how to get LED's to go back and fourth?

Discussion in 'The Projects Forum' started by stanman11, Jan 29, 2011.

  1. stanman11

    Thread Starter Member

    Nov 23, 2010
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    im trying to figure out a way to take a 555 and 4017 and make the led go in sequnce. (i got kost of it down with going one way. but getting it to come)

    1 2 3 4 6 5 4 3 2 1 can i use a 4019 up/down counter instead of the 4017 counter?

    also if i wanted to add 2 lights per pin, do i add a mosfet?

    how many LEDs can one mosfet power?
     
  2. Wendy

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    Mar 24, 2008
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  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    First , read Bill's material, especially CH 11, then decide on how many LEDs in chain. For a 4017 & 5 LEDs you can use a diode OR gate or a 2 in OR IC. Input 0 & 9, 1 & 8, 2 & 7, 3 & 6, 4 & 5. OR outputs drive FETs or transistor LED drivers. For longer string, cascade 4017's, or use 4 bit counter & CD4515 4 line to 16 to give a string of 8 LEDs for back-n forth.
     
    Last edited: Jan 29, 2011
  4. stanman11

    Thread Starter Member

    Nov 23, 2010
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    Can i use a 4029 up/down counter?

    or would this be easier to get a pic and program it?
     
  5. bertus

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    Apr 5, 2008
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  6. Bernard

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    What you use depends on what you want. You can use 4029 with a decoder like 4028, 4515 or 74c154 for 10 or 16 LEDs, or multiples.
    A PIC would not be easier for me.
     
  7. Wendy

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    Mar 24, 2008
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    The thing you are missing about the 4029 counter is it will need decoders. With a 4017 no decoders are needed, the chip itself is a decoder. With the 4017 only one of 10 outputs (the 4022 is 1 of 8) are on at a time, the other schematics show how to cascade multiple 4017s to create one of any number one at a time.

    The schematic is developed and ready. If you want to design something for the 4029 you can, but I suspect making decoders is going to use a lot more parts. It will take 3 4017s to do 25 outputs, use the diode steering for back and forth it can do a total of 13 LEDs. If you want fading that has been tested too, though it is a bit more complex.

    We have the technology, and it is old.
     
    Last edited: Jan 29, 2011
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