police flashing setup?

Discussion in 'The Projects Forum' started by dragracekid, Jun 8, 2011.

  1. dragracekid

    Thread Starter New Member

    Jun 5, 2011
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    I know Mr Marsden created a great setup for this but I'm going to b running it on 9 volts with only 2 red and 2 blue lights I was wondering what a good way to approach this would b all I really want is
    Group 1 3 quick flashes
    Half second pause
    Group 2 3 quick flashes
    Then repeat

    So how could I do this. Would a 4017 and 555 setup be good and last a little while? On a regular battery?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    You could do it this way, but you will need a bit extra with 3 flashes. The number of sequences go up.

    1. Red on
    2. off
    3. on
    4. off
    5. on
    6. off
    7. off
    8. Blue on
    9. off
    10. on
    11. off
    12. on
    13. off
    14. off
    15. reset

    The 9V is not a problem, but you would need to extend the number of counts (two 4017's) as shown. If you reduce the number of flashes, or use the schematic shown here with simplified driver circuitry (if you choose to go this route I will be glad to help), or you could use a µC if you can find someone to help you (I don't do µC like Arduino or Pic).
     
    Last edited: Jun 8, 2011
  3. dragracekid

    Thread Starter New Member

    Jun 5, 2011
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    I dont mind doing 2 flashes at all it would work just fine :) as for dual 4017s i have them and i have transistors i think i need but the electronics store is within walking distance :) so any help you can provide would be great thank you so much
     
  4. Wendy

    Moderator

    Mar 24, 2008
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  5. dragracekid

    Thread Starter New Member

    Jun 5, 2011
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    So just a quick question with that second as you said I can change the pattern with the diode but is it gonna be okay if I change the yellow to red I know it's a dumb question but I just had to ask
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    I'll redraw it to match what you said earlier when I get a chance. Basically you can set it up however you want. Just two colors of two LEDs is about as simple as it can get, most of the transistors are not needed.
     
    Last edited: Jun 9, 2011
  7. dragracekid

    Thread Starter New Member

    Jun 5, 2011
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    when you get a chance that would be great thank you so much and i will try to figure out parts on my own i dont want to be completely useless im here to learn :)
     
  8. dragracekid

    Thread Starter New Member

    Jun 5, 2011
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    i got it up and running about 20 minutes ago and it works absolutely perfect i like the pots that changes the speed thank you very much for this it is a fun experience and hopefully people will enjoy it
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    OK, you were peeking... :D

    Here is the final schematic...

    [​IMG]

    The LEDs are a bit overdriven with a fresh battery. However, 9V batteries drop fast to 7V, so it is balanced for that.
     
    Last edited: Jun 9, 2011
  10. dragracekid

    Thread Starter New Member

    Jun 5, 2011
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    I got two questions
    1. If I change r2 and r3 they will b a bit dimmer right?
    2. If I want three blinks I add another's lead to the outs for each color and make the corrisponding risistor changes correct?
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    R2 and R3 control current to Q1 and Q2. They can make it dimmer, but not in a good way. If you want the LEDs dimmer use R4-R7.

    If you want three blinks per side this schematic will not work, as there aren't enough sequences (explained in post #2). For 3 flashes per side you would need another 4017, to add to the number of possible sequences. I also showed an alternate way to do it with 3 555s and 6 or so transistors in post #4.

    The number of LEDs is just what lights, not much more.
     
  12. dragracekid

    Thread Starter New Member

    Jun 5, 2011
    13
    0
    Thank you very much for your help I may dim it a little but I'm fine with 2 flashes I will post again if I have problems thanks again :)
     
  13. #12

    Expert

    Nov 30, 2010
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    Referring to the schematic in post #9:
    Don't ever let R1 get to zero ohms. It will burn the timer chip. Add a resistor in series with R1 to keep the pot circuit from going to zero ohms.
     
  14. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You can actually get three blinks per side with the post #9 schematic by adding a diode from U2 pin 10 to the junction of CR1/CR2/R2, and another from U2 pin 11 to the junction of CR3/CR4/R3. There will not be a pause between the red and blue flash anymore though. However, it's very inexpensive and simple to try the change to see if you like it.
     
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