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Today I finshed our Carbide ignition system for December 31, that was created by +Johan Postema, +Elger Postema  and me.  This system is used to alarm the public before igniting our 1000 liter Carbide tank. 

For years we had a similar system that worked with a few simple shift registers, but that one somehow got lost. Thats why we decided to make a new one; and in this 'new era' it makes sense to use an Arduino or something like that and add some more features.

We also considered using a Raspberry for it, so we could start the count down by using our smartphones. But as usual everything took much more time than anticipated: we wanted the system to be secure, simple, robust and univsersal.

On the video below you can see a demonstration. Pay attention to the glow plug at the end of the movie: it actually glows.

So here is how it works and what it does:

An arduino will be the heart of our Carbide countdown and timing system. We didnt want to make any prints or do complex stuff, so we used one of those cheap but good 8-relay boards.

As soon as the system is turned on, the upper three sockets will be enabled. There are two power adapters in it for the arduino and the relay board. We will also connect a beacon light to it, to inform the other people that the system is armed. The 2 buttons will also blink slowly to indicate the system is armed. 

When the 2 buttons are pressed at the same time for longer than 1 second, the system will start to countdown. 

At this moment the wall-socket on the right will be enabled and disabled faster and faster. There will be a bell and a light connected to it, to warn everyone and to give kind of a 'count down' effect. We use wallplugs to make things easy and universal: just connect a random device that makes noise or light and off you go.

After counting down, the 'fire' socket will be enabled. A power supply that powers a glow plug will be connected to it. This will ignite the Carbide in our 1000litre tank. :) This powersupply has a build-in alarmbell as well, so its impossible to turn it on without anyone noticing.

After a few seconds fire-socket disabled again and the system will return to standby mode. The length of this time can be programmed by holding the 2 buttons and will be stored in NVRAM. 

So after pressing the buttons, we can drink beer and watch the fireworks, and dont have to worry. :)

Happy 2013 everyone! 

prototype on breadboard: Fireworks countdown timer

facebook page of the event:

source code:

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