Countdown at the press of a button?

Discussion in 'The Projects Forum' started by Gilbernata, Jan 10, 2015.

  1. Gilbernata

    Thread Starter New Member

    Jan 10, 2015
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    Anyone with more DIY experience than I? (I am a complete noob so the answer is yes of course!). I require some assistance with what i wish to do as a cool project.



    I do archery at my archery club every weekend. Ive been thinking of some neat tech related ideas for my bow, one of them being an arrow countdown. What i wish for the outcome of this project to be is...



    -A small digital display attached to my bow shows the current amount of arrows I have in my quiver. ("Quiver": Basically a belt made to hold your arrows)


    -Lets say I have 6 arrows in my quiver.


    -I take a shot at a target with my bow, the bowstring triggers a small switch which changes the amount of arrows displayed on the digital display from 6, to 5.


    -I shoot again, the display will show i only have 4 arrows now, and i shoot again, 3, again 2, again 1, again 0...


    -Reaching zero (0) will trigger a red LED to come on as extra warning that I have no more arrows left.


    -After I have shot all 6 of my arrows and the display reads zero (0) I will walk out to the target to retrieve my arrows. The display will read zero (0) until I press a reset switch on the bow.


    -When i press the reset switch it automatically brings my arrow count back up to six (6)


    -I also want the option to increase or decrease the number of arrows I have. So lets say I add 2 more arrows to my quiver, giving me a total of 8 arrows. I would need a switch for increasing my arrow count on the display, and i would also need a switch for decreasing my arrow count on the display.


    This will be best if i could get it all to work off of a 9V battery power source. If someone is experienced in DIY projects like this and can help me out here it will be greatly appreciated. What would be really useful to me is a list of components i would need and possibly a wiring diagram if you would be so kind.



    Thank you in advance for your knowledge and any help you can offer.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Doable, with some technical challenges here and there.
    I will let others chime in with their ideas.
     
  3. Gilbernata

    Thread Starter New Member

    Jan 10, 2015
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    Thank you. I do not know where to begin. I am a beginner with soldering knowledge and computer hardware/software knowledge but not much else. So even if anyone knows of or could sketch me up some kind of wiring diagram and a components list i could take it from there. And any ideas on how to simplify this idea a bit would be helpful too but not required.
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,449
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    Not to worry about the wiring diagram just yet. There are some design issues to consider.

    An LCD display will use much less power than LED display. Do you ever shoot in the dark or dim lighting?

    Instead of a digit display could you settle for a row of 10 LEDs?

    Is there a spot on the bow for a small unit?

    9V battery is overkill. You can do this with a couple of small coin batteries

    The "twang" of the bowstring is very intense. It would be very easy to build a circuit that detects when the arrow is released.
     
  5. Gilbernata

    Thread Starter New Member

    Jan 10, 2015
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    I was hoping the 9V battery would allow for a longer lasting power source. That way i wouldnt have to worry about changing the battery that often.

    The only problem with a row of LEDs would be that I would only be able to have a set amount of arrows, if i wanted to have 20 arrows but i only had say 8 LEDs then that would become a problem. But if it will be much easier in the end then i will consider it.

    Not to get too technical about archery (not sure what your experience is with the sport) But I have a compound bow, which has a mechanical part on it that the arrow rests on. This is called the arrow rest. when you shoot the bow the rest drops down out of the way of the arrow fletchings (or feathers) so that they may pass without any contact with the riser (the part of the bow you grip with your hand). A switch would be more useful to me as I could make use of when the arrow rest drops down. Each time it drops down (meaning each time i shoot) the rest would hit the switch, thus lowering the number by one.

    And yes there is a nice spot on the bow that i could attach the unit to.
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    The extent of my archery experience is making a bow from a sapling and arrows from cornstalks as a kid, also archery at summer camp.

    I think a mechanical switch is doable but I still like the idea of a solid-state sensor to detect when the arrow is released.
     
    Last edited: Jan 11, 2015
  7. Gilbernata

    Thread Starter New Member

    Jan 10, 2015
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    Sounds fun! But It may have to be a switch tho. Im not sure how.... light, for lack of a better word, of vibrations a solid state sensor would be able to pick up. My compound bow makes almost no vibration when the arrow is released, I specifically put vibration reducing rubbers on my bow for better accuracy. As well, I dont have a solid state sensor but i do have small tactile switches in my inventory of DIY stuff tho.
     
  8. crutschow

    Expert

    Mar 14, 2008
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    If you have computer hardware knowledge then perhaps a small micro to control everything and generate the output display would be the simplest and smallest solution.
     
  9. Gilbernata

    Thread Starter New Member

    Jan 10, 2015
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    What would your recommendation be?
     
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