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LED setup help needed.

Discussion in 'LEDs and Optoelectronics' started by jujulo, Dec 29, 2017.

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  1. jujulo

    jujulo

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    Dec 29, 2017
    Newbie here and glad I found this forum. I have a minor problem that I hope someone can help me with. I want to setup up 7 5mm leds in a row. I am going to be using a momentary switch to activate them. The problem is that I need them to come on one after the other. So for instance, if I click the switch once, one will come on. If I click the switch twice, then two will light up and so on until I click it eight times and then they all go off. Is there a way for me to set this up? If so, can someone tell me the components I would need and possible a schematic on how to set this up? I appreciate all the help in advance. Thanks

    Jay
     
  2. ramussons

    ramussons

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    Jun 10, 2014
    You can make a circuit using 8 D Flip Flops.
    The clock will be the switch.
    At each click, the output of the D Flip Flops can be Hi to light the LED's.
    At the 8th pulse, the Output of the Last FF will Reset all to Lo.

    An 8 bit Shift Register is also a possibility.

    But unless you know some basics of Digital Electronics, one of us will have to draw a schematic.
     
  3. duke37

    duke37

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    Jan 9, 2011
    The CMOS 4017 Johnson counter may do what you want with a transistor to drive each LED.
    You will need a 5 to 15V supply.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    A microcontroller would be the simplest solution (for a certain definition of simple).
     
  5. Audioguru

    Audioguru

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    Sep 24, 2016
    It sounds like school homework. We do not know if he was supposed to learn about flip flops, Cmos counters or microcontrollers.

    Duke37, a CD4017 lights only one LED at a time. He wants 2, 3... up to 7 LEDs to light up at the same time.
     
  6. duke37

    duke37

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    Jan 9, 2011
    Sorry about that, I just read "one comes on after another".
    The 4017 could still do the job with a few diodes to activate lower leds.
     
  7. jujulo

    jujulo

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    Dec 29, 2017
    Wow. Thanks guys! This helped me out a lot! Good to know there are sites like this to help people out. Now it's time to order some stuff!
     
  8. hevans1944

    hevans1944 Hop - AC8NS

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    Oh yeah? Without a schematic (a plan of action) just what "stuff" do you think you need to order? Howsabout an 8-deck stepping switch (old-school technology, simple and still available)?

    Each button push advances the wiper arm one position. Each of the eight "decks" is devoted to one LED. The decks are wired so the LEDs stay illuminated in succession. When the last LED is illuminated, the next button push or switch step advances to the ninth position and causes an automatic reset to the zero position, extinguishing all the LEDs. Image source and more info here.
     
  9. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    I think he should learn about ancient reliable technology before it disappears from the surface of the planet. Most of the stepper switches built for telephone exchanges are probably in landfills by now. New ones may not be manufactured to the same standards, and may be somewhat pricey compared to flip-flops, cmos counters, or microcontrollers.
     
  10. jujulo

    jujulo

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    Dec 29, 2017
    Ha Ha. Thanks hevans1944 for the laugh and suggestions. I just needed to know what components to use. I can make a schematic once I see the pinout of a specific component. After that, I just use my trusty breadboard to get me through the rest! Thanks again!
     
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