Need help with a LED projects

Discussion in 'The Projects Forum' started by Syt0x, Sep 6, 2008.

  1. Syt0x

    Thread Starter New Member

    Aug 28, 2008
    I was wondering if someone could help me by sending me a schmatic or telling me how to build the following circuit.

    I would like to have a ring of maybe 20 LEDs or more. I want them to light up and then turn off in sequence to make it look like a moving circle, like a dot is moving around in a circle. Almost like a chaser circuit but not have multiple LEDs lit. Anyone help?

    For a second circuit have it the same as above except instead on one dot moving around the circle have 2 going in different directions and they cross and continue on and then cross again. Thanks
    Last edited: Sep 6, 2008
  2. HarveyH42

    Active Member

    Jul 22, 2007
    Cascade two 4017 to get 20 LEDs. Only one will light at a time, one direction. It's the basic chaser-Knight Rider, use the search, it's been covered so many times, and all over the web.

    Suggest looking into microcontrollers, then you could do both with just one chip, even switch between the two at the press of a button. Shouldn't be a difficult starter project either, most people start with flashing an LED...
  3. SgtWookie


    Jul 17, 2007
    Do a Google search on Charlieplexing.
    I have an 8-pin PIC12F675 microcontroller flashing a dozen LEDs in selectable patterns sitting right next to me. Two of the pins on the PIC are power and ground. I'm actually only using 4 of the uC's pins to drive 12 LEDs.

    With Charlieplexing, you can only light a single LED at a time. However, if you light several LEDs frequently enough, persistence of vision will make them seem to be lit all of the time.

    Charlieplexing is a somewhat advanced concept. But if you can wrap your brain around it and get a handle on it, you can do some amazing things with it.