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disposable camera flash circuit

Discussion in 'Electronic Basics' started by Grostle News, Jan 20, 2007.

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  1. Grostle News

    Grostle News Guest

    I want to alter a circuit:

    I took out the flash circuitry (board, bulb and battery) from a Kodak
    disposable camera. The main flash electrolytic capacitor is rated at
    330v and 84 mfd. ( I think 84 is the value, but don't have with me at
    this time)

    The cap charge comes from a single AA 1.5v cell. It looks like within
    the flash circuit there is a small transformer with a transistor
    oscillator circuit that does the duty of raising the voltage.

    I have a non-photographic application for this type of circuit. After
    removing the flash bulb I need to change the cap by replacing it with
    one rated at 600-660v.

    QUESTIONS (2):

    (1) Would it be possible to use TWO cells in series [3v] instead of just
    the one in order to charge the replacement cap at it's 660v rating?
    1.5v cell---> 330v
    2 × 1.5v cells [3v]-----> 660v ?

    (2) Would other devices of the circuit need to be changed if the input
    voltage is doubled as described?

    I like the idea of getting use out of something that is commonly
    available and that would ordinarily be thrown away (disposable) after

    Important safety reminder: if you ever experiment with one of the flash
    units don't forget to discharge the capacitor before handling. When I
    discharged the one in my flash circuit it was remarkably loud and
    powerful enough to leave a small bead of molten chrome steel on my
  2. John

    John Guest

    Maybe, but it may cause the active electronics to lose their magic
    smoke :-(
    The resistor for the "ready" indicator should be doubled in value.
  3. No. The tube is designed for that capacitor - no more voltage, no more
  4. Bob Masta

    Bob Masta Guest

    You haven't mentioned what you plan for this, but I've
    seen Web pages devoted to making your own radiation
    detector that use disposable flash units (minus the flash tube).
    You might try searching along those lines, maybe include
    "scintillation counter" or even "Geiger counter" in the search.

    Best regards,

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!
  5. ehsjr

    ehsjr Guest

    You can "Rube Goldberg" two disposable camera
    flash units together. Remove the flash tubes.
    Than do this:

    1) Wire the (-) side of the cap (cap1) in camera 1
    to the (+) side of the cap (cap2) in camera 2.
    2) Install a spdt switch in camera 1, with the
    common connected to the (+) of cap1

    existing New discharge pushbutton
    camera 1 __
    circuit ----o o-------o o---+
    | \ |
    | o |
    | + | |
    | [Cap1] |
    | | [600 volt device]
    +---->|-----+ |
    + | |
    [Cap2] |
    | |
    | |

    Both the spdt switch and the pushbutton must
    be rated for > 600V.

  6. neon


    Oct 21, 2006
    to charge that capacitor to 600 volts no way it will blow up before it gets there. what can you do well use 4 caps of that kind to get 600v 84 mfd. if you put 84mfd in series to 600 v it becomes 42 mfd then you need two resistors to divide the voltage now you got 42 mfd 600v. basicaly you need another same setup to get you to 84 mfd 600 v. that is quite a few caps. I suppose doubling the voltage will boost it up to higher voltage but you have not increased the power input it may get there by tomorrow if then.BOTTOM LINE inpractical.
  7. default

    default Guest

    It might work just like you want, double the input, double the output
    - or the oscillator might pull enough current to kill the oscillator
    transistor. Ideally, I'd creep up the voltage with a variable source
    and watch for smoke and feel the transistor and resistors to find hot

    Or ditch the flash tube, replace the cap with a higher voltage one and
    try it - especially if you don't mind losing the first one you
    practice on. The output may exceed the normal voltage because
    efficiency improves as voltage goes up - the required transistor drop
    is met and everything over that goes to producing more output.
    There's always a safety factor built in with a higher voltage cap than
    the expected voltage and the electrolytic you use might withstand more
    than its rating by a few percent.

    Your use of the output may be more benign than what the camera
    intended and that could also work in your favor - the oscillator pulls
    more current when it is charging the cap from zero - flash it a lot of
    times quickly and it works the oscillator harder.

    We could use more data on the use . . .
  8. Grostle News

    Grostle News Guest

    Hi Bob, you wrote and guessed what I was going to use the circuit for
    (Geiger counter):
    You are a very good guesser and I will emloy your search strategy.


  9. Grostle News

    Grostle News Guest

    Thanks to "Rube Goldberg" and "default" for sharing your worthy
    knowledge and circuit design/conversion ideas.

    saxum, g.n.
  10. Grostle News

    Grostle News Guest

    Hi John, thanks for your assistance. You included info about the
    possibility of overheating:
    LOL!! I know about the "magic smoke", Over the years I've seen quite a
    bit of it wafting upward in its enigmatical way and then disappearing
    into thin air!! <abracadabra>

    saxum g.n.
  11. Ever seen it coming out of the boss's new $250,000 molding machine?


  12. Grostle News

    Grostle News Guest

    No, but it is that type of thing that makes electronics a hobby for me,
    and not a career.

    saxum g.n.

  13. That's what happens whenever Homer messes with something. No wonder
    his favorite beer is called Duff. :(

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  14. Nope. That's what happens when you let the Yanks build one instead of the

  15. quietguy

    quietguy Guest

    Just slightly off track, these cameras are also a good source of no-cost
    batteries (aa or aaa) for experimenters with limited means - just ask the
    local photo processing shop and they will give them to you by the dozens -
    but note the safety warning given by Grostle News

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