An optical keyboard that works using IR LEDs and phototransistors.

Take A Look At This Optical Keyboard

Making keyboards is easy, right? Just wire up a bunch of switches matrix-style to a microcontroller, slap some QMK and a set of keycaps on there and you’re good to go. Well, yeah, that might work for cushier environments like home offices and Hackaday dungeons, but what if you need to give input under water, in a volatile area, or anywhere else you’d have to forego the clacking for something hermetically sealed? Mechanical switches can only take you so far — at some point, you have to go optical.

the layers of an optical keyboardThis gorgeous keyboard works with reflected IR beams to determine when a finger is occupying a given key site (because what else are you going to call them?). Each key site has an IR LED and a phototransistor and it works via break-beam.

[BenKoning] wanted a solution that would be easy for others to build, with a low-cost BOM and minimal software processing cost. It just so happens to be extremely good-looking, as well.

The reason you can’t see the guts is that black layer — it passes infrared light, but is black to the eye. The frosted layer diffuses the beams until a finger is close enough to register. Check it out in action after the break, and then feed your optical key switch cravings with our own [Bob Baddeley]’s in-depth exploration of them.

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DIY Spot Welder Doesn’t Look Like It Will Immediately Kill You

We love hacks that involve mains voltage, but most of the time, for safety’s sake, we secretly hope for that one macabre commenter that details every imaginable way the questionable design choices will result in death. This spot welder may still be dangerous, but it looks like they took some precautions to make it non-lethal, and that counts for a lot.

After their extremely questionable high speed belt sander, this one is, refreshingly, extremely well done. It starts of as a dead standard microwave spot welder build: take apart microwave, try not to die from large capacitor, remove coil, modify coil, and hook up.

After that, it gets to some nice heavy metal music fabrication. Aside from a slightly shocking number of fresh OSHA reportable hand injuries (wear gloves!) the build goes together well. A lot of planning obviously went into it, from the actively cooled transformer to what appears to be a resettable timer circuit for the weld duration, not to mention the way that it just fit together so well at the end. There were some neat ideas as far as home mechanics go that we’ll be using in some of our projects.

In the end, the proof is in the spot-weld. The timer is set, pedal gets pressed down, and when tested, the sheet metal breaks instead of the weld. Video after the break.

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