Making Camera Power Supply from ATX PS

Discussion in 'Digital Photography' started by Nehmo Sergheyev, Jun 4, 2005.

  1. I have a HP M22 camera , and here are its power

    "Typical power usage: 1.35 Watts with Image Display on. 2.9 Watts
    maximum power usage.
    Power sources include the following:
    .. Either two non-rechargeable AA Lithium batteries (included) or two
    rechargeable AA NiMH batteries (purchased separately). Rechargeable
    batteries can be recharged either in the camera using the optional HP AC
    power adapter or optional HP Photosmart M-series dock, or separately in
    the optional HP Photosmart Quick Recharger.
    .. Optional HP AC power adapter (3.3 Vdc, 2500 mA, 8.25 W).
    .. Optional HP Photosmart M-series dock.
    Recharging in camera with the optional HP AC power adapter or optional
    HP Photosmart M-series dock: 100% in 15 hours."

    HP sells a $50 external power supply for the camera:
    HP Photosmart 3.3V AC adapter C8912B , which
    provides 3.3 Volts.

    A marking on the camera assigns the + polarity to the center connector
    of the jack, and it's a small jack.

    Q1: What do you call that kind of jack?

    Q2: Computer ATX power supplies have a 3.3 V line. I have some old
    unused power supplies (and I can buy them nearby for $5). Can I use an
    ATX power supply to power the camera?

    My understanding of an ATX is that normally one of the 5 V wires is
    always on but the rest of the lines are controlled by a soft switch fed
    to one of the wires.

    Q3: What do I do exactly to turn on the power supply? Do I ground pin
    14? ( pin out diagram scroll

    Q4: Will this camera, or camera's that require 3.3 V in general , work
    on the 3 V (setting of the) power supplies like Wal-Mart sells

    Q5: I see some universal adapters " Equipped
    with technology to calculate your camera's voltage " How does it
    determine the camera's voltage requirements?
    Nehmo Sergheyev, Jun 4, 2005
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  2. Nehmo Sergheyev

    philo Guest

    although in theory you could use the 3.3v connection of an atx
    supply...i don't think it would be worth trying to do so...
    as if you made a mistake you could damage your expensive camera...

    $50 for that adaptor is of course absurd...
    you could prob. find something at radio shack that would work...
    however...why not play it safe and simply remove the batteries from the
    camera and purchase a seperate charger.

    it would certainly be the cheapest and safest thing to do
    philo, Jun 4, 2005
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  3. Nehmo Sergheyev

    kony Guest

    They overprice it just a wee bit.

    "Tis the far more common arrangement but it's good that they
    marked it.

    Hard to tell from a picture but looks like a typical power
    brick barrel, coax plug. Main thing is knowing the external
    and internal dimensions in millimeters, and the tiny ones
    are harder to measure, and find.

    It'd be awefully bulky, but it's likely you can. However,
    you should put a certain minimum load on the 5V rail to
    stabilize the output. A 2 Ohm 10W power resistor should be
    sufficient, connected between the 5V rail and ground- either
    on one of the leads or inside the PSU if you feel competent
    inside a power supply to figure that out- if not I'm not
    going to tell you how to do it, but it isn't hard, just
    fiddly taking the thing apart to do it.

    Yes 5VSB is always on, as is the PS-On line. You can ignore
    the 5VSB and simply short the PS-On to a ground. If you
    were opening up the power supply anyway to add the resistor,
    I'd suggest drilling a hole in the casing and installing a
    switch to short the two wires, turn it on/off.

    yes, it's pin 14, usually a green wire.
    I don't know.
    The camera may have polarity protection, meaning you may
    easily need slightly more than 3.0V to get a pair of
    batteries charged fully.

    The other issue is the current capacity of the supply, the
    one you linked doesn't appear to have that listed.

    Since the HP supply is spec'd as 2.5 amps, that would be the
    general target... the camera might still work on less, maybe
    1.5A, but then there's the issue of what the supply does if
    it drops below any particular threshold voltage. I'd not
    risk a camera with a less than 2A supply, myself.
    I don't know but I'd go ahead and get one spec'd for 3.3V
    instead. Here's one, but you'd need come up with your own
    plug for it,

    Maybe this'd be helpful,
    but getting good measurements from the jack first would be

    Seems like I used to have an old electric shaver and a
    microcassette recorder that both used similarly small
    connectors, if you have such spare junk lying around it
    might provide a part or aid in measurements.
    kony, Jun 4, 2005
  4. Nehmo Sergheyev

    CWatters Guest

    CWatters, Jun 4, 2005
  5. Just buy a regulated universal adaptor at Radio Shack or whatever your
    local crapy electronics store is. It will cost about $30 and will work
    with a lot more than your camera.

    Switching power supplies can get twitchy outside of a their normal load
    range. I wouldn't connect one to my camera without doing some stability
    tests first.
    Kevin McMurtrie, Jun 5, 2005
  6. Nehmo Sergheyev

    Shep© Guest

    Not a lot of people know this(In fact I think only me<grin>).The two
    digi cameras I've had if I leave them connected to the PC after
    downloading piccys to the PC get trickle charged by the USB port :D

    Noticed when I left PC on overnight for downloading but left camera
    connected and knew batteries were low.Came back on the morrow to find
    fully charged Camera :D

    Also I think it's cheaper to buy and use Li-on re-charegable AA
    batteries and a good wall charger(Or a PC<BFG> :)
    Shep©, Jun 5, 2005
  7. Nehmo Sergheyev

    kony Guest

    You're not likely to find a non-switching regulated adapter
    worth the 2.5A of the one HP sells, and certainly not at
    $30. Almost all semi-regulated adapter in smaller forms
    supplying 1.5A or more will be switching.
    kony, Jun 5, 2005
  8. Nehmo Sergheyev

    Al Dykes Guest

    A PC power supply needs a minimum load so it won't power just
    your camera. I also don't know how you'd turn it on since
    it's controlled from the mobo.

    Look for a power supply on ebay or go to Radio Shack. They sell
    wall warts in all sorts of sizes.
    Al Dykes, Jun 5, 2005
  9. Nehmo Sergheyev

    Dave Guest

    Radio Shack
    3-6.5VDC/2500mA AC-to-DC Adapter
    Catalog # 273-1695

    Dave, Jun 5, 2005
  10. I didn't say that a switching power supply was bad. Nearly all of the
    good wall warts are of that kind. The problem is that switching power
    supplies are unstable by nature so they sometimes have an operating load
    range. An computer power supply designed to deliver 3.3v @ 10A to 50A
    might not be stable with a load that varies from 1mA to 1500mA.
    Kevin McMurtrie, Jun 5, 2005
  11. Nehmo Sergheyev

    James Sweet Guest

    I think I have some random 3.3v SMPS "wall wart" type AC adapters, you'd
    probably have to put your own plug on it but if you want one I'd be happy to
    send one for a couple bucks to cover packing plus postage.
    James Sweet, Jun 5, 2005
  12. Nehmo Sergheyev

    ASAAR Guest

    Was the <BFG> was just for using a PC as a charger, or for the
    entire statement? If the former, you should be aware than AA
    lithium batteries are primary batteries. They aren't rechargeable,
    despite their high price. The voltage of rechargeable lithium-ion
    batteries are also much, much higher than the 1.5 volts normally
    seen in AA batteries.
    ASAAR, Jun 5, 2005
  13. Nehmo Sergheyev

    mike Guest

    Please disclose your source for Li-on re-chargeable AA batteries
    and a charger for same. Please also disclose the prices you've been
    paying and your actual personal experience with the setup.
    Thanks, mike

    Return address is VALID but some sites block emails
    with links. Delete this sig when replying.
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    mike, Jun 5, 2005
  14. Nehmo Sergheyev

    philo Guest

    to turn on an ATX supply all you need to do is touch the green wire to
    but i still would not adivse doing such
    philo, Jun 5, 2005
  15. Nehmo Sergheyev

    kony Guest

    Ah, I misinterpreted what you wrote. That's true, normally
    one puts a ~ 2A load on the 5V rail to ensure stabilization,
    but it gets much more risky with open-frame swichers, those
    not intended for non-integrated usage, not to be hot-plugged
    (not that any are, but those with consumer-gear external
    cords tend to be designed with such events in mind).
    kony, Jun 5, 2005
  16. Nehmo Sergheyev

    Shep© Guest

    Sorry.My mistake they are the Nickel Metal Hydride type which are
    still better than the old Ni-cads.

    They are the newer common colour Green type in the UK and you can get
    them quite a few places.I bought some and a fast charger at a local
    market but also, ebay,
    They don't suffer from the old memory problem of the ni-cads AFAIK :)

    I now have a habit of leaving my digi camera at the side of my PC
    plugged in for a session after downloading piccys and the haven't used
    the wall charger for ages for the camera :)
    Shep©, Jun 5, 2005
  17. Nehmo Sergheyev

    Shep© Guest

    PS I got the 2500Mh ones :)
    Shep©, Jun 5, 2005
  18. ==============

    OT, but just had to comment. It is indeed your fault. You should have
    voted for somebody else entirely, like I did. Enough of those, and we
    would have won. Bush and Gore BOTH were losers! There were other
    Chief Suspect, Jun 5, 2005
  19. Nehmo Sergheyev

    Franc Zabkar Guest

    EIAJ DC plug?
    I'd modify my PC by locating a spare 3.3V plug on my PSU and running a
    cable to a slot bracket in an empty slot, or to a hole in the case, or
    to an unused 5.25" bay.

    WARNING: If you try this, I'd first ensure that the camera's USB
    ground and supply negative are at the same potential, otherwise you
    may damage your camera if you have both cables connected at the same
    time. You can do this by connecting a dummy plug to the DC socket. Use
    a DMM to test for continuity between the two grounds. Remove the
    batteries while doing this.

    - Franc Zabkar
    Franc Zabkar, Jun 5, 2005
  20. Nehmo Sergheyev

    kony Guest

    On Mon, 06 Jun 2005 06:17:44 +1000, Franc Zabkar

    I agree that the grounds need be same potential but have you
    ever run across any USB GND that wasn't already at power
    GND? AFAIK, they all are.
    kony, Jun 5, 2005
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