Trying to create a blinking LED

Discussion in 'General Electronics Chat' started by sebastianpatten, Dec 21, 2010.

  1. sebastianpatten

    Thread Starter New Member

    Nov 28, 2010
    Hi there - I think I've got my head around a basic circuit, but I want to create something a bit more tricky - a single blinking LED. I would like to achieve this using NPN transistors, capacitors, 1 led and resistors.

    Has any one seen any good schematic or diagram with how the current, voltage make it work?

    I've been trying to work it out on paper to no avail.

    Thank you!
  2. beenthere

    Retired Moderator

    Apr 20, 2004
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
  4. sebastianpatten

    Thread Starter New Member

    Nov 28, 2010
    I guess another follow up question would be - is it normal to try to do this in this manner - or should i be using something like a 555 chip? I've seen them mentioned a lot with regards to oscillation.
  5. tom66

    Senior Member

    May 9, 2009
    A 555 timer is the best option for stability and accuracy, but of course requires the 555 chip itself, which isn't among the components you specified.
  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
    I would use clock chip. We did this sort of thing in second year EE course, but we used frequency generator for the clock.

    That is also the point of the multivibrator mentioned above, based on values of the components, it will act as frequency generator, the clock.

    Connect the clock and source to AND gate. Source is always On, when clock is On, the AND gate output is On and led light up. Otherwise, led does not light up.

    So all you need is clock chip, AND gate IC like 74LS08, led, resistor, voltage source.
  7. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    There are a lot of ways to do it, all of them need an oscillator of some sort.

    Flashers, Chasers, 555's Blog by member Bill Mardsen here has great information and schematics.
  8. Wendy


    Mar 24, 2008
    I like the low voltage long duration variety myself.

    This is simple.

    The 555 Projects

    CMOS 555 Long Duration Minimum Parts LED Flasher


    I figure it will last a year with two alkaline D cells. This circuit depends on the low power supply voltage, do not use more voltage or things will smoke. You can buy the CMOS 555 from Radio Shack.

    The low power supply voltage makes the chip into the LED resistor. More power supply voltage and that chips resistance goes down.
    Last edited: Dec 21, 2010
  9. marshallf3

    Well-Known Member

    Jul 26, 2010