While early scientists and inventors famously underestimated the value of radar, through the lens of history we can see how useful it became. Even though radar uses electromagnetic waves to detect objects, the same principle has been used with other propagating waves, most often sound waves. While a well-known use of this is sonar, ultrasonic sensors can also be put to use to make a radar-like system.

This ultrasonic radar project is from [mircemk] who uses a small ultrasonic distance sensor attached to a rotating platform. A motor rotates it around a 180-degree field-of-view and an Arduino takes and records measurements during its trip. It interfaces with an application running on a computer which shows the data in real-time and maps out the location of all of the objects around the sensor. With some upgrades to the code, [mircemk] is also able to extrapolate objects hidden behind other objects as well.

While the ultrasonic sensor used in this project has a range of about a meter, there’s no reason that this principle couldn’t be used for other range-finding devices to extend its working distance. The project is similar to others we’ve seen occasionally before, but the upgrade to the software to allow it to “see” around solid objects is an equally solid upgrade.

Beer pong is a fun enough game for those of a certain age, but one thing that it lacks is a way of cranking up the difficulty setting independent of the amount of beer one has consumed. At least, that was the idea [Ty] had when he came up with this automated beer pong table which allows the players to increase the challenge of this game by sliding the cups around the top of the table.

The build uses a belt-driven platform under a clear cover with a set of magnets attached. Each of the cups on the table has a corresponding magnet, which allows them to slide fairly easily back and forth on the table. The contraption is controlled by an Arudino Nano with a small screen and dial that allows the players to select a difficulty level from 1 to 10. The difficulty levels increase the speed that the cups oscillate on the table, which certainly adds another layer of complexity to this already challenging game.

While we hope to eventually see a beer pong table that can automatically arrange the cups as the game is played, we do appreciate the effort to make an already difficult game even more difficult. Of course, if you have problems with the difficulty level you might want to pick up a PongMate CyberCannon Mark III to help with those clutch beer pong shots.

A few years ago, YouTubing madman [Colin Furze] took an old bumper car and made a 600-horsepower beast of a go-kart that managed to clock 100MPH with a headwind. This isn’t that. It’s a miniaturized, remote-control homage to [Colin]’s go-kart that is equally awesome.

[Forsyth Creations] started by CAD-modeling the chassis right on top of a still from the video. The entire body is 3D-printed in four large pieces, which took several days because each piece took around 24 hours. Inside the car there’s an Arduino brain driving a motor in the back and a servo in the front. This bad boy runs on a couple of rechargeable battery packs and can be controlled with either a Wii balance board or a PS2 controller. This thing really moves, although it doesn’t quite reach 100MPH. Watch it zoom around in the video after the break.

Got a Segway lying around that just doesn’t do it for you anymore? You could always turn it into a go-kart. Never had a Segway to begin with? Just roll your own.

There are a surprising wealth of parts inside of old laptops that can be easily scavenged, but often these proprietary tidbits of electronics will need a substantial amount of work to make them useful again. Obviously things such as hard drives and memory can easily be used again, but it’s also possible to get things like screens or batteries to work with other devices with some effort. Now, there’s also a way to reuse the trackpad as well.

This build uses a PS/2 touchpad with a Synaptics chip in it, which integrates pretty smoothly with an Arduino after a few pins on the touchpad are soldered to. Most of the work is done on the touchpad’s built in chip, so once the Arduino receives the input from the touchpad it’s free to do virtually anything with it. In this case, [Kushagra] used it to operate a stepper motor in a few different implementations.

If you have this type of touchpad lying around, all of the code and schematics to make it useful again are available on the project page. An old laptop in the parts bin is sure to have a lot of uses even after you take the screen off, but don’t forget that your old beige PS/2 mouse from 1995 is sure to have some uses like this as well.

We’ve heard of beer pong, but we’re not sure we’ve heard of wine pong. And certainly never wine pong automated with a ping pong ball throwing robot like this one.

There’s not a huge amount of detail available in the video below, and no build log per se. But [Electron Dust] has a few shots in the video that explain what’s going on, as well as a brief description in a reddit thread about the device. The idea is to spin a ball up to a steady speed and release it the same way every time. The rig itself is made of wood and spun by plain brushed DC motors – [Electron Dust] explains that he chose them over PWM servos to simplify things and eliminate uncertainty in the release point. The ball is retained by a pair of arms, each controlled by a pair of hobby servos. An Arduino spins along with everything else and counts 50 revolutions before triggering the servos to retract and release the ball. A glass positioned at the landing spot captures the ball perfectly once everything is dialed in.

Here’s hoping that build details end up on his blog soon, as they did for this audio-feedback juggling machine. And while we certainly like this project, it might be cool if it could aim the ball into the glass. Or it could always reposition the target on the fly.

What’s your secret evil plan? Are you looking for world domination by building a machine that can truly replicate itself? Or are you just tired of winding motor rotors and other coils by hand? Either way, this automated coil winder is something you’re probably going to need.

We jest in part, but it’s true that closing the loop on self-replicating machines means being able to make things like motors. And for either brushed or brushless motors, that means turning spools of wire into coils of some sort. [Mr Innovative]’s winder uses a 3D-printed tube to spin magnet wire around a rotor core. A stepper motor turns the spinner arm a specified number of times, pausing at the end so the operator can move the wire to make room for the next loop. The rotor then spins to the next position on its own stepper motor, and the winding continues. That manual step needs attention to make this a fully automated system, and we think the tension of the wire needs to be addressed so the windings are a bit tighter. But it’s still a nice start, and it gives us some ideas for related coil-winding projects.

Of course, not every motor needs wound coils. After all, brushless PCB motors with etched coils are a thing.

The Teensy platform is very popular with hackers — and rightly so. Teensys are available in 8-bit and 32-bit versions, the hardware has a bread-board friendly footprint, there are a ton of Teensy libraries available, and they can also run standard Arduino libraries. Want to blink a lot of LED’s? At very fast update rates? How about MIDI? Or USB-HID devices? The Teensy can handle just about anything you throw at it. Driving motors is easy using the standard Arduino libraries such as Stepper, AccelStepper or Arduino Stepper Library.

But if you want to move multiple motors at high micro-stepping speeds, either independently or synchronously and without step loss, these standard libraries become bottlenecks. [Lutz Niggl]’s new TeensyStep fast stepper control library offers a great improvement in performance when driving steppers at high speed. It works with all of the Teensy 3.x boards, and is able to handle accelerated synchronous and independent moves of multiple motors at the high pulse rates required for micro-stepping drivers.

The library can be used to turn motors at up to 300,000 steps/sec which works out to an incredible 5625 rpm at 1/16 th micro-stepping. In the demo video below, you can see him push two motors at 160,000 steps/sec — that’s 3000 rpm — without the two arms colliding. Motors can be moved either independently or synchronously. Synchronous movement uses Bresenham’s line algorithm to plan motor movements based on start and end positions. While doing a synchronous move, it can also run other motors independently. The TeensyStep library uses two class objects. The Stepper class does not require any system resources other than 56 bytes of memory. The StepControl class requires one IntervallTimer and two channels of a FTM  (FlexTimer Module) timer. Since all supported Teensys implement four PIT timers and a FTM0 module with eight timer channels, the usage is limited to four StepControl objects existing at the same time. Check out [Lutz]’s project page for some performance figures.

As a comparison, check out Better Stepping with 8-bit Micros — this approach uses DMA channels as high-speed counters, with each count sending a pulse to the motor.

Thanks to [Paul Stoffregen] for tipping us off about this new library.

There are times in everybody’s life when they feel the need to shoot at things in a harmless manner. For those moments there are rubber bands and Nerf darts, but even then they feel like mere toys. If that is the point at which you find yourself, then maybe [Austin]’s home-made electric disc shooter can help.

Operation of the shooter is simple enough. A stack of 3D-printed plastic discs is loaded into a tubular magazine, from which individual disks are nudged by a motor-driven cam controlled by the trigger. Once the disc leaves the magazine it reaches a vacuum cleaner belt driven by a much more powerful motor, that accelerates the disc to ejection velocity.

The video below the break shows the gun’s construction, as well as a sequence involving the destruction of plenty of balloons, soda cans, and food items. The 3D-printed ammunition seems to us to be the weak link as in our experience it is inevitable that there is a high ammunition loss rate with these type of weapons, but maybe [Austin] has a line on some cheap filament. Either way, his disc gun looks like the kind of toy that could provide an entertaining diversion for many readers.

If disc shooters are too tame for you, there is always the Great Coil Gun War.

There are times in everybody’s life when they feel the need to shoot at things in a harmless manner. For those moments there are rubber bands and Nerf darts, but even then they feel like mere toys. If that is the point at which you find yourself, then maybe [Austin]’s home-made electric disc shooter can help.

Operation of the shooter is simple enough. A stack of 3D-printed plastic discs is loaded into a tubular magazine, from which individual disks are nudged by a motor-driven cam controlled by the trigger. Once the disc leaves the magazine it reaches a vacuum cleaner belt driven by a much more powerful motor, that accelerates the disc to ejection velocity.

The video below the break shows the gun’s construction, as well as a sequence involving the destruction of plenty of balloons, soda cans, and food items. The 3D-printed ammunition seems to us to be the weak link as in our experience it is inevitable that there is a high ammunition loss rate with these type of weapons, but maybe [Austin] has a line on some cheap filament. Either way, his disc gun looks like the kind of toy that could provide an entertaining diversion for many readers.

If disc shooters are too tame for you, there is always the Great Coil Gun War.

A self-balancing robot is a great way to get introduced to control theory and robotics in general. The ability for a robot to sense its position and its current set of circumstances and then to make a proportional response to accomplish its goal is key to all robotics. While hobby robots might use cheap servos or brushed motors, for any more advanced balancing robot you might want to reach for a brushless DC motor and a new fully open-source controller.

The main problem with brushless DC motors is that they don’t perform very well at low velocities. To combat this downside, there are a large number of specialized controllers on the market that can help mitigate their behavior. Until now, all of these controllers have been locked down and proprietary. SmoothControl is looking to create a fully open source design for these motors, and they look like they have a pretty good start. The controller is designed to run on the ubiquitous ATmega32U4 with an open source 3-phase driver board. They are currently using these boards with two specific motors but plan to also support more motors as the project grows.

We’ve seen projects before that detail why brushless motors are difficult to deal with, so an open source driver for brushless DC motors that does the work for us seems appealing. There are lots of applications for brushless DC motors outside of robots where a controller like this could be useful as well, such as driving an airplane’s propeller.