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  1. #31
    Eugen Mezei's Avatar
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    Quote Originally Posted by BrianShaw View Post
    Have you tried this:

    http://www.google.com/patents?q=flash+bulb

    There is some interesting information that can be gleaned from patents.
    Thank you Brian.
    When I first thought about building a flashbulb my ideea was to search old Agfa patents as I know they were made publicly avaible by the Allies after WW2. Unfortunately found nothing, seems they didn't made it onto the net.

    I will study the patents you pointed me to.

  2. #32
    Eugen Mezei's Avatar
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    I have a flash with broken xenon tube. (It's a tiny flash, I think not much more power than the ones used in disposable cameras. I also have some disposable cameras so that would be another option.)
    Can I use this to ignite the primer? Where to connect it? I have 3 wires in the flash. One was originally coiled around the tube. I suppose I need to connect the primer to the other two. Am I right?

  3. #33
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    Quote Originally Posted by Eugen Mezei View Post
    ...nickrapack's hint with the electric matches was a very good one. I thought myself about something similar before but wasn't shure if this would work. I will try now to build some thin wire coated with black powder. Hope this would make a nice primer..
    You might try researching the black powder site a little more. Not sure what's inside a modern percussion cap, but I know that it isn't the old Mercury Fulminate. But it is something that fires and will ignite the rest.

    Some of the older photography references had instruction for making flash powder as well. That's related, but not exactly the same thing as black powder. Not sure how you could coat a wire with it, however.
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  4. #34
    Steve Smith's Avatar
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    Quote Originally Posted by Eugen Mezei View Post
    I have a flash with broken xenon tube. (It's a tiny flash, I think not much more power than the ones used in disposable cameras. I also have some disposable cameras so that would be another option.)
    Can I use this to ignite the primer? Where to connect it? I have 3 wires in the flash. One was originally coiled around the tube. I suppose I need to connect the primer to the other two. Am I right?
    No. The two main wires either end of the tube connect directly to the flash high voltage supply. In normal use the flash tube does not conduct so the capacitor can charge up. The tube will only conduct when it is ionised by a pulse on the third wire.

    If you connect a flash bulb to it, it will just fire when there is sufficient power in the high voltage supply - or the high voltage supply might not charge at all as you are putting a short circuit across its output.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  5. #35
    Eugen Mezei's Avatar
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    Michael, I use homemade flashpowder (Al powder + KMn04) and ignite it with a strip of paper soaked in KNO3. But Al powder is expensive and a few years ago kalium permanganate was put on the list of substances that can be used for narcotics preparation so you get it only in limited quantities and on recipe. It was free before in every drugstore. I know Al powder can be prepared by milling Al foil, but that results even more expensive.
    Still, maybe I will try a small amount of flashpowder to ignite the Al foil. I just doubt it will sprinkle around in the bulb sufficiently to ignite the load of foil from multiple points.

    Steve, my thought was to let the capacitor charge first and only after connect it to the electric match. In fact that is what the camera does by closng the X contact or what we do with the button for test flashes. So I connect the electric match to the two wires and let the third one unused. Than wait for the capacitor to charge (orange control light tube going on) and close the circuit with the test button or with the cameras hotshoe or x-contact onto the electric match. Is this correct or do I make a mistake somewhere?

  6. #36
    Steve Smith's Avatar
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    Quote Originally Posted by Eugen Mezei View Post
    Steve, my thought was to let the capacitor charge first and only after connect it to the electric match. In fact that is what the camera does by closng the X contact or what we do with the button for test flashes.
    Not quite. The camera contacts or the test button discharges a very small capacitor into the trigger transformer. This creates a high voltage spike which is applied to the third wire in order to ionise the gas inside the tube. The tube does not conduct until the gas is ionised. When it is, it discharges the main HV capacitor converting the energy to light.

    So the camera or test button does not directly apply the high voltage to the tube. The tube is permanently connected and only conducts when triggered.

    This circuit diagram might explain it better than words: http://repairfaq.cis.upenn.edu/sam/fflash1.gif


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  7. #37

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    Quote Originally Posted by haclil View Post
    While this is a bit OT, any outdoor photographers out there might be interested in my spin-off idea. First off, we know that steel wool burns with a nice warm glow.

    Now sometimes I want lighting (at night) that simulates the warm glow of a fire. (Usually I shoot in arid areas where there's precious little wood.) Next time I want faux-fire lighting I'll just light a wad of steel wool with a match or a 9V!

    it is why it is good to keep a C or D cell and steel wool
    in a glovebox for emergencies ...
    1.5v makes it glow red and makes it easy
    to ignite tinder / signal fire if you are lost broken down
    in an accident, stranded, hungry, have marshmallows to roast
    or you just feel like "MacGyver-ing "
    silver magnets, trickle tanks sold
    artwork often times sold for charity
    PM me for details

  8. #38
    greybeard's Avatar
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    kalium permanganate was put on the list of substances that can be used for narcotics preparation

    I'm not sure where you are located or how thorough the local authorities are, but it is possible that you will find potassium permanganate in a pet shop; it is (or was) used as a fungicide for tropical fish. Where I am, oxidizers such as potassium nitrate are unobtainable through local retail channels, unless you know to look for "stump remover", which is mostly KNO3....

  9. #39

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    You don't need anything THAT complicated to trigger an old style flash bulb.... I recall taking apart a flash unit that had a reflector that unfolded like a fan to form a complete circle. The power source for that was a rectangular battery that generated something like 27 volts. That was connected directly to the bulb and the camera's sync terminal in series.

    I'm sort of scared about this project as this is potentially quite harzadous. A small bulb about 1" in diameter was covered with a thick plastic of some kind. Once fired, it was that plastic that was holding the shattered and bulging glass inside.
    Develop, stop, fix.... wait.... where's my film?

  10. #40
    Steve Smith's Avatar
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    Quote Originally Posted by tkamiya View Post
    You don't need anything THAT complicated to trigger an old style flash bulb.... I recall taking apart a flash unit that had a reflector that unfolded like a fan to form a complete circle. The power source for that was a rectangular battery that generated something like 27 volts. That was connected directly to the bulb and the camera's sync terminal in series.
    I posted the circuit diagram for a bulb flash trigger circuit in the third post in this thread. It uses a capacitor and a resistor too. If my memory is correct, the standard battery for these was 22.5 volts and was similar in size to a modern 9 volt battery but had a contact at each end.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

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