need help building a scoreboard counter

Discussion in 'The Projects Forum' started by eric71m, Feb 18, 2015.

  1. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    Hi there, I've been out of electronics for a bit now, and could use some help with locating parts, wiring diagrams, and general input for building a scoreboard.
    I've found some 7 segment led's, I think that work for my purpose. These are what I was thinking of using (https://www.lc-led.com/Catalog/department/36/category/49/4).
    I've done some google searching, and seen a few wiring diagrams for two digit counters, but they used different displays (individule linked leds segments).
    I'd also like to add a wireless controler to it, count up and count down for score correction, and a reset.
    Thank you in advance for your help!
    Eric
     
  2. #12

    Expert

    Nov 30, 2010
    16,321
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    go: search, advanced search, scoreboard.
    I got about 150 hits.
     
  3. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    i tried that, thats why i started my own thread.
     
  4. #12

    Expert

    Nov 30, 2010
    16,321
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    OK. You might notice I am not in any of those conversations. There is a good reason for that.
    Next helper, please.
     
    absf likes this.
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  6. #12

    Expert

    Nov 30, 2010
    16,321
    6,818
    I think the hint here is that your post is coming across as, "Please design the whole thing and hand it to me."
    You need to cut this down to, "This is where I'm having difficulty."
     
  7. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    Welcome to AAC.

    Sorry, we're a bit confused. You mean you tried searching and couldn't find anything, didn't want to look through the results, or feel none of the results did exactly what you wanted?

    I've helped a handful of members with similar projects. I can link to a couple once we know more.

    Where will the display go - indoors or outdoors? If outdoors, will it be used in full sun or only in the evening/night?

    How big do you want the digits? From the link you posted, it looks like you want 1.5" digit height. What is the maximum distance the display needs to be seen from?

    How high a score do you need? 0-9? 00-99?

    How many scores/teams do you need to display?

    What is the maximum distance the remote will be from the display and still need to work?

    We assume you'll use wall power to power the display - is this correct?

    Assuming you just need to count up, down, and reset, I'd suggest looking at CD40110 IC's - you'll need one per digit.

    I'd suggest using common anode displays so you can use a ULN2004 IC to sink current to the digits. Again, you'll need one per digit.

    Can you read a schematic and solder a circuit from a schematic alone? This helps us better tailor our answers.

    Lastly, may we ask the purpose of this project? Something for friend, school project, club, etc.?
     
  8. elec_mech

    Senior Member

    Nov 12, 2008
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    From PM:

    I'll get back to you later - my laptop is about to die and I didn't bring the cord (doh), but I wanted to put this here so other members can chime in as well. We still need to know quite a bit about what you are looking for, otherwise we'll be doing a lot of backtracking. Please answer the questions I posted earlier when time allows.

    Resistor selection will depend on the forward voltage and current of each of the segments - these will vary by size and manufacturer. Are you looking to make your digits or buy pre-made?
     
  9. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    this is purly personal for my game room shuffle board table, I know there are prebuilt ones out there, but am looking to incoperate this with my hand built shuffle board table.
     
  10. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    Pick one of the examples that's close to you needs, and we'll help you adapt it.
     
    Last edited: Feb 20, 2015
  11. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    I have been looking at the premade digits, just for convinece and size. I plan on installing this in a arm/bridge over my shuffle board table (that I also custom built) so I may want to add a couple more repeat displays (so the scores can be seen from both sides i'll ask that later if the design tends that way). In my design I have been working on the design for the bridge display, I think the 2"- 2.5" displays work best for the score, and something like a 1" for the team wins displays. and then routing the score up/down buttons to each end of the table, along with the resets.
    I have seen lots of product, and even been suggested to make this programable system... ???? the problem with that, I understand logic, and have not worked on building any thing in a REAL LONG TIME. So if we could KISS / old school. that may help me understand things better. I have no test boards to build this with, so input on inexpensive pushin type test boards would be helpfull. Then I am assuming that once I have it all working, I could leave it on the test board???? or will i need to have a board printed for the final assembly.
    Again, thanks for the help.
     
  12. eric71m

    Thread Starter New Member

    Feb 18, 2015
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  13. elec_mech

    Senior Member

    Nov 12, 2008
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    You still haven't answered our questions, so I've pieced together what I think you are looking for below. For future reference, telling us to look at someone else's thread doesn't tell us what you are looking for. Inevitably, there is something different you want to do hence your reason for creating your own post. Please don't take this as harsh, but rather as constructive criticism. We're here to help, but we need you to tell us exactly what it is you want. This saves both you and us time and frustration.

    Indoor only for shuffle board. A quick look up for shuffle board sizes shows a maximum of 22 feet, so we'll assume you plan to put the scoreboard at the end or the middle and need to see the digits from about 30 feet or less.

    .

    So two scores counting from 00-99 each (one per team, two teams total) and a digit height of about 2.5 inches. Then two team wins, each counting 00-99 as well. These would have a digit height of about one inch. On top of this, you'd like a second display showing the same information.

    Going to assume about 30 feet as well here.

    Yes.

    If all this is correct, the schematic below should put you on the right track. As I mentioned earlier, it uses CD40110 IC's to count and control the digits and ULN2004 IC's to handle the larger current required by big digits. The post you linked to uses TTL logic IC's; these are fine, but it requires more parts and a 5VDC regulator. My design is CMOS-based and you can power everything from a 12VDC wall wart without the need for a regulator.

    The schematic below is for two sets of digits (two team scores or two team wins), so you'd make two of these to cover both the scores and wins. I've also shown how to attach a second set of identical digits and simply labeled them front and back. The nice thing here is you don't need an additional circuit since the ULN2004 can more than handle the current required for two digits in the sizes you're looking at.

    U1 is used to remove switch bounce so the display values don't appear to change to random values when you press a button.

    Futurlec sells good seven-segment displays in 2.3-inch and 1-inch heights. You'll want to get common anode (CA) displays as the ULN2004's sink current. I'd suggest sticking with single digits or dual digits that are not multiplexed, i.e., have a dedicated (not shared) pin for each and every segment. The circuit below will not work with multiplexed digits. If in doubt, tell us the colors you're looking for and we'll make some recommendations. We can show you how to select the resistor sizes once you pick out the digits. We need the forward voltage and current first to determine the resistor size, hence the reason I did not include values for R7-R55.

    It is possible to add wireless operation, but I may need to change the schematic slightly depending on the system used. eBay sells some decent cheap RF modules. If you go with a relay output module, then no changes need to be made. Something like two of these or one of these should work.

    Counter Circuit 2-21-15.png

    Counter Circuit 2-21-15.png
     
  14. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    I did answer your questions in red, something got messed up, and they got rolled up in your quote.

    This is awesome, I was thinking about using either the blue, or white displays you hyperlinked to for the main scores, suggestions? And the opposite color from before for the team wins or maybe like a green maybe.
    I am assuming your attempting to factor in ambient light in your resistor calculations? How difficult is it to add a dimmer, not the it would be accessed often but maybe if the table moves to a brighter location or something?
    As for the team wins, I'm only thinking one digit each, so I assume I'd just drop the second halves from your schematic?

    And the design is going for the double sided display. And choosing no remote at this time.
    Do you have suggestions for the push buttons?
    Thanks for you're help thus far.
     
  15. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Eric,

    My apologies, I didn't expand the quoted section you first posted with the answers to my questions in red. I'm used to seeing questions quoted and answers outside the quotes, but you did answer them and I failed to look harder. Again, my apologies.

    You asked for a PDF version in a PM. You should be able to click on the thumbnail image and open a large version in a separate window. However, this isn't always print friendly, so please find the PDF attachment below. Please note this is in ledger size, i.e., 11 x 17 inches. If this is problematic, just let me know and I'll break it up into a couple of standard letter-sized pages.

    Blue and white are popular "modern" looking colors these days - it really boils down to what you find visually appealing. In looking closer at Futurelec's offerings, only red or blue come available in 2.3-inch common anode (CA) and red, green, or blue for the 1-inch displays. The other colors are only available in common cathode (CC) which will not work with the ULN2004. However, you could use a UDN2981 or similar in place of the UDN2004. The '2981/2 are source drivers and would work with CC displays. The schematic would change ever so slightly, but I can post something if you decide to go with a CC display. You don't need to limit yourself to what Futurlec offers, but I have found them to be reasonably less expensive there than other places.

    As an aside, you may ask why lean toward sink drivers ('2004) instead of source drivers ('2981)? Sink drivers are more readily available and typically cost about half that of source drivers. The UDN2981/2 are no longer manufactured, at least by Allegro, so that drives the price up as well. There are other source drivers, but they still cost more than sink drivers - this is why I lean toward CA displays for large digits, but this doesn't need to limit your choices.

    Dimming would be a bit difficult. Off the top of my head, to dim I'd add a PWM circuit to pin 8 of each ULN2004 or perhaps to the Vcc supplying the CA of each digit. Before going down that rabbit hole, the question is do you need to dim? For an indoor application, I'd run them at slightly less than full brightness (slightly less than the rated typical running current to prolong life, you won't notice a difference visually in the brightness) assuming you'll be using them with the indoor lights on. I'd only consider dimming if you plan to play with the room lights on and off/nearly dark conditions (if, for instance, you were making an alarm clock). If not, I wouldn't worry about it. If you were planning to make a display for outdoors in full sunlight, we'd be looking for a much, much brighter display altogether. In outdoor applications, you need something special or make your own from high brightness LED's (several thousand millicandelas (mcd)) which would blind someone for an indoor application. :eek:

    You got it.

    How big do you want them? To give it an old school feel, you might consider arcade switches if they aren't too big. You can always run a cable between the display and switches if you want them in different locations.

    If you're going for a man cave feel, you could go extreme and wire the switches into the wall:

    arcade_button_light_switch.jpg

    Note most arcade switches are about 1 inch in diameter and 2 inches in length, so they'd require a lot of room in an enclosure.

    Alternately, you could use a joystick like this and wire it such that:

    Up - score increment

    Down - score decrement

    Left - team X increment

    Right - team X decrement

    Two joysticks altogether and four more switches for resetting or use only one switch to reset everything at once.
     
  16. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    Thanks for all your help.
    Due to size, I think I'll give these button/switches a shot.
    And for the LED's score I'll go with these .
    And for the team wins I'll go with these for team a, and these for team B.
     
  17. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    According to the data sheet for the white displays, you'll need +13VDC. In this case, I suggest a 15VDC power supply. I have to head out the door for a business trip, so I'll need a day or two to respond to the rest and suggest resistor values. Per your PM, you can get CD40110's from Futurlec here. Alternately, if you're in the U.S., I'd get most of the parts from Digikey or Mouser or Jameco.

    Are you going to make your own PCB or use a protoboard? If the latter, be a little careful with the switches as they are a hair shy of the 0.1" spacing found on most protoboards.
     
  18. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    sigh... 15vdc power supply, missed that on the LED display, so how much rework does that require on the whole circut? I am not THAT married to the white displays.

    As for the boards, I was thinking about proto boards. As for the switches mounting on the protoboards, didnt see any that small, so I figured that I would epoxy them into somekind of enclosure, and just directly solder the wires to the connectors, I intened to mount one set of buttons on each end of the suffle board table.
     
  19. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Here's the beautiful thing, nothing. We just have to make sure all our components are rated to handle 15VDC safely. The ULN2004's will handle up to 50VDC while the CD40110 and CD40106 will handle up to 18VDC max. We don't want to tempt fate, so we we never want to run a component at its max rating, but 15VDC should be okay.

    The switches you're looking at are designed to be mounted to a board which in turn is mounted to an enclosure with standoffs. Holes are drilled slightly larger than the outer diameter of the button and the button goes behind the enclosure surface - the tab around the button bottom is a stop. You can certainly come up with a different way to mount them, but I just wanted to be sure you understood how they're designed to be used.

    You could use panel mount switches (drill hole, put switch through hole, fasten nut on exposed end), but your color choices will be limited and you'd be hard pressed to beat the price you're looking at now.

    Okay, resistor values. Remember when your classmates complained they'd never use Algebra outside of class? Well now they can eat it. :p

    So, for the large (2.3-inch) white displays you plan to use for the scores, the datasheet says the typical forward voltage is 13.25VDC (14VDC max) and forward continuous current is 20mA with a 25mA peak (pulsed only).

    Note that I added D1 (1N4001) as a cheap, simple reverse voltage protector. If the power supply leads were to somehow get reversed, this simply prevents the circuit from operating instead of destroying the electronics. It comes at a price however, namely a 0.7V drop from the supply. If you use a regulated 15VDC supply, then Vcc will be 15 - 0.7 = 14.3V. If you use an unregulated supply, the voltage will be higher (can't say for sure by how much).

    There is also some loss of voltage across the transistors in the ULN2004's. If I'm reading the datasheet correctly, this can be 0.9V to 1.6V. Since we aren't pulling a lot of current from the ULN2004's, let's assume 1V to keep things simple. Now power goes from Vcc (~14.3V) through the LED's, through the resistors, through the ULN2004, then to ground. Mathematically speaking: 14.3 - V_led - V_resistor - V_transistor (ULN2004) = 0V. We know V_led will be about 13.25V and we've assumed V_transistor will be about 1V, thus: 14.3 - 13.25 - 1 = V_resistor = 0.05V. This isn't ideal since the resistor value would be next to nil (not good since it won't protect the LED's), so let's look at 16V power supply, then: V_resistor = 15.3 - 13.25 - 1 = 1.05V. This means we need to size the resistor such that there is about a 1V drop across it.

    Now using Ohm's law: E = IR where E is voltage, I is current, and R is resistance

    1.05 (drop across the resistor) = 0.02 (20 milliamps across each LED segment per the datasheet) * R

    R = 52.5 ohms, a 50 or 56 ohm (common values) would work fine.

    We also need to size the resistor to handle the power across it so it doesn't burn up. Power is P = EI. P = 1.05 * 0.02 = 0.021 watts. This is less than an 1/8W, but we often use 1/4W resistors, so that will work just fine.

    Now, you could leave off D1 if you can ensure beyond a doubt the power leads will never, ever get reversed and save the 0.7V drop. There is another method of reverse voltage protection using a P-Channel MOSFET - a tiny bit more expensive, but perhaps worth looking at. Another option that #12 introduced me to some time ago is using a bridge rectifier. This can be made with four 1N4001 diodes. The voltage drop would then be 1.4V (2 x 0.7V), but it allows you to use a DC or AC power supply and the circuit will still work even if the polarity is reversed. In this case, you could use an 18VDC: 18 - 1.4 = Vcc = 16.6V, then 16.6 - 13.25 - 1 = 2.35V = V_resistor; R = ~120 ohm and a 1/4W resistor is still good. It's late, so double check my math before committing to anything. And I apologize if I've overloaded you with information.

    The 1-inch blue digits only need 3.5V and claim 30mA. The green need 3.7V and 25mA. Note these will probably be amazingly bright. I'd suggest using 20mA in your calculations for each to start with. I then suggest to be prepared to double your resistors (put two in series) to halve the current going to the displays in case they are too bright.

    Since you mentioned you're out in the NW U.S. close to the west coast, I'd suggest Jameco or Digikey for the parts. While Futurlec sells inexpensive displays and IC's, I suggest buying the resistors elsewhere - I've bought Futurlec's resistors before and the leads are extremely thin compared to other suppliers and I just don't trust thinner leads with the same power rating as thicker leads. Jameco has a nice selection of power supplies, but I've found Digikey also offers decent prices on these as well (you only need one, so this shouldn't decide one supplier over the other anyway).

    As an aside you may also want to think about a filter to go over the digits. This is often a colored, transparent piece of plastic that allows the lit segments to show through and helps to hide the unlit ones making it easier to read the display, especially when other light is present, i.e., not in the dark. Just something to keep in the back of your mind.

    Okay, it's late and I'm going to bed. Let me know what questions you have after reading my dissertation (if it doesn't put you to sleep first). :) I can put together a BOM (bill of materials) for a specific supplier if it would help, but I'll need a few days.
     
  20. eric71m

    Thread Starter New Member

    Feb 18, 2015
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    ok, gota shake them cobwebs loose, but I think I can tackle this.

    I found a 18vdc power supply from here. I hope this is big enough, yet not too big?
    I do not feel comfortable taking out the D1, and the price for the 18vdc supply is slowly creaping up there, and I'm not sure how much a P-Channel MOSFET is goning to run, at inital looks (if I'm even looking at the right things), looks to be about another $26.00. So, in the understanding that some idiot reversed the polarity of house outlet, with the current configuration, the unit would not come on at all...
    So, do I go with a 16vdc and know that if I have the wrong polarity it wont work, or do I spend a few more bucks and add a bridge rectifier and go with the 18vdc power supply, and know that polarity doesnt matter.
    I say go with the Bridge Rectifier and play it safe. I remember bridge rectifiers back from my school days, its the flux capacior design... JK LOL

    So unless I did something wrong, I would say that the resistors required for the team scores would be 18vdc; VCC 16.6 - 3.7 - 1 = 11.9v. V_resistor; R = ~595 ohm @ .238 watt or as you said common values 680 ohm @ 1/4 watt (tending toward the higher resistance).

    After thinking this through a bit more, I KISS it my self too... drop the blue LED's and just use the green for the team scores.
     
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