We can race against the clock when assembling jigsaw puzzles online but what about competing against each other in the real world? [HomeMadeGarbage] came up with the simplest of solutions with his jigsaw puzzle timer that stops only when the puzzle’s completely assembled.
His simple solution was to attach copper foil tape to the back of the pieces, with overlap. He did this in a serpentine pattern to ensure that all pieces had a strip of the tape. The puzzle he used comes with a special container to assemble it in. At two corners of that container, he put two more pieces of copper foil, to which he soldered wires. Those two act as a switch. Only when the puzzle is completed will those two pieces be connected through the serpentine strip on the back of the puzzle.
Next, he needed a timer. The two wires from the puzzle container go to an Arduino UNO which uses an ILI9325 touch panel TFT display for both the start, stop, and reset buttons, and to show the time elapsed. Press the touch screen when it says START and begin assembling the puzzle. When the last piece is inserted, the serpentine strip of copper tape completes the circuit and only then does the Arduino program stop the timer. As you can see from the video below, the result makes doing the puzzle lots of fun.
[Matias] is just getting into hobby electronics and decided to push the limits of his skill by building this game clock (site dead try Internet Archive). He comes from a software design background and that really shows through in the UI design seen in the video after the break. We enjoy the journey through his prototyping process which started with an Arduino and a breadboard, and ended with this standalone timer.
After building the first working prototype with four buttons and a character LCD, he migrated to a plastic ice cream container as an enclosure. This worked well enough, but the flimsy case needed an upgrade. As he looked toward the next version he decided to move to an Arduino Nano board to save on space. The rest of the components were soldered to some protoboard, with a pair of pin headers to receive the Nano. The finished board is the same length as the Nano and only about twice as wide.
The box was modeled on the computer (it looks like SketchUp to us be we could be wrong) then cut from pieces of Masonite. It hosts the character LCD with a pair of arcade buttons for each player to shift the time burden to his or her opponent. The middle button pauses the game, and there’s a trimpot on the back to adjust the screen contrast. [Matias] managed to include a surprising number of settings which will make this little box useful for a wide range of game types.