please help with my crossroad traffic light project...

Discussion in 'Homework Help' started by D@rkL0rd, Jun 22, 2014.

  1. D@rkL0rd

    Thread Starter New Member

    Jun 22, 2014
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    hey guys,i was working on my traffic light project and i created circuit using 555 timer(mono-stable mode) and ic 4017 but when i run the simulation in circuit wizard only first led's light up .i don't know why is this happening please help...
     
  2. Jony130

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    Feb 17, 2009
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    Your circuit don't work because of your poor design. And you don't know how BJT work.
    Are you sure that you need this OR gates ? Why you don't use diode as a OR gates?
    Also why you connect all your LED's into BJT's emitter?
     
  3. djsfantasi

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    Apr 11, 2010
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    I am not a 555 expert (there are many on here!), but your wiring looks "funny". Take a look at the bistable multivibrator circuit in Bill Marsden's blog. Particularly in regards to your connections to pins 2 & 6. Also the connection to pin 3 looks odd and no connection to pin 7 is required.

    Please refer to the link to the blog above.

    Also, I agree with Jony130 observations about your BJT usage.
     
    Last edited: Jun 22, 2014
  4. Alec_t

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    Sep 17, 2013
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    Welcome to the forum!
    The mode should be astable (as in your sim schematic).
    I'm not familiar with Circuit Wizard, but the sim runs ok in LTspice.
    Are your logic and counter ICs configured for a 12V supply? (In LTspice they're configured for 5V by default).
     
    Last edited: Jun 22, 2014
  5. D@rkL0rd

    Thread Starter New Member

    Jun 22, 2014
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    Sir can you please tell me how it should be .i admit i dont know much about BJT's .And according to my assignment project i have to use any one of the 7 logic gates...Thnx
     
  6. D@rkL0rd

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    Jun 22, 2014
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    I am also not familiar with the circuit wizard but it it had all the ic's i needed so i used this one
     
  7. Alec_t

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    Yes, but CW may expect you to use a 5V IC supply!
     
  8. D@rkL0rd

    Thread Starter New Member

    Jun 22, 2014
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    no sir it does not solve the problem...
     
  9. Jony130

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    Feb 17, 2009
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    Simply in CW you can change IC supply.
    Project--->Simulation--->Power supply
     
  10. D@rkL0rd

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    Jun 22, 2014
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    while running simlulation after changing the power supply the y3 led just blew up...please explain how to avoid this...it said the reverse voltage distroyed it...please tell me how to avoid this...
     
  11. djsfantasi

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    Apr 11, 2010
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    1) how long do you want each pin to remain high? That is, what is the clock rate from the 555?
    2) Is your 555 circuit generating that rate? You can wire it's output to an LED for a quick check.
    3) Is the 4017 counting properly? If the clock rate is slow enough, you should be able to check with a DVM.
    4) independent of the 4017 and the OR gates, can your transistor drive one LED? Take a look at this article on this site's e-book on using an NPN BJT as a switch. Hint: You are missing resistors.

    Once these sub-circuits are known to be working, combine them.

    The secret in building/debugging is to break the problem down into simpler problems and make sure they are working. IMHO, I see you saying "I've got this big problem and don't know what to do!" Well, break it into smaller problems.
     
  12. Alec_t

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    Try a diode in series with the transistor base.
     
  13. sheldons

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    Oct 26, 2011
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    The transistors are connected with no base resistors, leds to the transistor emitter not the collector and the 4017 has no reset on power on plus the 555 needs to be correctly wired
     
  14. JoeJester

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    Apr 26, 2005
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    You have a power source, a clock, a controller, and an LED driver. Work on one thing at a time till you get them as you want them.
     
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  15. D@rkL0rd

    Thread Starter New Member

    Jun 22, 2014
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    1-i want each pin to be high for 1 sec.
    2-no it is not generating that rate ...please help here...i am a newbie here...
    3-no the output is not given by the counter.
    4-i am still working on that ...can you recommend the resistor values for driving 4 led's
     
  16. D@rkL0rd

    Thread Starter New Member

    Jun 22, 2014
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    i tried to build the oscillator but the pulse does not seem stable for 1 sec..please help me here...
     
  17. djsfantasi

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    I gave you a link that showed how to wire up the 555...
     
  18. D@rkL0rd

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    Jun 22, 2014
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    Ya but whats the problem in this one...please help...and it was for bistable mode...i think we need a monosatable mode...
     
  19. djsfantasi

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    Apr 11, 2010
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    It's wired wrong...

    Let me clarify something. You want a circuit based on a 555 that will generate a pulse once every second? Why do you think you need a monostable circuit?
    [​IMG]
     
  20. D@rkL0rd

    Thread Starter New Member

    Jun 22, 2014
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    so which one do you will be suitable here...
     
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