Quote Originally Posted by Matthew Long View Post
I was thinking that this would be a "stand off scale" effect only, so the speaker could well be elsewhere, perhaps a powerful car subwoofer with built-in amp in the rear fuselage pointing 45 degrees down and forward. I doubt anyone on the ground would be able to tell where the sound is coming from. On the LEDs, I don't agree, those new surface mount ones are pretty darn bright, blinding even.
Don't have any experience with modern LEDs, but would love to experiment. I'd use a 555 timer, but would probably need a power transistor or relay, assuming those bright LEDs suck a bit of juice. Could probably power it with some C-cells (or even AAs). I'd love to play around a bit, could you pass some part numbers/references for those LEDs?

Noise-wise, I'm a bit skeptical about getting a speaker strong enough to be heard a couple hundred feet away over the sound of the engine. On the PLUS side, you don't need good sound quality, just a hugmungous spike every 20th of a second or so. Just discharging a capacitor into a speaker might be enough for that. You'd need a bank of capacitors to get a high enough rate, of course. A Gatling gun! :-)

Another way might be strictly mechanical. Imagine a speaker cone with a wire connected to the apex, anchored by a strong spring. If you could "pluck" the wire at the right rate, you'd get a series of pulses from the speaker. A motor with a cam might do it.

Remember, when guns on FREDs are outlawed, only outlaw FREDs will have guns....

Ron Wanttaja