Igniting a Programmed Fireworks Display?

seg9585 asks: "I am interested in setting up a programmable fireworks display this New Years, and I was wondering if anyone from the Slashdot community had any advice as to how to set one up easily, inexpensively, and safely by someone with little experience with electronics/wiring. I do have a VEX controller which I can use for digital output, but I would rather not have to buy a ton of relays and create a spark by just shorting out the circuit. Is there a better way to do this?"

Comments

Model Rocket Igniters

[Anonymous Coward]

Have you considered using model rocket engine igniter? They're cheap, powered by electricity, and provide a decent flame.

Also, I am in no way liable for whatever you do here.

Model rocketry

[EnderGT]

You could try using the igniters used in model rocketry instead of depending on a spark. They come cheap and are available at almost any hobby shop. They require only a low voltage current to ignite, if I remember correctly. Should be easy to burn a few to determine average timing delay, and then set up a timing script to control the display. Although I would definintely recommend going the professional route if you have any doubts at all of your competencies.

Re:Model rocketry

[ec_hack]

A few pointers - I've been a model rocket flyer since the mid 60s.

Be very careful with modle rocket igniters - the modern ones do require very little current to ignite, which means that your circuits need to be designed right. There are other types of igniters that take even less current, so be cautious if you use them.

I'd suggest that you check the archives of the Usenet group rec.pyrotechnics for pointers to safe techniques. There are amateur pyrotechnic groups that do very impressive shows.

I'd also be careful not to run afoul of local, state, and federal laws on fireworks. And be very, very careful - "You'll shoot your eye out, kid!"

Electronic igniters

[jaxom_01]

The rocketry community has had this under control for a long time. You can buy commercially made igniters for about $2 each that will fire nearly instantly with the application of a 12v power source. You can also buy (or make) low voltage igniters (called e-matches) for about the same price. In the US, you are required to have a Low Explosive User Permit(LEUP) to buy/store/transport e-matches but if you make them yourself and use them on your own property, then you only have to store them in a type-3 magazine (a good metal ammo box lined with 1/4 plywood counts as a type-3 magazine) In a pinch, you could use some 31 gauge nichrome wire that is connected to a 12v source but that will take 1 or 2 seconds to heat up.

Re:Get a professional

[caffeinatedOnline]

He was killed when he was loading a tube and 'something' (theories abound, from static electricity to a short in the wiring... what caused it was never proven) caused the firework to ignite. These are not your average 'buy at the indian reservation' roman candles. They are class B explosive devices, which require a special permit from ATFE, so yes, what he was doing was mortally dangerous. Fluke? His friends and family think so, as he was known to be very careful on the job. But, when dealing with high explosives, things can happen. Warning: PDF!!! Consumer Protection Safety Commision 2005 fireworks report. He was one of the 4 who died last year. There was an article in the daily rag about it, trying to find it online...

No LEUP? Use rocketry ignitors and MOSFETs.

[Chembal]

I tackled this same problem several times with varying results.

My first attempt used a TINI controller board hooked up to relays hooked up to model rocket igniters. This worked well, but relays are expensive and don't scale well if you want to do this on the cheap.

My next attempt used a Freescale GP32 controller with MOSFETs. This worked very well, and is a more scalable solution. Again, I used model rocket igniters. If you look at my pictures, you can see how I made a nice set of firing racks, too, complete with power distribution scheme and chainable serial control. I wrote a program in Java to send control signals to the controllers to shoot the shells off in sequence.

After these attempts, I finally got sick of playing with the small stuff and got my explosives permit so I can play with 1.3g display fireworks. When you have your explosives permit, you're no longer limited to crappy model rocket igniters. You can buy professional quality e-matches that are meant for the task. They're a bit pricey, but they already are the right length of leads, and work GREAT. Also, the larger shells are MUCH easier to electrically fuse, since they use quick match instead of visco fuse. But, no vendor is going to sell you those nice e-matches without first seeing your LEUP. (Low Explosives User Permit.) That takes a bit of work to get, so I'll assume that's beyond your scope. Of course, there are also professional systems available for control, but they're pricey.

So, I'm going to take a guess that you don't have a LEUP and just want to hack something together to shoot off your 1.4g consumer fireworks. Here's what I've learned from my experience doing the same thing. It's not that tough to do, but don't underestimate the amount of wiring you have ahead of you if you intend on shooting off more than a few shells. With only a few weeks from new years, you'll probably get a more impressive display by buying several nice cakes. But, since that's not the slashdot way, here's how you can do what you want to do...

• First, don't do any of this in your living room! Don't go burning down or blowing up your house.
• Buy packs of estes model rocket igniters, and attach longer leads to them. This is the cheapest and most reliable way of doing what you want without getting an explosives permit.
• Buy the plain-jane 1.4g artillery shells from your favorite roadside vendor (NOT the canister style shells, because they're not easily electrically re-fused), and CAREFULLY cut or remove the fuses. Black powder is sensitive stuff, so be smart about this step!!!
• Cut a slit in the paper bottom of the shell. This is where the black powder lift charge is. Insert your igniter into the slit, and tape over it and any hole left over from the original fuse to hold the igniter in place and prevent the loss of your lift charge.
• Place the shells into your PROPERLY SIZED artillery shell tubes, and hook up the leads to your firing system, be that through relays, MOSFETs, or a simple switch. I can't emphasize enough how important it is to get the right size and type of tubes and to make sure they are stable! Pyro Universe is a good resource for this and other info.
• When everyone is a safe distance away, and the area is secure, hook up your system to power and apply current to the igniters. They will fire the instant you apply current if you've inserted the igniter correctly.

Please be safe about this! It's a ton of fun, but observe sensible safety precautions. I highly recommend taking a class on display fireworks to learn how to do all this right. Premier Pyro gives great classes on this every year, and you'll have tons of fun to boot. At the very least, give NFPA 11

If you have to ask

[Anonymous Coward]

This is falls under the category of if you have to ask then you have no idea what you are doing.

This is nothing to mess around with even model rocketry can be very dangerous if and when something goes wrong.
Fireworks are orders of magnitude faster explosives they can kill you faster then you can blink.
All the setups that I have see there are contacts that are MANUALLY closed for every event. The technician(s) has a score that lists what and when to fire. If anything is out of place person/animal on the range, wind direction/speed shifts anything that THAT ONE PERSON feels is UNSAFE they will not set the event off. There are a few very very high end computer controllers that are used for very very large displays. these cost tens of thousands of dollars and have more fail safes then any standard controller/PC setup ever could. They all have a active kill switch someone has to hold the control arm trigger or the events don't fire.

The shells are specifically configured for electrical ignition not just a spark on a fuse.

This is heavy duty shit that can/will kill you faster then you can blink.

Leave this to the experts you might know computers you don't know shit about fireworks if you have to ask.

Re:Get a professional

[Dion]

I'm sorry but that has to be the stupidest thing I have ever heard.

He's not asking for a way to set of handgrenades and claymores here.

What he wants is to set off normal, legal fireworks (well that's what we have to assume anyway), doing that electronically is much safer than doing it with the old cigar as most people do.

I'd suggest using a short length of constantan wire (5cm or so) wrapped around the fuse, you need a lot of current, but that will ignite the fuse every time.

You can also get some non-fireproof (duh) 1/4W resistors, experiment to find a good size (10Ohm perhaps) that give a good flame when hooked up to 12V, then solder the resistor to the wires and tape the resistor to the fuse.

Do make certain that noone is near the fireworks when you set them off, however, getting hit in the face with a rocket isn't much fun.

Re:I saw a television special once.

[Anonymous Coward]

The control panel you describe, if I understand you correctly, is known as a nailboard. They're easy to construct (by hand if necessary) and were commonly used for electically-fired displays a couple decades ago.

In recent times, firing current is usually provided by a much more complex setup. The show is pre-programmed into one or many firing boxes. As show time approaches, the operator boots and arms the firing box. In large shows with multiple firing boxes in separated positions, a timecode signal is provided by radio from a central "mission control". Thenceforth, all the firing boxes are synchronized; if they lose the timecode signal, they keep time with their internal clock. Come show time, the operator plugs in the single cable (XLR or similar) that leads to the field and then holds down a deadman switch.

The single field cable leads to one or many remove firing modules, which house the terminals to which each pyrotechnic device is individually wired. Each module has its own address, and so does each terminal. The complete address of a device is, thence, the combination of the module's address and the terminal's address.

If something goes wrong and it would be dangerous to continue firing, all the operator has to do is release the deadman switch. In the unlikely event of a firing box malfunctioning and firing dangerously out of sequence, the operator can always just turn the box off. The only time I have ever seen this used was due to a programming error, where the show was delayed by about 30 seconds; since there were live actors on stage, continuing to fire out of sync could have been hazardous.

For good measure, we always leave the cable that leads to the field unplugged when it is not in use, and always clear the field of personnel when the cable is to be plugged in.