Assembled 24 Hour Digital Clock with Circuit Diagram (HH : MM : SS Display)Assembled 24 Hour Digital Clock with HH : MM : SS Display Includes a circuit diagram for understanding how the clock works To set up the clock, use a small Phillips screwdriver to open the terminal block and insert the red wire to the "+" side and the black wire to the "" side, then tighten the screws to secure the wires in place. Requires one 9V battery for operation. One CR2032 button cell battery can also be used as a backup to save the time when