Usb charger

Discussion in 'The Projects Forum' started by starfox55, Feb 21, 2012.

  1. starfox55

    Thread Starter New Member

    Feb 21, 2012
    3
    0
    I made a simple usb charger with this schematic
    [​IMG]
    This one uses 6-AA rechargeable batteries which, on full charge, actually supply about 8.5-9 volts as regular 1.5AA batteries would but the amperage for these are high, 2300mAh.
    In this one, I used just a regular 9v battery.
    [​IMG]

    The difference is....the first schematic, utilizing 6-AA's, makes the regulator incredibly hot when I plug in my phone(5V 0.7A)
    The second schematic, utilizing 1-9v, produces barely any heat at all.
    The 5volt regulator is an LM7805C with maximum Input 35V and Output of 5V at 1.5Amps.
    Since the regulator only puts out 1.5Amps, is it acting like a resistor and lowering the 2.3Amps(2300mA) that's going in(thus producing heat), or rather, even lowering the 2.3A to the 0.7A taken by the phone? and also, what can I do(like what resistors can I add) to lower the 2.3Amps going into the regulator to a value much closer to 1.5A?
     
  2. starfox55

    Thread Starter New Member

    Feb 21, 2012
    3
    0
    The 5volt regulator actually puts out 1Amp, not 1.5Amps
    Doe this affect why it's getting really hot?
     
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