Audio playback device

Discussion in 'The Projects Forum' started by Lambolou, Nov 12, 2012.

  1. Lambolou

    Thread Starter New Member

    Nov 12, 2012
    4
    0
    Hi there, just a quick note, I'm sorry if I get any terms wrong or if my lack of knowledge is irritating.
    The project I'm trying to build is an audio device to fit into an air soft assault rifle. My plan is for every time the trigger is pulled the noise from the real gun will play from speakers hidden in the stock. Ideally I would like the sound to be as high quality as I can get it either using mp3 or .wav. It will be fitted in line between the trigger mechanism and the motor. The rifle has two firing modes, when it is semi-automatic a single 'burst' of electricity is allowed through every time the trigger is pulled, when in fully automatic the trigger is held down allowing electricity to continually flow through to the motor. Obviously it would seem silly for the noise to play once when the gun is still firing so the audio file would need to repeat itself with sustained electricity. I would like to be able to switch to a secondary audio file which would be the real rifle suppressed, to allow continued realism with a silencer attached to the airsoft rifle. I have a limited knowledge of electronics, can make breadboards, pcbs, solder and can follow circuit diagrams reasonably well. I've tried googling solutions but haven't found anything to satisfy my needs.
    To summarise:
    -mp3 or wav playback, best sound quality possible.
    -Push to make switch(trigger)
    -must be able to run off 9v battery efficiently(airsoft battery is a 9.6v 4400mah)
    -can play 2 different audio files changed by a switch, pref. 3 way switch. off, sound 1, sound 2.
    -if voltage continues audio repeats itself until the voltage stops.i will also need to be able to adjust the replay speed.
    Thanks for reading and sorry for long post
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    You'll need a microcontroller with enough storage for the sounds you want. Only you can define this - you need to specify the bitrate and time. That will determine what you need to store and playback.
    I think you already have the mechanical trigger, right? I mean, you should be able to tap into the existing electrical signal without needing a way to detect a trigger pull?
    Great, that should be fine.
    Not a problem, except you need to actually choose the switch. I'd consider a single microswitch that toggles the various options digitally. I assume ruggedness against water, dirt and impact is important? (I just went paint-balling and that's what I'm picturing.)
    I think if the above issues are dealt with properly, this should be no problem.
     
  3. Lambolou

    Thread Starter New Member

    Nov 12, 2012
    4
    0
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The speaker you can fit into the stock of a gun is tiny.
    Have you tried to play gun sounds through a tiny speaker? It doesn't sound like a gun.
     
  5. Lambolou

    Thread Starter New Member

    Nov 12, 2012
    4
    0
    It depends on the speakers you get and the quality. I've had a few 2-2.5" that have given 10" speakers a run for their money
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    I'll agree that you might be able to get a satisfactory result, but don't kid yourself. A 10" speaker has roughly 25 times as much surface area. A given deflection of, say, 1cm of the speaker cone, will produce 25 times as much air movement as that little speaker. And a 20Hz sound wave is 70m long.

    Of course what counts is what your ear drum receives. Proximity matters.
     
  7. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    I don't think this switch would work - in the description, they say momentary. This means when you push the switch in one direction, it will immediately return to the center (off) position when you release it. I think you need a latching switch.

    You could use two recordable greeting card modules, one for each sound. Their triggers would be tied to your trigger and their power inputs would go through the switch you mentioned so only one could be on at a time. You could use one speaker wired to both circuits to save space - again, only one will be on at a time.

    If you want better quality sound, there are small MP3 players that have built-in amplifiers and accept SD cards of various sizes. The only caveat is being able to select specific tracks as you want to do. Tracecom found this and mentioned it in another post: http://www.ebay.com/itm/170817129384?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649.

    I'm working with someone using a recording module that stores files on-board via USB only. Unfortunately, the website for the company seems to be down, so I can't post it at the moment.
     
  8. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    My computer speakers have 3" drivers with huge magnets. They are in 1 litre enclosures that the gun stock will not have unless it is completely hollow.

    I found gun blast demo sounds and played them through my computer speakers and it sounded realistic.
     
  9. Lambolou

    Thread Starter New Member

    Nov 12, 2012
    4
    0
    Could I use 2 cheap mp3 players with one sound file on each? They would then only be powered when the triple switch is selected for that sound bite. My only problem that I can't understand is that the play button is both a play/pause button? Surely if there is constant power to the play button it will just flick between play and pause and not repeat the sound bit? Or if the play button is triggered faster than the sound bites length it will pause it rather than play again?
     
  10. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Yes.

    Yes, again assuming the triple switch is used to select which player is powered. Keep in mind the players will probably need a few seconds up to a minute to warm up. In other words, you probably won't be able to flip the switch from one player to another (or from off to one of the players), pull the trigger immediately afterward and have it play a sound.

    Usually, this is common for most MP3 players.

    Depends on the player. You might be able to add a few components so that the signal to the play button is edge-triggered. This means if you press a button and hold it down, the player will only react to the initial pressing down. Some info here: http://www.kpsec.freeuk.com/555timer.htm#edgetrigger.

    By triggered, I assume you mean the play button is effectively pressed, released, and pressed again before the sound bite finishes? Certainly a possibility, but again it depends on the player. You could add a timer to account for this such as a 555. I don't know how much physical space you're limited to though.
     
  11. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    +1

    Most of the sound of a gun blast is low frequency, it will be completely missing from the sound reproduced. I suspect it will sound more like a hiss than a boom.
     
  12. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    It will sound like a small bird, "Cheap, cheap, cheap".
     
Loading...