Fireworks Controller

My brother-in-law puts on a hell of a fireworks show every year for New Years. Last year he upgraded to electronic ignitors so that he could fire them from 50-60 feet away. His system consisted of a 12v battery pack from a PowerWheels(r) car and two planks of wood with several nails punched through each. The nails were each wrapped with a couple turns of speaker wire that ran out to his ignitors, and the other leg came back to a central positive terminal that connected back to the battery. Not super elegant, but very effective and easy to troubleshoot and control.

I decided this year he deserved a better system to trigger his ignitors. So I built him this:

This ignition system has 24 channels or "queues", an internal power supply, and it looks pretty sweet too.

My parts for this build were pretty simple:

• 1/4" MDF (get 1/8", or use Paneling...the 1/4" MDF has an issue, see below)
• 24 momentary contact push-buttons
• 48 LEDs (24 green, 24 red)
• Key switch
• SPDT switch (with the red switch cover)
• 12 speaker terminals (each terminal has hookups for 2 ignitors, using 4 terminals)
• 12v LED strip from auto-parts store
• 12v battery
• Pretty case

First off I started with a blank piece of 1/4" MDF I purchased from Home Depot.This served as the base board for the electronics. I decided on a layout for the controls, and then using my drill press and my eyeballs I put the 24 holes for the push-buttons and then used a hand drill for the LED holes.
At this point my MDF looks like this.

I then used my Dremel tool with a router bit to free hand the slots for the speaker terminal connections. I am not a carpenter, nor to I claim to have any sort of artistic capability...this part is utilitarianism at its best.

It was at this point that I *noticed* my MDF was too thick for the buttons and switches to mount to without modification...so at this point I broke my Dremel back out and cut recesses around EVERY SINGLE button hole to reduce the thickness from 1/4" down to around 1/8". This was where I lost about 2 hours on my build, because these recesses had to be done free-hand, and it generated copious amounts of dust.

I painted the front of the board a brownish color because that is what I had handy. Next time maybe it will be black, or a high gloss silver.

Then I started mounting components. I started with the push-buttons and then the LEDs. The push-buttons had nuts to hold them down, and for the LEDs I just used a touch of super-glue right at the edge and it worked great. The speaker terminals and other switches were very simple to mount. This left me with a very pretty front panel (ignore the fact that I can't measure and things are a bit crooked).

Now I started wiring up the components. There are basically two circuits going on here. A Test Circuit, and a Live/Fire Circuit.

The schematic is pretty simple:

From the primary switch (key-switch) tie in each green LEDs long leg (positive). I used simple jumpers for this. I thought about etching up a PCB for this purpose, and I would if I had a little more time, but for this prototype I just jumped them all together. From the short leg of the green LED I ran the two 470ohm resistors in series, then tied that to the red side of the speaker terminal. I then tied all of the negative speaker terminals together and tied that back to the negative side of the battery.

This may not sound like much but after that step my wiring was getting a little cluttered:

I'm not the best solderer in the world, but I was kind of proud of how well this simple design was manifesting.

I also tied in a 12v LED module into the key ignition so that we could have a little light while hooking the ignitors up, plus it adds a pretty blue glow and also serves as a "power" indicator.

At this point I needed to mount the board in the case, and hook up the battery, and I was in good shape.
Some shots of the finished prototype are below.

If you have any questions or need more information, email me. jamesbradleyharris@gmail.com