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A Digital Counter

Discussion in 'General Electronics Discussion' started by Zedob, May 24, 2012.

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  1. Zedob

    Zedob

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    May 22, 2012
    Hi,
    I'm a total noob to designing circuits and I hope some of you gurus can help me out before I start smoking everything.
    .
    I'm working on a project for a buddy of mine that requires a digital counter display connected to a photoelectric sensor for counting parts. The display's info is below.

    I did some searching and found countless circuits, some simple and some way out of my league. My plan was to use the eye to trigger a reed type relay that would momentarily trigger the up counting (IN+) input. Is this best approach, or are there other ways?


    [​IMG]

    The display works fine on 9V.

    Thanks in advance.

    Russ
     
  2. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    It's unfortunate that your counter is triggered (Up/Down) with High side switching. Low side switching is much easier to interface to. Relays are not reliable in this application, as the contacts will bounce. This causes false counts.

    Please describe the objects you're counting. This is necessary to intelligently discuss interfacing optical counting. Are you counting when breaking the beam or are you reflecting the source beam off of the object. Be as detailed as you can. Object distance, size, etc.
     
    Last edited: May 25, 2012
  3. Zedob

    Zedob

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    May 22, 2012
    Thanks CD,

    Figures, I find a decent counter that seems to work fine and it isn't any good for the app.

    He's counting fish actually. Small size that will be flowing through a piece of 1-1/2 PVC pipe. Breaking the beam seems most logical.

    Thanks

    Russ
     
  4. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Very few things are absolutely impossible but many things are impractical. I don't think your counter is in either category. I think we can do this! I'll post a concept.
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Here's a 'basic' concept. It's possible but doubtful that a working (reliable) prototype will be as simple as this though. ;)

    Your schematic seems to indicate that the Up/Down inputs are debounced, as the manufacturer indicates common switches being used for counting. That's a good thing though. You do know fish will want to do a train dance though the tube. That's the nature of the buggers. :D See notes on the schematic.

    EDIT: None of the above takes into account the effects of light passing though a round tube of water. I'm sure it will mimic something like a convex lens.
     

    Attached Files:

    Last edited: May 27, 2012
  6. Zedob

    Zedob

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    May 22, 2012
    Hi CD,
    Sorry about not getting back sooner.

    I figured there will be a few snafus to deal with. I thought about the fish training each other, but I'll have to wait to see how they really act due to how they will be fed into the counter. They won't be going from tank to tank with the counter in between, but will be hand fed from a tray to help control the flow.

    As for light getting around, I guess that'll just have to be empirically tested, but what you've shown me so far is one step closer to what I need and something to try.

    Truly appreciated.

    Russ
     
  7. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    I've given this more thought and I'm thinking that the two most reliable methods would be two photoelectric gates. The first beam broken would set a flag that waits for the second beam to be broken. Only then would a count be generated.

    My second proposal is simpler. The phototransistor would trigger a 555 timer chip that could not be re-triggered until, let's say, a second or two has passed. This should eliminate a single fish causing multiple counts.

    If you do some experimenting please post your results. This is an interesting project and I'll stay with you through it.
     
  8. BobK

    BobK

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    Jan 5, 2010
    Fish debouncing!

    Bob
     
  9. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Fish de-bouncing. That's too funny! :D

    Chris
     
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