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opinion on wiring a camera flash

Discussion in 'General Electronics Discussion' started by Propman, May 27, 2010.

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  1. Propman


    May 27, 2010
    Hi everyone,

    I am currently getting into building props and costumes and I have an idea to use the flash from disposable cameras and incorporating them into the palms of an Iron Man costume. That being said, is it possible to extend the wiring from the flash so that the camera is housed in the back of the arm? I really want to do this but I don't want to electrocute myself from the capacitor and I want to make sure that the wiring can support that much electricity.
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    There's a number of things to be aware of (and note that all of this applies to the wimpy flashes in disposable cameras).

    1) the voltage on the capacitor is high (around 300 volts), and has close on enough energy to stop your heart if applied in the worst possible way (across your arms)

    2) the trigger circuit generates up to several thousand volts and will arc over if given the smallest possible chance. While not deadly, it will certainly make you jump.

    3) The current passing through the flash tube can easily be in the range of 50 to 100 amps once triggered.

    I would be extremely careful how I incorporated such a device into a prop that would fit into somebody's palm. Running wires from the capacitor to the flash tube is possible, but you would generally want fairly heavy wire. However you really can't run the trigger voltage down any sort of cable you're likely to easily find.

    I would also be very concerned that if there was a common trigger, the danger exists (at least as a theoretical possibility) that it could form a circuit which allowed discharge across the arms of the actor. Even if not fatal, it would certainly be very scary.

    Having said all of that, it is not beyond the realms of possibility that you could separate the battery from the rest of the circuit -- moving ot to the wrist or back of the hand perhaps), and maybe use a smaller capacitor and lower voltages (for safety and less dazzling light output).

    The issue would then be triggering. I would look at a opto-coupled triac driver as that would isolate the devices and minimise the risk of shock through the trigger.

    It's not a project that I would do, unless I had some experience making props, AND dealing with dangerous voltages. You would want to make absolutely sure the final device is well insulated.

    A rather simple alternative may be to use a high wattage LED (they are easily available in 1W to 5W ratings, and I have seen much higher. For very narrow pulses, heatsinking would not be an issue. In a dimly lit environment, a quick pulse from a high powered LED might be good enough. The voltages, being lower, mean that the risk to the performer is vanishingly small in comparison.

    p.s. Why does everyone want to be Iron Man right now?
  3. LTX71CM


    May 23, 2010
    I second most of what *steve* said.

    If I had to guess it's because Iron Man 2 was just released in the US.
  4. Propman


    May 27, 2010
    Okay, that is the kind of thing I was leery of. Thank you very much for the information I think I will drop the flash idea and focus more on the LED side of things.

    As for the whole Iron Man thing, it is a really great suit that looks awesome and I think it would make a portfolio really pop.
    Last edited: May 28, 2010
  5. macb6497


    Jun 1, 2010
    It will work

    Just reroute the wiring from the capacitor to a button and then to a small flash lamp.

    You can use 20 awg speaker wire to protect yourself.
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    I really don;t think you understand what we're talking about.
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