Make blinking LED Flashlight

Discussion in 'The Projects Forum' started by romeroom, Apr 17, 2014.

  1. romeroom

    Thread Starter New Member

    Apr 17, 2014
    I am an electronics newbie. I know very little about circuits, as will be clearly evident by my question.

    I have a number of LED flashlights like this . I would like to make these blink or flash.

    My question is: If I introduce a blinking LED like the one shown here in series at the "beginning" of the circuit, would the flashlight blink as well?

  2. wayneh


    Sep 9, 2010
    Sadly, I don't think so. I think the LEDs in those things are in parallel. Several similar flashlights have been dissected by folks posting in this forum. Maybe one of them will chime in.

    FWIW, you can get a very bright, multifunction (flashing, strobing, etc.) LED flashlight for under $10.
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Unfortunately I doubt it would work for this flashlight. With 3 AAA batteries driving 8 LEDs not all of them are wired in series, as that would take a higher voltage.

    So adding one blinkie LED will not get them all to blink, maybe just one or two or half, not all. And two blinkie LEDs will not blink at the same rate.

    And welcome to the forums!
  4. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    Using a self-blinking LED as a pulse generator in a circuit is a common trick, but only in low power situations. The LED you show should see no more than 20 mA current through it, not nearly enough to power a 9-LED light. Plus, the voltage drop acros the blinker must be kept within the range of 3.0 to 3.4 V, something the standard flashlight batteries cannot do while powering their own LEDs.

    Good idea, but wrong part for the job and expensive. As wayneh said, for the price of 2 blinkers you can buy a flashlight with blinking built in.

  5. romeroom

    Thread Starter New Member

    Apr 17, 2014
    Thank you all for chiming in so promptly. Very helpful. I think LED circuitry technology is a bit more complicated than what people think.