The small board UM-0516 mounts 16 LEDs which, through series resistors, connect to a 20-pin female IDC connector, ideal to be plugged into the corresponding male on a board to be tested.

With just the two single-in-line resistors in series with the LEDs, the luminous intensity of the LEDs is established.

Usually on this type of board I mount the single-in-line resistors not directly on the PCB, but on the female strip, in order to quickly change their value to adapt it to the different voltages in which I use the board (5V, 12V or 24V ).

According to the polarity with which the LEDs are mounted and how the PWR jumper is positioned, it is decided whether to turn them on with a LOW or a HIGH.

The 'PWR' jumper must be closed on GND to turn on the LEDs with PNP type outputs, or on 'GND' to turn on the LEDs with NPN type outputs.

Respecting the indication of pin 1, the PCB must be carefully inserted between the two rows of pins of the FEMALE IDC connector, then the soldering must be carried out.

With the exception of the IDC connector which must be mounted as indicated, all the other components can be mounted both on one side of the PCB and on the other.

This could allow to adapt the display of the LEDs to the conditions in which the card is used.

However, it must be said that the indications on the screen printing only satisfy the mounting on one of the two faces of the PCB.

With screen printing we try to form groups of four / eight LEDs, for easy reading of binary or hexadecimal values, but also to be able to easily remember and write (in hexadecimal) a pattern even in cases where it is not a hexadecimal number , but only the pattern of an output card when debugging.

The choice of LED color is free, but I suggest using LEDs of the same type if you want them to have the same light intensity.