Simple Timer Evolves Into Custom Kid’s Watch

Sporting a new wristwatch to school for the first time is a great moment in a kid’s life. When it’s a custom digital-analog watch made by your dad, it’s another thing altogether.

As [Chris O’Riley] relates, the watch he built for his son [Vlad] started out as a simple timer for daily toothbrushing, a chore to which any busy lad pays short shrift unless given the proper incentive. That morphed into an idea for a general purpose analog timepiece with LEDs taking the place of hands. [Chris] decided that five-minute resolution was enough for a nine-year-old, which greatly reduced the number of LEDs needed. An ATtiny841 tells a 28-channel I2C driver which LEDs to light up, and an RTC chip keeps [Vlad] on schedule. The beautiful PCB lives inside a CNC machined aluminum case; we actually commented to [Chris] that the acrylic prototype looked great by itself, but [Vlad] wanted metal. The watch has no external buttons; rather, the slightly flexible polycarbonate crystal bears against a PCB-mounted pushbutton to control functions.

With a snappy wristband, [Vlad] will be rolling fancy on the schoolyard. It’s a great looking piece that needed a wide range of skills to execute, as all watches do. Check out some other watch builds, like this lovely pure analog, another digital-analog hybrid, or this pocket watch that packs an Enigma machine inside.

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Hacking Together A Temperature Sensor For Boiling Milk

Ever have trouble justifying your hacking to anyone from another generation? [Domen] presented his mother with a custom-made device that monitors the milk temperature as it boils on the stove, preventing boil-over. And he made the device robust, simple to use, and foolproof. To his mom, it must look like he’s a wizard — able to conjure up home electronics out of solder smoke and some plywood.

Of course, we know better. Inside his gadget is a simple temperature sensor, an ATtiny841, a very nice home-made PCB, a buzzer, an LCD, and some pushbuttons. [Domen] rubbed together a few pre-existing libraries, and had a working prototype inside a nice wooden box on the quick. It’s a simple hack, but imagine how this must look to a muggle. For the detailed incantations, check out [Domen]’s GitHub for the project.

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