[spectrum]

We are currently involved in the production of very precise delay elements for use in defence related pyrotechnic devices, the delays we are producing are accurate to within 0.1 seconds over periods of function running into several seconds, the device we have developed and are building commercially is designed to function with a series of explosive events running sequentially. The project is gathering momentum and we will be producing these units in considerable volume in the very near future.

I have casually considered the possibility of incorporating this element into sound units for use in fireworks, maybe as a series of very precise crackers for use in effect mines with three successive volleys timed to function one after the other. The resulting mine (or shell) would release the units which would fire perhaps 10 at a time, with spacings of say 1 second between bursts. Of course the units would be loaded with delay charges of varying colours.

The problem I would face is that these units would be more expensive than Chinese alternatives (although I am not sure if there is anything close to this available from the far east), I would welcome views as to the commercial viability of this project. I hold the opinion that Chinese fireworks will never completely replace such items but am unsure whether or not this is realistic

[Andrew]

spectrum, on Jul 29 2007, 07:07 PM, said:

very precise delay elements for use in defence related pyrotechnic devices

In which case you'd have loads of money and not need the help of amateurs!!!

Also, 0.1 second is not that precise at all.

Anyway, 0.1 second precision, more over, resolution, can be achieved very accurately with any crystal operated micro-controller or sequential logic etc. It's very important to understand the difference between precision, resolution and accuracy; in order to know exactly what you are out achieve.

0.1s is a piece of piss the do (even with tuned RC circuits). If your looking for anything down to tenths of micro-seconds, crystals are the way to go (temperature compensated Xtals for increased accuracy). Once your into tens of nano-seconds, you'll need to look into devices called "active delay lines". You also have to bear in mind that once your looking that these sorts of delays (the sort that propergate commands through ALUs in processors), the length of tracks and the thickness of the substrait, blarr blarr blarr and so on will have dramatic effects on the delay time and also the response. But your not going that far so it is not important.

[marble]

0.1 seconds is not that great seeing as you can knock something together that will do that for $10

[YT2095]

a simple 7404 and a 1Mhz crystal set us as a master clock oscillator and then a few 4017`s to /10/100/1000 prescale it down to whatever frequency you like, prescaling also eliminates much of the problems of inconsistency with x-tal temp also, buy dividing down the error margin.

I have to ask though, What is "defense pyrotechnics"?

[spectrum]

marble, on Jul 30 2007, 06:37 AM, said:

0.1 seconds is not that great seeing as you can knock something together that will do that for $10

I thought this forum was for pyrotechnists not electronic geeks!!!.

I think you need to use a little imagination here lads and look at what was originally posted. The 0.1 seconds accuracy is achieved over extended periods of time, the example given was perhaps a little simple in the form of a Mine but nonetheless provides an alternative to that currently provided from the far East where, despite the cheap cost and apparent ease of manufacture you describe delay accuracy isn't that great at all and generally relies simply on cut lengths of safety fuse. Think of high quality Italian Roman Candles where a bank of say twenty units are required to fire multiple shots with absolute precision from beginning to end. This is not I suspect achievable on a ten dollar budget nor would the dismissal be taken seriously by the Italian chappy making them!!

The level of accuracy I describe, reproducable every time and over extended periods of time is NOT that easy and in the application we started out developing electronic solutions were not an option, it wouldn't be fair or relevant to compare them either. I suspect that if we produced the units at a reasonable cost - in the format similar to those supplied for years by the German supplier Zink they could be of interest, I was simply interested to take an opinion on this.

[spectrum]

YT2095, on Jul 30 2007, 08:03 AM, said:

a simple 7404 and a 1Mhz crystal set us as a master clock oscillator and then a few 4017`s to /10/100/1000 prescale it down to whatever frequency you like, prescaling also eliminates much of the problems of inconsistency with x-tal temp also, buy dividing down the error margin.

I have to ask though, What is "defense pyrotechnics"?

Defence pyrotechnics are effectively military fireworks employed for training and certain operational applications. Thunderflashes etc. Again, electronic solutions are not relevant in this application, okay for firing systems but not for stand alone disposable items such as the one we were engaged to develop.

[YT2095]

spectrum, on Jul 30 2007, 09:07 AM, said:

I thought this forum was for pyrotechnists not electronic geeks!!!.

erm... Ad Hom name calling aside, you didn`t exactly Specify that electronics was Not part of it, in fact you were the one that mentioned "Sound Units", and they are indeed electronic


consider this also, quick match fuze burns at roughly 100 foot a second, therefore 10 foot of this will be your 0.1 sec.

This post has been edited by YT2095: 30 July 2007 - 08:43 AM

[marble]

spectrum, on Jul 30 2007, 06:07 PM, said:

I thought this forum was for pyrotechnists not electronic geeks!!!.

Most people who like pyro also like science, and that includes electricity

[spectrum]

[quote name='YT2095' date='Jul 30 2007, 08:37 AM' post='36540']
erm... Ad Hom name calling aside, you didn`t exactly Specify that electronics was Not part of it, in fact you were the one that mentioned "Sound Units", and they are indeed electronic


consider this also, quick match fuze burns at roughly 100 foot a second, therefore 10 foot of this will be your 0.1 sec.

No offence intended with the name calling.

The operative word in your point is "roughly" - accuracy time and time again is what we were appointed to develop. If you simply cut quickmatch into 10ft lengths then it wouldn't be terribly convenient to install such lengths into devices as a versatile component. The units we are producing are approximately 10mm in diameter and 45mm in length. They comprise a pressed delay element at one end and an empty chamber which, for our purposes is charged with an explosive flash powder to produce an audible effect. They resemble the sound units I refer to supplied for many years by Zink and incorporated into mines and effect shells. The point I am making is that the delay element we produce within these units is very accurate and completely reproducible. The limits of delay range from 0.1 seconds to 10.0 seconds. The delays could be formulated to burn in a range of colours and spark producing effects. My request for opinions (I don't actually need help as one commentator stated) was whether or not there would be a market for this type of item but it all seems to have gone off track somewhere.

[YT2095]

I can`t really comment as to an Opening in a market, but these types of things are employed regularly (and in a range of colors as you mentioned), even Estes rocket engines have a delay charge in them, ariel salutes have delay charges (in colors) same for spherical shells (colors And effects in those).

burn rate dictated by the composition, and also the length of material to burn are the 2 main factors, so if you can have fuse that do 1 foot in a minute or 100 feet in a second, you can have anywhere in between also

This post has been edited by YT2095: 30 July 2007 - 09:16 AM

[paul]

Guys, I really don´t get what you´re all saying!

First of all spectrum: Tell us, HOW does your delay-charge look like?! A tube with
a slowly and steadiely burning powder pressed into it?! So basically a spolette with super
accuracy as a bonus?!

Next, @ all the others, especially Andrew: I think you´re all talking at cross-purposes
in this debate... Look, spectrum just mentioned that they produce a "special" very accurate
delay charge which could be used in "mines" or whatever!

Then in the first reply you try to bash him and what he says. Thats not how it works
I guess


First of all spectrum should mention more DETAILS regarding their super-accurate delay-charges!

[Andrew]

What you are trying to achive is accuracy in the form of limited "drift". What sort of extended time are you looking for?



4 hours; any watch crystal is accurate to 0.1 second.

2 days; high precision crystal oscilator.

Forever; Have a high precision clock based on a high precision crystal, and then (the important bit) either use the time stamp on a GPS signal or even better use a Rugby receiver to update the clock every day/6hours.



The latter is the method used in a declassified 19" rack mountable time peice used by the police and security services to provice a time stamp for survalence equipment. The time it says is based on an atomic clock and is never out, the system can go for a couple of days without a signal and only be a second off (it is constatly updated when it is receiving a signal from the GPS or Rugby). If you PM me I can point you in the right direction to get hold of this equipment; I can't post it in public view.

This post has been edited by Andrew: 30 July 2007 - 11:33 AM

[BrightStar]

I believe spectrum is discussing chemical based precision pyrotechnic delays here, rather than electronic delays. Spectrum, have you come across Pyroclock?

http://www.monetti.n...rotechnical.htm

This is a commercially available compressed grain delay system for fireworks, but used for linking together display chains rather than inside the fireworks. Would your product be similar?

Others: As I understand it, manufacturing a delay fuse that is consistent to 0.1s regardless of storage conditions, humidity, external temperature and pressure, manufacturing tolerances etc. etc. is not simple. For fireworks, PIC fuse is usually the best we can do.

The modern 'gassless' delays lead the way in precision here. They are usually made with a metal oxide or chromate in conjunction with an elemental fuel. Organic materials are avoided due to the CO, CO2 and N2 formed when they burn.

One to try for amateur purposes might be: red lead oxide 85%, silicon 15%, NC laquer 1.8% (the NC produces some gas). This burns at 1.7cm/s producing 10.6ml/g of gas. More exotic comps (BaCrO, Zr-Ni alloy, KClO4) produce only 0.7ml/g of gas!

If you compare these to a traditional somewhat pressure-sensitive BP fuse releasing 50% of its mass in gas, you can see the potential advantages in timing precision...

This post has been edited by BrightStar: 30 July 2007 - 01:50 PM

[pyrotrev]

If you can do 0.1 sec max in 4 or 5 sec then that's good Spectrum. Speaking as a display operator I would say the use in mines, shell inserts etc. is of minor interest, for the bulk of applications, a bit of spread in the timing of groups of salutes is actually a bonus in some ways, unless you're firing them in patterns (I'm sure Karlfoxman would buy some!), hoewever in Roman candles and shell lift delays (and general timing applications) than they could be useful if the price isn't too extortionate. Give Ron Lancaster a ring and see if he's interested! - Kimbolton make some nice candles at the kind of price that could maybe stand the cost and the coloured tails would be cool. The best Spanish candles I have fired have delays of this kind of accuracy if not better, all the shots rise essentially simultaneously right to the end. Pyroclock by the way is no great shakes on accuracy, when I timed 2 strings of 5 2 sec units, the last firings were about 0.6 sec out: and it isn't as waterproof as it looks!

[karlfoxman]

Too right trev, I would buy them!

It seems the delay units in pyroclock are the 10mm Martin and Martins time fuse, I have bought this stuff and its very very good. I have also made very short delays using a similar method to my beraq, I can get accurate timing with these by simply changing the thickeness of the delay path. The larger candles use either this 10mm Portugese fuse or 1/4" chinese fuse and the 10mm gives very good timing. If it was me I would simply make delay units similar to beraq delays, they are very simple to make and would do the job well.

Spectrum - if you need more info PM me.