Random LED Flasher - Robocop

[grandmasteralok]

Hi.

I am planning to build a 2-LED flasher like the light bar on Robocop's Ford Taurus police car.
If you'd notice in the movie, the police car has 2 lamps flashing alternately but at a random rate.
I'd greatly appreciate your help.

Basically, the 1st LED will flash, then after a random number of seconds, the 2nd LED flashes, then after another random number of seconds, the 1st LED will flash again. The process will just repeat. The flash behavior will be the same as a camera's flash.

Note: I do not have the knowledge nor the equipment for a programmed version. Please no programming. (* ", *)

The circuit will be powered by a 9-12v DC. The LED's are the 3v ultrabright 5mm red and blue.

Also, please include the parts list.

Thanks a lot.

 

[4pyros]

What makes you think the switch over rate is random?

 

[grandmasteralok]

Hi, 4pyros. Sorry, I didn't quite understand what you mean.

 

[4pyros]

Basically, the 1st LED will flash, then after a random number of seconds, the 2nd LED flashes

Why do you think its Random?

 

[Mike odom]

The only way to get a truly random time base in electronics is to have human intervention (or some other outside, unsynchronized force/signal). Even programs generate 'pseudo random' numbers. We had a whistle timer for ships, and it had a random sequence generator so that two ship's whistles wouldn't get in sync and stay in sync. Basically, after 10 cycles, it would reduce the delay 10 seconds, 50 instead of 60 between whistles. Then after 9, then after 8, then after 7, etc. Random, I think not, but for two systems to sync up they would have to be started at exactly the same time. You could do the same thing with counters, but they wouldn't be random. They might seem random, but every time you turned it on, it would do exactly the same pattern. Programming is much easier.

 

[grandmasteralok]

If that's the case, could anyone instead provide a circuit that will flash 2 LED's alternately, probably at least 2 or 3 seconds apart. The behavior of the flashing is still the same, like a camera flash. One LED will flash once, then after a few seconds (at least 2 or 3) the second LED will flash once.

I am really interested in programming but I do not have the equipment for it. :'(

 

[4pyros]

Do you understand this circuit?
**broken link removed**

 

[grandmasteralok]

I will give this a try. Thanks.
Will keep you guys updated.

 

[Mike odom]

good flasher circuit, but does not 'flash LED1' then wait, and 'flash LED2'. This circuit will turn each LED on for a period of time, then turn it off and the other one on, not flash LED1, blank for 2 sec, flash LED2, blank for 2 sec, flash LED1, etc...