Handheld Sudoku (Assuming You Have Large Hands)

[Hari Waguna] wanted to build a computerized Sudoku game. Ordinarily, that wouldn’t be a big deal. You can buy one, of course, but what fun is that? There’s plenty of apps for phones, but again, not much of a challenge. If you want to preserve your hacker cred, you’d use a CPU board like an Arduino or a Raspberry Pi with an LCD screen, right? But if you want to grow your hacker cred, you’d follow [Hari’s] lead and use 81 seven-segment displays and a membrane keyboard.

Driving that many displays takes some doing (in this case shift registers). [Hari] uses some other tricks, like reading the keyboard using a single pin (and a resistor network). He’s made several videos about the project, including the one below.

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Cute Countdown Timer Reminds You Of Impending Doom

As things get busy, whether it be an upcoming product launch, a pregnancy, or even the release of your favorite game (or movie!) sometimes it’s nice to have a little countdown timer. Not an app on your phone, but a tangible, physical timer to set on your desk. Which is why SevenSeg is such a cute idea.

[Mohit] wanted to design something that was simple, but aesthetically pleasing — he’d seen free-form electronic projects before and wanted to give it a shot. What he came up with is pretty elegant! A seven segment display is connected via 1/32″ brass rods to the controller, a Particle Photon — which is kind of like a Teensy with WiFi for the internet of things. After putting a few resistors in line with the display, and a bit of frustrating bending of wire later, and SevenSeg was complete.

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DIY Seven Segment Displays

[Esai] wanted to build an electronic clock from scratch. A noble quest, but ordinary seven-segment displays are just that – incredibly ordinary. Instead of a few displays that can be bought from the usual retailers for a dollar a piece, [Esai] made his own four digit, seven-segment display on some perfboard.

Before soldering 58 SMD LEDs to a small rectangle of perfboard, [Esai] traced out each segment with a marker. Two LEDs make up each segment, and they’re all connected to a breadboard-friendly pin header with 30 gauge wire.

Each segment is connected as a single column in the LED matrix, and each digit is a row. It’s a simple design, but there aren’t any resistors on this board. Hopefully [Esai] will be using a proper LED driver with this display; you really don’t want LEDs to burn out twice a day at 1:11.