LED "fireworks"

[HLHJ]

A throwable object which imitates fireworks. It should listen to the music and react to the beat etc.. It should be fire-safe, and not too harmful even if it lands on someone.

It might be a ball with lit streamers, a spinning wheel, or a flashing baton or cord for colour guards to spin.
A deluxe version might also sense how fast it is moving and produce a pattern in the air accordingly, like this clock.

[rickj]

This is a great idea with lots of variants.

It must be bright enough to be highly visible in daylight or under bright stage lighting, so it will need a lot of energy in each flash. On the other hand the period of use will be small, so the total energy requirement will not be too bad. A few AA cells will probably do it, which will keep the weight down for safety.

Since band Colour Guards conventionally throw (fake) rifles around, each weighing over a kilogram and with lots of sharp corners, anything lighter than that can probably be made adequately safe. We should target a weight below a kilogram.

For a first cut I'd be inclined to keep it simple. There can be a lot of noise on stage, and detecting the beat from the band may not be trivial. Since the user has to turn the device on and off manually, how about turning it on with two button presses, each press on the beat. The device can then flash on that beat until it is turned off.

[HLHJ]

The two-pushes method would work if the tempo is steady and the time the "firework" runs is very short, too short to develop a beat frequency. Could the user cue the device as to what part of the audio spectrum the beat was, using button pushes or manually? Drums often have a frequency pattern different from the rest of the music, and often the beat is held by the lowest-pitched instruments, often the low brass, which surely even a computer algorhythm can tell from a flute.

If it does not flash, it need not react to the beat at all. It could also react smoothly to the music, as the music visualizers in computer audio programs do. Those things can be hypnotic, and some are now open-source (Advanced Visualization Studio, for instance, is now under a BSD-style license). One could re-use the code but modify the display to suit the 3-D device -- may I call it a "flarework" until someone comes up with a better name? Smooth changes might also make it easier to avoid inducing epileptic fits; there are some standard tests to evaluate that risk.

Would it be possible to build it inside a beach-ball-style transparent inflatable ball? Those don't hurt when they hit you on the head. You could also inflate it with helium, or add a little heater (I'd prefer this, less wasteful), and tether it. A very long-lasting firework, more a musical lantern -- great for a garden party.

How about surrounding it with loops of that springy plastic spaghetti that is sort of like deliberatly leaky fiberoptic cable, the sort that you sometimes get to spread out LED lights on dance jewlwey? That would not hurt if it hit you.

For it to really look like most types of fireworks, multiple devices might need to be stuck together so that they would fragment at the top of their arc. Maybe a projector, the tiny ones from cellphones, could be used instead to get large-scale effects, sort of like a ballistic son-et-lumière. This sound complicated, maybe a later version.

Sorry, that's about five different related devices, I think.

[JenniferT]

sounds good.