Build a Brilliant 30-Socket Circuit Game Schematic

Circuit diagram:

Description

This electronic game challenges a human player against a ‘machine’. The opposing players utilize a common ‘game token’ and alternate moving along a path by one, two, or three steps, and the victor is the first to reach the goal precisely. Remarkably, this uncomplicated version of the ‘123’ game can be constructed without a microcontroller, and it presents a nearly unbeatable experience. The electronics for this design are built solely using diode logic (Figure 1).

The ‘input interface’ fundamentally comprises 30 miniature sockets to which a probe tip can be connected to indicate the location of the ‘game token’. To optimize compactness, the sockets are arranged in a grid, resulting in a serpentine path for the route following the sockets (Figure 2). The starting position is situated at the bottom right, while the goal is located in the center of the playing area. The electronics function as the ‘active player’ when the button is pressed.

The number of steps desired for movement is indicated by three LEDs (one, two, or three LEDs illuminate) at the top of the playing area. Naturally, the human player must move the ‘game token’ for the machine opponent. The winner is the first to reach the goal exactly. How can such simple circuitry represent such a formidable opponent? As previously mentioned, the path from the start to the goal is formed by 30 sockets. Each socket has a corresponding ideal next move.

There are three possibilities, of course: 1, 2, or 3. As shown in the schematic diagram, switch S1 closes the circuit (which signifies that the player requests the ‘computer’ how many steps it wishes to move) if the probe is touching one of the sockets. All 30 sockets are categorized into three types, represented in the schematic diagram by one socket for each type. All sockets belonging to a particular type are simply connected together electrically, which is not shown on the schematic diagram for the sake of clarity.

How the LED display works:

The player touches the right-hand contact with R4 (only LED D3 illuminates), the left-hand contact with R3 (LEDs D1 and D2 illuminate), or the middle contact with diodes D4 and D5 (all three LEDs illuminate). The two diodes prevent all three LEDs from lighting up if the player touches the left-hand or right-hand contact. The key to all this lies in the assignment of the 30 sockets to the three types of logic, which means the three types of ideal next move.

Working backward from the goal, no further move is possible when the goal is reached. For this reason, the last socket is not connected to anything. At the socket just before the goal, the ‘computer’ naturally wants to be exactly one step in front. Consequently, this socket is connected to R4. At the second socket before the goal, the electronics wants to move by two steps. This socket is thus connected to R3.

Obviously, three moves before the finish, a three-step is best as it leads to instant victory. Consequently this socket is connected to D4/D5. The correct response of the ‘computer’ is shown in Figure 2 by the number next to each position. As the two opponents take turns playing, the electronics always tries to arrive at a strategically favorable position (marked by the arrows). If the electronics manages to reach one of these positions, it’s impossible for the human player to win. This means that the human player can only win by starting first and always making the right move.