4N35 optocoupler issue

Discussion in 'General Electronics Chat' started by kaning, Jul 21, 2014.

  1. kaning

    Thread Starter Member

    Jun 2, 2014
    43
    0
    I want to use optocoupler 4N35 as switch to turn on a 5v fan.
    im using generic design of led input 5v in series with 1k resistor.
    i turn on led with 5v and i get reading of 5v on the other but when i connect the fan to the 5v on the other side i get only 2,3v... why such a big drop? internal resistance?

    i would apreciate some help, thnks in advance.
     
  2. MrCarlos

    Active Member

    Jan 2, 2010
    400
    134
  3. kaning

    Thread Starter Member

    Jun 2, 2014
    43
    0
    it needs 80mA
    on datsheet they say collector current is up to 150 mA.
     
  4. kaning

    Thread Starter Member

    Jun 2, 2014
    43
    0
    i used a transistor (bc457), where its base was fed by the optocoupler, collector with 5v and fan on emitter to ground and now everything is ok and working...
     
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