LED Turn signal for gokart

Discussion in 'The Projects Forum' started by stanman11, Jul 27, 2012.

  1. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    Hey guys still a noob at all this but does this all look correct and ready to go?
    And does any one have some Resistors i can buy?

    [​IMG]
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Nope. 3.6VDC will work with a CMOS 555, but not a conventional 555.

    With a CMOS 555 you then run into drive issues. You are also showing the LEDs in series, with such a low voltage it will not work. Nor are there current limiting resistors, which are not optional with LEDs.

    I have a standing offer to send resistors to anyone that needs them. Their cost is so low shipping is the expensive part.

    PM me with what you want. Included mailing address, including name (full address).

    Want help with designing? I am a firm believer in teaching people to DIY, but am always willing to help.
     
  3. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    "ive up the psu to 9.6v battery pack. Pretty much all I have in rechargeable batteries.

    Redid the design a little and put it in to a video so you can see the controls.
    I also added a brake light. As for the resistors im not sure what i will need yet. need to complete this circuit before i know which ones to use since im noobeh!.

    http://www.youtube.com/watch?v=0qNltX2GEHo&feature=youtu.be
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The video is private; apparently no one but you can view it.

    You should have a minimum of 100 Ohms per volt of supply between the supply and DIS/pin 7 of the 555; that will limit the current pin 7 has to sink to <= 10mA. Since you are now using a 9.6v supply, you will need at least 9.6v x 100 = 960 Ohms between DIS/pin 7 and the supply. A 1k Ohm (1,000 Ohms) resistor will work just fine.

    Had you used the 3 x 10 = 30 Ohms' worth of resistance with 3.6v as shown in your original schematic, pin 7 would have had to sink 120mA current, or 12 times as much current as I suggest should be the maximum.

    Also, you need to look in the 555 datasheet for the formulas to calculate what values of resistance you will need to use with a 10uF cap in order to get the time delays you want.

    You can keep 1k for R1. R2 (your single 10 Ohm resistor) will need to be increased very significantly in order to get closer to the flash time.

    Don't pay too much attention to the timing on the simulator you're using; it's not very accurate.
     
  5. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    I change the vid settings so you can veiw it.
    I also tried the 1k resistor and tried messing around to get it to work but i couldnt
     
  6. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    thnx for the help guys, any more tips would be greatly appreciated!
     
  7. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    I changed a few things on it
    1k R
    100 ohm R
    470nf

    [​IMG]
     
  8. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    You should not put LEDs in parallel, unless you have a large supply and are willing to test select them. LEDs do not have identical Vf, it varies from component to component. For reliable operation you should have a resistor per LED chain, given that resistors are around 2¢ each this is not an unreasonable requirement.

    I explain this in my article.

    LEDs, 555s, Flashers, and Light Chasers

    I also have some really long duration flasher circuits if you are interested.
     
  9. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    yup ok I quit. Theres no way i can learn all this on my own.
     
  10. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    Is this what you meant as series?
     
  11. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Yep, the results will be consistent. In other words, it will work the first time.

    Don't get discouraged, there have been times I've banged my head for a week before the light came on. Once learned, you move on to the next thing.
     
  12. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    It would be easier for me to learn this in school now that I can some what control my focus on what im doing. Instead of learning from google.
     
Loading...