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Hijacker needs help (LED traffic lights)

Discussion in 'LEDs and Optoelectronics' started by trickytrev, Apr 26, 2012.

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  1. trickytrev

    trickytrev

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    Apr 26, 2012
    http://www.555-timer-circuits.com/traffic-lights-4-way.html

    can anyone help

    i buildt my own version of a traffic light system it couldnt get enough power so i went online and built this one but on the q outputs arent high enough can you tell me a way to amplify the current to make this circuit work thanks
     
    Last edited by a moderator: Apr 26, 2012
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Firstly, don't hijack other people's threads.

    Secondly, what do you mean by "the q outputs arent high enough"?
     
  3. trickytrev

    trickytrev

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    Apr 26, 2012
    the Q outputs for the 4017 cant handle all of the leds because the Q outputs are only 5mA and i would say i need about 10mA to each LED
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Have you tried it?

    At 12V you should easily be able to get 10mA.

    Remember that the same current flows through each LED so you only need 10mA.

    You could use the output to turn on a transistor if it was insufficient.

    BTW: I've put the link back since whatever edit you did caused nothing to display
     
  5. trickytrev

    trickytrev

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    Apr 26, 2012
    and yeah i have tried it at 12 but doesnt work i have tried transistor to boost the current but still doesnt work
     
  6. KJ6EAD

    KJ6EAD

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    Last edited: Apr 26, 2012
  7. timothy48342

    timothy48342

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    Nov 28, 2011
    So whys he gettin nothin?

    tricktrev, are any of your LEDs connected in reverse?

    What is the voltage drop across each? They don't add up to near 12V in any one LED chain do they?

    You might try checking the voltage across the 100 ohm resistors. Find out just how much current flow you are getting. If its just microamps, then it's not a source issue.

    -tim
     
  8. duke37

    duke37

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    Jan 9, 2011
    I made one to drive a single light which included a red and amber phase. The 4017 drove three fets which could switch 5A at 12V.
    It is on this site somewhere, I could try to find it if you are interested.
     
  9. timothy48342

    timothy48342

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    Nov 28, 2011
    Hey duke37, that made me think of something.

    FIrst thought, fets don't take much current, so of course the 4017 could drive them.

    Second thought, he already tried to drive the LEDs with a transistor and that "didn't work." We don't know much about how he had it hooked up, so there is a million questions there.

    Third thought:
    trickytrev. Try hooking the 12V supply directly to one of your LED chians and see if it lights the LEDs. If a direct connection won't do it then the 4017 won't do it either.

    (and still find out the current by checking the voltage across each of the 100 ohms. With it connected as in your schematic and with it directly connected to the supply.)
    -t
     
    Last edited: Apr 26, 2012
  10. trickytrev

    trickytrev

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    Apr 26, 2012
    no all my LEDs are connected properly timothy48342 and yeah i am interested at your design duke37 as it might help me on my thanks :) and timothy48342 i connected a 12v supply directly to the chain it worked so its definately the 4017 thats the problem
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    OK, and the 4017 is running from 12V?

    When connected to the 4017 are the LEDs dimly lit, or not lit at all?

    Do you have anything else connected to the outputs of the 4017?
     
  12. duke37

    duke37

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    Jan 9, 2011
    I do not see how the red leds can show without other leds showing also. There are other traffic light circuits out there with the leds diode connected to the 4017.

    I attach a diagram of my circuit which was used to train children in the operation of traffic lights and so it needed to provide a lot of light. This circuit can drive 12V 36W bulbs without any heat sinks.


    Driving a few leds (or even a lot) would be trivial.

    You would need another array of diodes and fets if you wish to do N/S and E/W.
     

    Attached Files:

  13. trickytrev

    trickytrev

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    Apr 26, 2012
    the LEDs are on and i have diodes connected as well steve and thanks duke where do the 3 nang gates connect to though
     
  14. duke37

    duke37

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    The three spare gates need their inputs connected to something to stop them going bananas, I chose ground. The outputs are left open.
    The 555 will do the same job as the NAND gate but the NAND gate is a bit simpler.
     
  15. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    The three NAND gates go nowhere. Duke37 has used a quad schmitt trigger NAND gate to get a single schmitt trigger inverter.

    The other three MUST have their inputs connected somewhere, and he has chosen ground.

    Yes, you can get a 5 pin chip that has only a single inverter in it, but they're very small and you may not want to deal with surface mount chips.
     
  16. trickytrev

    trickytrev

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    Apr 26, 2012
    thanks :) just got it working by using the darlington pair transistors and made it more complex but now works thanks everyone for the advice :)
     
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