233 replies to this topic

[karlfoxman]

You would need a microprocessor like a PIC Chip to do it. Programing them is easy if you know how, but would take alot of reading and experimentation. You would need to figure out what voltage and current you need to supply the e-matches. It would not be easy to do but it is very possible, you would also need to etch your own PCB's and have good knowlage of electronics. Best thing to do is brainstorm the design and key features and figure out what you need from there. Components would not cost much but the PIC programming gear is quite expensive and you need to check what chips it will support.

PIC Chips are made by http://www.microchip.com/
Good source for components and stuff is http://cpc.farnell.com/ or http://rswww.com/ or http://maplin.co.uk (Maplin do a book on PIC Programming, unless its discontinued like everything else )
Check ebay for cheap PIC Programming gear but dont buy until your certain it supports the chip you going to use.

Good luck!

Edited by karlfoxman, 30 November 2006 - 11:15 AM.

[phildunford]

I recently saw an article in a flyer from RS components about a controller system created by Shellscape for their displays.

An interesting point about it was that they made it entirely from discreets (ie. no microprocessors) as they thought this would be much easier to 'certify' as safe.

I've often thought about making a micro based controller, but it occurred that given the 'mission critical' nature of the project, the consequences of a micro going off into a loop could be dire. You could get round this I guess by some additional hardwired enabling circuitry and watchdog timers etc but it would need a bit of thought to cover all eventualities and avoid a short (spectacular and possibly lethal) display!

Any opinions?

(I will see if I can get permission to publish the article if anyone is interested - unless there is a shellscape bod on the forum who could comment?)

[BrightStar]

I recently saw an article in a flyer from RS components about a controller system created by Shellscape for their displays.

Hi Phil, thanks for posting - I would be very interested to see the article.

I would never trust any electronic firing system, discrete or otherwise, to automatically fire proximate pyro that could cause injury or harm. On stage I always used to trust the good old fashioned power keyswitch with the 'mark one eyeball' to avoid blowing up the cast, and can't imagine trusting this to an automated system. With fireworks, I assume that once the power is connected, any cue might just fire and has to be safe if it does so.

It's difficult to understand how a firing system of any design complexity based on discrete components could be more reliable than a modern microcontroller based system. They are modular internally and the manufacturers always use something like JTAG to scan numerous test patterns in to each section and read out the results. The testing is so important that it forms a major part of the cost of modern VLSI devices. You can get hold of Mil-Spec processors for a few pounds more if needed. The microcontroller can CRC check the firing comms data, self-test the output transistors, monitor the supply voltage condition etc. etc. and shut down instantly if anything untoward occurs, seeming to provide much more safety than a discrete solution, given sensible output hardware.

Edited by BrightStar, 02 December 2006 - 10:25 PM.

[roaryyyj]

Ok, i have made a small (bit rubbish) kinda plan of what im going to make
heres a picture


Now the problem for me is power. To ignite, i was gonna just probaly speaker cable, and then at the end a small loop of nichrome wire to create the heat to ignite BP. How many 9V batteries do you reckon id require for this? If i connected 4 or 5 up do you think it would be fine? I mean i would just hook up like 6 to ensure it would be enough power to run all the led's and heat up the wire, however is there such thing as sending too much power to the wire to ignite the BP?

[parabolic]

roaryyyj,

I think it will depend on what size/guage of nichrome wire you intend to use, and the length of the cable run to each e-match,
If you are using the very thin perhaps 32 SWG (.28mm) nichrome wire in the e-match then I cant see why not just one 9v batt will do the job, but it may not last too long,

I think you might be better in introducing a seperate high amp battery source which is crosed over by the use of relays to fire the ematch,
Just use the 9v battery to control the switches/LED's and relay coil.

Iam currently in the middle of building myself a 7 cue system, using 12v supply to control the switch gear, but I have another box with relays which throw a nice 12v 10ah sealed lead acid battery power supply onto the e-matches.

you have indicated that you are wanting LED's on your circuit.. you will have to make sure that you apply a resistor of the right value in series with the LED to match the LED's current rating-- or else it will burn out.

Take care

Para

Edited by parabolic, 10 January 2007 - 10:15 PM.

[roaryyyj]

Ah right, thanks for the help

[electronicsuk]

Interesting to see there are so many people making their own firing systems. I came across this post while searching for some information relating to firing controllers. I've been into model rocketry for some time, but I've also had a keen interest in fireworks and I'm looking to take a training course, and hopefully get some practical experience eventually leading to a BPA exam.

That aside, mostly out of my own curiosity, I'm thinking (and have been for a while, but lack of time and all...) of designing and building my own firing controller. At the moment its applications would be purely for model rocketry, but in essence model rocket ignitors and pyro E-matches are the same. Clearly there are different specs with regard to continuity test current, firing current, etc... but it should be possible to make a system that will work safely in either application.

Now, I'm also heavily into electronics (I work in electrical and electronic engineering) and, in particular, microcontrollers and computers. I've looked over the FireOne system and would like to implement many of the features found within it. Here's my outline specification of what I'd like my system to do:

- Minimum 32 cues per firing module
- No need for separate firing rails, binding posts integrated into firing module
- Capacitive discharge firing circuits, each cue isolated from all other cues with its own capacitor to prevent the entire system being discharged in the event of firing into a dead short
- E-match continuity check, firing modules can report back the resistance of any igniter to central firing unit with accuracy of 0.1 Ohms
- Firing modules powered and controller by master host
- Only one combined power and control cables to all units in daisy chain or star wiring configuration
- LCD display for addressing and settings on firing modules
- Central programmable control unit for manual firing or pre-choreographed shows in semi-auto (i.e. press a button to advance to the next cue) and possibly full-auto with timing if this doesn't pose a safety hazard
- Computer control as a future possibility

Of course, that's just a few of the things I'd like to do with the firing modules. There will, of course, be all the usual safety features, the main firing controller will be designed for manual or pre-choreographed shows, and adding PC control would be a snap in hardware terms if I can manage to write a usable piece of software.

What I don't intend to do is transmit over bellwire. Instead, I'd prefer to use cat5 cable between all firing modules and central control unit. Its not as cheap, but its not expensive either, and its designed for use in data systems. It has enough cores to carry the power, and could also be used to carry DIFFERENTIAL transmit/receive RS-485 lines between the controller and firing units. As far as I'm aware FireOne doesn't do this, in fact I don't see how it could without using more cores and twisted pair cables.

Quite clearly the FireOne system does work, but one would assume that once you start getting some lengthy signal cables in the system you'd be picking up a lot of interference and losing a lot of data packets over the connection. It could only get worse in larger displays where even more cable is used, and these displays are going to be the ones that require the most bandwidth! I guess that's why they added the ability to store the show in the firing module and then run it using timecode.

Of course, I haven't done any of this yet. I'm trying to start a business and at the moment anything else is on the back burner, along with taking up any spare time and money I might have otherwise had. Nontheless, I'd love to hear from anyone that might be interested or has any feature suggestions for the system.

Of course, I'd be happy to design and build this system to some sort of timescale if there was potentially some gain at the end of it. In fact, if comparable systems were sensibly priced then I wouldn't be bothering to design my own at all, but its a niche market and manufacturers seem to be able to over-hype their prices.

Oh, and after all that rambling onto what I actually meant to ask. When I do make a start on this, I'll be needing to get hold of some E-matches for testing. However, I can't find *anywhere* in the UK selling them. Are there laws limiting their sale, perhaps because of the explosive coating on the tip? How do I get hold of them?

I hope this didn't hijack the thread too much, apologies for going on a bit! Hope you're all holding up ok in the weather.

Matthew

p.s. Mods, if you do feel this isn't particularly relevant to the thread then do feel free to split to a new topic. Cheers.

Edited by electronicsuk, 19 January 2007 - 06:17 PM.

[pyrotrev]

roaryyyj,

you have indicated that you are wanting LED's on your circuit.. you will have to make sure that you apply a resistor of the right value in series with the LED to match the LED's current rating-- or else it will burn out.

It's also important to make sure that the test current is well below the long tem minimum ignition current for the ematches !! For most commercial ematches this means 10mA or less.

[pyrotrev]

- Minimum 32 cues per firing module
- No need for separate firing rails, binding posts integrated into firing module

I don't think that more cues per firing module is always better - it can be useful when e.g. when firing lots of close packed single shot stuff, but when it's big cakes/shells smaller numbers of cues per module often avoids the rats nest of igniter wires and makes for a neater setup.

- E-match continuity check, firing modules can report back the resistance of any igniter to central firing unit with accuracy of 0.1 Ohms

Good idea this, I've put it on both the systems I've made and it's detected some serious and otherwise undetectable wiring errors

-What I don't intend to do is transmit over bellwire. Instead, I'd prefer to use cat5 cable between all firing modules and central control unit. Its not as cheap, but its not expensive either, and its designed for use in data systems. It has enough cores to carry the power, and could also be used to carry DIFFERENTIAL transmit/receive RS-485 lines between the controller and firing units. As far as I'm aware FireOne doesn't do this, in fact I don't see how it could without using more cores and twisted pair cables.

Cat 5 is a good idea, but if it were me I'd go for a cable with a braided screen for ruggedness.

Of course, I'd be happy to design and build this system to some sort of timescale if there was potentially some gain at the end of it. In fact, if comparable systems were sensibly priced then I wouldn't be bothering to design my own at all, but its a niche market and manufacturers seem to be able to over-hype their prices.

I'm not sure many do overcharge to be honest. The thing is, there's an enormous amount of hardware (connectors, boxes, terminals etc.) in a usable firing sysyem, and if it's made to work reliably under all weather conditions it isn't going to be cheap. All connectors really need to be IP65 waterproof with covers for when thy're not used IMHO. My system didn't really save me much over buying one off the shelf in the end, though I did get exactly what I wanted, and know how to service and repair it, which has some value.

[Caramanos2000]

Since my devices are getting larger and more sofisticated visco doesnt seem atractive anymore. So I was thinking of getting little project box from radioshack, a 9v or 2, an led, a momentary push button switch, and a toggle switch. I already bout a few hundred feet of nichrome. So, just dip the nichrome in bp, let dry and attach to the 2 wires and viola?

[paul]

Hey guys. What do you think about using thyristors instead of relays for firing units?

I tried one [rating: 600V 16A] and am impressed by its size/power ratio...

This is my scappy test unit.

Are thyristors widely used in commercial firing units?! I mean, they add to your firing boxes security.
No problem when your box gets a hard kick which might set of an relay...

Edited by paul, 25 April 2007 - 01:43 PM.

[pyrotrev]

You could use thyristors but there are issues with trigger current and turning them off should the ematch not go open circuit on ignition that would make a MOSFET or IGBT likely a better choice.

[paul]

MOSFETS need a very high Gate-voltage. There are TTL compatible MOSFETS which fire @ 4.5...5V but these are not compatible with high voltages...

I guess I have to search alot to find a good solution. (More secure than thyristors...)
Its hard to find information about special kinds of MOSFETS, IGBT´s or other parts, which are build for switching such high voltages and currents.

EDIT: Pyrotrev, what are the issues with trigger current you mentioned?!

Edited by paul, 25 April 2007 - 09:00 PM.

[wielder of fire]

i'm realy sory to burst anyones buble here but i made a perfectly good 10 way ignitor last saterday afternoon. (i could have done more but i only needed 10 and i was already desighning a wireless one anyway)

its hardly a GCSE main progect.

some advise, make the box seethrough cuz it just makes it look cooler

also, make it plug into the mains rather than on baterys cuz that makes igniting realy hot comps all at once soooomuch esier.


forgive me if i come over big headed or anythin

[paul]

Yeah, you got mains voltage everywhere you go? Additionally I think some members here got pro-units, so you won´t "burst any bubles" with your mains?!?!?! 10-way ignitor

And igniting "really hot comps" is not up to the voltage you use but to your e-match design... I promise, I can light thermite with a 1,5V cell. haha If you need mains voltage for it, fine!

This whole thread isn´t about how to make an simple x-cue firing panel. This is done with some basic electronic and soldering skill only. It´s about how to design it right to be a fool-proof and safe unit. Where safe means: False-trigger proof (especially when wirking with wireless units), relay-less (to avoid false-triggers when accidentally bumbing into your box...) at best.

Edited by paul, 06 May 2007 - 08:47 AM.