555 flashing led

Discussion in 'General Electronics Chat' started by Senz_90, May 22, 2014.

  1. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    Hi everyone. I am beginner and I just understand a little bit about this circuit. I am simulate it on Livewire because I don't know how to using other simulation tool and lack of knowledge how this circuit work.

    I hesitate about the results because Led D5, D10 and D3, D6 each series connected looks more brighter than others led on livewire simulation. I have try measure voltage across the led. and get like this picture result, that is maybe okay for white led but I want to use a red led where the voltage around 2.5 as I know.

    please could someone look at this and give some advice and what component should I change to get same brighter for all leds? I don't makes this pcb yet because I don't want get a bad result or my led get burns before make sure this circuit will working.

    should I change current limiting resistor value for this series led?

    sorry for my bad english.
     
  2. pwdixon

    Member

    Oct 11, 2012
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    Where did you get that circuit?
    The 4017 is a dead duck straight away with it's outputs joined together. And a 4017 can only have at most a 7V supply so that's going to help do in the transistors too.
     
  3. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    First try to remove all resistor starting from R1, R8, R9, R12, R14.
    Next try to choose LED resistor values and set LED's current around 10mA or so.
    Add diodes between Q7 and Q1 ; Q6 and Q2; Q5 and Q3.
    Also kept in mind that real LED's will behave completely differently than LED's from Livewire.
     
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    First, you should not connect the outputs of the 4017 together as you've done. You'll need diodes on each pin, to prevent short circuits when one output is high and the other low. Add a diode to output 4 as well so that the voltage drop is the same for all LED strings.

    Second, your current limiting resistors will need to change if you change the LEDs to a different color. The resistor value depends on the forward voltage drop of the LED (Vf). Remember that LEDs are current devices. So to calculate the resistor value, use this formula:
    R=(Vss-Vf)/Iled
    where Vss is your supply voltage, Vf and Iled are the forward voltage drop and the current required by the LED respectively.
     
  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    What are you talking about??
    CMOS CD4000 Series devices will work over a supply voltage range from 3 V to 15 V
     
  6. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    what is mean "dead duck straight away with it's outputs joined together".

    I have to lower the battery voltage? I don't see datasheet for 4017, maybe I need to see it.

    I get this from EFY(electronics for you) file, but i am modify it a little bit so it can move back and forth. I forget the site address where I get.

    So what will need to do to correct this? please help
     
  7. eetech00

    Active Member

    Jun 8, 2013
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    Not true...4017 can be operated with a 15vdc supply.


    eT
     
  8. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    btw what diode should I use? 1N4148 or 1N4004? where is the cathode anode should go? I am little confused to choose resistor values because the led are 2 series connected, R=V/I. voltage is Vf red led 2.5x2 / 10mA? ah nevermind djsfantasi give the ideas. I will try that and report the result. thank you.


    thank you sir. I will try this.
     
  9. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Use 1N4148, connect anode towards 4017.
    Also you can post simulation file but first zip it.
     
  10. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    this is the livewire file. I try it with current limiting resistor 700 ohm?:confused:
    I get this from formula (12-(2.5x2)/10mA. is this correct? I feel wrong because the led are very dim when move back.
     
  11. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Exact calculation are not so easy for this circuit. Too many unknowns.
    But check this version
     
  12. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    ah. my livewire is absolete. I couldn't open it because the version didn't same. would you mind give another format file like pdf or jpeg sir? btw thanks for your time.
     
  13. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    I'm using Circuit Wizard.
     
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  14. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    pop up window said that my livewire pcb wizard didn't support your new version :D. If I want to make it could move back and forth, just attach 1N4148 diode towards 4017 like my file on latest edit?

    I am usually using Eagle for make a PCB, I don't used to use PCB Wizard.
     
  15. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    But in new diagram (post 13) we don't need any diodes.
     
  16. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    I mean move back and forth like night rider circuit. is those led move back and forth likes night rider light?
     
  17. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    OK I see. So you need to add those diodes, but this time we don't want any short circuit in our design. So we need to add more diodes.
    And notice that Q3 is PNP.
     
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  18. Senz_90

    Thread Starter Member

    Jul 11, 2013
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    wow. Note !! thank you sir :). I want design my pcb so it could attach on my motorcycle :D
     
  19. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    But don't forget to do the breadboard test first. And if needed tweaks the component value.
     
  20. Wendy

    Moderator

    Mar 24, 2008
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    Metalmann likes this.
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