LED Button push light up

Depending on the requirements, another alternative to consider might be to drive a pair of 7-segment displays to give a numerical readout display.

There are a few designs floating around for creating large displays for sports timers etc.

 /challenges-projects/element14-presents/project-videos/w/documents/5196/episode-482-gigantic-3d-printed-7-segment-display-clock

https://learn.adafruit.com/ninja-timer-giant-7-segment-display

More documentation on the FastLED library here:

https://github.com/FastLED/FastLED/wiki/Basic-usage

ralphjyrecently tested a very interesting product that consists of a matrix of 10x10 addressable rgb leds that come unconnected and that can be very useful for a project like this, being able to use one or more leds for each score unit depending on the intensity of light that you need. And since they have to be wired, you decide the distance between each LED.

(+) NeoPixel Dice - Ralph Yamamoto's Blog - Personal Blogs - element14 Community

Well remembered ! Adafruit do something similar using their Flora pixels if you want something a bit larger to work with.

https://www.adafruit.com/product/1559

It is not clear though if the design of the scoreboard is already finalised or not. If it is a retrofit to a typical vertical style scoreboard then the LED strip spacing will need to be close enough to that of the spacing of the numbers already printed. The strings may be easier to work with than the tapes.

Some scoreboards have holes for pegs, so not sure if the intention is to try and stick a LED into an existing peg hole, so a round LED of suitable diameter may work better than a square pixel.

Also not clear as to the number of scoreboards involved. If it's a one-off, then hand soldering the 42 LEDs isn't much of an issue. If it is 10+ then pre-wired strings/tapes may start looking like a good plan.  

I am planning on drilling holes for the bulbs to go in. And the light next to the score to be lit. After 21 points I want it to have all lights go out on the next button push.  Once I have that figured out I need to do it for both sides. 

Perhaps create a variable to hold the button press count.

Each button press increments the count variable by one.

Then check the current value of the count variable.

If it is less than 1 then turn off all the LEDs. 

If it is between 1 and 21 then turn off all the LEDs and then turn on the LED that matches the current count value.  

If it is greater than 21, then turn off all the LEDs and then reset the count back to 0.

For the second side you just need a second counter that gets incremented by the second button.

It sounds like you could just connect a 22 bit Johnson counter to 21 lights with a debounced button to count up. Three CD4017 chips (~$0.11 each) cascaded would could make a 21 bit Johnson counter. You would need a MOSFET on each output to drive each light.

dougw that sounds like the best plan yet - I was biased into thinking of using a microcontroller, but using counter chips simplifies the whole process.

I have had very good success with units similar to this MOSFET module. The price was less than $2 CAN at one point but supply shortages have driven costs up. Shop around and you can get discounts if purchased in quantity. 

@dougw  @colporteur - would a transistor array chip work for that? I've never used them, but this ULN2004 chip available here on Newark seems to combine 7 transistors at 500mA each.