Mimicking Exoplanet Exploration At Home

Mankind will always wonder whether we’re alone in the universe. What is out there? Sure, these past weeks we’ve been increasingly wondering the same about our own, direct proximity, but that’s a different story. Up until two years ago, we had the Kepler space telescope aiding us in our quest for answers by exploring exoplanets within our galaxy. [poblocki1982], who’s been fascinated by space since childhood times, and has recently discovered 3D printing as his new thing, figured there is nothing better than finding a way to combine your hobbies, and built a simplified model version simulating the telescope’s main concept.

The general idea is to detect the slight variation of a star’s brightness when one of its planets passes by it, and use that variation to analyze each planet’s characteristics. He achieves this with an LDR connected to an Arduino, allowing both live reading and logging the data on an SD card. Unfortunately, rocket science isn’t on his list of hobbies yet, so [poblocki1982] has to bring outer space to his home. Using a DC motor to rotate two “planets” of different size, rotation speed, and distance around their “star”, he has the perfect model planetary system that can easily double as a decorative lamp.

Obviously, this isn’t meant to detect actual planets as the real Kepler space telescope did, but to demonstrate the general concept of it, and as such makes this a nice little science experiment. For a more pragmatic use of our own Solar System, [poblocki1982] has recently built this self-calibrating sundial. And if you like rotating models of planets, check out some previous projects on that.

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Alexa, Shoot Me Some Chocolate

[Harrison] has been busy finding the sweeter side of quarantine by building a voice-controlled, face-tracking M&M launcher. Not only does this carefully-designed candy launcher have control over the angle, direction, and velocity of its ammunition, it also locates and locks on to targets by itself.

Here comes the science: [Harrison] tricked Alexa into thinking the Raspberry Pi inside the machine is a smart TV named [Chocolate]. He just tells an Echo to increase the volume by however many candy-colored projectiles he wants launched at his face. Simply knowing the secret language isn’t enough, though. Thanks to a little face-based security, you pretty much have to be [Harrison] or his doppelgänger to get any candy.

The Pi takes a picture, looks for faces, and rotates the turret base in that direction using three servos driven by Arduino Nanos. Then the Pi does facial landmark detection to find the target’s mouth hole before calculating the perfect parabola and firing. As [Harrison] notes in the excellent build video below, this machine uses a flywheel driven by a DC motor instead of being spring-loaded. M&Ms travel a short distance from the chute and hit a flexible, spinning disc that flings them like a pitching machine.

We would understand if you didn’t want your face involved in a build with Alexa. It’s okay — you can still have a voice-controlled candy cannon.

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Eavesdropping Assistant Disturbs The Sound Of Silence

Unless you happen to be from Finland, this is just an all too familiar situation: you’re stuck in an inescapable situation with this one person who is really more of an acquaintance than a friend, and neither of you knows who should say something in hopes of keeping a conversation going. Awkward silence is inevitable, and the longer it lasts, the more excruciating the thought of opening your mouth becomes. Well, consider those days over, thanks to [Jasper Choi] and his friends, who blessed us with the System for Awkward Silence Solution and Interaction Enhancer, or SASSIE.

Built as a laser-cut rotating cylinder, and equipped with a pair of microphones, SASSIE detects and counts the duration of any ongoing silence in the room. Once a pre-defined time limit is reached, it rotates itself to a random direction, symbolically pointing a finger to one of the people present in the room to indicate its their turn to speak now. To break the silence right off the bat, the finger pointing is accompanied by some pre-recorded messages. Unfortunately the audio files exceeded the storage of the Arduino Uno used here, so the responsibilities had to be divided between two Arduinos, arranged with the help of some simple serial communication.

While this is obviously a tongue-in-cheek project, it might just be a welcoming relieve for people with social anxiety, and there is definitely potential to take the idea further. Maybe with some inspiration from this happy robot fellow, a future version might ease the conversation even further by suggesting a topic along the way.

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Battle Tested Current Limiter For Cheap DC Motor Controllers

Running a brushed motor in muddy or dusty environments takes a toll on controllers, with both heavy back EMF and high stall currents. This explains one of the challenge in Europe’s Hacky Racer series, which is decidedly more off-road than America’s Power Racing Series.

In pushing these little electric vehicles to the limits, many builders use brushless Chinese scooter motors since they’re both available and inexpensive. Others take the brushed DC route if they’re lucky enough to score a motor — and then the challenge becomes getting the most performance without burning up your controller. To fix this, [MechanicalCat] has come up with a current limiter for cheap DC motor controllers.

Circuit protection added to motor controller

The full write-up is in the included PDF file, and describes the set-up of an Arduino Nano sitting between throttle and controller, and taking feedback from a current sensor. The controller in question is a 4QD Porter 10 so an extra component is a DC-to-DC converter to provide a floating ground for the Arduino. However, there is also the intriguing possibility of the same set-up being used with absurdly cheap Chinese motor controllers. There is also advice on fitting flyback diodes, something which might have saved one controller in the Hackaday pits last year.

It’s yet to be seen what effect this will have on Hacky Racer competitiveness, however its applications go far beyond that field into anywhere a reliable small DC motor drive on the cheap is required. Meanwhile, if you’re unsure where this Hacky Racer stuff came from, you could start here.

Electric Drift Trike Needs Water Cooling

Electric vehicles of all types are quickly hitting the market as people realize how inexpensive they can be to operate compared to traditional modes of transportation. From cars and trucks, to smaller vehicles such as bicycles and even electric boats, there’s a lot to be said for simplicity, ease of use, and efficiency. But sometimes we need a little bit more out of our electric vehicles than the obvious benefits they come with. Enter the electric drift trike, an electric vehicle built solely for the enjoyment of high torque electric motors.

This tricycle is built with some serious power behind it. [austiwawa] constructed his own 48V 18Ah battery with lithium ion cells and initially put a hub motor on the front wheel of the trike. When commenters complained that he could do better, he scrapped the front hub motor for a 1500W brushless water-cooled DC motor driving the rear wheels. To put that in perspective, electric bikes in Europe are typically capped at 250W and in the US at 750W. With that much power available, this trike can do some serious drifting, and has a top speed of nearly 50 kph. [austiwawa] did blow out a large number of motor controllers, but was finally able to obtain a beefier one which could handle the intense power requirements of this tricycle.

Be sure to check out the video below to see the trike being test driven. The build video is also worth a view for the attention to detail and high quality of this build. If you want to build your own but don’t want to build something this menacing, we have also seen electric bikes that are small enough to ride down hallways in various buildings, but still fast enough to retain an appropriate level of danger.

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Furniture And Motors Make A Strange Bedfellow

Beds! They don’t move around enough, so the young people say. They need more motors, more horsepower, more self-driving smarts – right? Honestly, we’re not sure, but if that’s the question being asked, [randofo] has the answer.

Aptly named, Bedfellow is an art project that sought to create a bed that could explore and socialise with occupants aboard. The core principle was not just to create a bed that could move under its own power, but one that could intelligently drive around and avoid obstacles, too. This is achieved through the use of ultrasonic sensors, with an Arduino Mega as the brains. The bed chooses a random direction in which to move, checking for obstacles on the way. It’s pretty basic as far as “self-driving” technology goes, but it gets the job done.

Far from being a lightweight artistic statement, the bed has some serious performance credentials. The drivetrain is a couple of 4 horsepower DC motors with speed controllers cribbed from a golf cart. These are fed through a 20:1 gear reduction to boost torque and avoid the bed moving too quickly. [Randofo] reports it can comfortably haul 12 people without slowing down, and we don’t doubt it. With that much power, your average flatback bed would be ripped to pieces, but never fear for this one – there’s plenty of heavy engineering holding it together.

It’s refreshing to see an art project executed with both elegant aesthetics and brutally powerful hardware. Sure, it might not be much good for sleeping unless you live in a loft with a concrete floor, but hey – they’re awfully popular these days. Now all it needs are some ground effects.

Mini Drill Made From A Motor

We love this hacked-together mini drill by [BuenaTec] that uses a DC7.2V 10K-RPM motor with a 1/8” Dremel chuck added on. Power is supplied by a USB-A cable with the data wires cut off, with a switch controlling the voltage and a rectifier diode protecting the USB port or battery pack from back voltage from the motor.

The drill isn’t very powerful, only able to bore holes in PCBs, plastic, and similar soft materials. However, you could see how just a couple more components could make it even more robust — maybe a speed controller and voltage booster? Even so, we appreciate this bare-bones, ultra-low budget approach — only the barest essentials are included, with the components held together with hot glue and solder. Also, no one is allowed to complain about their soldering iron after viewing this video.

For more projects involving motors, read up on this brushless motor made from 3D-printed parts and this guide to hand-winding quadcopter motors.