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LED Circuit

Discussion in 'LEDs and Optoelectronics' started by weilerdo, Jun 24, 2017.

  1. weilerdo

    weilerdo

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    Jun 24, 2017
    Hello, I am very new to this and looking for some help. I have a circuit that I need to build that is 12v and it has 2 5mm blinking LED's and then it was 3 non blinking LED's on the circuit. When I try to wire it up the 2 blinking LED's back feed into the regular LED's and cause the entire thing to blink. I assume i need some kinda of resister or something to stop the blinking LED's from back feeding into the other lights. Thanks for any help that you can provide.

    upload_2017-6-24_16-7-52.png
     
  2. duke37

    duke37

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    Jan 9, 2011
    You should have no backfeed if you use a change over switch.
    Also, perhaps the power supply is not up to the job.
     
  3. weilerdo

    weilerdo

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    Jun 24, 2017
    Hi Duke,

    Thank you for the rely. The power supply is a 12v battery (A23) and seems to be fine with 7 regular 5mm LED's and fine with 6 blinking 5 mm LED's as long as I don't mix them My switch is a simple on and off switch with one input and 1 output. I am not sure what a change over switch is, I updated my sketch to sorry for any confusion.

    upload_2017-6-24_17-46-2.png
     
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    hope you have resistors in series with the LEDs ? around 1k
     
  5. weilerdo

    weilerdo

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    Jun 24, 2017
    Hi Davenn,

    No Sir I don't currently have any resistors in the circuit. I am very new to this and trying to understand and figure it out. So would I need a resistor between each LED or just between the Blinking and Non Blinking. Thanks
     
  6. davenn

    davenn Moderator

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    Sep 5, 2009
    between each LED and the positive rail

    upload_2017-6-25_9-22-25.png

    with you single pole single throw switch as presented power to all LEDs will be switched on and off at the same time

    ot sure about the effect the blinking ones will have on the non-blinking ones
     
  7. weilerdo

    weilerdo

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    Jun 24, 2017
    Thanks davenn,

    I will get the resistors tomorrow and give that a try.
     
  8. Audioguru

    Audioguru

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    Sep 24, 2016
    The datasheet from Energizer or Duracell shows that an A23 12V battery is a very weak little thing. It is designed to supply a current of only 0.5mA for a few days or much less current for weeks. You shorted it with your LEDs so now it is dead.

    An LED must have a series resistor to limit its current to no more than about 30mA. A few LEDs can be connected in series and have one series current limiting resistor but the voltage must be high enough.

    One LED can have its current limited to 10mA with a 1000 ohms resistor then a brand new A23 battery will light it for about 4 hours as shown on its datasheet. It will begin fairly bright but you will see it slowly dimming.

    Why does each non-blinking LED in your schematic have three wires? LEDs have only two wires.
    Did you know that an LED must be connected "the right way around"? The flat edge on its round case is nearest its negative wire.

    Most blinking LEDs have a built-in current limiting resistor but the maximum voltage is 9v (An added series resistor allows a higher voltage).
     

    Attached Files:

  9. Bluejets

    Bluejets

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    Oct 5, 2014
    55mah typical capacity ...not up to the job.
     
    davenn likes this.
  10. davenn

    davenn Moderator

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    Sep 5, 2009
    agreed, not up to the task


    A LED mush ... yes as I stated

    just the rough way he drew it .... I sorted that out in my quick edit


    but not all ... .that needs to be checked before purchase
     
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