Years ago, engineer and photographer Harold “Doc” Edgerton figured out how to “bend time” by pulsing a strobe light at the nearly the same speed as droplets of water, making them appear to move in slow motion, freeze, or even more backwards. Today, Nick Lim of jolliFactory has created the same effect, controlled by an Arduino Nano.

His excellent build is outlined here, including a surprisingly simple circuit that controls the pump, solenoid valve, and LED illumination via a trio of MOSFETs. 

One simply places the fountain over a water supply, which pumps it up into the solenoid valve, allowing 45 drops to fall per second. The lights then strobe at this speed—or slightly faster or slower—producing the time-bending display shown in the video below.

After Instructables user R0RSHACH’s son won a place at the World Scout Jamboree in 2019, the maker decided to create a fairground-style game for fundraising. 

The resulting device is akin to a Whack-a-Mole or Batak game that can be found at high-end gyms, and features eight large light-up buttons per player on a wooden frame.

When activated, an Arduino Mega turns on the button-lights in sequence to test how long it takes participants to push each one. While it can be made in a single-player version, the two-player game looks like a lot more fun, allowing participants to compete on opposing boards. 

Code and instructions are available here, and you can see it demonstrated in the videos below.

Javier Betancor is developing a system which collects power as you ride a bike, with the goal of powering data collection and lighting. “imPulse” uses a stepper motor for power generation, along with a geared hub to make the motor spin at multiples of the wheel speed.

While the project is still a prototype, the headlights and rear lighting assemblies already look very good, and CAD files as well as Arduino code are available here.

The aim of this project is to provide a cost-effective alternative to power generation on bikes using conventional stepper motors while adding other capabilities, such as: 

– An integrated data logging system to monitor power generated on each trip.

– A smart lighting system with addressable LEDs, working as indicators, braking lights and headlights, incorporating Light Dependant Resistors (LDRs) to sense the environment and to reduce the risk of glare.

– Power Distribution Board (PDB) to charge two different/generic powerbanks. While one powerbank is charged, the other one is used to supply energy to the system.

You can see a prototype of the lighting system in the video below, using an Arduino Uno for control as a turn signal and brake light, as well as a constant beam for visibility. Find additional information and follow along with Betancor’s progress in his Hackaday log. 

Stepper motors work by alternating a series of magnets in order to rotate its shaft by a certain angle. When the shaft is manually twisted, these magnets produce an electrical signal in a predictable pattern, which as shown in the video below, can be used as an encoder with the help of an Arduino Uno.

More information, including a circuit diagram and the Arduino code used for the stepper-NeoPixel and stepper-stepper examples can be found here. While the write-up notes that this stepper-encoder won’t work reliably if turned too slowly, it seems to work quite well at the fairly low speed shown in the demonstrations.

I want to tell you how to make incremental encoder from stepper motor. When we turning shaft of stepper motor it works like generator. It generates certain impulses on its coils. After some signal processing, we get same impulses as incremental encoder. This encoder has one problem, it can drop steps if you turning very slowly. But for many applications, it doesn’t matter.

The Unity engine has been around since Apple started using Intel chips, and has made quite a splash in the gaming world. Unity allows developers to create 2D and 3D games, but there are some other interesting applications of this gaming engine as well. For example, [matthewhallberg] used it to build a robot that can map rooms in 3D.

The impetus for this project was a robotics company that used a series of robots around their business. The robots navigate using computer vision, but couldn’t map the rooms from scratch. They hired [matthewhallberg] to tackle this problem, and this robot is a preliminary result. Using the Unity engine and an iPhone, the robot can perform in one of three modes. The first is a user-controlled mode, the second is object following, and the third is 3D mapping.

The robot seems fairly easy to construct and only carries and iPhone, a Node MCU, some motors, and a battery. Most of the computational work is done remotely, with the robot simply receiving its movement commands from another computer. There’s a lot going on here, software-wise, and a lot of toolkits and software packages to install and communicate with one another, but the video below does a good job of showing what you’ll need and how it all works together. If that’s all too much, there are other robots with a form of computer vision that can get you started into the world of computer vision and mapping.

Once upon a time, there was a music venue/artist collective/effects pedal company that helped redefine industry in Williamsburg, Brooklyn. That place was called Death By Audio. In 2014, it suffered a death by gentrification when Vice Media bought the building that DBA had worked so hard to transform. From the ashes rose the Death By Audio Arcade, which showcases DIY pinball cabinets made by indie artists.

Their most recent creation is called A Place To Bury Strangers (APTBS). It’s built on a 1959 Gottlieb Mademoiselle table and themed around a local noise/shoegaze band of the same name that was deeply connected to Death By Audio. According to [Mark Kleeb], this table is an homage to APTBS’s whiz-bang pinball-like performance style of total sensory overload. Hardly a sense is spared when playing this table, which features strobe lights, black lights, video and audio clips of APTBS, and a fog machine. Yeah.

[Mark] picked up this project from a friend, who had already cut some wires and started hacking on it. Nearly every bit of the table’s guts had to be upgraded with OEM parts or else replaced entirely. Now there’s a Teensy running the bumpers, and another Teensy on the switches. An Arduino drives the NeoPixel strips that light up the playfield, and a second Uno displays the score on those sweet VFD tubes. All four micros are tied together with Python and a Raspi 3.

If you’re anywhere near NYC, you can play the glow-in-the-dark ball yourself on July 15th at Le Poisson Rouge. If not, don’t flip—just nudge that break to see her in action. Did we mention there’s a strobe light? Consider yourself warned.

Want to get into DIY pinball on a smaller scale? Build yourself a sandbox and start playing.

Ultrasonic sensors are great tools for measuring linear distance or object presence. As shown in this experiment by “lingib,” two sensors can also be combined to determine not just linear distance to a sensor, but its position in an X/Y plane.

For his experiment, he hooked two of these units up to an Arduino Uno at a known distance from each other, with one emitter blanked out with masking tape. The non-blanked emitter pulses an ultrasonic signal, which is bounced back to it as well as the second sensor by the measured object. From the time it takes to receive the return signal, distance to each sensor can be inferred, giving a triangle with each side known. Trigonometry is then used to pinpoint the item’s position, and a Processing sketch displays coordinates on lingib’s computer.

This Instructable explains how to pinpoint the location of an object using an Arduino, two ultrasonic sensors, and Heron’s formula for triangles. There are no moving parts.

Heron’s formula allows you to calculate the area of any triangle for which all sides are known. Once you know the area of a triangle, you are then able to calculate the position of a single object (relative to a known baseline) using trigonometry and Pythagoras.

The accuracy is excellent. Large detection areas are possible using commonly available HC-SR04, or HY-SRF05, ultrasonic sensors.

Construction is simple … all you require is a sharp knife, two drills, a soldering iron, and a wood saw.

We’re all familiar with the experience of buying hobby servos. The market is awash with cheap clones which have inflated specs and poor performance. Even branded servos often fail to deliver, and sometimes you just can’t get the required torque or speed from the small form factor of the typical hobby servo.

Enter [James Bruton] and his DIY RC servo from a windscreen wiper motor. Windscreen wiper motors are cheap as chips, and a classic salvage. The motor shaft is connected to a potentiometer via a pulley and some string, providing the necessary closed-loop feedback. Instead of using the traditional analog circuitry found inside a servo, an Arduino provides the brains. This means PID control can be implemented on the ‘duino, and tuned to get the best response from different load characteristics. There’s also the choice of different interfacing options: though [James]’ Arduino code accepts PWM signals for a drop-in R/C servo replacement, the addition of a microcontroller means many other input signal types and protocols are available. In fact, we recently wrote about serial bus servos and their numerous advantages.

We particularly love this because of the price barrier of industrial servomotors; sure, this kind of solution doesn’t have the precision or torque that off-the-shelf products provide, but would be sufficient for many hacks. Incidentally, this is what inspired one of our favourite open source projects: ODrive, which focuses on harnessing the power of cheap brushless motors for industrial use.

Morse code may not be as widely used as in its heyday, but it still certainly has its adherents. One avid user is Tanya Finlayson, who has been using this as her method of communication for roughly 40 years. Now, with the Gboard phone keyboard supporting input via dots and dashes, the world of Android computing has been opened up to her as well.

In order to get button presses to the phone, Ken Finlayson used an Arduino Leonardo to read inputs from a trio of buttons, indicating dot, dash, and mode select. The third button allows for phone navigation in addition to text input. Because of its built-in HID capabilities via the ATmega32U4 chip, the Leonardo is a great choice for this application, demonstrated in the video below. 

Many people cannot use keyboards and touchscreens to control their digital devices. Instead, they use custom hardware switches that emulate typing, swiping, and tapping. The Android operating system provides software that allows these switches to control Android devices, and recently Google provided a new Morse Keyboard within the Gboard keyboard for people who find this method easier for text entry.

This experiment is a DIY hardware adapter that enables assistive tech developers to connect existing switch based input systems to their Android device. Once connected, 2 switch assistive systems (with an additional switch for mode switching) can control both the standard Android accessibility func

tions as well as text entry through Morse on Gboard.

This experiment is built using Arduino and is compatible with most standard assistive 2 switch systems with 1/8” mono outputs.

Cultural probes aim to elicit unique responses by asking people to respond to a question, many times in the form of a photograph. While disposable cameras once worked quite nicely for this purpose, their relative rarity today meant a new digital alternative was needed. For this, Interaction Research Studio came up with a series of ProbeTools cameras that anyone can make and customize.

The most basic type in this series of cameras is known as the TaskCam, which features a 3D-printed frame and an Arduino Uno at its core. A shield with several snap-off sections provides user interface, including a trio of buttons, and a display that shows questions that are read off of a micro SD card. Users then respond to queries with photographs, saved with the corresponding question for future analysis.

TaskCams recreate the proven Cultural Probe technique of relabelling disposable cameras with requests for pictures. The 3D Printed TaskCam is the basic workhorse of the collection, robust and flexible enough to use across multiple studies.

The 3D Printed TaskCam has a small screen on the back that shows a scrollable list of requests for pictures.  Researchers can load their own list of requests onto the camera to prepare for a study. When users take a picture, the image is tagged with the current request, and stored on a standard flash drive that can be removed for downloading.

The casing for the 3D Printed TaskCam can be printed successfully without support materials even on low-end printers. The device requires a custom Arduino shield,  buy online at cost price, or follow the open-source plans to make yourself. Smart power management mean that two AA batteries provide more than enough power for an entire user study.

You can find more details on ProbeTools here, as well as in Designboom’s recent article.