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Circuit for reactive archery target

  1. Jul 20, 2016 #1
    Hi guys! I'm new to tinkering with electronics, but I would like to design a reactive archery target that consists of two foil plates, that connect when pierced with an arrow, closing a switch, causing a photography strobe to go off. Does anyone know where to start? I bought an arduino and a breadboard but haven't been successful in getting this thing to work yet.

    I would also like to add multiple targets for a round of shooting (without walking up to the circuit to reset the system).

    Any help would be much appreciated. Thank you!!

    Screen Shot 2016-07-20 at 9.35.32 AM.png
     
  2. jcsd
  3. Jul 20, 2016 #2
    That sounds like a nice project...


    Do you apply voltage (5 V) to one foil, and measure the voltage on the other via the ADC (analogRead())? What kind of foil do you use, and how are the separated, are they gonna be replaced after every shot?

    It might also work by using a special arrow, or measuring the presence of an arrow capacitively (change in capacitance of the foil) or inductively, magnetically (hall sensor + magnet). - Or more easily, by an impact sensor! Simply a piezo speaker that picks up vibration (contact mic), that can be amplified and measured. Or some light/IR barrier... many possibilities there. - Do you need to know the exact position of the bolt on the target?


    Either use one arduino, and long cables to hook them all up to one central one, use multiple ones for every target or connect them to the player via radio (look up 433 MHz modules for simple serial communication (cheap, but error prone), or WiFi (ESP8266 and the like), or things like ZigBee/Xbee/nrf24l01 for more advanced/reliable systems).

    I recently made a small test with laser diodes, and simple LDRs to activate a target in small point'n'shoot game prototype... but it's certainly not the same as using a bow and arrow! That needs more skill....
     
  4. Jul 20, 2016 #3

    anorlunda

    Staff: Mentor

    What have you tried so far? The most straight forward way would be two pieces of tinfoil, separated by less than the length of the metallic arrow point. You may need an interrupt to respond quickly enough with the Arundino. You might consider skipping the computer and wiring the foil right to the strobe trigger.

    If I were you, I would be posting this question on photography forums rather than electrical engineering. I'm sure that countless photographers have done similar things.
     
  5. Jul 20, 2016 #4
    Hi 1rel! Thank you for your response.

    I cutout the flat part of a paper plate, fold it over on itself and glue foils to it, so that when the arrow pierces, it connects the two pieces together and closes the circuit. These would have to be replaced every shot. So far I've tried to connect the strobe, a resistor, and the switch in series hooked up to 5V on the Arduino and nothing is happening. Should I be doing something to protect the Arduino from the high voltage spike of the strobe?

    I have thought about an induction target. I will look into the hall sensor + magnet scenario and the possibility of measuring a difference in capacitance. Because the arrow pierces the target (and 4 inches of foam behind it), an impact sensor wouldn't work I think. For this first round, I want to figure out how to get it to work the simplest way I can and then I'll experiment with different methods of triggering the strobe.

    I am looking at using long cables to hook all of them to the central arduino. Is there a way to do this without an arduino?
     
  6. Jul 20, 2016 #5

    anorlunda

    Staff: Mentor

    You should have one foil attached to 5v, and the second foil attached to a voltage sensing input to the Arundio. Then a digital output from the Arundino triggers the strobe. Software in the Arundino senses the change in input and commands the trigger to fire.

    Have you tried photography forums, books and magazines? Have you seen Mythbusters on TV? How do you think they trigger those high speed cameras? It is a very common thing to do. You should not need to design your own solution.
     
  7. Jul 20, 2016 #6
    Probably, it will be difficult to make this very reliable/consistent, because you never know if the the foils really make a good contact for every hit. You could try to use an interrupt instead of polling the pin (via ADC or digital), that might catch the change in voltage on the pin when the arrow hit and raises/lowers the voltage for a short amount of time. https://learn.sparkfun.com/tutorials/logic-levels ... using a pullup or pulldown resistor, and a capacitor to dampen/"extend" the spike - some kind of debounce circuit (it will certainly never give you a stable good contact, so a simple, repeated digitalRead() (polling) on the pin will possibly not work).

    There's also an interesting material called velostat, that could help to make some kind of pressure sensor. Or to make it more conductive and reusable, you might use conductive fabric/textiles, and a conductive/metal arrow head.


    When you'd like to work with the microcontroller/arduino, just print out some messages via serial to see what's happening. I'd leave the strobe away for now, to make the detection work first.

    How do you trigger the strobe, with some kind of relay? I don't know much about that part...


    After thinking about it for a bit, I guess that it depends on the size and accuracy you need for the detector.

    The infrared LED + photo diode/transistor solution might work, when the arrow only triggers in one tiny spot (precise hit).

    On the other hand, with the piezo vibration detector idea, the problem would be that it would trigger also when the arrow hits the target just somewhere you don't want it to (it might be possible to hang the target on some springs, or dampen the vibration it with foam...).

    Both of those solutions would not be that hard to get working, I think.


    Anorlunda mentioned, that you could leave the (tiny) computer away altogether, and try to detect it with an (analog) cirucit (in case of the piezo/IR solution, it would probably involve OpAmps as voltage amplifier, peak detector and schmitt trigger of some kind - I've once tried something like that for a pluck detector of a string...).
    Or you can also use a different microcontroller (like the ATtiny85 for example, which is also Arduino compatible, but smaller and much cheaper, or some ARM controller for more speed/advanced features like cap sense) to get rid of the cost of the Arduino...
     
    Last edited: Jul 20, 2016
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