All credit to Allen Pan for the idea and providing a tutorial on hackster.io.
His YouTube: https://www.youtube.com/sufficientlyadvanced
The basic idea is that some butane gas is stored inside a metal tube with one end connected to an electric valve. Once the microcontroller detected a punch in the data coming from the accelerometer, the electric valve is opened for a short amount of time. Simultaneously, a high voltage source is switched on, producing an arc inside the outflowing butane gas stream and ignites it.
After all the different tubes, reducers etc. arrived, a first prototype was quickly built and tested.
One of the first test runs is shown below in the video.
In the first one or two blows, the gas pressure is very high, getting it to ignite and not blowing out the arc is a bit tricky. Possibly different positioning of the M3 screws, where the arc forms in between, could be tried out. Also, increasing the distance between the arc and the valve helps for more reliable igniting, but the range of the fireball will then be decreased.
The HV-source is incredibly noisy when activated, so some very basic EMC measures (e.g. star ground layout) have to be implemented in order to prevent arbitrary behavior of the microcontroller (which happened during early testing).
I use two MOSFETS in lowside configuration to turn on the HV-source and the valve independently.
It was really fun to build!
