Scoreboard-CD40110B Circuit

Discussion in 'The Projects Forum' started by Oxbo Rene, Apr 3, 2009.

  1. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Have been working on this scoreboard project a little while now.
    Finally finished up the circuit diagrams for the "Period" LED sequencer part.
    This is the next phase, designing the Team scores (Away/Home) counter.
    Have been receiving a wealth of help from Sgt Wookie and Bernard and a couple other folks.
    I would now like to show this diagram for inspection.
    This just shows one team's score, and, it will consist of two 4" 7-segment LEDs
    (Kingbright Pt # SC40-18GWA)
    Max rating for this 7-segment LED = 2.5V @ 25ma, pr segment. (I think)
    Typical rating = 2.2V @ 20ma == 490 ohm limiting resistors
    I have chosen to use 470 ohm limiting resistors.
    The CD40110B chip is capable of sourcing 25ma pr segment. (I think).
    Anyone find anything questionable, please speak up, etc.....
    Tx's so much....
  2. SgtWookie


    Jul 17, 2007
    WHERE did you get that idea? :rolleyes: It sure wasn't from the datasheet! ;)

    Download the datasheet from this page:
    Look at the little schematic in the lower right hand corner of page 1.

    Then go to page 2, and find the Vf specification.
    THEN tell us what it really says!
    You should know by now that you INCREASE resistance to DECREASE current through them, right?

    Did you look at the datasheet for the CD40110B?

    What does it say?

    Do you know where/how to find datasheets? If not, there are several places to look.
    1) The manufacturer's website.
    2) The vendor where you bought them's website.
    3) - a good source for finding who sells parts you're looking for as well as datasheets.
    4) and are useful websites.
  3. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Yea, Yea, Yea.....
    I looked at the datasheet.
    Gimme some time, will come back with how I got my figures, etc.......
  4. SgtWookie


    Jul 17, 2007
    I'm not trying to be a jerk; I'm just trying to keep you from letting the smoke out of your newly-acquired components any earlier than necessary, despite your best efforts to do so. ;)

    Don't make me get my stick! :eek:
  5. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    OK Sarge,
    Started the day out good, was into the new circuit, learned a lot and was ready to put all that learning to use.
    Got a couple little 7-segments from Radio Shack, dwnld'd PDF on em, figured out the limiting resistors, and, set up the circuit, been working perfect all day. Got my clock circuit pumpin pulses into em and they just count away, etc...
    So, did same figuring for big 7-segments.
    I just "Scanned" the sheet so you can see where I got the figures.
    I guess I'm wrong, sure looks good to me.
    I decided I would look at the "Max" rating and figure what the resistor would be for that, then figured for the "Typ" rating and that one was higher, which makes sense, and I opted for closest standard value, which just happened to be a little bit less than typ, but, well within range.
    I just knew I got it right !
    OK,here's the sheet/w/my writing, etc.
    Will probably have to blow it up a bit, etc.....
  6. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    I got to looking at the schematic of the diodes and yours says pins 1 & 8 are the CC pins.
    On mine it shows pins 3 & 8.
    That got me looking, apparently I have the sheet for the SC40-19 and not the SC40-18 !
    But, why the heck do they put all that info in there covering "ALL" of them, then again, maybe "ALL" of these are 19's, even the diff colors, CHeeeezzz !
    OK, I'll eat this one !
    Appreciate your guidance ! !
  7. SgtWookie


    Jul 17, 2007
    Just for curiosity, what are the part numbers on the Radio Shack 7-segment displays?
    I don't know where you got that datasheet, but it sure doesn't look like the official Kingbright datasheet for the part number that you specified.
    See the link I posted in my 1st reply.

    OK. You ALWAYS want to start out calculating for the typ Vf@current value, particularly when lifespan/reliability is more of an issue than blazing brightness. You really don't want this thing to break. The more current you run through the LEDs, the more quickly they will get dim; and ALL LEDs get dimmer as they age.

    Also, you really don't want to go below the calculated resistance result. The resulting reduction in life will have you kicking yourself a few months down the road.

    There's something else to consider; the voltage drop across the CD40110's outputs when sourcing current. At 20mA source current with a Vdd of 12v, you'll have between 1v and 1.1v drop from Vdd.

    The typical Vf @ 20mA for the 7-segment display is 8.8v.
    The typical Vf @ 20mA for the decimal points is 4.4v. This makes sense when you look at the schematic of the displays on page 1.

    So, for your supply voltage, you already have been informed that you will lose at least 1v from Vdd. Let's calculate for the segments first.
    Rlimit >= (Vsupply - VfLED) / DesiredCurrent
    Rlimit >= (11 - 8.8) / 20mA
    Rlimit >= 2.2/0.02 = 110 Ohms. This is a standard E24 value.
    Wattage = E x I = 2.2 x .02 = 0.044; doubled is 0.088 Watts. You could use 1/10W resistors if you wanted.

    Now you calculate the resistors for the decimal points.

    I'll have my stick handy. [​IMG]
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  8. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Ok, standby, just standby !
    I, I, I"m overloading ! !
    Too much stuff to figure and try and get back to you within reasonable time.
    Is 9:30pm, got to get up @ 3:30am, can't do this much longer, got to have time to myself and deal with all these questions without being in a rush, etc.
    Will pull the plug for tonight and work on this stuff some, then rest of it tomorrow after I return from fishing.
    Will be back online sometime tomorrow afternoon with (hopefully) all the info, etc, etc, etc..............
    Tx's so much.....
    Last edited: Oct 14, 2009
  9. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Radio Shack Pt # = MAN70A
    I used 150 ohm resistors (Brn/Grn/Brn)
    Ain't got time to go back and figure how I came up with that value right now, but, seems like I did err in the conservative side for these. (Hopefully).....
  10. SgtWookie


    Jul 17, 2007
    From the RS website:
    7-Segment LED Digital Display
    Model: 276-075 | Catalog #: 276-075
    Typical forward current: 20mA
    Typical forward voltage: 1.7V
    Peak wavelength: 655Mm

    So, if you're feeding the CD40110B with 12v, and at 20mA current it'll drop 1 volt leaving 11v...
    Rlimit >= (11v - 1.7v) / 20mA
    Rlimit >= 9.3 / 0.02 = 465 Ohms. Closest standard value is 470 Ohms.
    Power(Watts) = 9.3 x 0.02 = 0.186; x 2 = 0.372; 1/2W resistors needed.

    How on earth did you come up with 150 Ohms?

    I guess you're just hell-bent on turning your new components into a smoking pile of rubble?

    Or are you using 5v to supply these smaller displays?
  11. SgtWookie


    Jul 17, 2007
    If you're using 5v for the small Radio Shack 7-segment displays, then...
    the CD40110B will still drop about 1v typically when sourcing 20mA, so that leaves you with 4v.
    Rlimit >= (4-1.7)/20mA = 2.3/.02 = 115 Ohms. 120 Ohms is the closest standard value.

    Let's see what that does to the current.
    ILED = 2.3/120 = 19.17mA - that's fine.

    Wattage: 2.3 x 19.17mA = 0.044091 W; doubled = 0.088182. You can use 1/10 W or larger.
  12. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Good morning;
    I didn't make my fishing trip !
    Had some kind of chest pains after going to bed, got real bad, couldn't sleep because of the constant pain/pressure on my upper chest. Was up most of the night, had to take some sleeping pills/pain pills to get any relief, finally got to bed feeling better. Guess I got to admit I'm a smoker and I believe that's what the problem is, just been smoking way too much lately, etc.......
    Anyway, is 11:30am and am somewhat better this morning.....

    First thing;
    Sorry Sarge, forgot to tell you, I used 5V for VCC on the Radio Shack 7-Seg LEDs.
    So, {Vf=2V @ 20ma} =5V-2V=3V/.020 = 150 ohm limit resistors (Brn/Grn/Brn).

    You say the CD40110B can scource 20ma w/12V VDD ? I find a reference to 25ma but not 20ma, are you being conservative here ? (1st page in discussion of chip.
    3rd page of PDF= I can't make out heads or tails of all that mess.
    What is VOH/IOH, What does "OH" refer to ?? How come these values are negative for output drive for 7-seg outputs.

    Yes, the new datasheet for the big LEDs is definitely different than the one I had.
    I found Vf = 8.8V//DP = 4.4V//both @ 20ma.

    Can I always assume I'll drop 1-1.1V across a chip ??

    12V-1V = 11V - 8.8V = 2.2V/.020 = 110 ohms limit resistosr for Big LEDs.
    Pwr = 2.2VX.020A = .044X2 = .088w = use 1/10 watt size, I'd probably use a 1/4w

    DP= 4.4V @ 20ma = 12V-1V= 11V-4.4V= 6.6V/.020= 330 ohm limit resistor.
    Pwr= 6.6VX.020= .132X2= .264= I'd use a 1/2w watt resistor there.........
    Last edited: Apr 4, 2009
  13. SgtWookie


    Jul 17, 2007
    Utoh. Not good. If you feel those pains coming back again, call 911 for an ambulance. I'm not kidding.

    In the meantime, call your Doc on Monday to schedule an appointment, and tell them about your chest pains. Limit your intake of caffeine (coffee, colas/caffenated soft drinks/energy drinks, chocolate, etc), and consider taking one aspirin a day to thin your blood a bit.

    OK, that's all good then.

    Texas Instrument's datasheet for the CD40110B states on the first page that it can source up to 25mA current, but the details are further on in the datasheet.
    VOH = Voltage when the Output is High
    IOH = Current when the Output is High
    The values are negative, because current is flowing out of the IC (sourcing current) instead of into the IC (sinking current)
    If you look at VOH when Vdd is 5v, 10v, 15v and IOH=20mA, the typical voltage at 25°C is about 1v less than Vdd.

    There ya go. :)

    No. :)
    The CD40110B is a special-purpose counter/7-segment display driver IC. Some other 4000-series that perform similar functions (7-segment display drivers) may have similar characteristics, but you need to consult the datasheet for the particular IC. Remember, the 4017 wouldn't take more than about 4.5mA load before it's VOH started dropping like a rock.

    OK, good to go.
  14. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Good Morning;
    I have redrawn the 2-555's as a single 556 circuit.
    Am posting the diagram here for your perusal.
    Will set this situation up on breadboard today and see
    if everything works as planned, etc.
    Have a good day.
  15. SgtWookie


    Jul 17, 2007
    You don't have a ground attached to pin 7 of the 556.

    Not much is going to happen without that.
    OK, I didn't see the junction before. You do have it connected to ground. The junction dots in your schematic capture program are TINY, and my monitor is getting a bit blurry with age.
    Last edited: Apr 5, 2009
  16. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Circuit works great !
    Am now pulling off of this project to see if I can get this dad-gummed boat burglar alarm installed.
    Here's a question for ya.
    From what little circuit board fabrication experience I have. I have always used the dry transfers.
    The dry transfers I have presently are over 10 yrs old, and, I noticed when I built the PCB for my 15 sec timer that the glue came off and onto the copper around where I rubbed the traces. When I etched the PCB the glue also protected the copper under it, so, I wound up with a rather splotchy and messy board.
    I guess I'm going to have to upgrade my PCB fab techniques.
    I don't have a Laser printer, but do have an inkjet.
    Have read where one gets these special sheets and does them up on printer, then "Irons" them on the copper boards.
    Guess I'm going to have to graduate to that particular type of fab.
    Just ain't got time for guessing and hoping it'll turn out right. Read somewhere that ironing is a hope and pray technique.....
    Any advice would certainly be appreciated.
    Tx Yu.
  17. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Good morning;
    Would just like to pass this by you.
    The Segment limit resistors will be figured from 11V as to 1V drop across the CD40110B chip.
    12V-1V = 11V-8.8V = 2.2V/.020 = 110 ohm @ 1/4watt.
    Now, I figured the DP limit resistor also from 11V, but, I don't think it should be figured that way as it is not drawing from the chip, rather, straight from VCC.
    So, 12V-4.4V = 7.6V/.020 = 380 ohm @ 1/2watt.
    Can you concur sir ?
    Latest drawings......
    Actually, not going to use DP in these setups but think it would wise to include the resistor, just for possible future use in some altered configuration, etc.
    Leaving DP open would be OK right, not necessary to tie to GND ??
  18. SgtWookie


    Jul 17, 2007
    Yep, that'll do it.
    Well, 380 Ohms is not a standard E24 resistor value, so you'll need to go to 390 Ohms. You won't notice the difference in brightness.
    It never hurts to plan for the future. ;)
    Tying the cathodes of the DP to Vcc isn't a bad idea, and neither is leaving pads for a resistor, just in case you want to light 'em up later. You could even put the resistors in, and leave a place for a solder bridge or jumper in the trace in case they're needed in the future.
  19. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Tx's Sarge;
    Finally got my boat alarm installed, so, finished with that.
    Now that I have the "period" and "Team Scores" schematics done on this scoreboard, will be concentrating on finding a frame to mount this thing in,
    and that'll give me some sort of platform to mount my circuit boards on.
    Still got to lay the circuit boards out and fabricate them, get LEDs mounted.
    Big thing is, I want a small display on the operators console that reflects what's being displayed on the big board, etc.
    So, got plenty to think about.
    Tx's so much, lots to do.
  20. Oxbo Rene

    Thread Starter Active Member

    Feb 20, 2009
    Have combined circuits here too show one complete "Team Scores" circuitry.
    Here I propose that the output from the 556 sends the same pulses to the "Console" LEDs (Radio Shack), and also to the "Big Board" LEDs (Kingbright).
    I see the operation, as, a person sitting at a table operating the console and thus watching the info on the console LEDs, and that info being mirrored on the big board LEDs which is mounted on a pedestal approx six foot off the floor, standing next to the table.
    I figure there will be an approx ten foot cord connecting the two units etc.
    If you would, take a look and agree/disagree that the 556 can provide both circuits with enough power to operate the clock inputs.
    I'm sure it will, I believe the 556/555 is capable of sourcing up to 200ma, which should be more than plenty for this application.
    I don't believe there is a need to isolate the output of the 556 between the two circuits, however, would rather be safe (ask you to look at it) than sorry, etc......
    Tx's so much,