Stefan Hamminga has made Scrobby, a robot designed for cleaning solar panels autonomously.

Scrobby was built by Stefan Hamminga using a Teensy 3, a Bluetooth LE module, six ultrasonic sensors and two internal motor driven spools. It is powered by its own solar panel. When Scrobby’s sensors detect rain, it moves across the solar panel surface, scrubbing it clean. When rain stops falling, Scrobby goes back to a special resting platform, meaning that the body of the robot doesn’t block any valuable sunlight. You can find build logs and explanations of Hamminga’s mechanical design decisions over on Scrobby’s Hackaday.io project page.

Holger (C0d3man on the forum) posted details of some excellent synth projects that gets a powerful Dexed FM synth plugin running on Teensy.

Holger combined a custom PCB with a Teensy and the PJRC Audio board to make a neat synth module that supports MIDI, both DIN and USB. Holger also ported multi platform, multi format plugin synth Dexed to this module.

Holger has published details of three separate audio projects that use this system, the Teensy MIDI Audio, MicroDexed and Micro MDAE Piano, all of which are Open Source Software and Hardware. You can listen to a recording of some of the sounds from MicroDexed and Micro MDAE Piano on Holger’s website. You can also read more details about these projects on the PJRC forum and the Zynthian forum.

Christoph has published a number of cool projects over at Hackaday.io. His latest hack, for the Hackaday Tell Time, is turning an IKEA LACK table into a ceiling-mounted robotic LED clock.

Christoph used an IKEA LACK table, twelve small hanging lamps, twelve servos, a Teensy microcontroller and an ESP 32 to make this project. Each lamp can be moved up and down by its own individual servo, stopping at one of five positions: 0% (fully down), 25%, 50%, 75% and 100% (fully up). The position of the lamps tell the time, for example at 01:15 lamp one would be at 75%, lamp two 25% and the rest at 0%. You can find build logs and code for this project over on the Hackaday.io website.

The other winners of the Hackaday Tell Time contest are also really worth checking out. The PJRC blog has previously featured the overall winner, this beautiful and technically impressive ferrofluid clock by a talented team of students from University of Oslo.