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How to modify the circuit board to trigger a camera?

user4184095
Prodigy 195 points

Hi:

Could anyone help me to check if my solution is right or wrong? I have realized that I should modify the system circuit board to trigger a camera! There are two solution below:

1.detach the R292 and weld a 0 ohm resistor to R291 as the picture below:

2,detach the R292,weld a 0 ohm resistor to R291 and R295 as the picture below:

the following picture is the camera' trigger circuit pictrue:

So I think the correct solution is the picture below:

Could anyone tell me which solution is right? if both solution are wrong,how should I do?

Thanks a lot !!!

  • 0
    TI__Mastermind 30875 points

    Hello,

    Your hardware mod basically taking out a 5.0V reference signal as triggerout to connect to the camera.

    My suggestion is make the hardware suggestion by referring to your camera trigger input configuration, also note that the LightCrafter EVM can give few mA of current for the trigger signal, so even though you might see a valid (as per the hardware modification shown by you ) 5V trigger pulses coming it may not be able to trigger camera because it is not having sufficient current to trigger the camera.

    One more thing, many cameras come with opto-coupled trigger inputs, so they are supposed to work with low current signals also. 

    Refer to the application note here http://www.ti.com/lit/wp/dlpa032/dlpa032.pdf 

    Regards,

    Sanjeev

  • 0 in reply to Sanjeev
    Prodigy 195 points

    Hi Sanjeev:

    Thank you for you help!

    There are some information about my camera. Can you tell me if my solution in my first post is right?

    Cable connection method is as follows:

    External trigger signal electrical parameters of my camera:

    TRIGGER + (inner core): + 2V ~ + 24V or -24V ~ -2V pulse,

                                              Polarity can be defined

    TRIGGER- (shell)   :   0 ± 0.1 V

    I F ： 2mA<I F<20mA

    Pulse width:> 45us

    Trigger signal input requirements:

    Strobe (inner core): 5V pulse

     Strobe (housing): Ground

     Pulse width: user settings

    Thanks a lot

    Lijianglong

  • 0 in reply to user4184095
    TI__Mastermind 30875 points

    As discussed in this appnote use Pin-1 and Pin-3 of J7 for connecting to Center (inner core) and housing respectively. Ensure cable is not too long, just to make sure everything alright, test with the same cable and use external signal generator if the camera is able to trigger properly. Then connect to LightCrafter hardware.

    Regards,
    Sanjeev

  • 0 in reply to Sanjeev
    Prodigy 195 points

    Hi Sanjeev:

    Thank you for your rapidly respond.

    As you answer me, I think the solution maybe like the picture below:

    Use Pin-1 and Pin-3 of J7 for connecting to Center (inner core) and housing respectively.  Am I right?

    I am most concerned about is how to  change the circuit board!!!

    Should I detach the R292, solder  0 ohm resistors to R291 and R295 as the picture above? 

     

    Thank you very much!

    Lijianglong

  • 0 in reply to user4184095
    TI__Mastermind 30875 points

    Yes, you are right about Trigger connection.

    I see you have red,white,green and blue connector wires at the J7 connector, where this one is connected? I am assuming that Red and Green wires are now going to the camera connector cable. Is it correct?

    About the resistor changes, you are correct, repeating again, detach R292 and install 0Ohm at R291 to get 5.0 trigger o/p setting, then R295 to get the signal at Pin #1.

    Can you send me the camera model? if you don't want share the the info in the forum send me details via private friend's request.

    Regards,

    Sanjeev

  • 0 in reply to Sanjeev
    Prodigy 195 points

    Hi Sanjeev:

    THANK YOU VERY MUCH!

    I have send my camera's specifacation to you by email,because I don't know how to share it an out  forum! Sorry!

     As you see the red,white,green and blue connector wires at J7, I connect nothing at the the other end of the fire!

    According to your answer,I know that I should detach the R292,then install a 0 ohm resistor to R291 to get 5V supply,and then install a 0 ohm resistor to R295 to get signal at Pin#1.

    Thank you again!

    Lijianglong