
              
              A.
              
              -- 
              Adam Sherman
              me@...
              VA3SHR
              
              
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