Electronic replacement for AG1 bulbs?

Discussion in 'Lighting' started by davidw99, Mar 7, 2013.

  1. davidw99

    davidw99 Member

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    Does anyone know of an electronic replacement for AG1 and AG1B bulbs? I'm thinking of a flash the has a tab that goes into the flash socket to get the signal from the camera. Kind like a hot shoe. Any thoughts?
     
  2. AgX

    AgX Member

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    -) first the camera must trigger in x-configuration, thus without advance

    -) second you need an electronic device that transfers the electric impuls (charge) from the camera in switching the flash-light trigger circuit.
     
  3. AgX

    AgX Member

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    I just checked with my own collection: the only bulb-trigger/electr. flashlight adapters I got are based on Magicube sockets, thus mechanically triggered.
     
  4. bdial

    bdial Subscriber

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    Polaroid had electronic flashes that could plug into the flashbar socket on the SX-70 cameras, but I don't recall anything similar that could plug into the socket for a single AG1.
    Probably the easiest approach would be to use an LED bulb that has the same base as the AG1, such things exist at places like superbrightLEDs.com
    Probably not quite as bright as the AG1, but close, maybe.
     
  5. AgX

    AgX Member

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    Oops. I forgot about those Polaroid adapters (there were PC-cord adapters aside of the complete proprietory flashlights...) Even got such.

    One could try to use a circuit from such an adapter with a DIY AG-plug.
     
    Last edited by a moderator: Mar 8, 2013
  6. Mike Wilde

    Mike Wilde Member

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    The number of contacts will be a challenge, as well as the size of most ag-1, up to M-25 flash holders.
    Flashbulbs hold their light output in the form of wire ready to be oxidized inside the bulb.

    A small priming charge, made to ignite from the glow of a filament heated by current from a single pair of contacts.

    Electronc flash has it's energy stored in an external capacitor, fed from an oscillator circuit.

    he flash tube has two main contacts to discharge the main current though, and a trigger band that is fed from the firing transformer, which kicks a brief high voltage to the trigger band.

    The trigger band causes the electric field potential in the area to rise, thus ionizing the gas mixture in the tube, allowing the main flash charge to discharge as a result of the ion electron current.

    So for electronic flash you need three contacts to the flash tube.
     
  7. AgX

    AgX Member

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    Mike, I guess the question was not of constructing a new type of electronic flash, but rather of adapting an existing flash to somehow be triggered from an AG-bulb socket.
     
  8. henry finley

    henry finley Member

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    The problem of sync still remains. I can think of no dependable way of fabricating a timed circuit. To catch the shutter blades fully open each and every time with a delay circuit would be nearly impossible with the mechanical shutter. When Houston timed the camera panning of the LEM separation on the moon because of the speed-of-light delay, and actually pulled off the feat, luck had something to do with it also.
     
  9. davidw99

    davidw99 Member

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    AgX,

    You're right. I am thinking that maybe I could mount a small electronic flash on a mount and run a couple of wires to the contacts in the camera's bulb holder. Then the current from the camera would provide the signal for the electronic flash to flash. In other words, the current from the camera would bridge the two contacts on the flash (I'm talking a real simple Sunpak flash). The flash will flash if those two contacts are bridged with a wire. Will the current from the camera do the same thing? Proof of concept will be to jimmy a suitable AG1 socket plug similar to the AG1 bulb base and long enough to reach from the recesed bulb hole and then press the camera shutter with wires contacting the two terminals on the flash. Weekend project!
     
  10. AgX

    AgX Member

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    Trying to trigger an electronic flashlight directly with the charge of a camera flash-bulb socket seems no good idea to me.
    With an old type electronic flashlight you would put two (polarized) charge condensators (from camera and flashlight trigger circuits resp.) in series.

    With modern type electronic flashlight I'm not absolutely sure of the effect. In any case the flashlight trigger contacts are intended to be bridged and that should be the way to go.

    Either use a circuit as described by me above or use a solenoid as switch. The latter way would lead to a small time delay.
     
    Last edited by a moderator: Mar 8, 2013
  11. Chan Tran

    Chan Tran Member

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    I thought the AG1 bulb is used in a flash holder? and the flash holder has a cable plug in to the pc connector.
    I have an electronic flash unit that replaces the magicube for the Kodak 110 camera model 50.
     
  12. AgX

    AgX Member

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    There were cameras that include flash bulb sockets, intended for single bulb over cubes up to bars. All these cameras have incorparated a trigger devise. With the exception of Magicubes the triggering is by electric charge. These cameras do not have a electric switch controlling the trigger circuit of an electronic flashlight, nor that PC socket. Bridging the gap from electric charge to switching the flashlight is the concern of this tread.

    With Magicubes the triggering is done mechanically. And by this, transfered by a simple key-switch, used for triggering an electronic flashlight in those adapters/flashlights you refer to.
     
  13. AgX

    AgX Member

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    Here is a circuit diagram of an opto-coupler based adapter for a Polaroid SX-70 camera.

    Keep in mind that the SX-70 camera has a trigger voltage of 4.5 V, the typical AG-bulb trigger circuit would be at 15V. So that circuit would have to be corrected. Those 18Ohms resistors are related to Flashbar control and of no interest here.

    http://www.sx2pc.com/



    The choice of an opto-coupler enables switching quite high voltages. This approach would also be beneficial for a coupling device to trigger old style electronic flashes by modern cameras with electronic switching.
    (I assume my SX-70 adapter contains a transistor.)
     
    Last edited by a moderator: Mar 8, 2013
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  15. John Koehrer

    John Koehrer Subscriber

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    Wouldn't it be easier to add contacts to The shutter? fully open closes the contacts, flash goes off-POOF!
    Not gonna be a bright as an AG-1.
    Want a circuit board from a simple P&S camera? Bare board, you would have to find something to put it in.(no insulation at all.
     
  16. AgX

    AgX Member

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    Well, the shutter already has contacts for flash triggering. In case these are adjusted for x-synchronisation one only would need to lead the wiring outside or install a PC-socket.

    But, this would mean a modification to the camera not everybody tolerates, and furthermore loss of working of the bulb socket.

    And in case one has several models of this type of camera, the modification of one of those old Flashbar-socket adapters seems even more appropriate.
     
  17. davidw99

    davidw99 Member

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    Success! I made a device with two wires wrapped in tape and sandwiched between two pieces of thin plastic. The wires extened below the bottom of the plastic and turned up like the wires on the flash bulbs. I put this end in the flash socket. On the other end the wires extened about three inches out of the plastic sandwich. I touched these wires to the contacts on the flash, turned the flash on and hit the shutter buttonon the camera. The flash flashed. Now I have to make one strong enough for daily use.

    Thanks for all the suggestions and help.

    AgX: Those SX-70 flash adaptor are cool.
     
  18. AgX

    AgX Member

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    I'm surprised that it worked. I assume the battery in the camera was empty and the camera capacitator thus uncharged.
    So the electronic flashligh trigger capacitator send its charge to the camera trigger capacitator yielding enough current to trigger. This should not work when reversing your selfmade contact.
     
  19. AgX

    AgX Member

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    In a next step you should test

    -) if you can trigger your electronic flashlight repeatedly and not only once

    -) if your camera synchronizes correctly
     
  20. davidw99

    davidw99 Member

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    Hi again,

    For your first suggestion, yes I did fire the electronic flash repeatedly.

    For your second suggestion, I haven't tried it to see if the camera synchs with the flash. At the time I had no film. Now I can give it a go.
     
  21. AgX

    AgX Member

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    Concerning the issue of synchronisation for electronic flashlight you won't need film:

    Charge and connect your electronic flashlight, open the back, look from behind into the camera Barrel and then press the camera release.
    If you see the flash lighting through the lens, the synchronisation should basically work.
     
  22. ell020

    ell020 Member

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    Hello Chan Tran

    please can you tell me which flash unit you have or had that replace the magicube for the kodak 110 model 50?

    regards
    ell020
     
  23. Chan Tran

    Chan Tran Member

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    It's a no name Cortina CS260. I would post some pictures when I have them.
     
  24. Steve Smith

    Steve Smith Subscriber

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    An LED to triac opto isolater would do it. You would need to use x sync contacts though, or include some sort of delay circuit as the trigger for a bulb happens early to allow the bulb to get going.

    A series resistor (needed anyway) and a capacitor across the LED side of the opto isolator could work.


    Steve.
     
  25. Truzi

    Truzi Subscriber

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    I have an ACME-Lite 138 that I use with my Grandmother's Minolta Autopak 600-x (126 film camera), though it does it in the way of the Minolta's few controls. It works in place of Magic Cubes and Flip Flashes. I think it would clamp onto a 110 camera.

    Here's a photo someone put on flickr:
    www.flickr.com/photos/22746498@N02/9286355557/in/pool-33116133@N00/

    You could probably find one on ebay.
     
  26. alanrockwood

    alanrockwood Member

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    I skimmed through the posts but did not read them all in detail. Therefore, I apologize if my comments have already been covered.

    There are at least two technical issues to deal with that relate to synchronization. First, for flash bulbs there is (I believe) a delay between triggering of the flash and opening of the shutter. This is because for flash bulbs it takes some time between the trigger and the main part of the light output. With electronic flash the delay is short and can be treated as if it were instantaneous.

    The second is that flash bulbs emit light over a rather extended amount of time whereas electronic flash emits light over a very short amount of time which can be treated as if it were instantaneous.

    In principle it is possible to design electronic circuits that will compensate for both of those effects. In fact, the second is already implemented in some commercially available electronic flash units. In some products it is called FP synchronization, and it works by dividing the total output into a series of repeated flashes, each of lower power.

    This extended flash duration is mainly useful for cameras that use a focal plane shutter. For cameras that use a leaf shutter, or for focal plane shutters at low shutter speeds, it is sufficient to just compensate for the first effect, i.e. to introduce a delay between trigger and the beginning of light output.

    There are, of course, also some other technical issues to deal with.
     
    Last edited by a moderator: Feb 1, 2015