... flows to the lower half like sand. ... Principle of Operation:At the beginning, green led light on the ... seconds, the screen will turn to yellow, the sandy clock will show “3, 2, 1”, then screen turn ... , the cycle will go on…Function of control system:1. Control time of the funnel is adjustable, 1 second ... is a unit.2. Display order of the color is adjustable.3. The operation is completed ...