Rocketry is very exciting hobby. But building and letting plain rockets wouldn’t be so fun without countdown. For this you don’t need much – An Arduino, ULN2003 chip to actuate relay and dot matrix LED display – the bigger the better.
You can guess what it does actually. So code is pretty simple. When button is pressed countdown starts. When it reaches zero, Arduino triggers the relay where the ignition is connected. That’s it – enjoy the show.