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Capacitor Discharge Project Fireworks

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by hfireworks, Oct 18, 2006.

  1. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Assuming Midi can only control 128 devices, it's because it's only using 7 addressing bits (a single byte, less 1 bit) - by increasing the addressing to use two bytes you then get 65,000 odd addressable devices. Bear in mind, for your purposes it doesn't have to be as fast as Midi - so increasing the packet size won't be a problem!.
     
  2. Hero999

    Hero999 Banned

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    That looks like a professional board from the 80s!
     
  3. mybuickskill6979

    mybuickskill6979 New Member

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    nichrome has a resistance of 675ohm/cmf(i'm pressuming its basically per foot) at 100 ft. its 675x100. thats 67500 ohms of resistance. 250v/67500 gives 3.7mA. at the farthest point on the wire. i don't quite think thats enough.
    if you were to up the voltage more. wouldn't the resistance become of less importance and end up with more amperage at the end?
    i'm just going off what i've learned so far. could most definitely be wrong.
     
  4. dave

    Dave New Member

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  5. wakanga

    wakanga New Member

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    we only use 1inch to 2inch of nichrome for our e-matches as a bridge wire that shorts and heat up...what we are using for those long wires/cables (100' to 1000') are solid/stranded copper wires 18 to 24 gauge...so if you want to compute the resistance (length) of the wire...it is the resistance of the copper wires and not the nichrome wires...:)


    @hfireworks,

    i also like your idea of that midi decoders....if nigel could help us to make our way to it...that would be good...=)
     
  6. mybuickskill6979

    mybuickskill6979 New Member

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    i was thinking about that lol. i was all why not run cables to run the e matches off lol. okay i got you.
     
  7. wakanga

    wakanga New Member

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    that's ok sir...we're all learning here...and i hope we could developed a system that could cater those DIY'ers with their needs...
     
  8. mybuickskill6979

    mybuickskill6979 New Member

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    i have a question i seen the word pop used a couple of times is that the ematch igniting "pop" or the wire going like ane overloaded fuse like "pop"?

    how much current is necessary to to fire the black powder on the ematch?
    where can i read about the laws(theories) relating to this stuff. i would like to do a way smaller version for at home use!!
     
  9. hfireworks

    hfireworks New Member

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    The term pop usually means the exploded ematch head or pytogen head the ignites.

    The amount of current needed to ignite an ematch is depending on brands is about 50ma to 75ma

    I hope this answers your questions:)
     
  10. hfireworks

    hfireworks New Member

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    Nichrome wire is used for bridge wire between the the copper wire strands.

    This might clarify a little, 24 gage wire has 25.67 ohms per 1000' or 0.02567 ohms per foot.

    200' of cable is 400' out and back.
    400' * 0.02567 = 10.268 ohms

    300' of cable is 600' out and back.
    600 * 0.02567 = 15.402 ohms

    Lets assume an ematch is 2 ohms
    amp = volts / ohms

    amp = 24 / (10.268 + 2) = 1.95 amps (200' of cable)
    amp = 24 / (15.402 + 2) = 1.38 amps (300' of cable)

    Well you need 0.5 - 0.7 amps to fire a commercial ematch, so you have enough to fire one ematch.

    This is the reason we are looking for alternative ways to fire our ematchs not enought voltage or amps to do large fronts. I am not saying it can't be done because it is using fuse and multiple ematch and cues.

    Capacitor discharge is a better way of increasing the voltage and increasing the carrying power to the ematch.

    This may seem a little cloudy to understand, but it works.

    Neil:)
     
  11. mybuickskill6979

    mybuickskill6979 New Member

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    i got yeah. Awesome.
     
  12. wakanga

    wakanga New Member

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    i have a question...what do we use to cut the current flowing to the capacitor once it is fully charge? i mean automatically...and having a led indicator to tell if it is charging (blinking) or fully charge (steady)...thanks in advance
     
  13. wakanga

    wakanga New Member

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    anyone here wants to help with the design of what i want in a capacitive discharge circuit? thanks
     
  14. mybuickskill6979

    mybuickskill6979 New Member

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    dude i was messing with a camera(throw away) flash circuit earlier and got buzzed by the cap like three times in five minutes. and it burned my pointing finger lol!! what a rush.
     
  15. Sceadwian

    Sceadwian Banned

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    Those circuits can provide a lot of fun, as well as spot weld small gauge wire if you're in a pinch =) Just file the tip of the wire down to a super fine point and slowly press it against another piece of metal. They charge to around 300 volts on a 1.5 volt battery. You can remove the flash capacitor from the board and supply your own leads to feed a bigger capacitor. If you raise the supply voltage above 1.5 volts you should be able to get more than 300 volts, though I wouldn't push it as you'll fry the circuit.
     
  16. mybuickskill6979

    mybuickskill6979 New Member

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    yup. those SMD things are crazy man. i was looking all hard and realzied that thing has 4 transistors on it. two Caps two Transformers a diode an LED and a few resistors. I'm just trying to figure out how the transistors make DC act like AC to get the two Formers to workin. i found a few schematics for the flash circuits. but the first shock i got i jumped up outta bed like a snake was after me. lol.

    and i'd think that the Batt would die quick. but its been in there since 02 and still chargin the cap pretty quick. Any one got a MM for sale?

    Sorry didn't mean to hijack a thread lol!!
     
  17. Sceadwian

    Sceadwian Banned

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    It's easy, pulsed DC is AC. Some of those transisotrs are probably used as an osiclator, which sends pulses to the transformer.
     
  18. Sam Jelfs

    Sam Jelfs New Member

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    afternoon all, I'm new here, so I apologise if i look a fool.

    quick comment would be not to use MIDI for the control of pyro's / fireworks. There is no EDAC (Error detection and correction), and no real way to make sure that if you send the message "fire channel 10" that that is what is received, we wouldn't want 11 going off by mistake now would we. I'm currently working on a pyro controller for my final year project at uni using a different protocol, the aim being to make it more stable, and less chance of errors.
    There is also MSC (Midi Show Control) which does have the fire commands and such set out in it, but again I would never use it for a safety critical system.

    quick question, does anyone have any documented evidence of the resistance of an e-match, and the current required to fire it? I need something I can reference as fact. Is there a specific company / companies that make them?

    I realise that you guys n gals may not be pyro experts, just though my comment was worth making.

    Cheers

    Sam J
     
  19. hfireworks

    hfireworks New Member

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    This site may give you what you need

    http://www.pyroinnovations.com/ematches.html

    Usually and ematch will require 50 to 75ma to fire anything under that is a no fire.:)
     
  20. wakanga

    wakanga New Member

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    hey sam would you like to share that project of yours once finished?..don't worry ask anything here about pyro related stuffs and we will answer it for the best of our knowledge...
     
  21. Sam Jelfs

    Sam Jelfs New Member

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    hfireworks - Thanks for that, may well use it, though have managed to convince my tutor that buying me pyrotechnics and setting them off at uni whilst monitoring the current flow is a necessity for my project, far be it from me not to take up the chance. Pending completion of the right risk assesments, of course ;)

    Wakanga - Once i've got it working i'll post the schematics up, months time and it should all be working... i hope! ordered some of the parts today to start testing my theory, so we shall see how it goes.

    Sam J
     

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