InstaBeat Started Out Of Spite

November 24, 2019 by Gerrit Coetzee 27 Comments

[Tom] teaches electronics with this small programmable MP3 player, but it didn’t get its start as a teaching tool.

As all parents are sometimes required to do, [Tom] was acting as chauffeur for his daughter and his friends. When he played the Beatles one of his passengers informed him that she was completely devoid of taste and didn’t like them at all. So he decided what the world needed was a Beatles appliance. This way all the ignorant plebs could educate themselves at the push of a button.

The machine is based around some SEED studio parts and a simple PCB. It was able to hold all 12 original albums and even announced their titles in a generated voice. Since the kit is easy to put together it was quickly re-purposed as a teaching aid. They get to learn the laser cutter and do some through-hole soldering.

He has plans to turn it into a more formal how-to workshop that anyone can duplicate.He’d also like to make a small software suite for playing with text-to-speech and hacking the speaker into other roles such as a multi meter.

Use Your Earbud’s Media Controls On Your Laptop With This Useful Dongle

November 9, 2019 by Gerrit Coetzee 3 Comments

[David] sends in his very nicely designed “Thumpware Media Controller” that lets your mobile phone headphones control the media playback on your PC.

We realize that some PCs have support for the extra pins on cellphone earbuds, but at least some of us have experienced the frustration (however small) of habitually reaching up to touch the media controls on our earbuds only to hear the forlorn click of an inactive-button. This solves that, assuming you’re still holding on to those 3.5mm headphones, at least.

The media controls are intercepted by a PIC16 and a small board splits and interprets the signals into a male 3.5mm and a USB port. What really impressed us is the professional-looking design and enclosure. A lot of care was taken to plan out the wiring, assembly, and strain relief. Overall it’s a pleasure to look at.

All the files are available, so with a bit of soldering, hacking, and careful sanding someone could put together a professional looking dongle for their own set-up.

Worried About Bats In Your Belfry? A Tale Of Two Bat Detectors

October 17, 2019 by Pat Whetman 33 Comments

As somebody who loves technology and wildlife and also needs to develop an old farmhouse, going down the bat detector rabbit hole was a journey hard to resist. Bats are ideal animals for hackers to monitor as they emit ultrasonic frequencies from their mouths and noses to communicate with each other, detect their prey and navigate their way around obstacles such as trees — all done in pitch black darkness. On a slight downside, many species just love to make their homes in derelict buildings and, being protected here in the EU, developers need to make a rigorous survey to ensure as best as possible that there are no bats roosting in the site.

Obviously, the authorities require a professional independent survey, but there’s still plenty of opportunity for hacker participation by performing a ‘pre-survey’. Finding bat roosts with DIY detectors will tell us immediately if there is a problem, and give us a head start on rethinking our plans.

As can be expected, bat detectors come in all shapes and sizes, using various electrickery techniques to make them cheaper to build or easier to use. There are four different techniques most popularly used in bat detectors.

Heterodyne: rather like tuning a radio, pitch is reduced without slowing the call down.
Time expansion: chunks of data are slowed down to human audible frequencies.
Frequency division: uses a digital counter IC to divide the frequency down in real time.
Full spectrum: the full acoustic spectrum is recorded as a wav file.

Fortunately, recent advances in technology have now enabled manufacturers to produce relatively cheap full spectrum devices, which give the best resolution and the best chances of identifying the actual bat species.

DIY bat detectors tend to be of the frequency division type and are great for helping spot bats emerging from buildings. An audible noise from a speaker or headphones can prompt us to confirm that the fleeting black shape that we glimpsed was actually a bat and not a moth in the foreground. I used one of these detectors in conjunction with a video recorder to confirm that a bat was indeed NOT exiting from an old chimney pot. Phew!

Continue reading “Worried About Bats In Your Belfry? A Tale Of Two Bat Detectors” →

Make “Wireless” Earbuds Truly Wireless

October 7, 2019 by Kristina Panos 9 Comments

[Don] bought some off-brand Bluetooth earbuds online that actually sound pretty good. But while it’s true that they don’t require wires for listening to tunes, the little storage/charging box they sleep in definitely has a micro USB port around back. Ergo, they are not truly wireless. So [Don] took it upon himself to finish what the manufacturer started. Because it’s 2019, and words have meaning.

Finally, he had a use for that Qi charger he’s had lying around since the Galaxy S5 era. [Don] pried the earbud case open with a guitar pick and found a nicely laid-out charging circuit board without any black goop.

Once he located ground and Vcc pads, it was just a matter of performing a bit of surgery on the coil’s pins so he could solder wires there instead. Miraculously, the Qi coil fit perfectly inside the bottom of the case and the plastic is thin enough that it doesn’t interfere with the charging.

Want to try it for yourself? [Don]’s done an excellent job of documenting this hack, with clear pictures of every step. Soon you’ll be able to rid yourself of all those pesky USB cables.

Of course, [Don] still has to plug the charging base into the wall. If he ever wanted to add another level of wireless, he could always retrofit the base coil into his laptop.

PVC Pipe Turned Portable Bluetooth Speaker

October 7, 2019 by Tom Nardi 7 Comments

We’ve always felt that sections of PVC pipe from the home improvement store are a criminally underutilized construction material, and it looks like [Troy Proffitt] feels the same way. Rather than trying to entirely 3D print the enclosure for his recently completed portable Bluetooth speaker, he combined printed parts with a piece of four inch pipe from the Home Depot.

While using PVC pipe naturally means your final hardware will have a distinctly cylindrical look, it does provide compelling advantages over trying to print the entire thing. For one, printing an enclosure this large would have taken hours or potentially even days. But by limiting the printed parts to accessories like the face plate, handle, and caps, [Troy] reduced that time considerably. Of course, even if you’re not in a rush, it’s worth mentioning that a PVC pipe will be far stronger than anything your desktop FDM printer is likely to squirt out.

[Troy] provides links for all the hardware he used, such as the speakers, tweeters, and the Bluetooth audio board itself. The system is powered by an 1800 mAh 3S RC-style battery pack that he says lasts for hours, though he also links to a wall adapter that can be used if you don’t mind being tethered. Unfortunately it doesn’t look like he has any internal shots of the build, but given the relatively short parts list, we imagine it’s all fairly straightforward inside.

While this is certainly a respectable looking build considering it started life in the plumbing aisle, we have to admit that we’ve seen some portable Bluetooth speakers with fully 3D printed enclosures in the past that looked absolutely phenomenal. The tradeoff seems pretty clear: reuse existing materials to save time, print them if you don’t mind reinventing the wheel occasionally.

Scratch Built Media Player Channels 1980s Design

September 15, 2019 by Tom Nardi 51 Comments

No, you aren’t looking at a 30 year old Teac graphic equalizer that somebody modified. The MWA-002 Network Music Player created by [GuzziGuy] is built entirely from new components, and easily ranks up there with some of the most gorgeous pieces of homebrew audio gear we’ve ever seen. Combining modular hardware with modern manufacturing techniques, this 1980s inspired build is a testament to how far we’ve come in terms of what’s possible for the dedicated hacker and maker.

The enclosure, though it looks all the world like a repurposed piece of vintage hardware, was built with the help of a CNC router. It’s constructed from pieces of solid oak, plywood, and veneered MDF that have all been meticulously routed out and cut. Even the front panel text was engraved with the CNC and then filled in with black paint to make the letters pop.

Internally, the MWA-002 is powered by a Raspberry Pi 3 running Mopidy to play both local tracks and streaming audio. Not satisfied with the Pi’s built-in capabilities, [GuzziGuy] is using a Behringer UCA202 to produce CD-quality audio, which is then fed into a TPA3116 amplifier. In turn, the output from the amplifier is terminated in a set of female jacks on the player. Just like the stereo equipment of yore, this player is designed to be connected to a larger audio system and doesn’t have any internal speakers.

The primary display is a 256×64 Futaba GP1212A02A FVD which has that era-appropriate glow while still delivering modern features. [GuzziGuy] says it was more difficult to interface with this I2C display than the LCDs he used in the past due to the lack of available libraries, but we think the final product is proof it was worth the effort. He bought both the VFD spectrum analyzer and LED VU meter as turn-key modules, but the center equalizer controls are completely custom; with dual MCP3008 ADCs to read the state of the sliders and the Linux Audio Developer’s Simple Plugin API (LADSPA) to tweak the Pi’s audio output accordingly.

We’re no strangers to beautiful pieces of audio gear here at Hackaday, but generally speaking, most projects involve modernizing or augmenting an existing device. While those projects are to be admired, the engineering that goes into creating something of this caliber from modular components and raw building materials is really an accomplishment on a whole different level.

C++ Reverbs From A Matlab Design

June 8, 2019 by Inderpreet Singh 6 Comments

The guitar ‘Toing’ sound from the ’70s was epic, and for the first time listener it was enough to get a bunch of people hooked to the likes of Aerosmith. Reverb units were all the rage back then, and for his DSP class project, [nebk] creates a reverb filter using Matlab and ports it to C++.

Digital reverb was introduced around the 1960s by Manfred Schroeder and Ben Logan. The system consists of essentially all pass filters that simply add a delay element to the input signal and by clubbing a bunch together and then feeding them to a mixer. The output is then that echoing ‘toing’ that made the ’80s love the guitar so much. [Nebk]’s take on it enlists the help of the Raspberry Pi and C++ to implement the very same thing.

In his writeup, [nebk] goes through the explaining the essentials of a filter implementation in the digital domain and how the cascaded delay units accumulate the delay to become a better sounding system. He also goes on to add an FIR low pass filter to cut off the ringing which was consequent of adding a feedback loop. [nebk] uses Matlab’s filter generation tool for the LP filter which he includes the code for. After testing the design in Simulink, he moves to writing the whole thing in C++ complete with the filter classes that allows reading of audio files and then spitting out ‘reverbed’ audio files out.

The best thing about this project is the fact that [nebk] creates filter class templates for others to play with. It allows those who are playing/working with Matlab to transition to the C++ side with a learning curve that is not as steep as the Himalayas. The project has a lot to learn from and is great for beginners to get their feet wet. The code is available on [GitHub] for those who want to give it a shot and if you are just interested in audio effects on the cheap, be sure to check out the Ikea Reverb Plate that is big and looks awesome.