Phone Line to USB Question

Discussion in 'General Electronics Chat' started by harutz, Mar 31, 2011.

  1. harutz

    Thread Starter New Member

    Mar 31, 2011
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    Hi.
    I am wondering about how to regulate normal (I realise it tends to vary) Phone Line current to normal USB current (say 5.5v or so) for a computer or PDA device.

    Can anybody pitch out an idea?

    I don't have much electronic background, it's just for theoretical ruminating mostly.

    Thanks!
     
  2. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Hello, harutz. Welcome to AAC :)
    I am a little confused about what you are trying to do, but if you are trying to power a computer or PDA from a phone line, it is important to know that this is illegal in most places. It is not legal to use power from the phone line for applications other than those intended.
    Der Strom
     
  3. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Oh, okay. I just wanted to point it out, just to make sure :) My apologies.
     
  4. harutz

    Thread Starter New Member

    Mar 31, 2011
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    Yes, of course.
    But if I had an App on my PDA that would allow me to make a call on a land line,
    how would I go about constructing a circuit to allow me to do this without frying my device?
     
  5. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Oh, I see. I suppose you would need the "data" wires, not the "power" wires. I don't know what kind of app or device it is, so further assistance would be difficult. Could you possibly give more information? It would be much appreciated :)
    Der Strom
     
  6. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    an option would be to send it from your device via bluetooth to a reciever, which would then hook into your subscription line.
     
  7. harutz

    Thread Starter New Member

    Mar 31, 2011
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    0
    Thanks for the suggestion. Bluetooth is something to consider.

    I'm using a Palm Treo 700, but really it's just theoretical development right now.
    I think it would be a nice thing to do.
    I've seen somebody splice a USB cord into a phone line extension (not connected to the grid) to run a long distance and then back to USB to plug into his computer, so I'm not really worried about data problems so much as there being too much power in the phone line for a little device to handle. As long as the 'data' lines correspond correctly, the rest is mainly just a software issue I think.
     
  8. Papabravo

    Expert

    Feb 24, 2006
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    Are you asking how much power you could extract from the phone lines at a regulated 5.5V? You may be wondering if you can extract more thhan the 100 mA @ 5.0 Volts you can get from a USB port on a computer without negotiation. I'm not sure you can do it without detection and consequences. What makes you think it is possible?
     
  9. Papabravo

    Expert

    Feb 24, 2006
    10,135
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    How do you get "data" wires and "power" wires on a single pair? How do you plan to keep the phone company from detecting your little scheme?

    The DC voltage is -48V so you need an inverter and a regulator. The problem is there are resistors and protection circuits so you can't draw very much power from the phone lines. The more power you try to draw the more like you are to be detected. You might be in for an unpleasant visit from some folks you'd rather avoid.
     
    Last edited: Mar 31, 2011
  10. bertus

    Administrator

    Apr 5, 2008
    15,638
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    Hello,

    I merged the threads and removed double posts.

    Bertus
     
  11. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    It is highly unlikely that you'd have any data integrity over the extended line. USB is very specific about the physical aspects of it's transmission. It could work, but it's not something you'd base development on.
     
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