LED Connections problem

Discussion in 'General Electronics Chat' started by ect_09, Sep 23, 2014.

  1. ect_09

    Thread Starter Member

    May 6, 2012
    180
    1
    Hey,
    am confused , i design generic board where i can program MCU through programmer and can get input and output frm different ports.
    but problem is that i want to connect LED in it in the start circuitry to show power is ON. i have 5V source.
    when i connect this LED i get the output voltage 3.87v that is not enough for MCU.
    please tell me how i connect this LED in circuit.

    Regards,
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,504
    380
    hi,
    Do you have a current limiting resistor in series with the LED.?
     
  3. adam555

    Active Member

    Aug 17, 2013
    858
    39
    Are you connecting the LED in series with the 5v source, or in parallel? You need to connect it in parallel; and also limit the current to 20mA with a 250 ohm resister (220 ohm is the closest standard value).
     
    ect_09 likes this.
  4. ect_09

    Thread Starter Member

    May 6, 2012
    180
    1
    if i have one resistor and voltage source of 5V then how can i connect it in series...

    ??
     
  5. adam555

    Active Member

    Aug 17, 2013
    858
    39
    You need to connect the LED with the resister between the 5v source and ground.
     
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