What is the Matrix…Clock?

We’re surprised we haven’t seen this kind of clock before, or maybe we have, but forgot about it in the dark filing cabinets of our minds. The above picture of [danjhamer’s] Matrix Clock doesn’t quite do it justice, because this is a clock that doesn’t just tick away and idly update the minutes/hours.

matrix clock

Instead, a familiar Matrix-esque rain animation swoops in from above, exchanging old numbers for new. For the most part, the build is what you would expect: a 16×8 LED Matrix display driven by a TLC5920 LED driver, with an Arduino that uses a DS1307 RTC (real-time clock) with a coin cell battery to keep track of time when not powered through USB. [danjhamer] has also created a 3D-printed enclosure as well as added a piezo speaker to allow the clock to chime off customizable musical alarms.

You can find schematics and other details on his Hackaday.io project page, but first, swing down below the jump to see more of the clock’s simple but awesome animations.

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RGB Bike Rim Lights

[Yvo] sent us his latest creation, this awesome POV RGB bicycle rim light build, which features a circular interweaving of common RGB LEDs that face outward along the rim as they display constantly changing animations based on the wheel’s rpm.

Like many POV wheel builds, [Yvo]’s takes advantage of a hall effect sensor and stationary magnet to determine how fast the wheels are spinning. Unlike most POV builds, however, [Yvo’s] creation doesn’t have just one or two RGB sticks clamped onto a spoke. Instead, his wheels boast several individual RGB LED modules mounted along the rim.

Each wheel has six modules, and each module contains a scratch-build LED controller (a daisy chain of 74HC595 shift registers) that fits into a custom-made 3D-printed enclosure. The enclosures mounts onto some aluminum strips along with the RGB LEDs, and the aluminum strips mount to the wheels by straddling the rim.

At speed, the lights go into POV mode to simulate headlights / brakes with white in the front and red in the back. Check out the difference these custom circular modules make when riding and when at rest in a video below.

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Secret Attic Library Door

We have a pretty good guess where [Krizbleen] hides away any seasonal presents for his family: behind his shiny new secret library door. An experienced woodworker, [Krizbleen] was in the process of finishing the attic in his home when he decided to take advantage of the chimney’s otherwise annoying placement in front of his soon-to-be office. He built a false wall in front of the central chimney obstacle and placed a TV in the middle of the wall (directly in front of the chimney) flanked on either side by a bookcase.

If you touch the secret book or knock out the secret sequence, however, the right-side bookcase slides gently out of the way to reveal [Krizbleen’s] home office. Behind the scenes, a heavy duty linear actuator pushes or pulls the door as necessary, onto which [Krizbleen] expertly mounted the bookcase with some 2″ caster wheels. The actuator expects +24V or -24V to send it moving in one of its two directions, so the Arduino Uno needed a couple of relays to handle the voltage difference.

The effort spent here was immense, but the result is seamless. After borrowing a knock-detection script and hooking up a secondary access button concealed in a book, [Krizbleen] had the secret door he’d always wanted: albeit maybe a bit slow to open and close. You can see a video of its operation below.

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$15 Car Stereo Bluetooth Upgrade

We’ve seen all sorts of ways to implement Bluetooth connectivity on your car stereo, but [Tony’s] hack may be the cheapest and easiest way yet. The above-featured Bluetooth receiver is a measly $15 over at Amazon (actually $7.50 today—it’s Cyber Monday after all) and couldn’t be any more hacker-friendly. It features a headphone jack for plugging into your car’s AUX port and is powered via USB.

[Tony] didn’t want the receiver clunking around in the console, though, so he cracked it open and went about integrating it directly by soldering the appropriate USB pins to 5V and GND on the stereo. There was just one catch: the stereo had no AUX input. [Tony] needed to rig his own, so he hijacked the CD player’s left and right audio channels (read about it in his other post), which he then soldered to the audio output of the Bluetooth device. After shoving all the bits back into the dashboard, [Tony] just needed to fool his stereo into thinking a CD was playing, so he burned a disc with 10 hours of silence to spin while the tunes play wirelessly. Nice!

Programmable Lithium Charger Shield for Arduino

Surely you need yet another way to charge your lithium batteries—perhaps you can sate your desperation with this programmable multi (or single) cell lithium charger shield for the Arduino?! Okay, so you’re not hurting for another method of juicing up your batteries. If you’re a regular around these parts of the interwebs, you’ll recall the lithium charging guide and that rather incredible, near-encyclopedic rundown of both batteries and chargers, which likely kept your charging needs under control.

That said, this shield by Electro-Labs might be the perfect transition for the die-hard-‘duino fanatic looking to migrate to tougher projects. The build features an LCD and four-button interface to fiddle with settings, and is based around an LT1510 constant current/constant voltage charger IC. You can find the schematic, bill of materials, code, and PCB design on the Electro-Labs webpage, as well as a brief rundown explaining how the circuit works. Still want to add on the design? Throw in one of these Li-ion holders for quick battery swapping action.

[via Embedded Lab]

Throwing Pis into the Stratosphere

It’s always exciting to see the photos from High Altitude Ballooning (HAB) outings. While it’s no surprise that the Raspi is a popular choice—low cost, convenient USB jacks, etc.—this is the first build we’ve seen that uses an OLED during the trip to show real-time data on-screen to be picked up by the on-board webcam. (Though you may have to squint to see it at the bottom middle of the above image).

[Fabrice’s] payload made it to 26,000m, and the screen he chose, an ILSOFT OLED, performed admirably despite the extreme conditions suffered (temperatures can reach -50C). The last time we saw a near-space Raspi payload was a couple of years ago, when [Dave Akerman] was closing in on UK balloon altitude records. [Dave] hasn’t stopped launching balloons, either, testing new trackers and radio modules, as well as his most recent build that sent a Superman action figure to the skies—all recorded in glorious HD.

Check out both [Dave] and [Fabrice’s] blogs for loads of pictures documenting the latest in High Altitude Ballooning, and stay with us after the jump for a quick video of [Fabrice’s] OLED in action.

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The Tumblemill: Homemade CNC Milling

[Jens] aka [Tumblebeer] has compiled an impressive overview of the Tumblemill, his homemade CNC mill. It warms our hearts to learn that [Tumblebeer] was inspired to pursue electronics by projects featured here on Hackaday, even if it means he dropped out of med school to pursue electrical engineering. We’re glad he’s following his passion, though, and reading through his blog reveals just how far he’s come: from fiery disaster in his first projects to a gradual obsession with making a CNC device, [Tumblebeer] has made plenty of mistakes along the way, but that’s how it should be.

His first iteration was a CNC router that used rubber wheels as linear bearings. It worked…barely. His latest build grew out of meticulous Solidworks modelling, with a moving gantry design constructed largely from aluminum, and upgraded linear motion: this time a bit overkill, using HIWIN HGH20CA blocks. Rather than sourcing a traditional spindle mount, [Tumblebeer] opted for the housing from a LM50UU bearing, which provided both the perfect fit and a sturdier housing for his 2.2kw spindle.

Visit his project blog for the details behind the mill’s construction, including a lengthy installment of upgrades, and hang around for a demo video below, along with the obligatory (and always appreciated) inclusion of the Jolly Wrencher via defacing an Arduino.

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