Police lightbar

Discussion in 'General Electronics Chat' started by archangeljess, Jan 7, 2014.

  1. archangeljess

    Thread Starter Member

    Dec 27, 2013
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    Good day to everyone!

    I am very new to electronics the fact is I just want to a police-like flashing light on my son's toy car. I have searched for the schematics and found one to work on. This is the schematic of it:
    [​IMG]

    I have bought all of the parts at a local electronics shop. My problem is when i try to build this on a breadboard, nothing happens. Well maybe I made a mistake in mounting the parts. I am a complete novice on electronics. I am a programmer by profession and I thought having electronics knowledge would be great.

    If somebody could guide me on this or suggest a tutorial on how to read and build from a schematic, it would be a really great help.

    Thank you and God bless.

    Jess.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    It might help for you to take a clear, well focused photograph of your breadboard and post it for us to look at.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    I have designed several of these in my time, including high power versions. Mr. Chips idea is a very good one though.

    There is an old open source saying, many eyes do bugs eliminate.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I think pin 7 and a second resistor is required to keep the 555 astable and drive your counter chip.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    No, the 555 is a valid design. It is a basic 555 Hysteretic Oscillator. The power supply can not drop below 5V or so, but that is the only limitation.

    This from my Bill's Blog.
     
  6. archangeljess

    Thread Starter Member

    Dec 27, 2013
    34
    0
    Here is what I did on the breadboard:

    [​IMG]


    [​IMG]

    I hope I haven't messed everything up. Thanks for the help guys.

    P.S.
    I appreciate you guys helping me and I didn't realize it was early in the morning your time. Its around 1PM Philippine time.
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    Check the vertical bus rails.
    These could be discontinuous at the mid points at holes 30.
    Install jumpers on all four rails.
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    Older protoboards are not always a continuous wire on the bus. They have a break in the middle, new ones do not do this.

    Just repeating what Mr. Chips said differently to see if it helps.

    http://www.allaboutcircuits.com/vol_6/chpt_1/2.html

    [​IMG]

    Look closely at this protoboards buses, this from the AAC book shown at the top.

    [​IMG]
     
  9. archangeljess

    Thread Starter Member

    Dec 27, 2013
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    I am very grateful for your reply but I am a complete novice. I really don't know where those holes are. There's nothing connected to hole 30. In the picture the breadboard is inverted.

    Could you point this out for me? I'm sorry for being so stupid.

    Thanks a lot.

    Jess
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    I know my instructions are not clear. I am not able to post a picture for you.
    Look at what Bill Marsden has circled in red.
    You need four jumpers like these.
     
  11. archangeljess

    Thread Starter Member

    Dec 27, 2013
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    Yes, I didn't know the breadboard I have isn't entirely connected. I'm so sorry. Thank you both for the help. I'll try this one in a moment.
     
  12. archangeljess

    Thread Starter Member

    Dec 27, 2013
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    Thanks for the great help guys. I was able to turn the LEDs on. Problem is, they don't blink at all. This is supposed to flash like a police car's. As shown in the youtube video : http://www.youtube.com/watch?v=uIgfDRaqxlg
     
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    The two diodes, 1n4148. Remove those completely and check
     
  14. Wendy

    Moderator

    Mar 24, 2008
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    Don't get discouraged, problems like these are how we learn.

    Now you have a continuous power supply bus you will need to break it down.

    I have written a lot of articles, and tend to draw the actual protoboard layouts to make it a bit easier. My time on and off the site has been a bit spotty due to health issues, but Riffa's suggestion about removing a few components at a time also has merit.

    Each of the outputs of the 4017 is on one at a time, so each output will flash a LED for a short duration.

    I'm going to steer you to an article I wrote that started as a tutorial for LEDs. It also has a police flasher section (links to follow). If you find it too intimidating don't worry about it, and we'll keep on working with you on your design. Note: the 4022 is very similar to the 4017, just fewer outputs.

    LEDs, 555s, Flashers, and Light Chasers

    Chapter 9....Light Chasers
    Chapter 11.l.Making Patterns

    Chapter 11 has a circuit very similar to yours, but it is done differently.

    Like I said, if this feels like we're going over your head just ignore it and we'll focus on your layout.
     
  15. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I have drawn the needed connections on your breadboard photo:

    [​IMG]

    Here are the wires that Bill_Marsden and MrChips have told you.

    Bertus
     
  16. archangeljess

    Thread Starter Member

    Dec 27, 2013
    34
    0
    I have read all your recommendations. I will try removing the two 1n4148 diodes and will get back to you as soon as I'm done testing it.

    Thank you,
    Jess
     
  17. archangeljess

    Thread Starter Member

    Dec 27, 2013
    34
    0
    I have tried R!f@@'s suggestion to remove the 1N4048 diodes. All is working well. The LEDs are turning on but not flashing. I also noticed that the 555 timer is getting hot. Is this normal?

    Thanks
    Jess
     
  18. archangeljess

    Thread Starter Member

    Dec 27, 2013
    34
    0

    I have already done this Bertus. However, the LEDs aren't flashing as it should be. I also tried R!f@@'s suggestion to remove the 1N4148 diode. When I tested it, the LEDs just light up no flashing. Any suggestion on what I should do next?
     
  19. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
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    Double-check your wiring.
    It looks like 4017 pin 8 is connected to V+ instead of ground.
    4017 output pins 6,9 and 11 appear to be connected to gnd or V+.
    These unused outputs should be left disconnected.
     
    Last edited: Jan 9, 2014
  20. sirch2

    Well-Known Member

    Jan 21, 2013
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    Whilst it might be "normal" when I prototype things ;), I doubt that yours should be getting hot. Check you have +ve and -ve connected correctly, you may need a new 555
     
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