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RF trigger circuit...

Discussion in 'Radio and Wireless' started by eight08, Apr 16, 2010.

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  1. eight08


    Apr 16, 2010
    Hey guys, i'm trying to build an RF trigger circuit, something like this,, just scroll down, you'll see an RF wireless trigger...

    but unfortunately, he didn't include the parts list and the schematic, it seems simple to build, but does anyone have another or better idea?

    i don't mind soldering or circuit building. :)

    thanks for any help
  2. NickS


    Apr 6, 2010
    He did not provide the scematc and partlist because he wants you to buy his product.

    Now I speculate that you want to make them as a cost savings? In which case your bill of materials for Rx and Tx plus your circuit board fab cost cannot exceed $80 for you to be saving money. It is unlikely that you could even come close to that for small quantities.

    The frequency being used 430MHz is to high for you to whip out a breadboard and string wires back and forth. Impedance changes in high frequencies = loss and reflection so you need the trace impedance control that a custom PCB could give you.

    However I don't wish to crush your aspirations so if you still want to make one knowing that you will need to spin a impedance controlled board then let me know and perhaps we can track down the right IC's to base your circuit around.
  3. eight08


    Apr 16, 2010
    Thanks NickS. I'm a DIY type, i'm trying to build it for my camera's external flash, i'm gonna hook it up with another one of my projects for it to trigger. I can't afford the original or fabricated one already... :(

    Thanks for the help again! I'm gonna look around!
  4. NickS


    Apr 6, 2010
    That is fine. There is not a lot of high frequency DIY out there because many of the DIY methods become impractical at high frequency. It will be tough so in your hunting think lower frequencies may be a better fit for you.

    In fact now that I think about it you may be able to do something in the hobby R/C bands(~27MHz) and you may be able to mod a cheap R/C toy to assist you with the comm's stuff then it would be a matter of interfacing with the appropriate switches/relays and supporting low frequency and DC circuitry to accomplish your goal.
  5. 55pilot


    Feb 23, 2010
    Are you trying to use the RF to trigger an external flash? If so, you have some serious time constraints that you need to worry about. The flash has to happen fairly quickly while the shutter is still open. Some of these approaches will not work because they take too long. A relay is going to take several milliseconds to close, which may eat up most of your time budget.

    Also, as Nick has already pointed out, your first post was asking for help in committing theft. I can not speak for anyone else, but I do believe that most of the regulars here will not help you steal. If such requests becomes a pattern, you may find it very difficult to have people answer any of your questions.

  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    For most cameras, you can rely on the shutter being open for around 5 mS after the signal to fire the flash (it will never be more than about 10mS for a 1/60 exposure).

    Most of the energy in a flash is emitted in 2 or 3 mS (it depends a lot on the power -- at lower power settings the flash can be much more brief, and studio flash units can produce a quite prolonged flash at high power)

    All of which means that you have to trigger your flash in no more than 2 mS. Given that you need time for the transmitter to start, and time to recognise a signal (rather than react to noise), you have quite a tricky task.

    It may be easier to have the transmitter running continuously and to *stop* it to trigger the flash.
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