FlexLED Is A Unique Take On Persistence Of Vision

July 9, 2019 by Lewin Day 13 Comments

Many hackers have experimented with the persistence of vision effect. Whip around a bunch of LEDs, flash them at just the right times, and it’s possible to make images to appear to hang in the air. There’s plenty of ways to do this, whether by manually shaking the LEDs by hand, spinning them around, or even putting them on your bike wheels. [Carl Bugeja] went a different route, taking advantage of the possibilities created by flex PCBs.

[Carl]’s project goes by the name FlexLED. This aptly describes the build, which, in prototype form, mounts a single LED on the end of a flex PCB. The PCB itself has a pattern of traces creating a coil, which enable it to interact with magnetic fields more strongly. By passing the right current through the coil, the flexible PCB can be made to flap up and down, moving the LED on the end at a rapid rate. By then controlling the flashing of the LED, it’s possible to create a persistence of vision effect.

Currently fitted with only one LED, capable of 3 colors, the visual display of the FlexLED is somewhat limited. However, [Carl] reports the effect is more impressive in person than on camera, and is already working on plans to scale up the project to a multi-LED diplay.

POV technology can do some pretty impressive things – even volumetric displays are possible. If you’re working on something yourself, be sure to let us know. Video after the break.

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Trap Chess Keeps Players On Their Toes

July 8, 2019 by Lewin Day 22 Comments

Chess is a game that originated so long ago, we don’t have concrete information as to its origins. Rules have changed throughout history, and many continue to study and experiment with the game. [Yann Guidon] has a neighbour, [Bob], who is just one such enthusiast, and together, they built a working Trap Chess game.

What is trap chess, you may ask? It’s a variant of chess where pieces randomly fall into traps at the change of turns. This is easy to simulate in a digital game, but that wasn’t enough for [Bob]. Enlisting [Yann] for his electrical skills, the duo built a board with ten trapdoors built in. Whenever the timer is hit, there’s a chance a trapdoor can open, removing a piece from the game.

The build relies on a PIC16F818, an 8-bit microcontroller from Microchip. This helps interface between the timer and servos and generally runs the whole show. The board is built into a table, and we’re impressed by the fit and finish of the final product. From a distance, it’s difficult to notice anything is awry, and it would make a great prank when playing with an unsuspecting mark. Just make sure there’s no money on the table first.

We’ve seen other impressive chess hacks before — like this board that can move the pieces for you. Video after the break. Continue reading “Trap Chess Keeps Players On Their Toes” →

Smart Shelf Hides Some Serious Functionality

July 7, 2019 by Lewin Day 12 Comments

Today, it can feel like you’re always connected to the grid. We’re constantly alerted to notifications from smart phones, smart watches, and our houses have begun to swell with all manner of internet-enabled devices. [Jake P] wanted a less connected lifestyle, and built a shelf to help realise that goal.

The idea of [Jake]’s Analog Smart Shelf is to serve as a digital check point in his home. It’s a name that more reflects the ethos of the shelf rather than the components. The shelf contains a Qi wireless charging platform, so smartphones can be placed on the shelf when entering the house and left to charge. The shelf also conceals an Amazon Fire tablet behind woodgrain veneer, which displays the time, weather, and basic notification data. This enables [Jake] to see relevant digital information at a glance, while being able to switch off from the online world by simply walking away.

It’s a well-executed project, which artfully blends wood, concrete, and epoxy to create an attractive final product. It also bears some similarities to smart mirror projects we’ve seen before. It’s a piece we’d be proud to see on our walls, and a great concept for managing one’s digital life, too.

Phase Shift Pump Control? There’s An App For That.

July 6, 2019 by Tom Nardi 19 Comments

The sort of pumps used in the filtration systems of fountains and swimming pools don’t take kindly to running dry. So putting such a pump on a simple timer to run while you’re away comes with a certain level of risk: if the pump runs out of water while you’re gone, you might come home to a melted mess. One possible solution is a float sensor to detect the water level in whatever you’re trying to pump, but that can get complicated when you’re talking about something as large as a pool.

For his entry into the 2019 Hackaday Prize, [Luc Brun] is working on controller that can detect when the pump is running dry by monitoring the phase shift between voltage and current. With an inductive load like a pump, the current should lag behind the AC voltage a bit under normal operation. But if they become too far out of phase with each other, that’s a sign that the pump is running in a no-load condition because there’s no water to slow it down.

As [Luc] explains in the project write-up, simply monitoring the pump’s peak current could work, but it would be less reliable. The problem is that different motors have different current consumptions, so unless you calibrated the controller to the specific load it’s protecting, you could get false readings. But the relationship between current and voltage should remain fairly consistent between different motors.

The controller is powered by a Arduino Nano and uses a ACS712 current sensor to take phase measurements. Since he had the ability to toggle the pump on and off with a relay attached to the Arduino, [Luc] decided to add in a few other features. The addition of a DS1307 Real Time Clock means the pump can be run on a schedule, and an HC-05 Bluetooth module lets him monitor the whole system from his smartphone with an Android application he developed.

Since the theme of this year’s Hackaday Prize is designing a product rather than a one-off build, judges will be looking for exactly the sort of forward thinking that [Luc] has demonstrated here. As the controller is currently a mass of individual modules held inside a waterproof enclosure, the next steps for this project will likely be the finalization of the hardware design and the production of a custom PCB.

Building A Smart Speaker From Scratch

July 5, 2019 by Lewin Day 6 Comments

Smart speakers have proliferated since their initial launch earlier this decade. The devices combine voice recognition and assistant functionality with a foreboding sense that paying corporations for the privilege of having your conversations eavesdropped upon could come back to bite one day. For this reason, [Yihui] is attempting to build an open-source smart speaker from scratch.

The initial prototype uses a Raspberry Pi 3B and a ReSpeaker microphone array. In order to try and bring costs down, development plans include replacing these components with a custom microphone array PCB and a NanoPi board, then implementing basic touch controls to help interface with the device.

There’s already been great progress, with the build showing off some nifty features. Particularly impressive is the ability to send WiFi settings to the device using sound, along with the implementation of both online and offline speech recognition capabilities. This is useful if your internet goes down but you still want your digital pal to turn out the lights at bed time.

It’s not the first time we’ve seen a privacy-focused virtual assistant, and we hope it’s not the last. Video after the break.

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MIDI-Gurdy, MIDI-Gurdy, MIDI-Gurdy Man

July 4, 2019 by Brian Benchoff 19 Comments

The hurdy gurdy is the perfect musical instrument. It’s an instrument with a crank, and a mechanical wonderment of drone strings and weird chromatic keyboards. No other musical instrument combines the sweet drone of bagpipes with the aural experience of an eight-year-old attempting to play Hot Cross Buns on a poorly tuned violin.

Now, the hurdy gurdy is going digital. The Digi-Gurdy is [XenonJohn]’s entry into this year’s Hackaday Prize, and it’s exactly what it says on the tin: it’s a musical instrument that drones on and on, with keys plunking out a melody.

If you’re not familiar with a hurdy gurdy, this video is a varily good introduction. It’s a box with somewhere between four and six strings mounted on the outside. The strings vibrate by means of a wooden wheel powered by a crank. There’s a keyboard of sorts along the body of the instrument that ‘fret’ a single string providing the melody; all the other strings are drone strings that sound continuously. I think it was in, like, a Led Zeppelin video, man.

While it’s a slightly complicated build to make an analog hurdy gurdy, delving into the digital domain is easy: [XenonJohn] is building a hurdy gurdy that simply outputs MIDI commands with some buttons and a Teensy 3.6 microcontroller. The parts are 3D printed, and since this hurdy gurdy is completely digital, you can change the tuning of the drone strings without actually tuning them. Awesome.

Neural Network Smartens Up A Security System

July 3, 2019 by Lewin Day 11 Comments

It’s all well and good having a security camera recording all the time, but that alone can’t sound the alarm in the event of a crime. Motion sensing is of limited use, often being triggered by unimportant stimuli such as moving shadows or passing traffic. [Tegwyn☠Twmffat] wanted a better security system for the farm, and decided that neural networks would likely do the trick.

The main component of the security system is a Raspberry Pi fitted with a camera and a Movidius Neural Compute Stick. This allows the Raspberry Pi to run real-time object identification on video. The Raspberry Pi is programmed to raise the alarm if it detects humans approaching, but ignores the family dog and other false targets. In the event of a detection, the Raspberry Pi sends a signal over LoRa to a base station, which sounds an alarm. The pitch of the alarm increases the closer the target gets to the camera, thanks to some simple code with bounding boxes.

It’s a nifty way to create an intelligent security system, and all the more impressive for being entirely constructed from off-the-shelf parts and code. Neural networks have become increasingly useful; they can even tell when your cat wants to go outside. Video after the break.