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Police Lights Problem

Discussion in 'LEDs and Optoelectronics' started by Liviu, Feb 4, 2015.

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  1. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    Hi!
    I have a problem with my police lights project. the main thing that this light should do is to blink 3 times on the red leds and 3 times on the blue leds.
    In my case that doesn't happen and the leds blink in the same time but the difference is the brightness of the leds.
    I am beginner and I tried to resolve the problem but nothing.
    Bellow you have a video posted by me.
    I made to jumpers: from 8 and 16 pin of the 4017 decade counter to ground respectively 12V.
    The voltage divider to 8 pin of the 555 timer was removed and the PCB doesn't contain it.

    Thanks!
     

    Attached Files:

  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    1. You need a resistor in series with each LED or LED string (your schematic does not show if they are series or parallel)

    2. It is hard to see what is happening on the video because they are flashing too fast. Slow it down and you might be able to see what is actually happening.

    But here is what your circuit will do if it is operating correctly:

    Blue on
    off
    Blue on
    off
    Blue on
    Red on
    off
    Red on
    off
    Red on


    Bob
     
  3. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    Yes, the circuit should work correctly like you said. The led works on 12V and i thought they don't need a resistor(they have resistors on the strip).
    I will slow down the speed by mounting another 2.2uF capacitor in parallel with the c1 capacitor.
     
    Last edited: Feb 4, 2015
  4. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    I slowed down the speed but i can't understand what is happening with the leds
     
  5. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    I slowed down the video and even then it is hard to see what is going on. It looks like the blue ones are flashing on every period for a short time and maybe the red ones are actually doing what they should.

    Bob
     
  6. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Argh! I just saw how you are powering the 555. Lose the voltage divider! You cannot power the chip that way. It will run fine with 12V on the Vcc pin. I am not sure this will help, but it is wrong and should be fixed.

    Bob
     
  7. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    I removed the voltage divider but still not work.
     
  8. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Well, I would try slowing it down another 10x (use a 47uF if you have one) so you can see the individual flashes.

    I also don't like that you have a 470 to ground on each base. I would use something like 10K there.

    Bob
     
  9. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    Now i have an 100uF and an 2.2uF capacitor in parallel. More than 10x slower but i found only an 100uF capacitor.
    I hope it is slow enough to be shown what matters.

     
    Last edited: Feb 4, 2015
  10. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Double check your wiring.
    It looks like something got crossed...
    Try completely removing the blue side of the circuit and see how the red behaves.
     
  11. Jouellet

    Jouellet

    86
    19
    Feb 2, 2015
    Just out of curiosity: why haven't you used some CPU, like a Arduino ????

    Pretty cheap (especially on Ebay) , extremely easy to program and easy to implement speed adjustment !
     
  12. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    I used Arduino and is extremely easy to program.

    I want to learn electronics but the arduino is a good solution.
     
    Last edited: Feb 5, 2015
  13. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    I don't really know what the problem should be, i verified the wiring and nothing wrong,
    Maybe the pins of 4017 decade counter are not connected correctly.
     
    Last edited: Feb 5, 2015
  14. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Try hooking up an LED to one of the unused output of the 4017 and see if it flashes in a regular pattern, at 1/10th the speed of the input as it should. I am wondering if there is some noise triggering the 4017.

    Bob
     
  15. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    I will try but the first thing i shoulda do is to make it on breadboard first
     
  16. Gryd3

    Gryd3

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    Jun 25, 2014
    Not everything is a microcontroller project. This project is perfect for learning how to use some of the simpler electronics ICs.
    Props to the OP for taking this route instead of grabbing an MCU.
    Build it progressively and test each section along the way.
    The interesting part I see in the video is when both sets of lights turn off before alternating from one color to the next... It appears to be wired so that there is no delay going from red to blue.
    Can you please confirm the part numbers you are using?
     
  17. Liviu

    Liviu

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    0
    Feb 4, 2015
    What did you mean with "part numbers"?
     
  18. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    I mean the numbers printed on the transistors and the two Integrated Circuits you have on the board.
     
  19. Liviu

    Liviu

    13
    0
    Feb 4, 2015
    BC547C , HCF4017BE and NE555P
     
  20. Liviu

    Liviu

    13
    0
    Feb 4, 2015

    This is the same circuit.
     
    Last edited: Feb 5, 2015
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