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  1. #1
    holmburgers's Avatar
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    Triggering an Autonomous Flash - Flash bulb circuit question

    So, let's say I have a 15V battery connected to an old-fashioned flash bulb. Would completing the circuit fire the bulb and then automatically disconnect the circuit safely?

    Furthermore, what methods are used to trigger a camera to make an exposure autonomously? I know that Edgerton used sound to trigger his flash, but that means the shutter would have to be open beforehand. How about triggering a shutter as well? What kinds of cameras support this, what kinds of triggers, etc?

    Thanks!

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    Ian Grant's Avatar
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    Flashbulbs require a sync built into the camera/shutter to delay the shutter firing by 10/20/30 milliseconds depending on the type of bulb.

    So the shutter must be tripped and the bulb circuit closed while a delay mechanism prevents the shutter from opening while the flash builds up towards it's peak output.

    With electronic flash there's no delay.

    Ian

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    holmburgers's Avatar
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    Thanks Ian. For what I'm trying, the shutter can be open (complete darkness) and in that case, will the simple circuit I describe do the trick? There aren't any other components in a simple flash-bulb gun are there?
    If you are the big tree, we are the small axe

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    Mike Wilde's Avatar
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    high speed photography is a good term to search under. I will show turn up circuits to build to trigger flash in non-conventional ways.

    Due to the time lag between firing a bulb and the light reaching its best intensity it was common to hard wire multiple flash when using flash bulbs. I have a gadget I think was called a 'sputnik' that has one male PC terminal and three female PC terminals. The modern equivalent is to buy wireless triggers from gadget infinity or the like (poor man's pocket wizards) and set multiple receivers on the same channel as the single transmitter.

    Flash bulbs firing circuits usually incorporate a capacitor, with a bleeder resistor to charge the cap. The capacitor ensures that there is enough current on hand to quickly initiate the priming paste inside the bulb.

    Be prepared to be a bit of an electronics shop dabbler to advance these efforts. I am lucky that there are several such shops within a 20 minute drive; many areas are limited to mail order, which can cramp one's spontaneous creative urges.
    my real name, imagine that.

  5. #5
    holmburgers's Avatar
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    Hmmm, ok. Well I've always wanted to get into and know more about electronics but I've yet to find the right resource. What I need is a good book.

    Sooo, if I might need a capacitor, perhaps it will be easier to just use my Honeywell Tilt-a-mite and hook up to the existing PC cord. Does it matter if I use the pin or sleeve for + or - on the battery?

    Delay mechanism aside, a camera merely completes the circuit to fire the flash, right?
    If you are the big tree, we are the small axe

  6. #6
    Ian Grant's Avatar
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    Open flash is very straight forward, and you can just use a bell button switch to fire the circuit, no electronics just find a cheap second hand flash bulb attachment they are next to nothing these days.

    I've just been asked about adding flash sync to an early Thornton Pickard roller blind shutter, not feasible for flash bulbs where only open flash could be used (open shutter trip flash, close shutter) but dead easy with electronic flash. Should sync even at 1/90th

    Ian

  7. #7
    Rick A's Avatar
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    Quote Originally Posted by holmburgers View Post
    Thanks Ian. For what I'm trying, the shutter can be open (complete darkness) and in that case, will the simple circuit I describe do the trick? There aren't any other components in a simple flash-bulb gun are there?
    Try it out. The worst that can happen is success. I've done something similar with electronic flash. Lock the shutter open then run around in the dark firing the flash via the test button.
    Rick A
    Argentum aevum
    BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"

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    Check out a Tilt-A-Mite flash, you can find them in ebay all the time, they run on 15v and have a capacitor in them to fire the flashbulb. I have fired mine with a little battery pack I made out of 10 AA batteries, I normally just hook it to the PC connector on either my Pentax 6X7, or Nikon FM, FA, or N90s. I did try slaving one off an SB-28 flash once, learn from my mistake and don't do that.

    Anyway, you can use either a PC to PC extension cord, there is a the caver's method of having your friends fire the flash bulbs when you tell them to, or you can get those wireless flash slaves they sell on ebay. If there is a chance that you could kill a flash slave it may as well be a $20 one.

    One other word of caution, do not fire a flashbulb in an enclosed space with or really close to a wet cell battery (motorcycle or car battery) they can explode, and photographers, models and kids firing flashbulbs with car batteries have been injured by this.

    BTW, your about two weeks late, I tossed out my old altered Polaroid flash that I used to use on my Pentax, I would have given it to you, and yes, it was working and had a battery in it.
    "Would you like it if someone that painted in oils told you that you were not making portraits because you were using a camera?"
    "Shouldn't it be more about the joy of producing and viewing the photo than what you paid for the camera?"

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  9. #9
    holmburgers's Avatar
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    Thanks guys. bblhed, I acutally do have a tilt-a-mite, it's a beauty!

    Rick, I think I will just go for it and see what happens. You've gotta break eggs to make an omelet, so I guess you've gotta flash some bulbs to .. uh, well whatever...

    If you are the big tree, we are the small axe



 

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