This blog post will be updated later today to include a technical writeup of how we did all of this and a circuit diagram so you can wire it up at home!
UPDATE: (15:00 CST)
In case any of ya'll are wondering how we did this here is a brief writeup detailing our methods (and probably our madness). Post comments or video responses if you have any questions about our implementation!
The goal of this project was to create a fireworks show automatically synchronized to a song using beat detection analysis and simple, low cost data acquisition hardware.
A song is imported into software for analysis; a Fourier Transform is then used to compare the power of a selectable frequency band to the average power in that band to detect a beat. When a beat is detected, a digital high is sent out through a USB-DAQ device. This device is wired as the base of a Darlington Pair Transistor that will switch on a high current power supply connected to the firework triggering method.
- National Instruments USB-6009 (USB Data Acquisition Device)
- TIP120 Darlington Pair Transistor
- 24 Volt DC , 1 Amp power supply
- LabVIEW with Sound and Vibration Toolkit
- Electronic Match (Build your Own)
- C6-0 Estes Model Rocket Engine
- Omni-directional Spark Charge (must have pro License)
- Kerosene Charge (must have Pro License)
- Windows XP Computer
A Fourier Transform is taken of the song so the varying powers of the different frequencies can be observed. A certain frequency band is then isolated (such as the bass of the song to watch for kickdrum beats) and the power of that frequency band is measured. A running average of the past X number of power measurements is calculated and compared to the current power. If the current power of the band rises above the running average this is defined as a beat. The software we used is available here, and you can get LabVIEW and the Sound and Vibration Toolkit evals to run it.
HARDWARE FIRING METHOD
A USB-DAQ device is wired to the Base of a Darlington Pair Transistor. When a digital high signal is sent from the DAQ device the transistor will switch, allowing a power supply to flow through the igniter. The igniter is comprised of a low resistance, low power resistor coated with pyrotechnic material. When the current from the power supply flows through the igniter’s resistor it overheats and ignites the pyrotechnic material, lighting the firework it is embedded in.