5-minute chess clock

n games of speed chess, where each player has only 5 or 10 minutes to complete all his moves, mechanical chess clocks leave something to be desired in terms of accuracy, es-pecially when both players have only 30 or 40 seconds left. The author of the circuit decribed here offers a solution to this problem by employing LEDs to provide an unequivocal display which counts off the time remaining in multiples of 10 seconds.