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Followup -- auXiliary cell phone power source

Discussion in 'Electronic Design' started by Ignoramus27317, Apr 1, 2007.

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  1. A few days ago, I complained about my Motorola V557 phone discharging
    too quickly when I used it as a model (with a linux laptop and
    bluetooth). It also is way too slow to charge.

    Since then, I bought an extra cheapo wall wart charger, cut its DC
    cord and found out the following:

    1) Open circuit voltage is about 5.81 VDC
    2) When charging, the voltage is about 5.61 VDC

    I also experimented with my phone and a lab style HP DC power supply.
    I found out that the phone starts charging when voltage reaches
    approximately 4.8-4.9 volts.

    So, my thinking goes, if I can get a power source that would be
    limited to about 5.6 volts, then I couls safely use that as a
    supplement to the cell phone battery. I would just take the plug from
    the cheapo charger mentioned above, solder it to that hypothetical
    source, and plug my phone into that.

    I found out that eBay has plenty of 6V rated Nicad battery packs for
    remote controlled toys. There is plenty of new packs sold with 3 hr
    chargers.

    So, I decided to buy a 6v pack/charger combo, and add a little voltage
    limiter so that the voltage that the phone sees, never exceeds
    5.6v. That limiter can be a simple linear regulator type of thing, I
    will try to just buy some TO-220 chip on Digikey for simplicity.

    i
     
  2. _________________________________^^^^^^ <-- modem

    i
     
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