Interesting idea. Have a look at the tech forum on http://www.nutsvolts.com/ someone there may be able to help out. Yast year(I think) they had an L.E.D. candle project that was designed to flicker just like the real thing, but without the fire hazard. It may be possible this project could be modified to do what you want.
How about some of those blinking minature Christmas lights? If you put multiple flashers on a string you could get them blinking all over the yard. Just an idea...
Rex
Tom Trigg
Real fireflys are all over my outdoor layout.
JimC.
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