Electronic Dice Circuit

An electronic dice is a classic first project for those getting interested in electronics. A timer, counter and a few LEDs makes a circuit that can also add a new twist to some old boring board games. When the switch is pressed, a 555 timer in astable mode pulses a BCD counter which lights up a series of LEDs wired to mimic a dice. Two AND gates are used to reset the count back to one whenever the BCD output is seven. Thus, the circuit is not truly random but the natural bounce present in a pushbutton and the normal human ability to operate much slower then the oscillator make the output of the circuit seem random.

Schematic

Parts

Part Total Qty. Description Substitutions R1, R5, R6 3 22K 1/4W Resistor R2 1 10K 1/4W Resistor R3 1 4.7K 1/4W Resistor R4 1 150K 1/4W Resistor R7 - R13 7 330 Ohm 1/4W Resistor C1 1 1uF Electrolytic Capacitor C2 1 4.7uF Electrolytic Capacitor D1 1 1N4148 Signal Diode D2 - D8 7 Red/Green/Yellow LED Q1 1 2N3904 NPN Transistor U1 1 555 Timer IC U2 1 74LS192 4 Bit Counter IC U3 1 74LS08 Quad Intengreted AND Gate IC S1 1 SPST Momentary Pushbutton Switch MISC 1 Board, Wire, Sockets For ICs, Case Notes Pushing and holding S1 causes the LEDs to rapidly cycle. Releasing the button locks the pattern and shows a number from 1 to 6. When building the circuit, make sure to position the LEDs as shown on the schematic. Otherwise the pattern of the dice will look weird. Two circuits can of course be both powered by one switch to make a dual dice.