led projects

Discussion in 'The Projects Forum' started by kuxz2008, Jun 13, 2010.

  1. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
    0
    i would like to build a electronics project that look similar to the flashing of the blue n red lights that is found on police car.

    the blue light should be flashing twice before the red light that will be flashing twice. and this whole process continue.

    how do i start ?
     
  2. erich_7719

    Active Member

    Oct 14, 2009
    92
    7
  3. oidium45

    Active Member

    Apr 24, 2010
    130
    8
    Try a 556 timer. It will allow you to adjust the speed of the blue and red separately.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
  5. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
    0
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    The lettering on Electro Schematics on my screen is verry fuzzy. By guesswork Blue flashes 50 ms, then again .4 s later,long pause, .8 s, R flashes twice, followed by only .15 s for B again. Unless I mis read the numbers, I would connect R to Q5 & Q7 to make a more uniform display.
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    You can see the flash pattern on YouTube links I put on that area, I also added a pot to control the number of flashes. The design is verified, and will handle the number of LEDs specified.

    The other design will work. I don't thinkt has very little control over flash timing other than the duration, but for your application it may not matter.

    Check this article out, it might have some other ideas on how to do it.

    LEDs, 555s, Flashers, and Light Chasers
     
  8. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
    0
  9. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    I think it needs to be 100K. RS seem to have plenty.
     
  10. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
    0
    how do i go about chosing the types of LEDs (view angle, Luminous Intensity) to use for this circuit ?

    what types of LEDs do you use ?


     
  11. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
  12. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
    0
  13. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
  14. John P

    AAC Fanatic!

    Oct 14, 2008
    1,632
    224
    Actually the CMOS 555 specs say output current is 10mA sink, or 50mA source. If that 50mA isn't enough for your LED, you have one hell of an LED! But yes, the regular 555 would provide even more.
     
  15. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Many LED blinking circuits use a CD4060 oscillator/counter and a few diodes at the outputs to select the flashing.
     
  16. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Depends on the voltage feeding the CMOS 555, at 12 to 15 volts you might get that, but at 3 V you are lucky to get 10ma, the norm is 2ma.

    Take a look at those specs again with an eye for supply voltage.
     
  17. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    For the experiment I use run of the mill high intensity LEDs. You might try modifying the LEDs you can get.
     
  18. kuxz2008

    Thread Starter Member

    Nov 16, 2009
    84
    0
    what is the range of mdc n view angle for the LEDs that you used ?
    what is the range of mdc n view angle for bright white n colour LEDs ?
     
  19. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Truth to tell I have not a clue. I buy my LEDs from many sources (but mostly off the shelf), nowdays they are high intensity (the kind you can't look directly into) but narrow beam. There are tricks you can use if you want to defuse them, such as fogging up the clear lense or adding translucent paper or plastic. At the HAM Con they had a bunch of different colors (6 to a bag) for $1 each.
     
  20. John P

    AAC Fanatic!

    Oct 14, 2008
    1,632
    224
    Actually the regular LM555 isn't specified for a power supply below 5V, whereas the LMC555 (CMOS) will work down to 1.5V. The spec sheet doesn't seem to say how much current it can source/sink at that level, but if the device has to run on batteries for a long period, CMOS is definitely the best bet. As happens so often, choice of parts depends on what's most important.
     
Loading...