Help regarding Digital Switch

Discussion in 'The Projects Forum' started by SlasherPay, Jul 16, 2012.

  1. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    Dear Friends, I need some expert guidance here. I'm making a device to control my digital camera from a Remote that I will connect using a wire.
    I'm avoiding use of solid state relays to keep the switching end as compact as possible. Keeping the sensitivity of sophisticated digital camera electronics in mind, what should I use to switch camera controls (I mean camera buttons for zoom, shutter etc) [Bilateral Switch, Opto-Isolator what??] I don't want any kind of voltage from the switching circuit flowing into the camera under any circumstances, so what will be used for added protection. Please provide me a schematic if possible, mainly for protection. I will be very grateful for this. :confused:
    [​IMG]
    Another question, a small one, which protocol should I implement that has reduced complexity for developer, instantaneous response, and most importantly simultaneous transmission of multiple signals since I will be pressing multiple buttons on the remote. [1-wire, I2c, SPI etc??] I can also use 434Mhz wireless, but have no experience with that so I can't tell if it fulfills above objectives (Simultaneous, Instantaneous) :)
     
    Last edited: Jul 16, 2012
  2. WBahn

    Moderator

    Mar 31, 2012
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    How about getting a camera this is intended for remote operation?

    You need to specify what you mean by "instantaneous" and "simultaneous". They have very specific meanings in the world of engineering and, if you really want those, then you will find that you (a) can't have them and (b) can't afford what would get you closest to them.
     
  3. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    Thanks for your reply.
    MICROCONTROLLER= AVR
    Instantaneous I'm referring to time between pressing the button on my remote and the response from Camera through the Receiver. I'm not going for such a Camera that comes with a remote for a "variety" of reasons. First of all, the exact spec Digital Camera I want does not come with a remote, and even the ones that come, don't generally offer anything more than just a shutter release. So I am customizing a remote as per my requirements.
    Simultaneous as I said in my initial post, I'm referring to pressing multiple buttons on my remote and want that my command signals should be transmitted simultaneously rather than one by one. I could be Zooming to a subject while simultaneously panning the camera (through a stepper ofcourse). So I need both of these events to occur real time and simultaneously when I command them to from remote.
    And answering your final query, affording is not a limited factor for me, and one way or the other, I will have what I want. If someone can help me, I will be thankful from the deepest corner of my heart!!
     
    Last edited: Jul 16, 2012
  4. Sensacell

    Well-Known Member

    Jun 19, 2012
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    3 meters!

    Just buy some multi-conductor cable and wire up switches- no "protocol" necessary!

    KIS Keep It Simple
     
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  5. wayneh

    Expert

    Sep 9, 2010
    12,129
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    You're asking us? Without telling us what camera you have? RTFM

    The thread and circuit here might give you an idea of how to simulate a button press, if that helps.
     
  6. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    Bro my diagram is self explanatory related to my question. It doesn't matter which camera model I'm using. As you asked me, its Nikon Coolpix S8200 CMOS. This link is based on the 555 and will not do at all, I don't want to use any type of relays. I want to substitute camera controls with an electronic switch, but it should not pass any voltage back to the camera. I'm not sure what it has to be, a Bilateral Switch, an OptoIsolator, a combination of both or something else. :)
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,

    If you want the isolation by an optocoupler, you could take a look at the following optocouplers with fet outputs.
    (see attached datasheets).

    Bertus
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    As I said, "instantaneous" means zero time delay. Not 1 second, not 1 microsecond, not 1 nanosecond, but zero. Since you want to operate it from 3m away and since it takes light about 10ns to travel that far, and since you are intent on instantaneous, the project is impossible.

    Any wireless approach is going to involve latency. The transmitter has to transmit a signal and the receiver has to spend enough time looking at the signal in order to recognize the information it contains. You are not permitting any time to do that. So forget wireless.

    Running multiconductor cable to your camera is an option, but it still won't be instantaneous. In fact, the delay will be two to three times the light speed delay of a radio signal since the speed of propagation for a signal in a conductor is less than that of an E/M wave in vacuum (and free air is close to vacuum for this purpose).

    Then go to the manufacturer of the camera you want and commission them to make the modifications you want, but be sure to tell them that you want it to be both instantaneous and simultaneous.
     
  9. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    I suppose you've read my question now but interpreting it in the "literal" terms. I perfectly understand the Propagation theory, latency etc, so asking my question and using these terms automatically implies I'm not trying to do something that is impossible or to bend the laws. If you are still so sticky about the terms, then okay "Near Instantaneous", I hope it is okay with you and now I can hear some viable solution from your side.
     
  10. WBahn

    Moderator

    Mar 31, 2012
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    A viable solution depends on having viable specs. "Near Instantaneous" is only a little bit better than "instantaneous". There is a world of difference between being able to tolerate 100ms of latency and only being able to tolerate 1µs.
     
  11. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    This looks like a good option. I'm inclined towards using a quad Bilateral switch since I will be getting 4 switches in a single package, so three or four of these will do the job. I need to know if Bilateral Switches are safe to switch sensitive electronics like that of the digital camera.
     
  12. WBahn

    Moderator

    Mar 31, 2012
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    They should be. The main thing you need to determine is if their "on" resistance is low enough to be seen the camera as a pressed switch. You can do this by taking a resistor that is about twice the max rated "on" resistance and putting it across all of the various switches you intend to interface to and seeing if they reliable see it as a closed switch. You should probably do the same thing with a resistor that is half the minimum "off" state resistance to ensure that you can release the button, but this is probably not going to be a problem.
     
  13. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    Great and Thank you friend. How about this one and its low Power ON Resistance?
     
  14. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    Yes this seems like a perfect test. The 4066 manual says High Effective Off-State Resistance: 10 pA. What resistor shall I be looking for to test the OPEN state of switch? :) And it also says, Crosstalk between switches -50dB so I don't think it will be a problem. And lastly, it says "Extremely low OFF Switch Leakage 0.1 nA" Can I add a small resistor small enough to make sure even this is entirely blocked? :) Thanks again for all the help :)
     
  15. wayneh

    Expert

    Sep 9, 2010
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    All you said previously was "digital". I have several digital cameras for which this project would be near impossible. Actually, I'd add your camera to this list. You must be prepared to disassemble your camera to gain access the the various buttons?

    The circuit I linked does indeed use a 555 timer to debounce the input. Your camera probably does this already, so that part may not be necessary. But in that project, the OP was able to use a MOSFET to simulate a button press. The stopwatch and his circuit shared a ground, but there was no path for current from the circuit to the stopwatch. All very similar to your needs.
     
  16. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    My friend, My solution can be applied to any Digital Camera in the world (ofcourse except the functionality in the touchscreen camera other than shutter release), no matter how tightly packed or small or DSLR. Yes the camera needs to be disassembled just once, just enough to solder link wires for respective switch inputs. I will make this feature accessible using a female header that will be bonded to the camera body by making a neat slit using a cutter, making sure it certainly looks "factory". I will post the pictures and the video on youtube when I'm done :) It will not just offer the shutter release, but zoom as well besides other functionality (other buttons on the camera) and Pan/Tilt as per the setup (camera can be fixed on the Servo/Stepper Jig though the Tripod mount hole). Now tell me how is it NOT possible or near Impossible :) Using a couple of Quad Bilateral switches instead of too many MOSFETS, will also reduce the energy consumption and complexity of this project.
     
    Last edited: Jul 16, 2012
  17. wayneh

    Expert

    Sep 9, 2010
    12,129
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    Ha, well I admire your skills. Many new members come here with no experience and little understanding of basic electronics, so please excuse me underestimating your ability. Having opened a camera or two myself, I have great respect for anyone that can work inside of one.
     
  18. SlasherPay

    Thread Starter New Member

    Jul 16, 2012
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    No problem my friend, I've read your other thread and have seen how you extend yourself to help others solve their problems and I've respect for you :)
     
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