My arduino powered firework sequencer. 2018 version!

[CopperCone]

you can have a static charge occur between the igniter wire and the earth. Should not happen because of insulators but charcoal and metal powders are conductive and you have moisture. You need to ensure there is a favorable area for a spark to form away from the powder charge chamber. Only posted because it's not obvious and relates to why metal/shield design is a good idea. Or a spark occur on a broke igniter wire, they are usually thin or very fragile if you are 'smart' enough to use a light bulb. 

[stj]

it's obvious most people here dont know electric matches are a virtual shortcircuit and need a MINIMUM 0f half an amp to fire - usually atleast double that to be sure it will go.

they arent like airbag triggers - they cant be fired by static.

[CopperCone]

it's obvious most people here dont know electric matches are a virtual shortcircuit and need a MINIMUM 0f half an amp to fire - usually atleast double that to be sure it will go.

they arent like airbag triggers - they cant be fired by static.

its well known that they are surrounded by a conductive powder. It's also obvious that if you beak the wire a spark gap forms. If the enclosure is wet or covered with powder, and touches the earth, a spark gap forms between the wires connected to the igniter and the chassis.

It's also obvious that you don't need much energy to ignite a microscopic particle of carbon that has had oxidizer and sulfur beat into it by a ball mill or recrystallized inside of it.
Even if you use smokeless powder or pyrodex (which has charcoal in it) its often lubricated by very fine graphite (forgoing the usual conductive charcoal black powder), though it should be more difficult to ignite so long its been polished well in a mill to break off corners that can lower ignition temperature. But transport and temperature fluctuations may cause a fracture and formation of small particles that have a drastically lower ignition behavior.

 

[usagi]

it's obvious most people here dont know electric matches are a virtual shortcircuit and need a MINIMUM 0f half an amp to fire - usually atleast double that to be sure it will go.

they arent like airbag triggers - they cant be fired by static.

yep, pyrogen igniters are very robust electric firing devices -- which explains why they are used. they are very safe and reliable. the only unintentional ignition i can recall is due to direct lightning strikes on the shooting site, no real way to prevent that!

nichrome igniters are also an option. you need a beefy system to ignite them though. the igniter wire is also very fragile and easy to break when fusing up.

my firing system has safe defaults, multiple interlocks, and idle shunts. the system uses encrypted spread spectrum with 2-way handshaking. i even have separate i2c buses for devices, none of the buses are shared.

[Teledog]

Nifty stuff!
Friends in the entertainment business were always using pyrotechnics for stage shows.
Strange happenstance that Big Clive just did a video on the electric matches;

Looked them up, and the specs do state 500mA for a single match & 800mA for series ignition.
Doubt I'd ever get into it (with our nanny state laws), but interesting non-the-less! 

[CopperCone]

whats that gotta do with lightning? You clearly wrote that you don't give a shit based on your handling of pyrophoric, toxic and carcinogenic chemicals and synthesis of high explosives without safety precautions in your boxers. TNT, RDX, HMX, nitrated plastic / plasticizer fumes.. all that stuff is not great for you buddy. Do you even know the properties of nitric acid oxidized encapsulant fumes? Maybe read about effects of substances like TNT on a human.

Maybe you should not be doing safety analysis ? I would not want to get TNT containing solution spilled on me. Perhaps invest in a lab coat, fume hood, goggles and a mask?

[Dubbie]

Despite all your big words coppercone, it's clear you have no idea what you are talking about.
You honestly sound like a raving lunatic.

What the heck has TNT got to do with pyrotechnic displays?

[KaneTW]

Honestly it says a lot more about your own views on safety that you infer a disregard for safety precautions from "I currently have some strong acid blend for decapping chips within arms reach, and I'm only wearing a boxer and a shirt."

In arms reach, in a tightly sealed, appropriate container.

Not like you'd expect anything else from a poster with a Homeland Security avatar.

[CopperCone]

Despite all your big words coppercone, it's clear you have no idea what you are talking about.
You honestly sound like a raving lunatic.

What the heck has TNT got to do with pyrotechnic displays?

You gotta read all the posts man, you can't understand a thread unless you read all the posts. Your post comes off like you just smoked your user name lol 

Maybe you need to cut down man 

[CopperCone]

Honestly it says a lot more about your own views on safety that you infer a disregard for safety precautions from "I currently have some strong acid blend for decapping chips within arms reach, and I'm only wearing a boxer and a shirt."

In arms reach, in a tightly sealed, appropriate container.

Not like you'd expect anything else from a poster with a Homeland Security avatar.

Did you ever try to store fuming white nitric acid? It tends to gas through seals. I hope you got some wax on those seals. I would recommend storing that in a fume hood. And hanging out in a chemical storage room in your boxers is generally a bad idea.

I have a bunch of white phosphorus but it is not stored near me and I don't go handling it in my under pants like someone that was up for 4 days cooking meth.

[usagi]

coppercone, stop posting in this thread. you are contributing nothing to this thread and keep sending it off the rails.

[David Chamberlain]

coppercone, stop posting in this thread. you are contributing nothing to this thread and keep sending it off the rails.

I think this thread would be going fine if every one just stopped feeding the troll. Their is no requirement to respond to everything every one says just move on and ignore it.

BTW usagi, I really enjoyed your video and detailed posts last year. Please let us know more about what you changed, or plan on changing, modifications and lessons learnt and so on.

[usagi]

i changed everything to wireless this year, which will let me scale up to pretty much unlimited cues. building each receiver takes quite a while though, i'd love to find a decent pcb fab that does pick & place.

anyway, the show went well. here's the video.

[Nusa]

Wireless is scary when it's connected to things that go boom. It adds a whole set of new safety considerations in terms of lockouts. You need communications security features on the receiver side in the case of unauthorized transmitters (deliberate or accidental) on your frequencies, or unauthorized users on your transmitters.

[stj]

it would be better to use the 446MHz LPR band radio modules.
you wont have every asshole with a smartphone seeing and trying to mess with your net.

[usagi]

it would be better to use the 446MHz LPR band radio modules.
you wont have every asshole with a smartphone seeing and trying to mess with your net.

what frequency do you believe this transmitter uses and why do you believe smartphones in the US can mess with it?

is there some reason you believe 446mhz is an unlicensed band in the US?

[stj]

you said "wireless" so i took that to mean wifi modules.

search LPR yourself, it's used for stuff like car fobs.

[usagi]

you said "wireless" so i took that to mean wifi modules.

search LPR yourself, it's used for stuff like car fobs.

i'm using encrypted spread spectrum 915mhz, which is a much better solution.

315mhz/433mhz car fob frequencies are not available for use in the US for general purpose unlicensed communication. the band use is quite restricted.

446mhz which you mentioned earlier is used in Europe for PMR unlicensed. in the US, that is right in the middle of the licensed 70cm band.

[Stray Electron]

So what the industry is a buncha cheap incompetent fucktards what else is new?

Based on your recent post, I think you are what you have said.
You are paranoid and egoistic.
If all you care is NASA or MIL-STD quality, then don't spam on a forum with most users making consumer/industrial stuff for a living.

have you ever seen a large gasoline fire ball go off? Or a 15 inch shell explode? Or maybe some high explosives someone had laying around to add some ground boom to a show?

   Yes, yes (and bigger) and no, not a fireworks show, otherwise yes up to 500lbs .MIL.

You can connect this thing to a fused blasting cap if you want.

   Blasting caps aren't used in commercial fireworks. EVER.

What do you think I am complaining about a fucking alarm clock? It's a detonator circuit.

  Wrong again, motor-mouth.

Do you think someone is gonna give a shit about class D restrictions at a private party or something? 

   Are you accusing the OP of ignoring the restrictions at a private party?  Would you care to provide some proof of that accusation?

I think its just people that never experienced a close up explosion or real heat in their life talking a buncha idiotic shit in this thread.

    I think the only person in this thread that that applies to is yourself.

    FPAG member and I've been been making safe fireworks for over 50 years.  You OTOH don't know WFT you're talking about.

   I usually ignore threads like this that display obvious signs of major stupidity but I got tired of you ragging on about things that you clearly don't have any knowledge of.  In at least half the cases you don't even know the proper names of the items that you're carrying on about. 

   OP, nice work, carry on.

[Stray Electron]

whats that gotta do with lightning? You clearly wrote that you don't give a shit based on your handling of pyrophoric, toxic and carcinogenic chemicals and synthesis of high explosives without safety precautions in your boxers. TNT, RDX, HMX, nitrated plastic / plasticizer fumes.. all that stuff is not great for you buddy. Do you even know the properties of nitric acid oxidized encapsulant fumes? Maybe read about effects of substances like TNT on a human.

Maybe you should not be doing safety analysis ? I would not want to get TNT containing solution spilled on me. Perhaps invest in a lab coat, fume hood, goggles and a mask?

  Blah, Blah, Blah.  The OP talks about a firing box and YOU start carrying on about inadequate wiring and ignitors and now you throw in Nitric Acid, RDX, TNT, HMX and other things that are not and have NEVER been used in fireworks.  I'll say again that you have no idea what you're talking about and are just making s**t up!  You need to stop before you prove yourself any stupider than you already have!

   Interestingly there is one high explosive that at one timewas widely used in fireworks.  It's one of the few names that you haven't thrown into your arguments so obviously you don't know what it is.

[usagi]

hi Stray Electron,

do you know offhand what typical resistor values are used for igniter safety shunts? commercial igniters are typically twisted shorted for transport, which would be effectively 0 ohms shunt   I suspect commercial systems like cobra use some value like 10k.

[texaspyro]

Some day I will write up my high power (fired many P class motors) model rocket launch system...

Radios are high power 915 MHz Xbees.   Encryption starts with 160 bits of hashed password.  Xbee channel and PAN codes provides 2^18 bits of unique radio id info.   All messages are signed/verified with 32 bit cryptographically keyed message authentication codes.   

The firing command is a challenge-response system using a 128 bit key / XTEA encryption and a 64 bit TRUE random number (generated from ADC and IMU noise, etc).  When you send the ARM command to the pad, it responds with a double-encrypted version of a 64-bit true random number that the LCO box has to decrypt once and send back with the FIRE command.  The pad controller decrypts that number the second time and the results must match the original number.  The true random number generator has been verified against numerous random number test suites.  The XTEA algorithm has been enhanced with extra rounds and a variable seed value.

Oh, and you have one chance and 20 seconds to crack the encryption between the ARM and FIRE commands... the crypto expires after that.

[usagi]

BTW usagi, I really enjoyed your video and detailed posts last year. Please let us know more about what you changed, or plan on changing, modifications and lessons learnt and so on.

For 2019 i've moved from mechanical relays to Darlington arrays, more integration onto single PCB. Lesson learned, put as much work into the PCB to avoid as much manual wiring as possible.

Also going to use pre-fabbed boxes probably from Hammond mfg. Constructing lasercut boxes is a lot of work.

[Yansi]

it's obvious most people here dont know electric matches are a virtual shortcircuit and need a MINIMUM 0f half an amp to fire - usually atleast double that to be sure it will go.

they arent like airbag triggers - they cant be fired by static.

Airbags can't be fired by ESD either. Even 9V battery is struggling to fire one.

[texaspyro]

it's obvious most people here dont know electric matches are a virtual shortcircuit and need a MINIMUM 0f half an amp to fire - usually atleast double that to be sure it will go.

they arent like airbag triggers - they cant be fired by static.

Airbags can't be fired by ESD either. Even 9V battery is struggling to fire one.

Electric matches have a "no fire" and "all fire" spec on current.  Any current below "no fire" will not cause them to fire.  Currents above "all fire" are "guaranteed" to fire the e-match.  Some e-matches have surprisingly low "no fire" specs.