Lightning LED flasher

[Michael Bean]

Hi All,

I'm trying to design a LED flasher circuit that does a decent job of emulating real lightning. I was thinking maybe a 555 with a flash rate of something like 4 Hz or so, and a 20% or so duty cycle to directly control the LED's. Then there'd be something (cascaded counters?) to provide a pseudo-random trigger to control the 555 output to get a realistic lightning effect. There's probably a million ways to do that, but everything I've come up with so far (mostly "thought experiments") seem to grow into something cumbersome. 🙁
Any thoughts?

Mike

 

[rayma]

I'm trying to design a LED flasher circuit that does a decent job of emulating real lightning.

How about using a good recording of thunder in a loop, and using that to modulate the LED intensity?
Or, a group of LEDs connected as in a VU meter function, with all of them on below the momentary level,
but not mounted in a line, rather in a cluster.

 

[DF96]

Do you want random (e.g. count noise from a zener) or pseudo-random (e.g. PRBS)? Do you want a constant storm or one which varies in intensity (either manually or automatically)? In either case you need to find out what are the likely statistics for lightning, and then think about how to provide some simple approximation to this. 'Hollywood storms' rarely look real.

 

[Michael Bean]

Hi DF96...

Do you want random (e.g. count noise from a zener) or pseudo-random (e.g. PRBS)?

Yes! 😀

But seriously, it doesn't matter. The goal is to create enough "randomness" to be acceptable as lightning to a casual observer.

Mike

 

[Mooly]

Many many years ago, Elektor did a simple CMOS pseudo-random generator using 3 chips, a clock (4011 etc) a counter and an ex-or ?? gate. It was intended as an intruder deterent for a car as it gave the impression that it was watching you and flashed as you moved.

There must be circuits like that on the web.

 

[gmphadte]

Two different freq astables each driving a CD4017, then AND their outputs.

Gajanan Phadte