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Two LED blinking

Discussion in 'LEDs and Optoelectronics' started by vick5821, Jul 26, 2012.

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  1. vick5821

    vick5821

    700
    0
    Jan 22, 2012
    Hey guys, I have constructed this circuit : http://www.eleccircuit.com/two-led-flashing-alternate-display-using-lm324/

    But, I realised that it only blink for once and then remains :(

    For example initial is RED High, then few seconds change to GREEN HIGH then RED LOW.then remain like this forever


    Anyone knows what's the problem ? And how this circuit works actually ? First time doing LED blinking without using Timer IC. :D

    Thank you.

    -Vincent
     
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    That is some broken English in that description, if I'm reading it correctly between the lines of broken English, if it 'sticks' you need to adjust the value of R6...
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Broken English? That's perfect grammar in the hood! :rolleyes:
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Since I had a few minutes to blow I did this circuit in an online simulator, as pictured it didn't work, but when I flipped the op amp around (flip + and -) it worked... Take it for what it's worth, as it's only a simulator...

    Cut and paste...

    Code:
    http://www.falstad.com/circuit/#%24+1+5.0E-6+140.81048482046955+66+5.0+43%0Av+48+368+48+96+0+0+40.0+6.0+0.0+0.0+0.5%0Ar+128+96+128+304+0+100000.0%0Ar+192+304+336+304+0+100000.0%0Ar+192+304+192+368+0+100000.0%0Ar+192+144+336+144+0+1.0E7%0Ar+432+224+432+176+0+100.0%0Ar+432+224+432+272+0+270.0%0A162+432+96+432+176+1+2.1024259+1.0+0.0+0.0%0A162+432+272+432+368+1+2.1024259+1.0+0.0+0.0%0Aw+48+96+128+96+0%0Aw+128+96+432+96+0%0Aw+192+208+192+144+0%0Aw+336+144+336+224+0%0Aw+336+224+432+224+0%0Aw+336+304+336+224+0%0Aw+192+304+192+240+0%0Aw+192+368+432+368+0%0Ac+160+208+160+368+0+1.0E-7+-2.1482003462719717%0Aw+160+368+192+368+0%0Aw+160+208+192+208+0%0Aw+128+304+192+304+0%0Aw+48+368+160+368+0%0Aa+224+224+336+224+0+15.0+-15.0+1000000.0%0Aw+192+208+224+208+0%0Aw+192+240+224+240+0%0A
     
  5. vick5821

    vick5821

    700
    0
    Jan 22, 2012
    When I flipped the opmap( + and - ), the circuit works fine !! Thank you :D
     
  6. vick5821

    vick5821

    700
    0
    Jan 22, 2012
    How the circuit works actually? First time doing blinking not using timer ic
     
  7. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    Initially - input is held low by capacitor. + input is held higher by resitors, so output is high.
    This makes the + input at 2/3V+ via the resitors. (50K to V+ 100K to gnd)
    The capacitor then charges through the feedback resitor.
    Eventually the - input exceeds the + input and the output goes low.
    Now the voltage on the + input is reduced to 1/3V+ so the output is still low.
    Now the capacitor discharges through the feedback resistor until it goes below 1/3V+
    Then the output flips high again, the voltage on + input is 2/3V+ and cycle starts over.

    Bob
     
  8. vick5821

    vick5821

    700
    0
    Jan 22, 2012
    Your explanation based on original schematic or the flipped one ?

    Thank you
     
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