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My arduino powered firework sequencer. 2018 version!

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DaJMasta:

--- Quote from: usagi on March 08, 2019, 08:15:16 pm ---For 2019 i've moved from mechanical relays to Darlington arrays, more integration onto single PCB. Lesson learned, put as much work into the PCB to avoid as much manual wiring as possible.

Also going to use pre-fabbed boxes probably from Hammond mfg. Constructing lasercut boxes is a lot of work.

--- End quote ---

Less setup when you have time constraints and other factors certainly sounds like a good move.  Maybe some combination of the two could work for boxes?  Something like using a prefab enclosure with a laser cut face for connectors/switches/what have you?  Maybe not required if the prefab boxes can meet those requirements, though.

Yansi:

--- Quote from: texaspyro on March 09, 2019, 06:25:00 pm ---
--- Quote from: Yansi on March 09, 2019, 02:38:03 pm ---
--- Quote from: stj on July 04, 2018, 04:36:34 pm ---it's obvious most people here dont know electric matches are a virtual shortcircuit and need a MINIMUM 0f half an amp to fire - usually atleast double that to be sure it will go.

they arent like airbag triggers - they cant be fired by static.

--- End quote ---

Airbags can't be fired by ESD either. Even 9V battery is struggling to fire one.

--- End quote ---

Electric matches have a "no fire" and "all fire" spec on current.  Any current below "no fire" will not cause them to fire.  Currents above "all fire" are "guaranteed" to fire the e-match.  Some e-matches have surprisingly low "no fire" specs.

--- End quote ---

Why are you quoting me? I am not the one spreading bullshit that ESD can fire an airbag.

texaspyro:

--- Quote from: Yansi on March 09, 2019, 08:23:05 pm ---Why are you quoting me? I am not the one spreading bullshit that ESD can fire an airbag.

--- End quote ---

I quoted a post about electric match firing current...  your part of that post came along for the ride.

Oh, and ESD can fire ANY pyrotechnic device, including airbags.   It might not fire the pyrogen, but ESD has its ways of causing havoc.  Any person involved in pyrotechnics that forgets this fact will eventually be reminded of it in a rather spectacular manner. 

usagi:
so my design currently uses port expanders driving darlington arrays.

i'm thinking i can get better integration with high power shift registers like tpic6b595...

texaspyro:
My rocket launch controller uses 2 MOSFETS (rated at 1000 amps) for each channel.   There is a high side FET and a low side FET.   The ignitor connects between the two.  Both FETs have to turn on for current to flow.  The gate drive signals to the FETS are generated by transformer / capacitor coupled AC signals that have to be around 30 kHz to get through.  No static "stuck at"  or transient condition can turn on both FETs and cause a firing condition.  The drive waveforms for the high and low FETs are generated by two different mechanisms.  Both FETs are continuously monitored for unexpected turn-on.  Any faults sound an alarm and shut down the system.

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