Monorails aren’t just the core reason why The Simpsons remains on air after thirty-six seasons, twenty-six of which are unredeemable garbage. They’re also an interesting example of oddball rail travel which has never really caught on beyond the odd gadgetbahn project here and there. [Hyperspace Pirate] recently decided to investigate the most interesting kind of monorail of all—the gyro stabilized type—on a small scale for our viewing pleasure.

The idea of a gyro-stabilized monorail is to use active stability systems to allow a train to balance on a single very thin rail. The benefits of this are questionable; one ends up with an incredibly expensive and complex rail vehicle that must always run perfectly or else it will tip over. However, it is charming to watch in action.

[Hyperspace Pirate] explains how the monorail vehicle uses control moment gyroscopes to keep itself upright. The video also explains the more common concept of reaction wheels so the two systems can be contrasted and compared. It all culminates in a wonderful practical demonstration with a small 3D printed version of a 20th-century gyro monorail running on a 24″ track.

If you’re studying mechanical engineering this is a great project to pore over to see theoretical principles put into obvious practice. Video after the break.

Over the last decade or so, we’ve been inundated with appliances with wireless or “smart” technology that is often of dubious utility. No one really needs a tablet in their refrigerator or Wi-Fi on their coffee maker. A less glamorous kitchen appliance that actually might benefit from some automation and connectivity is the garbage can, or “bin” for those speaking the Queen’s English, and [Mellow_Labs] is here to show off just how to get that done with this automatic garbage can lid.

As he explains, the real impetus behind this build is to not have to touch a dirty lid while cooking to avoid having to take time to wash one’s hands again afterwards. There are a few other design criteria as well; it has to be roommate-approved so nothing permanently attached to the lid, overly complicated, or with an unnecessary amount of wires or other fixtures. A servo with an extension sits on the lid itself, and when activated forces the lid open. A distance sensor provides basic gesture recognition and a microcontroller with wireless connectivity controls both and provides home automation integration as well. With a 3D printed case that includes a quick disconnect function for easy cleaning of the lid, the build was ready to be put into service.

The first iteration used an infrared distance sensor, but placing it by an open window caused it to continuously open and close since sunlight has the same wavelengths of light the sensor is tuned for. A quick swap with an ultrasonic sensor solved the problem, and the garbage can is working flawlessly in the kitchen now. Another appliance that is generally not targeted by off-the-shelf automation solutions is the range fume hood, but another build tackled that problem a while back.

[Hugh] has been going back through episodes of the Hackaday podcast, and Elliot mentioned in episode 67 that it can often be inspiring to go back through the archives of Hackaday to find ideas for new projects. Well, he did just that and came across a single-pixel camera made using an infrared photodiode. He decided to try and hack together his own single-pixel camera, but this time on the cheap and using an ever simpler component – a photoresistor!

His description of the project tickled me – “I’ve used an ESP32, MicroPython, two servos, a peanut butter jar lid, a toilet paper roll, a paper towel roll, magnets and scrap wood for this version.” That’s certainly a much simpler bill of materials than the original (which was written up by Hackaday way back in 2015), which used a nice metal frame to hold everything together. However, there’s absolutely nothing wrong with improvising with things you happen to have to hand.

In this case, the sensor is mounted at the back of a paper towel tube, with black tape covering the front and a tiny pinhole poked in the tape to act as the aperture. Similarly to the original, the sensor is scanned over the scene in an XY altitude/azimuth pattern to capture the samples one at a time. It takes just under eight minutes to capture 8100 “pixels” in a 90×90 grid. The servos are driven using a PCA9685 PWM/Servo driver, which makes motor control a lot easier. An important lesson [Hugh] learned during construction was that weak power supplies can cause all sorts of issues when motors or servos are involved. He had been encountering uneven rotation and random halting, but as soon as a beefier power supply was attached everything worked smoothly.

[Hugh] used a much more powerful ESP32 to do the actual gathering of the analog data, which is then sent over a serial port to a Python processing engine which uses Pandas, numpy and matplotlib to do the bulk of the image processing. The resulting processed photo is very recognizable, considering the differences in linearity and sensitivity between a photoresistor and the infrared photodiode used in the original project! It really is incredible what you can do with a few spare parts, some random construction materials, and a little bit of creativity.