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trigger for digital camera

Discussion in 'Electronic Basics' started by DorkyGrin, Sep 29, 2008.

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  1. DorkyGrin

    DorkyGrin Guest

    I've got a digital camera that I am trying to connect to a motion
    sensor. I've disassembled it and have the wires available to wire into
    a circuit. I have three relays. I need a circuit to trigger the camera
    in this fashion:

    1. Receive signal, activate Relay A and hold for 10 seconds
    2. Same signal, after a couple of seconds, activates Relay B for 5
    3. Same signal, after a couple of seconds, activates Relay C for 2
    4. Then reset all relays for next event

    These steps simulate Power, Focus and Shutter.

    It's been awhile since I've worked with 555 timers, but I think tying
    them together in a circuit might be the simplest way to make this
    happen. I believe a 555 timer configured as a monostable one-shot
    could be used for Relay A. What I'm not sure about is steps 2 and 3,
    maybe a 556 timer that has some sort of startup delay?

    Or would this project be easier with some sort of PIC?

    Open to ideas.

  2. neon


    Oct 21, 2006
    You got it right use LM555 AS MONOSTABLE FOR THOSE TIMES one after the other to do whatever you do since pin 2 needs only 50ua to trigger it is very well suited for that task. However i might point out maxim does have these devices for cameras 2mm x2mm each costly. the lm555 can source and sink 300 ma load so direct interface is possible without relay. have fun.
  3. DorkyGrin

    DorkyGrin Guest

    Hey JF, thanks for the reply. Yes, the shutter should be activated
    after the focus. I think your diagram is correct.

    So, Relay A (pwr) is on for the entire event, Relay B (focus) comes on
    a couple of seconds later and stays on for 5 seconds, Relay C
    (shutter) comes on a couple of seconds after Relay B is activated.
    Then everything times out for next event.

    I suppose something could be done to keep activating Relay C when an
    event from the motion sensor is received during the 10 seconds, but I
    wanted to keep it as simple as I could.
  4. ehsjr

    ehsjr Guest

    It might be easiest for you to use two 555's (or a 556) and
    a 4017. The first 555 (set for 10 seconds) and activates
    relay A. The second 555 (set for 1 second) pulses continuously
    whenever relay A is energized.

    The 4017 counts from 0 to 9, advancing one count each time the
    1 second 555 pulses. Each count has its own output pin on the
    4017. Tie the needed 4017 outputs together with diodes to get
    the needed duration and delay. For example, you wanted a 2
    second delay before relay B energizes, and you want it to stay
    energized for 5 seconds. To do that, use counts 2,3,4,5, and 6
    tied together through diodes to turn on an NPN transistor which
    in turn energizes relay B. In the same manner, energize relay C.
    (I'm not sure when you want C to turn energize - at count 8?)

    Here is a representative partial schematic:
    + Vcc ----+
    ----- |
    { } [Relay]
    |4017 |-2--->|----+ |
    | |-3--->|----+ /c
    | |-4--->|----+--[1K]---| NPN
    | |-5--->|----+ \e
    | |-6--->|----+ |
    { } |
    ----- |
    Gnd ------+

    You need to add a diode across the relay with anode tied to
    the collector side. The numbers 2 through 6 are the count
    numbers (not the pin numbers) of the 4017. Each count is
    connected to t6he anode of a diode - all diode cathodes
    are toed togehter and connected to the base of the NPN
    through a 1 K resistor.

    You can find an example 4017 circuit here:
    You would connect the output of the 1 second 555 to the
    clock input (pin 14) of the 4017 and would not use the
    4093 circuit. The outputs would be wired as indicated

  5. DorkyGrin

    DorkyGrin Guest


    I don't have a data sheet on the PIR as it's something I picked up
    couple of years ago a closeouts place. It's actually a wireless PIR
    that, when motion is sensed, makes a receiver play some sort of
    recorded message ("intruder", "quit picking my flowers", "get off my
    lawn"). I think it has adequate range between pir and receiver, maybe

    I'm planning on hacking the receiver and finding some kind of output
    and pushing that to the circuit.

    I've been having great conversation on another forum about using a PIC
    (picaxe) which seems like it would be loads easier due to the timing
    issues. Pretty cheap too.
  6. DorkyGrin

    DorkyGrin Guest

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