This PCB has 2-digit 7-segment led to show numbers that changes from 0 to 99, like for example a counter.

On the PCB there are all components required for this purpose: the CD4511 chips to drive the displays, the resistors for the leds, the diodes to turn off the non-significant zero on the left.

The power supply and the 4 bit digital data to manage the display come in the PCB from a 10-pin stripe that you can solder on front or back of the board as it is better for you. The 10 pins are arranged in this way:

VCC | GND | dD (8) | dC (4) | dB (2) | dA (1) | uD (8) | uC (4) | uB (2) | uA (1)

The first two are for supply, then there is a group of 4 bit for each digit where "d" stands for tens and "u" stands for units, these pins receive the value to show in BCD format.

The 4 diodes linked to the signals for the tens make the pin BL of the CD4511 chip go low when value is zero to switch off the leds for a non-significative zero.

Being a generic PCB, you can use it in various mode, the only important thing is to respect the way the CD4511 works. The module works so long as you send the values for both 7-segment leds in the BCD format.

For example, if you solder the 10-pin stripe on the back, you can stack this module on top of the main board that sends supply on the first two pins and data using the CD4510 chips for a counter on the other pins. In the beginning I have developed the module for this reason.