Summary： This is an overview of my game project, which utilizes combination logic in its design.
Introduction
The Reaction Game offers competitive experience for two players, built around combinational logic principles. The setup includes three main LEDs, with gameplay relying on quick thinking and player interaction to decide the winner. Each player has a colored button, aiming to press it as soon as both central LEDs show the same color. Whoever reacts first and correctly presses their button when the colors match earns a point, signaled by their push button lighting up. After a correct response, the other player is locked out for the rest of that round, ensuring fair play. Each participant gets only one try per round and pushing the button when the LEDs don’t match yields no points. Milestone scores—three, six, and nine—are marked by dedicated scoring LEDs, and the first player to reach nine points wins. When this happens, a central tri-color LED lights up in the winner’s color. Optional features include a celebratory beep or a Note Sequencer that can play up to nine musical notes.
Circuit Overview
The electronic design for the Reaction Game employs ten CMOS integrated circuits to accomplish its logic and timing functions. The ICs used are:
• One 4001 Quad 2-Input NOR gate
• Four 4017 Decimal Counters, each providing ten outputs
• Two 4043 Quad NOR R/S Latch
• One 4072 Dual 4-Input OR Gate
• One 4081 Quad 2-Input AND Gate
• One 40106 Hex Schmitt-Trigger Inverter
The circuit consists of Round Generation, Scoring, and Score Tracking with winner declaration.
Round Generation
Timing and randomness within the game are governed by three clock circuits, each utilizing the CD40106 Hex Schmitt-Trigger Inverter:
• The first clock operates a 4017 counter to randomize the color of the central LED.
• The second clock, which can be adjusted via a potentiometer, determines the duration of each round by toggling the central LEDs on or off.
• The third clock, also adjustable, sets the cycling speed for the colors of the second LED and is linked to a 4017 counter.
Scoring
Scoring relies on an AND-OR logic circuit that monitors the outputs of the two 4017 counters, allowing points to be scored only when the LED colors match. The result is routed through player-specific AND gates, so when a player presses their button at the correct moment, their score advances. Scoring stops via a four-input OR gate when a player scores, wins, or both LEDs are off between rounds.
Each player has two RS latches in the circuit, which reset at the beginning of every round. Pressing the player’s button sets the first latch, generating a pulse to the scoring AND gate. After a successful point, a second latch disables further scoring for that round. The AND-OR logic is located at the lower left of the schematic: one AND gate incorporates inverters and a NOR gate to reduce the number of additional chips required.
Score Tracking with winner declaration
The remaining two 4017 counters and 4043 Quad NOR R/S Latches are wired with their reset pins connected to +9V via a 0.1µF capacitor and grounded through a 100K resistor. This setup resets the game on power-up; to reset after a win, simply toggle the power, or add a dedicated reset switch by installing a normally closed momentary push button in series with the power switch.
Each player has three LEDs marking progress at 3, 6, and 9 points, controlled by a 4017 counter. RS latches keep the LEDs for 3 and 6 points lit, while output 9—signaling a winner does not require a latch. Output 9 of each 4017 lights the winning player’s third LED triggers the tri-color winning indicator, and feeds into an OR gate that halts play. Outputs 9 from both 4017 ICs are connected to a NOR gate, which generates a low signal at the conclusion of the game. This configuration ensures that the player's button remains illuminated until it is reset.
This output can also trigger my Note Sequencer project (available on PCBWay) or activate a piezo buzzer when connected between this output and +9V.
A YouTube video of this project is here:
https://www.youtube.com/watch?v=gYBMlOfJTuA
You can find my shared projects at this link:
https://www.pcbway.com/project/member/shareproject/?bmbno=B5EABA2F-5A02-40
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