Accidental power supply for Canon A80

Discussion in 'Canon' started by Dave Martindale, Nov 8, 2004.

  1. Someone gave me a dead Casio Cassiopeia PDA (it runs Windows CE).
    The PDA is indeed dead, but the AC charger/power supply that came with
    it is rated 5 V at 2 A. It appears to be a nice little switching power
    supply. Moreover, its cord ends with the right size and polarity of
    coaxial connector to fit my A80.

    The A80 manual recommends a particular Canon external power supply which
    is rated at 4.3 V and 1.5 A. The Cassiopeia's power supply is slightly
    higher voltage but I know from past experience that's OK, and current is
    more than adequate. It is a regulated supply, not a cheap unregulated
    wall wart. So I decided to try it on my A80.

    It seems to work just fine. It would probably be fine for other Canon
    Axx models with similar external power supply specs. And I can't beat
    the price.

    Dave
     
    Dave Martindale, Nov 8, 2004
    #1
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  2. Dave Martindale

    Larry Guest

    Joseph, Im following up on YOUR post because I dont have
    the OP's post on my server.

    To the OP


    Volts are volts, and amps are amps.

    If the power supply you are using is "slightly" higher than
    recommended, then something inside the camera is getting
    hotter than it should. There is no "Free Ride" and those
    extra volts go SOMEWHERE! (usually into heat).

    Having the SAME voltage and extra amperage is OK.. Having
    HIGHER voltage with the equall or higher amperage may very
    well damage the camera.
     
    Larry, Nov 8, 2004
    #2
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  3. Dave Martindale

    DHB Guest

    Dave Cohen,
    as a retired E.T. I will add my opinion on this issue.
    Potential problems of an over voltage are rather easy to understand
    but the same can apply to an under voltage situation as well. Also
    unlike a CD player which draws a fairly constant amount of power when
    running, aside from a bit extra to get the CD up to speed, a digital
    camera draws a reasonably steady amount of power punctuated by short
    busts of higher power for certain operations. This is largely true
    when it writes to it's memory card, when the lens is zoomed in or out,
    when the flash is charging, when the LCD come on & etc....

    This is the reason why higher capacity alkaline "AA" batteries
    don't last very long in digital cameras compared to lower capacity
    rechargeable Ni-MH which seriously out perform them in this
    application. This is not simply a function of the capacity in mah
    ratings but the way the chemistry of the battery responds to brief
    high drain loads. Most CD players are fairly low drain devices &
    alkaline "AA" cells usually outperform rechargeable Ni-MH "AA" cells
    in this application.

    As to why your CD wall power supply is working on your A40
    (yes, I own an A40 also), likely it may be due to what functions you
    are using with it & the likelihood that it has a fairly large filter
    capacitor within it that is providing most of the peak demand voltage.

    Two additional related notes, just because something works for
    a while, does not mean that it will continue to do so in the long run
    or that it is the equal to a part or product that it is being used to
    replace. Everybody knows that a blown fuse can be replaced with a
    coin or a bolt & the circuit might work, but who would conclude that
    doing so proves that there is no need for the fuse or that the coin or
    bolt will perform the same function as the fuse?

    With all of this said, if money is tight 1 can often find or
    modify an existing "regulated & filtered" power supply to run a
    digital camera rather than buying an expensive power supply from the
    manufacture.

    For the Canon Axx line a "regulated & filtered" 5 VDC power
    supply, either with a linier or switching voltage regulator should
    work fine if you add a general purpose silicone rectifier diode in
    series with 1 lead. This will result in a fairly constant voltage
    drop across the diode which in turn will reduce the voltage output
    that the camera see's to about 4.4 VDC. This is much closer to the
    stated 4.3 VDC of the Canon power supply & certainly much safer than
    feeding the camera 5 VDC, +0.7 VDC higher than specified.

    All of this is just my opinion, it's your camera & you can do
    what you believe is OK, but I would be remiss if I did not input my
    opinion & reasoning for your consideration & for other's who might
    read this. I'm not a big fan of Radio Shack, however you should be
    able to find both the (regulated & filtered wall wart) "power supply"
    & a general purpose silicone rectifier diode "50PIV @ 3A" should due
    at a reasonable price, or check with on-line electronic surplus supply
    vendors.

    Hope my post does not sound like any kind of insult, if it
    does, that was not my intent. Just wanted to point out that in some
    cases an under voltage situation can be just as big a problem as an
    over voltage problem, though it may take longer for a device to fail.
    Lastly, I don't have the schematics of Canon Ax cameras, so I don't
    know if they use the same internal voltage regulation or monitoring
    that is used with the batteries. It's likely that they do not because
    they may assume that the supply is already regulated & should not drop
    below safe a operating voltage the way "AA" batteries will, thus the
    camera informs the operator & they will power down to prevent damage
    if the batteries are not replaced.

    Respectfully, DHB


    "To announce that there must be no criticism of the President,
    or that we are to stand by the President, right or wrong,
    is not only unpatriotic and servile, but is morally treasonable
    to the American public."--Theodore Roosevelt, May 7, 1918
     
    DHB, Nov 8, 2004
    #3
  4. Dave Martindale

    Chris D Guest

    The A series are supplied with 4 AA Alkalines in the box, giving
    6V, so the 5V should be just fine. That said, Canon aren't
    gonna do anything under warranty if they find out!

    -Chris D
     
    Chris D, Nov 9, 2004
    #4
  5. Dave Martindale

    Larry Guest

    Generally speaking, if you are in the US, you can probably
    match the voltage and the amperage with regulated power
    supplies from Radio Shack.
     
    Larry, Nov 9, 2004
    #5
  6. The camera has to cope with a battery voltage of up to 6 V with fresh
    alkalines, perhaps 6.4 V from single-use lithium AA. So 5V is really
    not likely to be a problem.

    If the camera uses linear voltage regulators internally, the "extra"
    voltage increases heat in the regulators, but they have to be designed
    for the even higher battery voltage. If the camera uses switching
    regulators, a higher voltage simply results in lower current drawn from
    the power supply, and no change in waste heat.
    Excessive voltage, yes. But not for voltage within the range the camera
    is designed for.

    Dave
     
    Dave Martindale, Nov 9, 2004
    #6
  7. Alkalines have high internal resistance, but NiCd, NiMH, and AA Lithiums
    have much lower internal resistance. And the camera is normally
    operated from one of these low-impedance types; alkalines are almost
    useless for powering it.
    I believe I did take the risks into account. I did try it on my own
    A80. And I reported the results on the grounds that other people would
    be interested in them. I do assume that people are adults and can make
    their own decisions. If you want something that's guaranteed to work or
    Canon will fix it under warranty, by all means buy the Canon adapter.

    But I'm willing to take a bit of risk (and the risks are small), and I
    assume other people may be interested too.

    Dave
     
    Dave Martindale, Nov 9, 2004
    #7
  8. Dave Martindale

    DHB Guest

    Joseph Meehan,
    at the risk of diverging well off topic, this is a
    great & insightful quote. Sadly many here in the USA now believe that
    almost any criticisms or even just asking questions of our government
    is unpatriotic. As my use of this quote implies, I believe that now
    more than ever, we need to be asking questions & demanding answers.
    Unfortunately our media no longer seems to be practicing true
    "investigative journalism", so it falls on the citizens USA to
    undertake this task, just as it would in any democracy!

    What scares me most is not what we are being told, but rather
    what we are obviously "not" being told!

    Respectfully, DHB

    "To announce that there must be no criticism of the President,
    or that we are to stand by the President, right or wrong,
    is not only unpatriotic and servile, but is morally treasonable
    to the American public."--Theodore Roosevelt, May 7, 1918
     
    DHB, Nov 9, 2004
    #8
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