traffic light help SOS

[mbarazeen]

I never saw where the op wanted 3x4 LEDs
I proposed using separate RED, YELLOW, GREEN LEDs
no real different though???

you can see his second posting..he has mentioned R1,Y1, G1......G4, total of 12 LEDs. also it has to work in such a way not independent, i mean at a time only one green or one yellow should be on. just go through what he mentioned on that post.

if we use seperate LEDs how will you wire your diagram to fit for the requirement??

 

[MrDEB]

simplified schematic

as per the ops first post this schematic meets all the requirements.
at least the way I read the ops post
has 3 leds per signal with 4 signals
only TTLs are used. nothing fancy, just down to earth simple D flip flops.

 

[mbarazeen]

you have used R1,R2,R3& R4 in two places???? also in real practice, R,Y&G s will not have same mark space ratio. see the op, he has mentioned to keep the green "on" for 3 state changes and to keep the yellow for only one??

the timing diagram i posted is the one for all LEDs how it has to be sequenced for a real implementation, i hope your diagram will not fit for the timing circuit.

what will be your circuit to follow the timing diagram??

 

[reila]

would love to thanks mbarazeen, MrDEB, Sceadwian and kpatz.

thank you so much for helping.
and for the circuit and timing diagrams.
these really helped me a lot in my project.
and i realized more through this discussion

the project finally work well =P
i am soo happy and glad.

thank you everybody =)

edit : i learned a lot from you guys. things that i don't learn in school =)
glad that i bumped into this forum =P
p/s : i am a girl by the way =P

 

[MrDEB]

have looked but no mention of 2 sec on etc?

Only thing I saw was for a 40hz clock using a 555
I posted a circuit last night that lacked a few connections.
Maybe I missed something but never saw any reference to green on for 20 seconds while yellow on for 2 seconds.
Unless its in that truth table which was very unclear.
I still like the 4017 idea, then just add some divide by two D flip flops if you want the yellows on less.

 

[mbarazeen]

would love to thanks mbarazeen, MrDEB, Sceadwian and kpatz.

thank you so much for helping.
and for the circuit and timing diagrams.
these really helped me a lot in my project.
and i realized more through this discussion

the project finally work well =P
i am soo happy and glad.

thank you everybody =)

edit : i learned a lot from you guys. things that i don't learn in school =)
glad that i bumped into this forum =P
p/s : i am a girl by the way =P

oooooooooops, he he...so sory to mention as "he"
no matter boy or girl, its our pleasure to share and learn
its really making happy to know u got it worked finally. congrads.

Mr.DEB was continously replying to me, it really encouraged me to write more.

for his last post,
he has used 16 LEDs on the circuit that is, 4 extra??
and he missed a point to consider real world application, still he can work out and get it done using 74ls74 instead of 4017, bythe way 4017 it self having 4 flip flops and some logic built in.

if i will find enough time i will post a circuit for the same as my timing diagram using 74ls74 only with some logics.

thanks a lot to you all guys.

 

[MrDEB]

I agree, the 4017 is perfect but

SHE, the op wanted to use only 74ls family.
using the 7474, plus some additional components, it can be done.
16 LEDs? pretty sure I only have 12??
I didn't take my shoes off so must be only 12---lol