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Traffic lights

Discussion in 'LEDs and Optoelectronics' started by Gregoraci Joseph, Oct 15, 2012.

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  1. Gregoraci Joseph

    Gregoraci Joseph

    5
    0
    Dec 14, 2011
    Hi,

    I am just a teen and love to make some projects for my self. This time i want to build a traffic light circuit. Which I had saw from this site http://www.kpsec.freeuk.com/projects/trafficlight.htm. But i want to inculde a buzzer which it would pulse on the red led to make it more realistic and fun. Can some help me how can i add the buzzer?

    Thanks
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    I'm not sure how traffic lights work in your part of the world, so I can't suggest anything more than generalities.

    I would use another 555 oscillator to make the red LED flash. This could be controlled by the 4017 outputs to have the LED on, off, or flashing (which would be good if the red only flashes at one particular stage.

    If the red always flashes, the simple solution is to get a red LED that flashes (some are available with inbuilt flashers)
     
  3. Gregoraci Joseph

    Gregoraci Joseph

    5
    0
    Dec 14, 2011
    Steve,
    Our lights are that when you push the switch you wait for the red light to appear, to be able to cross the road. For the drivers to know, that they need to stop to wait for them to pass, a pulse sound switches on as soon as the red light appear. In the circuit I had found and which I posted yesterday do not include a pulsing sound. I like to add only the buzzer pulsing while the red light is on, and not also the red led flashes. I wish someone would help me to introduce the buzzer with the circuit.

    Thanks
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    If you want to just add a 'buzzer' sound and no flashing, you can use a self contained 'buzzer' unit and simply replace the output to the red led in that circuit with a transistor and have that transistor drive the buzzer and red led... No time to draw it up but it's not all that hard, Google up how transistors work as a switch...
     
  5. screwball

    screwball

    89
    1
    Jan 9, 2012
    You want to add another 555 for the buzzers pulse so pretty much the same circuit again, i quickly drew up what you want to add (add a resistor in series with the led)

    [​IMG]

    Not tested but should work
     
  6. Gregoraci Joseph

    Gregoraci Joseph

    5
    0
    Dec 14, 2011
    Where the 5 goes?
     
  7. screwball

    screwball

    89
    1
    Jan 9, 2012
    Pin 5 on the 555 timer is the control voltage pin, you dont need to use pin 5 in the circuit, you may also notice pin 5 is not used on the original traffic circuit also (well it doesnt appear to be there)

    Hope that helps :cool:
     
  8. Gregoraci Joseph

    Gregoraci Joseph

    5
    0
    Dec 14, 2011
    The resistor which you told me to add, it needs to be 20k also? and the transistor under the supply, is that an NPN transistor? because it is not clear.

    thanks.
     
  9. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    The resistor you need to add goes here, the value is determined by your LED choice using Ohm's Law... The transistor is an NPN...
     

    Attached Files:

    Last edited: Oct 17, 2012
  10. Gregoraci Joseph

    Gregoraci Joseph

    5
    0
    Dec 14, 2011
    screw ball,

    This circuit i found it very helpful, but i want the correct type of the transistors you've drawn to be able to build the circuit correctly.

    thanks a lot.
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    BC547, 2N2222... In general it's going to work with almost any NPN transistor you can find.
     
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