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What components to make LED bar graph up/down counter?

  1. Oct 5, 2013 #1
    Hey all,

    Wanting to create an up/down counter that uses a photogate as a trigger, and a 12 segment LED bar graph to display the count. It will need to begin at full illumination, turning off one at a time on activation of the photogate. Will also need a reset switch, though I'm thinking a simple break in the circuit to turn off when disengaged, reverting to full illumination when power restored would do?

    Wondering if I can retrofit a standalone up/down counter kit, or whether I'd need to go as far as to invsst in an arduino board and learn code? if theres a route that achieves what I need that avoids going to that extent, id prefer that.

    Size and power both small if possible.

    I've done some reading, but without a firm point of reference on which to draw a bearing, I fear I'm going in circles and not getting anywhere.

    Any help much appreciated!
  2. jcsd
  3. Oct 5, 2013 #2


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    Gold Member

    You could use a shift register to build such a "thermometer" code display. Here is a good page on shift registers.


    Even if you used an arduino, such a circuit saves IO pins (which is sometimes important).

    My bias is generally to use a processor since you can easily tweak your code to modify behavior, deal with startup and reset conditions, change sensitivity rules, etc. Learning to use arduino is move into the future.
  4. Oct 5, 2013 #3
    Thanks for pointing me in the rght direction, MBG!
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