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Author Topic: Fun electronics project  (Read 2848 times)

ksuguy

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Fun electronics project
« on: November 13, 2014, 10:42:05 pm »
As some of you know,  I'm a big geek that likes to attend the occasional convention.  Last year I finally decided to do the costume thing and I went as a Cobra trooper from the old GI Joe cartoon.  It was a lot of fun, and I enjoyed it more than I thought I would. 

The next big event is Planet Comicon up in Kansas City in March, and I've decided I need kick things up a notch and turn my airsoft AK-74 into a "working" laser rifle with light and sound.   After some initial research, I think this should be doable.   My airsoft rifle has a bore diameter of about 6mm.   I think I should be able to get some battery powered blue LED's like these and feed them through the barrel.    The only difficult part will be figuring out where to put the battery pack.   If it was a real AK, that would be easy.  There would be plenty of room in the magazine if I took out the spring and follower.   However, that's a bit tougher with an airsoft magazine. There is a bunch of stuff in the way and the guts of the airsoft mechanism actually take up more space in the receiver than the components of a real AK.   Would it be possible to cut off the battery pack and wire the lights into the batteries normally used by the airsoft gun?  If I disconnected the wires from the airsoft motor and connected them to the leads from the lights, I would think they would light up every time the trigger was pressed.   The standard airsoft batteries are higher voltage, so I might need to add a resistor to avoid burning them out.

After a lot of searching, I was finally able to find copies of the Cobra laser gun sounds online here:  http://www.cartoonopolis.com/sound-effects-library/    I figure I can get one of those small sound chips that are used for greeting cards and toys to do the sound.  The only tough part will be finding space to put the chip and speaker.  I am hoping I can slide it in sideways under the front handguard  in the space where the gas tube would be on a real one.     

So what do you guys think?  Any other suggestions that might help? 
Kansas

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    JesseL

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    Re: Fun electronics project
    « Reply #1 on: November 13, 2014, 10:53:43 pm »
    Just a resistor isn't the most efficient way to limit the current to the leds, though if you wire them in series it may not be necessary.

    The sound circuit is going to need a lower voltage too. The easiest thing would probably be to rip the 5v regulator out of a cheap cigarette lighter to USB adapter. That could power your sound and let you drive the leds with much smaller current limiting resistors.

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    ksuguy

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    Re: Fun electronics project
    « Reply #2 on: November 13, 2014, 10:58:01 pm »
    Well most of the sound chips have their own built in batteries.   If I mount that by the handguard, I can just press the push button to activate the sound with my other hand at the same time I pull the trigger.   

    I suppose I could also put a smaller battery pack in the stock instead of the standard airsoft one and connect that to the trigger.   Since it doesn't need to drive the airsoft motor,  it doesn't need as much juice.  Then I wouldn't even have to mess with resistors.   
    Kansas

    ksuguy

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    Re: Fun electronics project
    « Reply #3 on: November 14, 2014, 09:21:30 am »
    Actually,  I am thinking one of those cheap micro mp3 players might be the way to go.   The smallest ones are only about 1-1.5" square and about a quarter inch thick and cost less than $10.   Then I can just find a standard tiny speaker with an RCA or 3.5mm jack to make the noise.  This would also let me do a wider variety of sound effects.
    « Last Edit: November 14, 2014, 10:09:06 am by ksuguy »
    Kansas

    luke213(adamsholsters)

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    Re: Fun electronics project
    « Reply #4 on: November 14, 2014, 12:32:09 pm »
    First what kind of AK do you have, if it's a clone of the TM products then there is space above the bolt area under the top cover for a fairly large battery pack. TM made a folding stock version of their AK that had a stick battery above the bolt area which should give you enough room for 2 stacked batteries to get your voltage down to a more usable level for your need. I guess where I would start is figure out what voltage you need for your laser as well as sound system. Then decide how to push that voltage either by getting a pack that fits the need or using resistors etc. You could leave the mech box in place, pull the motor, use the leads from the motor to power your sound system and laser when the trigger is pressed. Most mechboxes are pretty simple inside and that should just give you a connection, you might need to be on full auto to get constant power but likely single shot will work. Then remove the hopup assembly and pull the barrel right out, build up your laser and whatnot in that area, you should have room to pass the wiring up into the area on top of the bolt assembly area, then it might be tight but you should be able to get those wires down to the motor area. Or alternately you can pull the mech box and move the wires up to the top area to get where you want to be. Lots of ways to do it depending on how you want to tear into it.

    Luke
    MichiganI am the owner/proprietor of www.adamsholsters.com Custom holsters made for you. To contact me please use E-mail rather than Private Messages, [email protected]

    ksuguy

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    Re: Fun electronics project
    « Reply #5 on: November 14, 2014, 12:53:56 pm »
    It is a CYMA CM31,  the full size AK-74 with the synthetic furniture and fixed stock.  I am going to need to look at some you tube disassembly videos to see how much of the crap I can pull out of the way to make more room.   I would like to leave the charging handle in place on the side if I can so it looks right.   Don't want an open ejection port with a bunch of wires hanging out.

    It is a shame I can't use a real one for this,   it would be so much easier to cram all the necessary electronics in there.  Ideally, it would be awesome to do something like this guy did for his Star Wars blaster.  I am dealing with less room though. 

    http://www.instructables.com/id/Make-an-LED-Blaster/
    Kansas

    luke213(adamsholsters)

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    Re: Fun electronics project
    « Reply #6 on: November 14, 2014, 02:28:21 pm »
    Here is a picture of the top the way it should look. Seems like this is a TM copy which should have this open space up top:



    If so you should have most of the room you need, won't effect the bolt/charging handle at all since it's basically a battery compartment that TM designed for some of their AK variants.

    MichiganI am the owner/proprietor of www.adamsholsters.com Custom holsters made for you. To contact me please use E-mail rather than Private Messages, [email protected]

    ksuguy

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    Re: Fun electronics project
    « Reply #7 on: November 14, 2014, 02:45:13 pm »
    Yeah I was kind of thinking the same thing when I was looking at it last night.    I am hoping I can get the feeding mechanism out of the way from the bore.   If I was using my real AK,  I would feed the lights through the bore and then run the wiring through the chamber area up under the bolt carrier.   There is some stuff in the way on the airsoft gun though.

    I think I should be able to get a micro mp3 player under the front handguard for the sound,  but I will need to find a small speaker with a 3.5mm jack on it.   
    Kansas

    luke213(adamsholsters)

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    Re: Fun electronics project
    « Reply #8 on: November 14, 2014, 02:50:47 pm »
    Well the only thing in the way should be the hopup assembly attached to the barrel, if you pull that all out of there you should be able to leave it together. I'm not sure if the nozzle on that is attached to the tappet plate within the box or not, but the nozzle might not be in the way anyways once you get the hopup chamber up out of the way. Shouldn't be too bad though overall, worst case put the laser in the flashhider area, and run the wires down the barrel assembly area to the middle of the gun.


    Luke
    MichiganI am the owner/proprietor of www.adamsholsters.com Custom holsters made for you. To contact me please use E-mail rather than Private Messages, [email protected]

    ksuguy

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    Re: Fun electronics project
    « Reply #9 on: November 14, 2014, 02:54:48 pm »
    Yeah, that is an option too.  If I use black wires,  I could go along the outside of the barrel through the "gas tube" and up under the dust cover.  I might also be able to get a blue laser diode and put it in the brake like that guy did with the red one for his star wars blaster.
    Kansas

    kunkmiester

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    Re: Fun electronics project
    « Reply #10 on: November 14, 2014, 10:02:11 pm »
    Some airsoft guns are pretty dang close to the originals, you might actually be able to put a regular magazine in.  Certainly something to check.
    WashingtonEvil is Evil, no matter how small

    ksuguy

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    Re: Fun electronics project
    « Reply #11 on: November 14, 2014, 10:59:49 pm »
    Already did.   This one does look damn close to my real one, but the mag well is different.   The catch is up much higher on the airsoft magazine, right at the top of the magazine and it is thinner.   The real one has a larger lug further down.   
    Kansas

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