K8035 with larger display

dear sirs
i have already assemble the k8035 kit which works perfectly.
i want to use it for keeping score and i need much larger displays.
i tried to do that but the voltage on every seagment of the provided displays is only 1.5v aproximatelly so the large display which works with with 9v does not lit.
please give me a solution even if i have to not use the small displays.
best regards

p.s. the game is in this weekend so please help as soon as possible.

That is not that easy!

For this, you need to add a kind of buffer with transistors or transistor arrays on the cathode lines of the displays. After that, you can connect the anodes of the displays to 9 Volts instead of the 5 Volts they are on now.
If you can’t understand how to do it on your own, be carefull before you start experimenting …