4x4 Switch Matrix Module Board 4x4 input switch matrix module board. This MOB can operate at both 3V3 and 5V. Schematic PCB Layout Bill of Materials paperboard 5x7cm 2 x 4-pin (Molex-KK) data (rows, /cols) connectors 4 x led current limiter resistors 10Kohm 16 x green 3mm led