Newbie needs help (LED "Flashbang" project)

Discussion in 'The Projects Forum' started by Deus, Jul 29, 2015.

  1. Deus

    Thread Starter New Member

    Jul 29, 2015
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    Hello all :)

    Peter from Denmark here (so excuse any spelling blunders!)

    I have just started fiddling with different kinds of electronics, most have to do with my hobby (Larping). I am going to a Firefly LARP (as a alliance police officer) in 4 months time and for that I require different kinds of equipment.

    I can handle most of it but one of my (insane) ideas are a bit out of my league I´m affraid...

    An "LED Flashbang".

    And before any1 gets starter ;) Its a gimmick, a toy and I have NO intention of creating ANYTHING that could hurt or otherwise injure people!

    My idea so far is to use some High lumen LEDs (I am thinking 750+ lumen per LED), wired to a 555timer, something that gives a Strobe effect, an automatic shut-off thingymajigger (that shuts off the lights after lets say 30 secs?), batteries and an On switch - All incased in some form of see through casing (think hamsterball).

    Unfortunatly I do not have the knowledge to build it - granted I would just wired something up and pray to god that it works... But TBH I would really like to make something that works :)

    So if any1 of you could spare the time to help me plot out a schematic and/or write a list of the components or just give general advice? I would appreciate it Very much! :D

    The following is my brainstorm component list:

    # LEDs - I have listed a few different kinds as I have NO idea which one will get the job done (or even works with a Strobe mode?)

    220 Lumen LED: http://eud.dx.com/product/youokligh...m-24-smd-1206-12v-4pcs-844382062#.Vbidj_ntlBc

    These are Cheap, small and easy to wire - But are they good enough?!

    400 Lumen LED: http://eud.dx.com/product/t10-5w-40...rner-lamp-dc-12v-2-pcs-844252097#.Vbie5PntlBc

    Almost the same as above - A bit higher lumen but will there be a big enough difference in the light output?

    750 Lumen LED: http://eud.dx.com/product/t10-10w-7...rner-lamp-dc-12v-2-pcs-844255612#.VbifQ_ntlBc

    Now we´re talking! High lumen still pretty cheap.

    I have chosen the above as they are non-directional and 4~~ should be able to cast light in every direction in either a ball or a tube casing. But do they work? Can I wire them up to give a Strobe effect, ect?

    # Timer - I have read that a 555timer should do the trick(?) I want the LEDs to start flashing (strobing? o_O) 6~10 secs after I push the "on button". Will that be possible with the 555?

    # Strobe effect - Without the Strobe effect I would just be creating a pretty glowing ball - which is cool no doubt! But I want it to Strobe like there is NO tomorrow! Think Cree flashlight Strobe mode! I have NO idea how to do this? Please help :)

    # Automatic shut off thingymajigger - I want the LEDs to automaticly shut off after around 30 secs after they start flashing. What can make it do this?

    # Batteries - I haven´t really thought about these yet... Seeing as it depends on the components, ect.

    # Casing - I am not set on the "hamster ball" casing seeing as perhaps a tube is easier to get a hold off. Any ideas would be appreciated!

    If you made it this far I would like to say thank you and I really hope that you can either help me with the project or point me in the right direction ;)

    Best regards
    Peter
     
  2. pwdixon

    Member

    Oct 11, 2012
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    You will need at least 3 timers, one for the initial delay, one for the strobe and then one for the off timer. Though you could use a processor and do it all in one device. You will also need a driver circuit to push power to the LEDs. I imagine that the car lamps that you have selected might well work but you never know they might have some fundamental frequency limit as they are designed to flash as indicators but you'd need to try them out at any higher frequency when working as a strobe. As these are only car indicator lamps even with such large output intensities they are not a real strobe light so you might find your "shock-and-awe" bomb device might not be as impressive as you might like unless it's really dark.

    The battery will need to be of reasonable capacity to run multiples of these high power LEDs for any reasonable period. You will probably need a charger too as non-rechargeable batteries might be very large to get the thing to work at all.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    image.jpg The first is the delay before start

    The second keeps the third on for 6 to 10 seconds.

    The resistor by the LED will need to be much smaller than shown. Assuming you use a 4.6V lithium battery, and 1 amp LED, then you need about (4.6 supply - 3.3v LED)/1.0A = 1.3 ohm.

    Use a 1.5 ohm, 2 watt resistor.
     
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  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Also, it's worth considering using LED floodlight chips; Extremely bright, wide dispersion and available in different colours.
     
  5. Deus

    Thread Starter New Member

    Jul 29, 2015
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    Thank you every1 :D

    After reading through your comments (and trying to understand the "magical" schematic :p) I have been looking for some new LEDs and a strobe circuit driver.

    LEDs: http://eud.dx.com/product/diy-10w-9...light-9-led-module-12v-844151538#.Vbjd9fntlBd

    Circuit driver: http://eud.dx.com/product/t6-2500-3...diy-flashlight-4-5-18v-844128269#.VbjeC_ntlBe

    I have choosen to make the "flashbang" casing flat and circular (like a landmine). If I add either some smooth cloth / plastic on the bottom side, I can slide it along the floor instead of throwing/bouncing it.

    I have attached (an UGLY) drawing of my new idea.

    Unavngivet.png

    Would this idea work with the above Driver and LEDs?

    Oh and if you could "dumbdown" schematics and lingo that would be awesome! I am a complete newb hehe

    Best regards
    Peter
     
  6. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Those LEDs will do the job but you don't need the driver board. Since the duty cycle will be very short you can be afford to be less cautious than might be the case for continuous operation. A low value resistor is all that is required to limit the current, you almost certainly won't need a heatsink, either.

    You will get better coverage if all the leds are arranged in a circle and angled upwards at around 45 degrees.
     
  7. Deus

    Thread Starter New Member

    Jul 29, 2015
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    But dont I need the board to get the Strobe effect? Or is there a simpler / easier way to get that effect?

    As far as having the LEDs at an angle - the drawing was suppose to show that :p Paint sucks, but it was the easiest way hehe

    But the LEDs will be at an angle (and evenly spaced around the casing) so that all the light is either shun sideways & upwards or directly upwards (center LED).

    Some of my friends where talking about using the Arduinio Lilypad for the delay, timer and shut off functions. Any idea if that will work?
     
    Last edited: Jul 29, 2015
  8. Deus

    Thread Starter New Member

    Jul 29, 2015
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  9. blocco a spirale

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    If you use an Arduino (or any micro-controller) you would generate all functions, including the strobing, within the device. Even if you go the 555 timer route it would be preferable to use an extra 555 astable stage for the strobing as this would give you control over the pulse width.

    This is a very good application for a small micro-controller as it would give you full control over all timings with the minimum of hardware.
     
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  10. Deus

    Thread Starter New Member

    Jul 29, 2015
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    Could you modify the circuit to use the following LED (I want to use 5 of the LEDs in the "flashbang")?

    http://eud.dx.com/product/jrled-jr-...-white-dc-10-11v-5-pcs-844330706#.VbnoGfntlBc

    Some say that each LED needs a driver, some say that it doesn´t?

    As for the Strobe effect I am looking for an effect as close to the one normally used at parties, ect.

    Remember that it has to run on batteries (rechargable is ofc. prefered)

    I really am a complete newbie... So if your circuit schematic could reflect this I would really appreciate it :D

    Best regards
    Peter
     
  11. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Peter,

    Before I do that, let me know what battery you plan to use. There are not many 12V batteries. Especially not on that could support 5 x 10w = 50 watts of LEDs. Now, flashing will reduce the power needed by the battery (10% on and 90% off will bring battery load down to 5 watts). In fact, such a. Right LED can probably still be blinding at 1% on and 99% off. Even more effective because it is hard to find the proper squint to block the flash when the impulse is so short - yet still bright enough to keep your eyes saturated with light.

    Anyhow, a 12v battery quickly discharges to 11 v and, at that point, any current limiting is greatly modified. Charging 12v batteries or replacing 12V worth of batteries is not so easy - make a plan and then let me know. I will change drawing accordingly once power options are defined.
     
  12. Deus

    Thread Starter New Member

    Jul 29, 2015
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    I will get right on that! And thank all for all the help! :D

    Do you have any suggestions as far as batteries go?

    I wont use the flashbang very much (a 5~10 times/uses a year is my best guess), so changing the batteries would not be that much of a hassle. If I need a powerful battery and one that lasts long the first thing that comes to mind is a 12v SLA battery - now I know that they are heavy, ect. but they pack a bucket load of "juice" and are not too expensive. Would they work or is it better to use one or more "normal" batteries?
     
  13. Deus

    Thread Starter New Member

    Jul 29, 2015
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  14. blocco a spirale

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    I'd go for Lithium Polymer batteries. SLAs are entirely unsuitable for this application.
     
  15. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Before you get to far into this ...
    Have you considered using Zenon strobe/photo flash units?
    They can be harvested from disposable cameras and pack a powerful visual impact. The little units come complete with the high voltage generation circuitry and use common low voltage cells. YouTube has several primers on harvest and application techniques.
    Use a dozen or so by themselves or add a few to your LED gizmo.

    Just something to consider
     
  16. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Can we recharge zenon cap fast enough for strobe effect with limited power supply?
    Some thoughts: Battery 7.4 V Li- pol, 1 A hr. Boost converter 7V to 12V, eBay for about $ 6.00. Modified strobe ckt.
    N ch FET not yet selected, 10 A, 50 m ohm RDS, 20 V give or take. A 3055V was used on costume 18 LED dual ring. High Power Strobe 00000.jpg
    Note: R1 & R2 need to be interchanged, my goof.
     
    Last edited: Aug 8, 2015
  17. Deus

    Thread Starter New Member

    Jul 29, 2015
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    Wow thanks for all the inputs! :D

    I have a bunch of 3,7v Trustfire batteries (TrustFire 14500 3.7V 900mAh Lithium Rechargeable)

    Would they do the trick?
     
  18. Bernard

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    Aug 7, 2008
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    3 might work, but need real Vf's of LED's; if there is room, then I would lean toward 4 batteries, then R4 would be around 4 ohms @ 3 W.
    Might be well to add a red LED as power monitor as reminder to shut off unit when LED's stop flashing.
    N ch. FET maybe 10A, 20V or better, 50 m ohm or better. A SMT,
    3055V was used on origional ckt.
    C4-5 up to 10,000 uF combined. On origional ckt. R1-R2 were pots to set desired operation, then replaced with fixed values.
     
  19. Bernard

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    Aug 7, 2008
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    It just might work. A skimpy simulation used 10 worn out AA Alk, 14V to charge 10,000 uF cap thru 5 ohm R, dumping into a simulated load of 2 ohms, a good 5 A. A 3 W LED with 10 ohm R paralled load. On discharge V fell from 12V to 10 V in 20 m sec. giving a verry bright flash. Recharge seems to take about 150 m sec. At 5 flashes / sec. seems like a decent strobe rate & 20 m sec flash.
    Now if batteries behave in similar manor we might be home free.
     
  20. Deus

    Thread Starter New Member

    Jul 29, 2015
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    Sounds cool! Whats the next step then?
     
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