Greetings!

I need to build a stage prop to be used during a "Mission Impossible" segment that a chorus I am working with is doing on a large stage. While the singing is going on, a fake pack of dynamite will be passed around like a hot potato that no none wants to hold. The prop will probably be wooden dowels strapped together with electrical tape, but here is the challenge... I want the top of it to look like it has a lit fuse. I am imagining several bright strobe LEDs (I am assuming LEDs are the way to go) that seem to be going off at what appears to be random to look like sparks on the fuse; then of course the previously mentioned fuse; a battery pack in one of the center sticks of fake dynamite (which the center one could be a PVC tube to hold the electronics); and then a switch to turn it on and off.

Since the "TNT" will be constantly passed around while it is on stage, the audience of about 1000 people who are at least 20 feet away will never be able to get a good close look at it. I don't want it to accidentally get switched off, so the switch needs accessible but not bump-ible, if you get what I mean. From the audience’s perspective, it needs to look like it is a lit bundle of dynamite that is being passed around on stage that no one wants to hold.

Who's up for the challenge of helping me with this one?

Thank you.

Steve
Indianapolis, IN

 

how about some fiber optic fibers, light coming out the ends from the led's.

 

how about a single red LED inside a small clear plastic tube. a simple gear motor could reel it in, moving it up the tube. additional effects could be triggered at various point along its travel.

 

For high intensity with moderate power consumption the LEDs may have to be a narrow-beam type. Since the prop will be at an arbitrary angle to the audience you would need an array of LEDs aimed in different directions but located close to each other. I'm guessing perhaps 20 or more LEDs in the array?

 

Instead of dowels for the dynamite, I'd use the dowels just to make a fiberglass shell. This allows for room for electronics and batteries. .

I'd use a key switch to turn it on and off, as there is nothing to "bump" to turn it off.

You could make a Pseudo-random sequencer with shift registers, and connect its outputs to your LEDs. I'd use an 8 bit register to maximize the length of the pseudo-random sequence. Use this link for an example of a circuit to do this.

Or you could use a microprocessor, such as an Arduino (if you're new to microprocessors) or a PIC to randomly light the LEDs.

For realism in the fuse, I like the suggestion from @alfacliff to use fiber optics. If you use acrylic fibers, you can melt the ends a little to make a blob for the spark, which could be seen from different angles.

(FYI, I have a hobbyist theater background and was an expert in Technical Theater)

 

How about a 556/4017 combo to produce a 10 LED fuse that could blink then shorten itself?

 

A pair of addressable LED strips back to back inside a clear PVC tube should do it.