Pocket Dice Kit Model K-28 by Elenco

The Pocket Dice Kit is made up of fourteen LEDs to represent two dice, and three main circuits: Clock Oscillator, Presettable Counter, and Decoder Circuit. There are seven LEDs per dice for the six possible dice combinations. To create a number on the dice (LEDs), a switch is pressed down, causing a short, and producing a number. The Clock Oscillator is an IC that consists of two NAND gates that are digital integrated circuits that inputs are tied together to form an inverter circuit. The frequency of the oscillation is about 60 cycles per second producing a square wave. By pressing the switch one causes a short and the feedback stops hence the oscillator halts. The Presettable Counter function are two IC. These two IC convert the square wave of the Clock Oscillator. Every time the clock puts out a pulse, the counter will change its output. The two counters convert the clock pulses in six combinations of "1" and "0". The Decoder Circuit takes the output of the Presettable Counter and lights the correct LEDs. It consists of a NAND gate and an OR gate.