Firework ignitor using mosfets and led matrix

[4pyros]

I don't think so. I want complete control of when cues are fired. Will a sequencer fire the cues in a fixed succession? With a fixed time interval between each fire?

Yes
Maybe you could get an off the shelf unit and then add the micro.

 

[alec_t]

Source and Drain of mosfets would be connected to 12v car battery.

That should give quite a pyrotechnic display in itself, as you would be shorting the battery as soon as the FETs turned on

 

[john6v54]

That should give quite a pyrotechnic display in itself, as you would be shorting the battery as soon as the FETs turned on

Sorry, didn't read what I wrote before I sent it. In the original concept each push button would be replaced by a MOSFET. Source would be common ground, drain would be +12v and gate would be from uC output pin. Is this feasible?

Also, would it be feasible to have a 10x10 grid with each row controlled by a MOSFET and each column controlled by a MOSFET?

 

[4pyros]

Sorry, didn't read what I wrote before I sent it. In the original concept each push button would be replaced by a MOSFET. Source would be common ground, drain would be +12v and gate would be from uC output pin. Is this feasible?

Also, would it be feasible to have a 10x10 grid with each row controlled by a MOSFET and each column controlled by a MOSFET?

Do you know what your all fire and no fire currents are for your e-matches?

 

[john6v54]

Circuit for electronic fireworks igniter

This is an over-simplified circuit for a fireworks igniter. The objective is to signal the ignition of many individual cues while limiting the number of parts and wires.

In general, is arranging mosfets in this manner a good solution? If it is, then I will work on the details of it.

View attachment 65585


Each of the diagonally oriented resistors is a what fires a cue. Its a segment of nichrome wire that will burn red hot then burn out creating an open circuit. It takes about 1 amp. The wires from the mosfet to the cue would be 100-200ft long.

I realize the dangers involved with fireworks and any device used will incorporate safety features according to NFPA code.

 

[john6v54]

[MODNOTE]Please do not start a new Thread for the same Topic[/MODNOTE]

 

[ronv]

Basically that would work. The problem I see is displaying which circuit is "armed".

 

[john6v54]

Basically that would work. The problem I see is displaying which circuit is "armed".

The firing of the cues will be programmed into the uC, if that's what you mean. LEDs are used to indicate continuity. There is generally a 'test' mode and a 'fire' mode. The test mode limits current to 10-15mA. I would probably use a physical switch to switch between the two.

 

[john6v54]

[MODNOTE]Please do not start a new Thread for the same Topic[/MODNOTE]

I apologize, I was hoping that posting a circuit diagram would attract more help, but that it would get overlooked if put in the same thread.

 

[ronv]

Yes, I guess it would work. A whole row would light if all the matches were installed and missing ones would be dark.

 

[KeepItSimpleStupid]

John:
You can always reference the post number or right click the schematic or the post # and get the link location and you can post that. There are ways to make the link appear as "New schematic" in blue e.g. **broken link removed**

The way to do this is:[url = https://www.electro-tech-online.com/attachments/]New schematic[/url]

The differences of a regular URL are shown in bold. The = sign is supposed to be bold.

 

[alec_t]

The matrix of FETs looks ok in principle, but you will need to consider what safety features to add to prevent spurious triggering, e.g. by static build-up or induced voltages.

 

[john6v54]

John:
You can always reference the post number or right click the schematic or the post # and get the link location and you can post that. There are ways to make the link appear as "New schematic" in blue e.g. **broken link removed**

The way to do this is:[url = https://www.electro-tech-online.com/attachments/]New schematic[/url]

The differences of a regular URL are shown in bold. The = sign is supposed to be bold.

Thank you. Do I do this using the Post Reply button?

 

[john6v54]

you will need to consider what safety features to add to prevent spurious triggering, e.g. by static build-up or induced voltages.

Are they any components you can recommend? My understanding is that induced voltages would be from something such as a coil or motor and a diode is used to prevent the 'back spike' (I don't know the proper term). Should I add these just to have that extra safety measure? How do I make sure static build-up is not an issue? Is having it properly grounded to most effective method?

 

[john6v54]

Mosfet Configuration in a grid

Regading the schematic I posted here:

Also shown here:
**broken link removed**

If I understand correctly, for each row/column one mosfet will have to be PNP and the other NPN. Is this correct?

 

[alec_t]

MOSFETs are referred to as N-channel and P-channel (your schematic shows those correctly).
If you are using both 5V and 12V components you will have to interface those correctly.
I'm concerned that your electronics knowledge may not be enough to build this project to a high safety standard. I have no practical experience of pyrotechnics so regret I am unable to advise on the safety aspects; you should get advice from someone who has the right background and knowledge.

 

[4pyros]

Safety should be a primary concern with a firing system not an after thought!
I think we should close this thread.

 

[ronv]

Sneak Path

There is a sneak path that might be a problem. The current is lower..... but.....

 

[4pyros]

There is a sneak path that might be a problem. The current is lower..... but.....

Yes and what happens to the matrix if an igniter or two shorts out after firing?