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Not your typical Up / Down Counter - Need Help

Discussion in 'General Electronics Discussion' started by Chris Llewellyn, Jan 12, 2017.

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  1. Chris Llewellyn

    Chris Llewellyn

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    Jan 12, 2017
    I am trying to make a circuit to control LEDs for a vehicle turn signal. There doesn't seem to be a counter chip that will do what I am proposing.

    I need to build an 8 bit (at least, 16 would be better) counter / display where the LEDs will light up in order from the least significant bit to the most significant bit and then turn back off from the most significant bit to the least significant bit. After a short delay if would repeat this process as long as there is an input tot activate the circuit. Please see the attached file LED Pulse GIF.gif for an example.
     

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    A shift register and a couple of 555s could do what you want.

    A microcontroller might be easier.
     
  3. Chris Llewellyn

    Chris Llewellyn

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    Jan 12, 2017
    Yes, I can do it with the mcu but I was hoping for a more compact and possibly dependable way to do it. Not sure if the mcu would be as reliable with having to run code. Are you thinking dumping a new set of 8 bits into the resister for each update of the LEDs?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    No, one 555 clocks the shift register, the other determines if the input bit will be high or low.
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Why should this not be reliable? It works in billions of devices.
    Nevertheless, here's another option: Using an LM3914 bar graph driver and a triangle wave generator (example).
     
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