New to circuits - Need help with simple up-down counter.

Discussion in 'The Projects Forum' started by jholder82, May 5, 2009.

  1. jholder82

    Thread Starter New Member

    May 5, 2009
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    Thank you in advance, This is my first project and am struggling with it. When I started, I knew absolutely nothing...But I have learned a bit since then.

    First: Here was the goal of my project:

    I wanted a 2 digit up down counter housed in a round case. I wanted to control the up and down count with a ring on the outside of the device that spins. This seems pretty hard to do, and if it becomes too much of a problem, I would like to have a wheel partially extruding from the side of the device that essentially works the same way. Spinning clockwise count up, counter clockwise counts down. I also want the device to be able to preset to a number I choose...with a reset button to reset back to that number. This device must be battery powered. Here is a quick design of my project:
    [​IMG]

    Here is the schematic I have chosen:

    [​IMG]

    [​IMG]

    These are taken from http://members.shaw.ca/roma/up-down.html


    These are the parts I am going to order so far:

    2x Single Hi-Red 2.3" CC 7-Segment LED Display $3.90
    200x 330 Ohm, 1/4 Watt Resistor $3.00
    200x 10K Ohm, 1/4 Watt Resistor $3.00
    200x 1K Ohm, 1/4 Watt Resistor $3.00
    2x NTE NTE4510BT IC-CMOS UP/DWN COUNTER $2.54
    2x NTE NTE4511BT IC-CMOS,LATCH DECODER $1.96
    4x Solder IC Socket, 16 Pin $0.28
    5x .1 uF mono radial capacitor $0.75
    4x 2N2222 Transistor $1.16




    And here are my questions:


    1.) How would I modify this schematic to to use the spinning wheel to count up and down? I have been told the easiest way would be with an octocoupler and a shmitt trigger..but I have no idea how to incorporate that, or what it is. I though I could just hook up a rotary switch.

    2.) Is this circuit battery powered? If it isn't how would I make it battery powered?

    3.) Have I chosen the correct parts so far? What else will I need?

    Thank you again...I am about to start ordering parts, but I wanna make sure everything is right first.
     
    Last edited: May 5, 2009
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
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    A code wheel with alternating black- reflective segments & two optical reflective sensors + decoding logic will give direction, with out physical contact with wheel. You can have your " equater " wheel; a hollow shaft connects two almost hemispheres, leaving space for wheel; wheel with bearing is mounted on shaft.
     
  3. jholder82

    Thread Starter New Member

    May 5, 2009
    7
    0
    That sounds like a really cool idea. But how exactly would it know if I was spinning up or down? Wouldn't it reflect the same? Also how expensive would it be to incorporate this?
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    1. wheel , in first post if it makes it.
    2. From 330Ω would appear to operate from 9V, battery or otherwise.
    3. Seems there should be a resistor from emitter of 2N2222 to ground?
    4.Are you using just manual count advance?
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Instead of sphere, maybe a flat bottom, wheel, & hemispherical or or other cover. Add two more LED's , red & green for rotational direction.
    Cost for additional electronics about US $ 5. Mechanical, depends on equipment that you have,mostly a drill-press. Cover from utinsel section of grocery store.
    If the 82 in your name is your age- then we have something in common.
     
  6. jholder82

    Thread Starter New Member

    May 5, 2009
    7
    0
    Yes the 82 is the year I was born :)

    Thank you for the responses, but please bear with me, I am very new to this kind of thing and still trying to visualize this stuff in my head.

    You've pretty much answered my question on the batteries...I would just have to figure out how to hook up the battery connections. (although 9 volt is pretty large, I wanted this to be as thin as possible.

    But in regards to this wheel...I am still a little confused. I like the sound of the optical setup. But I can't add anymore 7 segment displays. I was thinking about using a setup like this....

    http://bobodyne.com/web-docs/Images/Wheel.png

    I figure this would be really easy to do...counting up with the wheel touched the flimsy plate to the screw...and counting down when the wheel touches the plate to the other screw.

    But now I just have to figure out how to hook this into the schematic.

    Do you think the optical setup would be better to use?

    Oh and yes I want it to be a manual count. Only counting up and down...one number at a time when I tell it to.
     
    Last edited: May 5, 2009
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    How big is this device, diameter, height ? Shape ? Batteries come in all shapes and sizes,and capacity. Selection depends on space availabl and running time per set. also on how bright the display is. Three lithium " coin " cells,each about size of two stacked quarters would be about 3/16 in thick . The drawing is just to give you an idea of what is involved in a reflective decoder. Two identical modules are required, one connects to the clock in of a D type FF [or JK FF], the other is data input. The Q output is the up/dn control signal. Check ACC Vol IV Synch counters for illustration of a wheel encoder. Which ever wheel arangement you choose, a FF or similar dev. will be needed to remember direction. As to direction if there as some sort of decoration on tht wheel rim, direction of rotation should descernable. Sorry for rambling- too much brain fog today.
     
  8. jholder82

    Thread Starter New Member

    May 5, 2009
    7
    0
    I want this device to be as small and thin as possible. No measurements yet, I am going to- wait and see how small I can get the board and such first.

    I'll research it a bit more, but I do believe this to be well over my head. :p

    Thank you for that though. Now I have a direction in which to research.
     
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