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LED Oscillator Circuit

Discussion in 'The Projects Forum' started by nqtraderman, Oct 26, 2012.

  1. nqtraderman

    Thread Starter New Member

    Oct 26, 2012
    I've been looking at building this LED Oscillator circuit which alternately switches on/off the 2 LED's via the NE555 :


    However I'd like it to flash at this rate and with a slight delay from switching off one LED to switching on the other :


    Can someone advise what needs changing in the circuit to do this ?

    The ability to vary the flash rate with the potentiometer isn't needed and can be replaced with the relevant resistor value to fix it as necessary.

    thank you
  2. Audioguru


    Dec 20, 2007
    The LEDs that blink for a short time use a very low average power supply current so a battery lasts for a long time.
    But an old original 555 oscillator draws a fairly high amount of current all the time.
    I made some Chasers and used extremely low power Cmos ICs instead of a 555 and each LED blinks brightly for only 30ms. The two or four AA alkaline cells last for months.

    I have a Cmos oscillator (instead of a 555 oscillator) driving Cmos mono-stables that are made from Schmitt-trigger inverters.

    EDIT: Try the original circuit like this and maybe with a little 9V battery:
    Last edited: Oct 26, 2012
  3. nqtraderman

    Thread Starter New Member

    Oct 26, 2012
    Hi, thank you for the revised circuit.

    With regard to your first comment re: eliminating the 555, I found this alternate circuit which might do the job however the LED's appear to behave with less of a "flash" then in the earlier 555 circuit :

    If required, is it possible to modify this circuit to give more of an "off" delay between the LED's changing over ?

    thanks for your help
  4. MrChips


    Oct 2, 2009
    You need a 555 oscillator, a 2-bit counter and some gates.
    Or you can do it with one microcontroller IC.
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
    Or a 555 and a CD4017.