Here's my recommended design. Right-click it and choose Save Image As then view it at 1:1 zoom in an image viewer.
View attachment 18473
It requires a power source of 15V DC that's able to supply at least 2A. It uses twelve ICs - six CMOS 4000 series devices, five ULN2003 driver ICs and a 78L09 regulator IC. Here's a circuit description.
U1, a CD4093B quad NAND gate with Schmitt trigger inputs, is shown as four D-shaped objects on the diagram. Three of its four gates are used, for debouncing the pushbutton inputs. This is required because mechanical switches produce contact bounce (look it up on Wikipedia or Google) which would cause multiple increments of counters on each press and must be eliminated.
Each pushbutton (SW1~3) and its pullup resistor (R1~3) produces a voltage that's high (+9V) when the button is not pressed, and 0V when the button is pressed. This voltage is delayed and smoothed by R4~6 and C1~3 and produces a slowly changing voltage on the input to the respective gate. The Schmitt trigger (Wikipedia or Google) input on the gate "cleans up" the slowly changing input and produces a clean signal at the gate output, which goes high when the pushbutton is pressed and returns low when it is released. These signals clock the three counters.
The first counter, for the home score, is implemented by U2 and U3. These are CD4033 divide-by-ten counters with built-in decoding for seven segment display drive. The outputs go high (+9V) to enable the segment. They are fed into a ULN2003 IC (one for each digit) which contains seven transistors with open collectors. When the ULN2003 input is driven high by the CD4033, the corresponding transistor turns ON and pulls its collector down towards 0V. This causes current to flow through the corresponding resistor element in the resistor array (RA1, RA2) and current flows through the corresponding segment of the display (LED1, LED2).
U2 controls LED1, the ones digit of the home score display. Its RBIN (ripple blanking) input, pin 3, is held high so it always displays its digit, even if that digit is 0. When this digit carries from 9 to 0, U2's CARRY output transitions from low to high and increments the count in U3. U3 controls LED2, the tens digit, and its RBIN input is held low, so it only activates its digit if the score is 10 or higher.
The second counter, for the visitor score, is implemented by U4 and U5 and is identical to the first.
The third counter, for the period, is implemented by U6. It is a single digit counter with its RBIN input held low, so it only activates its digit if the period is 1 or higher.
All counters can be reset by pushing pushbutton SW4. This button does not need debouncing because multiple resets don't cause any problem.
SW5 activates the lamp test feature in U2~6 which causes all segments to be activated and is useful for checking the displays and drive circuits.
The display brightness is set by the resistance of RA1~5. I have specified 120Ω which runs the segments at 50 mA, their rated maximum, for maximum brightness. For lower brightness, increase the RA1~6 resistance.
The power supply should be 15V DC and able to supply up to 2A. A 12V power supply will work but RA1~5 resistances must be decreased to achieve the same brightness, and brightness may be less consistent between displays with the lower supply voltage.
All CD
n capacitors, and C4 and C5, are decoupling capacitors and must be ceramic capacitors, connected as closely and directly as possible between the VDD and VSS pins of their respective ICs. For CD1, this is pins 14 and 7 of U1. For CD2~6 this is pins 16 and 8 of U2~6.
Here are some Mouser part numbers.
RA1~5: 8x120R resistor network Mouser 652-4114R-1LF-120
U2~6: CD4033B Mouser 595-CD4033BE
U7~11: ULN2003 Mouser 511-ULN2003A
LED1~5: Mouser 604-SA40-19GWA (green), 604-SA40-19EWA (red) or 604-SA40-19SURKWA (super-bright red)
Use IC sockets for the 4033s and ULN2003s