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Alternative A/C adapter for HP Photosmart camera

Discussion in 'Electronic Basics' started by David Turrell, Oct 28, 2004.

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  1. I recently purchased an HP Photosmart 435 digital camera. I'm
    looking for an A/C adapter that is less expensive than that made
    by HP, which costs ~$50 (the camera itself was only ~$100, and I'm
    not necessarily going to get another HP camera).

    The power requirements for the camera, via A/C adapter, are listed
    as 3.3 to 3.7V and 2500mA. I haven't been able to find a generic
    adapter that matches those specs.

    The closest that Radio Shack seems to have, of their standard,
    non-adjustable adapters, is 3V and 500mA. This adapter system has
    the advantage of a wide array of tips, the smallest of which (female,
    0.7mm interior diameter) would seem to fit the HP camera.

    While 3V seems too low, I wonder how the camera is able to make do
    with two 1.5V batteries as a power supply!

    A Radio Shack universal adapter, which I didn't see, would, based
    on the one I have for a radio, have 3, 4.5, 6, etc. volts, which
    seems not close enough; and it probably wouldn't give the correct

    Digi-Key's catalog has a wider range of voltage and amperage choices,
    but only matching the voltage, not the amperage. Also, I don't
    see a standard tip for them that is small enough for the camera.
    A custom-made tip, which they offer, would possibly bring the cost
    to where I might as well buy HP's version.

    There's always the possibility of a jury-rigged device, but I'm
    trying to avoid something that messy.

    What substitutions are possible under the circumstances?
  2. Bob Salomon

    Bob Salomon Guest

  3. Ken Weitzel

    Ken Weitzel Guest


    Respectfully, no it sure won't...

    The original puts out 2.5 amps; whereas the rs version
    delivers only half an amp. That's a world of difference.

  4. I'm guessing the reason the voltage is higher than the battery voltage is
    that there's a protective diode or something. But 3 volts may well work.

    2500 mA is a *lot* of current!!!! Does this camera really draw 2500 mA?
    If so, it must run down its batteries almost instantaneously.

    Does this camera have a flash built in? If so, I'll bet the heavy current
    drain is only for charging the flash, and that without flash, you could get
    by with a considerably lower-current power supply.
  5. Thinking about it, the 0.7V diff might be the drop across a rectifier
    diode, so maybe all the camera needs is 3VDC.
    You might try using a 3A rectifier diode to drop the 4.5V down to 3.8 or
    so volts.
  6. Jamie

    Jamie Guest

    the 3 volt level should be ok since its most likely is putting out more
    than 3 volts to start with.
  7. Rich Grise

    Rich Grise Guest

    Yabbut, not a 500 mA wart, when the device needs 2500.

  8. mA?

    And a few hundred uF at 330VDC is a lotta capacitor to charge up in a
    few seconds. And that takes a lotta current, maybe not forever, but for
    quite a few seconds.
    No, they're 2000 mAh which means they should last for the better part of
    an hour. But a camera isn't on very long.
    The LCD and backlight demand a lot of current, too. A lot.
  9. Graham W

    Graham W Guest

    Another factor not yet mentioned is that the supply *may* be able
    to recharge the cells while supplying power for taking more photos.
  10. Al Bundy

    Al Bundy Guest

    I've been fooling with my 435 power supply because the battery grain
    is so high on these. The NiMH cells only have 1.2V nominal and fully
    charged they run the camera fairly well, but within a couple days they
    are in the low battery mode. So I searched for a jack to use on the
    AC/3.3V input and found one at an electronics store for $1.99. It's
    the same size as slot car power supply jacks and Radio Shack sells
    them for $4.95. I am sure you can use a 3.6V cell phone charger on
    that jack with no harm. At least it worked for me. However, the
    charger will try to charge any batteries in the camera. I did not want
    that happening. What I was really after is to put a DC source into
    that jack so I could furnish more total power to the device. So that
    idea flunked my testing.

    What I ended up doing was working from the battery compartment. I took
    an old AA cell and cut it in half. I cleaned out the inside. Then I
    ran a wire to the plus and minus ends. I replaced the missing half of
    each cell with a wood dowel with a hole drilled in the center. In
    essence I made these fake batteries to put into the battery
    compartment and run a cable out the door, with a slot cut in the door.
    I took a 3.6V cell phone battery (removed from the case) and cabled it
    to that compartment. Fully charged the battery puts out 4.2V. I
    estimate the dam thing will take 200 pictures on a charge, but I
    recharge at 3.7V. I took the chance of over powering the camera
    because I was fed up and got to the point that I considered it
    expendable. I was stupid lucky this time. I have the power supply
    problems absolutely solved. I've taken 600 pictures with no problem
    from a power standpoint. I often get dark pictures and always have,
    but that's an unrelated issue. The white balance and E/V adjustments
    don't fix that consistently.

    That's what I did anyway.
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