Fireworks/pyrotechnics Sequencer

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Pete Firth

New Member
Hello all, Sorry I'm a bit of a neewb (this is my first post), I have a fair understanding of electronics and circuits but when it comes to resistors capacitors micro controllers etc I'm totally out of my depth!

I'm trying to work out the circuit for what I believe (maybe showing my ignorance!?) should be a fairly straightforward project. and I'm hoping that some of you may be able to help with the circuit design/planning.

The Dream: a simple sequencer that is triggered from an electrical pulse (sent from an existing firing system) triggers a sequencer, i.e. an electric pulse incoming, and on each subsequent input pulse advances to the next output, each output is a pulse of current that goes to an 'electric match' basically a resistor that gets overpowered and burns up igniting a firework fuse or lift charge.
So similar to an led counter circuit where each press of a button lights a different LED, just in this case theres an led and a current sent to the ignitor to fire the firework connected.

The system will be powered by 2 x 9v batteries (18v), there should be a continuity test function with an LED to indicate a complete circuit, and an LED indicator for each output pulse (can use the same LED), the counter should also reset to 0 on power cycle, in theory a simple CD4017 decade counter should do the trick as I only want 6 or 10 queues / channels on this system, the continuity test will need to be at less than 15mA, the ignitors are not sensitive to current direction, and once fired the circuit is broken, however some sort of dead short protection is probably a good idea.

So, its a stand alone system with its own 18v power supply, when switched on it should show/indicate if there is continuity on each of the output circuits, the trigger is a pulse of current from a separate system, each time an input pulse is detected it should send current to an ignitor in sequence [pulse #1 (p1) fires queue 1(q1), p2 fires q2, p3 fires q3 and so on..].

Its worth noting that it should not include any mechanical relays etc, as in a failure this could cause a dangerous occurrence! these sort of systems often employ fets (but I'm not entirely sure I understand what they do..

I hope thats enough information to get started? I think I can get my head around circuitry that would make this work but I'm clueless as to what resistors capacitors etc I would need to protect the circuit and make it function reliably.

Any help would be much appreciated!
 
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I should add that there are a few similar ideas floating about on this forum, but none that quite get me there, however the discussion linked below does answer a few questions:

Electronic firing system - for fireworks

Hi guys, Firstly let me say that I have my licence for fireworks, so this is all above board. I am trying to avoid paying for a professional firing system, as they are really expensive. I don't have the too much experience in building circuits, and I thought it would be a lot easier than...
www.electro-tech-online.com

the circuit they came up with in the end is linked below, it would need modifying to cope with 18v, and rather than a push switch to fire a single queue an input current and maybe a decade counter to automatically advance to the next queue in the sequence:

obviously no need to reinvent the wheel.. but if someone has the knowledge and is willing to help with combining the two ideas into a circuit that might work it would be much appreciated!
 
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One possibility, single chip. Right hand window shows many more onchip
resources available. 16 channels shown, I think 32 would rout..... A simple OLED
could be added for user interface....




Here is what is onchip, many have multiple copies :



IDE (PSOC Creator) and IDE free, board dependent on # channels (eg. I/O needed) but the $15
CY8CKIT-059 board good starting point.

Would be able to incorporate a timing facility that inserts inter shot waits / delays dependent on what is being shot.
 
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Thanks both for your responses!

danadak, although that may be a little overwhelming, I need a maximum of 10 channels per unit (the plan would be to make 4 of these ideally) and no need for any timing facility or variable delays between queues, the timing should come from the input pulse. this would mean that from 1 queue on my existing firing system I can fire 10 queues via this circuit by re 'firing' or activating the queue.

rjenkinsgb, the standard current pulse time is 1/10th of a second but worst case would be 2 seconds, and 18v 2A would be more than enough current to fire pretty much any igniter (a 9v battery touching the wires would fire most queues without issue)... generally you want a minimum of 12v 1A at the ignitor/match
 
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I would use auto-protected Mosfets.
I have used the Omnifet II series from STMicro, they are extremely rugged.
OnSemi also has a similar Smart Switch series.

Those have over current, temperature and voltage protection, plus the gate is fully clamped.
 
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hello all, heres my attempt to draw the circuit I had come up with, I understand I will need further components to protect the system and effect an auto reset and note that I have no idea about the actual components needed and their values. any help to flesh this out into a workable idea gratefully received.
 

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  • fireworks sequencer circuit 1.jpg
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This would use Arduino. Use block language to program. This would be a
basic design.




Note post #4 may look complicated but its drag and drop, and includes the SAR
to be able to verify connections to match(s) is good. Each resource has API's
written to manipulate it, so programing pretty simple. And whole design is 1 chip.

The design at top is simpler, Arduino boards pretty cheap and simple to work with.
6'th graders are using it to program direction finding robots in schools. The program
used is mBlock and Arduino, both free.

As an aside I use block programing for many projects being a visual learner. For
projects that have more stringent HW issue I use C. C is a "strongly typed" language,
and has a significant learning curve. Gives users more control at the expense of
un yielding rigid typing.

Regards, Dana.
 
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Thanks danadak, I was hoping to avoid the micro-controller thing, mainly as I have no experience with programming so it all feels a little black magic to me, mechanical servos switches and rc gear is my wheelhouse (I'm a drone operator by trade, amongst other things) but Arduino is something Ive not played with, it may be easy for a 6th grader in this day and age but will be a massive learning curve for me... although I'm not entirely opposed to it if thats the best way to go... If it is then what Arduino chip would I need? there appears to be a whole range of different ones (don't know if it makes any difference but I'm uk based).
 
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The Arduino isn't a 'chip' it's a simple micro-controller training board - usually (but not always) based on an AVR processor.

The basic standard board is the Arduino Uno, and that would be fine for your purposes.

However, the Arduino is natively programmed using C++, danadak is the only person is the only person to ever mention it (perhaps he wrote it?).

Your CD4017 circuit in post #8 is completely non-functional, you can't use the CD4017 to drive the igniters.
 
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Sorry for using the wrong terminology Nigel Goodwin.

I'll have a look at the Uno's (I've just been researching the nano).

Yes, I realise that the CD4017 will not handle the current I need, and that the circuit was most likely completely non-functional, I was just trying to display my thought process really, and realised there would be a need for further components and circuitry to get to a functional system..

Although it does appear Should learn more about micro-controllers. But will the Arduino's be able to drive the ignighter's? from what I've seen so far they tend to operate primarily 5v circuits, so presume I will still need some sort of mosfet or capacitors to make it work, or ive not learnt enough yet...
 
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maybe transistors are the key to all of this... both my original idea of using a CD4017 to switch to a higher power circuit, or for a micro controller to also switch a high power circuit separate to a low voltage supply to the controller..
 
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Pete Firth said:
Sorry for using the wrong terminology Nigel Goodwin.

I'll have a look at the Uno's (I've just been researching the nano).
Click to expand...

The Nano is fine, but the Uno is better for the initial development - once finalised you can transfer to a Nano for the completed project (as it's smaller), or a ProMini (smaller still).


Any solution is going to require drivers, either FET's, transistors, or IC's. You really need a highside switch, simple example in my tutorials, 6th diagram:

 
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Thanks Nigel Goodwin, Thats actually very helpful!!

I'm sure Ive mentioned, the need to avoid mechanical relays above at some point, the lift charge in larger fireworks could create enough vibration through the earth to 'bounce' a relay and create a dangerous occurrence, also a relay failing closed could equally create a disastrous and dangerous outcome.

but what Ive been reading about transistors and your tutorial certainly suggest that most likely are the solution, while keeping high voltage and low voltage circuits separated.
 
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Arduino UNO has an interface that can accommodate various interface boards. Called "hats"
or "shields". These plug in to the headers on the UNO board and make life easy for many
varied applications.

25 Useful Arduino Shields That You Might Need to Get | Random Nerd Tutorials

Arduino shields are boards that will expand the functionalities of your Arduino. You just need to plug them over the top of the Arduino board.
randomnerdtutorials.com

Shields & Carriers

Elevate your projects with our carriers and shields collection.These intelligently engineered accessories effortlessly integrate with your Arduino boards, offering specialized capabilities such as connectivity, sensing, motor control, and more.
store.arduino.cc

Arduino Official Store | Boards Shields Kits Accessories

Explore the full range of official Arduino products including Boards, Modules, Shields and Kits, for all ability levels and use cases.
store-usa.arduino.cc

Here is an example of a high side driver board, you can go to aliexpress, ebay for others.


Some versions of these boards have protection features as well.

With respect to block programming, many starter videos on YouTube and elsewhere.
Keep in mind if you have used a calculator you have been programming most of
your life. Eg. concept of math operations, sequence of operations, intermediate values
stored in memory..... The beauty of block programming is ease of use, learn one you
essentially can use many of the variants. Start simple circuit like blink LED, or a photo
resistor turning on a LED or.....

A couple of examples of what can be done without going to University -

GUI Codeless Processor Design

Micro design has for years relied on ASM and C programming and other languages. Often many tasks are fairly simply but these tools were focused and quite a learning curve, especially ASM and C and C++. There are a number of new GUI based tools that essentially take out the "strong typing"...
www.edaboard.com

Pulse Sequence Generator / Smart Timer

Often users, developers, hobbyists need timed and qualified event generators, many resorting to 555 timers and the like. The venerable 555 has had a long run but its limited in accuracy and capability. This approach uses block language to create...
www.electro-tech-online.com

I am not telling you in 5 minutes you are up and running, thats what the YouTube videos will
help do. But none of us here (I dont think) have a Phd in Rocket Science, one step at a time.
If you are in a rush take the path of least resistance, but consider getting a board for future
stuff, its fun and enlightening, and quite useful if you keep at it.



Regards, Dana.
 
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so could this circuit work? diagram attached (accepting that I would need additional circuitry to reset the decade counter etc, as well as potentially other components that are beyond my current knowledge). thinking something like the IRF3205 Power MOSFET where a transistor is indicated (the 'gate' operates at 4v and is capable of a maximum of 20v, so seems like it should work, Diver300 suggests that a different power source may be required on the low voltage side, but thats no problem to change).

appreciate that people with much greater understanding than me are saying to use a micro controller, and if that is the way then I'll happily give up this thinking of using a decade counter, it was only the simplest way I had found of 'stepping' from one circuit to the next to fire queues sequentially, my thinking was if pressing a button to signal a decade counter could make LED's light up and switch off sequentially then this wasn't a great stretch to assume I could 'light' fireworks instead using a similar circuit triggered by my existing firing system.
 

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  • fireworks sequencer circuit2.jpg
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Pete Firth said:
so could this circuit work? diagram attached (accepting that I would need additional circuitry to reset the decade counter etc, as well as potentially other components that are beyond my current knowledge).
Click to expand...
The CD4017 has one output high at a time. The transistors that buffer the outputs would have to be NPN transistors in emitter-follower mode and then they transistors will never produce more voltage than the supply of the the CD4017, so you will either get only about 3 V to the outputs when on, or you need a higher supply voltage to the CD4017.
 
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You might consider using ssr's :


OR


More high side switches - https://www.analog.com/en/parametricsearch/12970#/ps6=high

Your schematic is not driving the switch properly, in order to shut off PMOS you
need to take the gate higher than the source.

Another possibility, do low side switches for each channel, but gate the power for all channels
on before triggering the specific channel. That way interface simple NPN or NMOS/channel,
and one high side power to supply power for all channels. many shields available for low side,
and you implement high side with discrete..... This approach could allow you with Arduino to
detect a fault if no trigger done but you switch on power and find power drain......something
wrong.....

Or use intelligent MOSFETS that have protections, interface possibilities, called smart MOSFETs.
 
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