Reflex Trainer Puts Athletes To The Test

Being a top athlete in this modern age is a full-time job. No longer do athletes simply practice at their nominated sport of choice. They undergo strength training, full nutritional programs, cardio, and even reflex training.

Reflex training involves a series of nodes that an athlete must identify when lit up, and touch them to switch them off. By triggering them in a fast sequence, the athlete must work hard to both identify the lit node and then move to switch it off. TrainerLights is just such a system, built around the NodeMCU platform.

The system consists of a minimum of four lights – one acting as a server, the others as nodes. The lights each contain a nodeMCU board which communicates over WiFi, while the server has an additional board – acting as a WiFi hotspot that controls the system.

With the lights switched on, the coach connects to the server with a smartphone, and configures the lighting sequence and timings depending on the desired excercise regime. The server then communicates with the lighting nodes, which light their LEDs  at specified intervals. The athlete must clear the lights by swiping at the nodes, which detect the athlete’s hand via an ultrasonic proximity sensor. The sensitivity is configurable, to allow the system to trigger from a distant wave or a direct touch from the athlete. This allows a variety of training uses, from tennis to taekwondo.

With a 3D printed case and parts readily available from any good maker supplier, it’s a project you could tackle in a weekend to add to your own training regime.

We see plenty of athletic hacks in these parts – like this line-following robot for training sprinters. Video after the break.

[Thanks to Baldpower for the tip!]

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Let’s Look At Some Cool Old LEDs

LEDs are now a mature technology, with all manner of colors and flavors available. However, back in the 1970s, it was early days for this fledgling display tech, and things looked very different. [IMSAI Guy] happened to work at the optoelectronics division of Hewlett-Packard during their development of LED displays, and has a handful of prototypes from those heady days.

The video is a great look at not only vintage display hardware, but also rarely seen prototypes that seldom left the HP offices. Matrix, 7-segment and even 16-segment devices are all in attendance here. There’s great macro photography of the packages, including the now-forgotten bubble displays as well as hermetically sealed glass packages. The parts all have a uniquely 1970s look, drenched in gold plating and otherwise just looking very expensive.

The followup video breaks out the microscope and powers up the displays. [IMSAI Guy] shares some useful tips on how to best tinker with unknown LED parts, as well as knowledge about the chemical compounds and manufacturing processes involved in LED production. If you don’t know your III-V compounds from your II-VI compounds, prepare to learn.

It’s always interesting to take a look back, and even better to get a peek at the experiments of engineers of the past.

If you’re wondering about applications of this hardware, we’ve seen messageboards and watches before. Video after the break.

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NTP Morse Code Clock Powered by ESP8266

We’ve featured a great many unique clocks here on Hackaday, which have utilized nearly every imaginable way of conveying the current time. But of all these marvelous timepieces, the Morse code clock has the distinct honor of simultaneously being the easiest to construct and (arguably) the most difficult to read. As such, it’s little surprise we don’t see them very often. Which makes this latest entry into the field all the more interesting.

[WhisleyTangoHotel] has taken the basic concept of the Morse clock, which at its most simplistic could be done with a microcontroller and single LED, and expanded it into a (relatively) practical device. With both audio and visual signaling, and support for pulling the time from NTP, this is easily the most polished Morse code clock we’ve ever seen. Using it still requires you to have a decent grasp on Samuel Morse’s now nearly 200 year old encoding scheme of course, but on the bright side, this clock is sure to help keep your CW skills sharp.

For those following along at home, [WhisleyTangoHotel] provides a hand-drawn diagram to show how everything connects together in his Morse timepiece, but there’s nothing on the hardware side that’s likely to surprise the Hackaday reader. A single momentary push button represents the device’s sole user input, with the output being handled by a LED “tower” and speaker on their own respective pins on the microcontroller. Here a Adafruit Feather HUZZAH is used, but any ESP8266 would work in its place.

Of course, the advantage of using an ESP8266 board over your garden variety MCU is the Wi-Fi connectivity. This allows the clock to connect to an NTP server and get the current time before relaying it to the user. Some might think this overkill, but it’s really a critical feature; the lack of a proper RTC on the ESP means the clock would drift badly if not regularly synchronized. Assuming you’ve got a reliable Internet connection, this saves you the added cost and complexity of adding an external RTC.

[WhisleyTangoHotel] wraps up his blog post by providing his ESP8266 Arduino source code, which offers an interesting example in working not only with NTP and time zones on the ESP, but how to handle parsing strings and representing their principle characters in Morse code.

Interestingly enough, in the past we’ve seen a single LED clock that didn’t use Morse code to blink out the time, which might be a viable option as an alternate firmware for this device if you’re not in the Samuel Morse fan club.

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A Neat Pen POV build

We’ve seen a lot of persistence of vision (POV) builds on bike wheels, sticks, and many other holders, but this one puts it on something new: a pen. [Befinitiv] was looking for a new way to add some smarts to everyday devices, and the result is a neat POV display that fits over a pen. At 128 by 64 pixels, it is not high definition, but this build uses a number of interesting techniques.

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Wonderful Sculptural Circuits hide Interactive Synthesizers

When it rains, it pours (wonderful electronic sculpture!). The last time we posted about freeform circuit sculptures there were a few eye-catching comments mentioning other fine examples of the craft. One such artist is [Eirik Brandal], who has a large selection of electronic sculptures. Frankly, we’re in love.

A common theme of [Eirik]’s work is that each piece is a functional synthesizer or a component piece of a larger one. For instance, when installed the ihscale series uses PIR sensors to react together to motion in different quadrants of a room. And the es #17 – #19 pieces use ESP8266’s to feed the output of their individual signal generators into each other to generate one connected sound.

Even when a single sculpture is part of a series there is still striking variety in [Eirik]’s work. Some pieces are neat and rectilinear and obviously functional, while others almost looks like a jumble of components. Whatever the style we’ve really enjoyed pouring through the pages of [Eirik]’s portfolio. Most pieces have demo videos, so give them a listen!

If you missed the last set of sculptural circuits we covered this month, head on over and take a look at the flywire circuits of Mohit Bhoite.

Thanks [james] for the tip!

A Guide For Driving LED Matrices

Building an LED matrix is a fun project, but it can be a bit of a pain. Usually it starts with hand-soldering individual LEDs and resistors together, then hooking them up to rows and columns so they can be driven by a microcontroller of some sort. That’s a lot of tedious work, but you can order an LED matrix pre-built to save some time and headache. You’ll still need a driver though, and while building one yourself can be rewarding there are many pitfalls and trade-offs to consider when undertaking that project as well. Or, you can consider one of a number of drivers that [deshipu] has outlined in detail.

The hangups surrounding the driver board generally revolve around the issue of getting constant brightness from LEDs regardless of how many in the row or column are illuminated at one time. Since they are typically driven one row or column at a time, the more that are on the lower the brightness each LED will have. Driver boards take different approaches to solving this problem, which usually involve a combination of high-speed scanning of the matrix or using a constant-current source in order to eliminate the need for resistors. [deshipu] outlines four popular chips that achieve these purposes, and he highlights their pros and cons to help anyone looking to build something like this.

Most of these boards will get you to an 8×8 LED matrix with no problem, with a few going a few pixels higher in either direction. That might be enough for most of our needs, but for something larger you’ll need other solutions like the one found in this 64×32 LED matrix clock. There are also even more complicated drivers if you go into extra dimensions.

Photo credit: Komatta [Public domain], from Wikimedia Commons

LED-ifying A Guitar, Part Two

An electric guitar is all about stage presence. Need to be cooler than a single guitar? No problem — there are double neck guitars. Need to be cooler than that? No problem, the guy from Cheap Trick has a five-neck guitar. Need to be cooler than that? Robbie Robertson played a guitar with an extra mandolin neck on The Last Waltz. Where do you go from there? Obviously, the solution is putting a TV in your guitar with a boatload of individually addressable LEDs in a guitar. That’s what [Englandsaurus] is doing, and the build thread is now getting into how to turn a bunch of LEDs into a display.

In the first installment of this build thread, [Englandsaurus] went over the construction of the guitar itself and how a hundred individually addressable RGB LEDs were installed inside two pieces of plexiglass. When the guitar is displaying white at full brightness, the power draw is 500 W. This, in itself, is remarkable; no sane person would ever plug a guitar into a 500 W amp, and even 100 Watts is just too damn loud. There’s more power going to the lights here than the amplifier, and that’s awesome.

Simply sticking LEDs in a guitar does not a build log make, so how are these pixels addressed? How do you make a display out of a bunch of LEDs? This is a hell of a problem, but with Artnet and Resolume Arena 6 these pixels can be mapped into a cartesian grid, and from there it’s just putting video on the guitar.

While the first installment of this build is great and shows you how far you can take electronics in a guitar, this installment is a great demo of turning a bunch of LEDs into a display, something that applies to more than just a gigantic glowey guitar.