red light random like airports.

[Alan-soto]

Hi everybody, I need to create one project with red and green lights in random mode just pushing one button and also install one selector switch with four
positions, position one: one red light random in 5, position two: red light in 10, position 3, in 15. position 4, in 20.
I will appreciate if somebody can give me a hand.
Tanks Alan

 

[dougy83]

By "red light in 10", do you mean that any of the first 10 LEDs is lit? Then likewise, "in 15" means that any of the first 15 LEDs is lit? Is there 20 red LEDs total? Do the green LEDs ever come on?

 

[Alan-soto]

thanks for ask. is only one red and one green light, 1 in 5 means that when I push a button I have 20% chances that is going to be red light, 80% will be green light. 1 in 10. is 10% will be red 90% will be green and so on, in random mode means that if the selector switch is in 1 in 5, I push the button and it may be red, and I push it again and it may be red again. is not like in sequence 4 greens and one red, 4 greens one red.
Thanks. Alan

 

[jpanhalt]

"Red and green lights, random, like airports." That doesn't make sense to me. The only random thing at an airport I have observed is the TSA competency.

Are you trying to make a rotating beacon? The colors are not random.

John

 

[MikeMl]

Yes, as an active pilot, I never see any randomly flashing lights at airports. Everything at airports have definitions and standards that are the same everywhere in the world.

Sounds like you want a psuedo-random sequence generator. I would be looking at an Arduino or other micro-controller for that.

 

[Pommie]

A fast running johnson counter (4017) with the reset switched from the various outputs would achieve this. The red LED would only light if output 1 is high.

Of course using a microcontroller would also achieve this but would require programming.

Mike.

 

[misterT]

Yes, as an active pilot, I never see any randomly flashing lights at airports. Everything at airports have definitions and standards that are the same everywhere in the world.

Sounds like you want a psuedo-random sequence generator. I would be looking at an Arduino or other micro-controller for that.

I've heard that some airports have a push-button at security checkpoint. You push the button and if you get a red light you will have to go through more "intensive" security check where they inspect all your stuff.. or something like that.

**broken link removed**

 

[Alan-soto]

HI .
Some companies control the exit of the trailers leaving the plant, every day hundreds of trailers leave the facility and they can't check one by one, so they have
un button that the driver have to push and if is green the trailer just pass. if red has to go to another area for more intensive check. I'm working with a
Allen Bradley P.L.C. 1300, but is expensive. I wander if arduino or pic controllers can do the same, I have not much experience with those controllers
thanks

 

[KMoffett]

I've heard that some airports have a push-button at security checkpoint. You push the button and if you get a red light you will have to go through more "intensive" security check where they inspect all your stuff.. or something like that.

**broken link removed**

What determines whether the light turns green or red? TSA coin tosses?

Ken

 

[misterT]

What determines whether the light turns green or red? TSA coin tosses?

Ken

I do not know. My mexican friend says he allways gets the red light (true story, no joke).

 

[Pommie]

An Arduino or Pic could manage this but would require programming. What programming language(s) do you know?

Mike.

 

[dougy83]

A simple solution uses a single 555 timer IC, and should achieve accuracy about as good as the resistors you put in it. By changing the selector switch, the rate of the RED LED being lit will be 1/5, 1/10, 1/15 and 1/20 (from left to right selector position). Schematic attached.

The duty cycle of the 555 is D=1-RB/(RA + 2*RB), which if set to 1-1/5, 1-1/10, 1-1/15, 1-1/20, will allow you to have your desired rate of RED LED active. The pushbutton is then used to cause the 555 to oscillate between RED/GREEN, and when released, the output will remain stable. The two 4M7 resistors connecting to the capacitor will stop the output changing due to leakage currents from the 555 inputs into the capacitor.

EDIT: I copied the equation incorrectly; resistor values updated.