A Wireless Speaker Pair From Dead Earbuds

May 5, 2021 by Danie Conradie 23 Comments

Building a Bluetooth speaker is easy with the availability of cheap Bluetooth receivers, but surprisingly there isn’t a simple way to build a pair of truly wireless stereo speakers. [Matt] from DIY Perks realized that modern Bluetooth earbuds contain all the electronics to do just that.

Due to the popularity of these earbuds, a broken pair can be picked up very cheaply on eBay. Usually, it’s only the battery or speaker unit that give out, neither of which are required for this build. [Matt] goes through the process of taking a pair of earbuds apart, and then soldering on battery and speaker wires. The speaker wires are connected to an audio amp, which drives a mid-range and treble speaker driver, and a subwoofer. The outputs to the amp are also filtered to match the speakers. Power is provided by a set of four 18650 cells.

[Matt] housed the driver and electronics in some attractive CNC machined wood enclosures. In the video, he places a lot of emphasis on properly sealing all the gaps to get the best possible audio quality. As with all of his projects, the end result looks and performs like a high-end commercial product. We’re almost surprised that he didn’t add any brass to the speakers, as he did on his USB-C monitor or PS5 enclosure build. Continue reading “A Wireless Speaker Pair From Dead Earbuds” →

Airports Are Now AirBNBs For Honeybees

April 30, 2021 by Kristina Panos 12 Comments

In the summer of 2012, honeybees swarmed the Pittsburgh airport, probably because the conditions are favorable there. Like many airports, the tarmac is surrounded by wild, wide-open fields that exist to contain the cacophony. And a couple of nearby creeks are dotted with plenty of forage-worthy wildflowers.

Now, nearly a decade later, the airport is home to 110 colonies that house around 4 million honeybees. And they aren’t alone. Several other US airports are getting in on the apiary action, including O’Hare, Sea-Tac, and Minneapolis-St. Paul.

The relationship between honeybees and airports is a symbiotic one — the honey the bees produce is a litmus test for air pollution levels around the airport, which must fall within regulations. German airports have employed bees as ‘bio-detectives’ for over twenty years, and they give the honey away for free inside the terminal. It’s okay, though — analysis reveals that the hydrocarbon and heavy metal levels in the airport honey aren’t any higher than honey from non-industrial bees.

Given that honeybees pollinate around $15 billion in crops annually in the US alone, it’s a wonder that we aren’t doing everything possible to fight colony collapse disorder and other problems around the world. This mysterious issue has grown in the last few years, and 2020 saw highest death toll since 2016. Colony collapse disorder aside, plenty of problems persist for our fuzzy friends — pests, pesticides, pathogens, and poor nutrition.

What’s the deal with bees, anyway? How do they fly? Because they aren’t supposed to fly.

Run Out Of GPIO On Your Pi? Don’t Despair!

April 28, 2021 by Jenny List 25 Comments

When the first Raspberry Pi rolled off the production line back in 2012 it sported a 26-pin expansion header that seemed to conceal endless possibilities. A later upgrade to the 40-pin header we have today unleashed a few more precious interfaces, but even then it’s still possible to run out. This was the problem faced by [woj], who needed a PWM line to drive a cooling fan but whose other work had used everything on the header. The solution? Dive into the other connectors on board looking for an unused GPIO.

Every full-sized Pi has a connector for the camera and the LCD screen, and to operate some of the functions of those peripherals they contain a few extra GPIOs that aren’t normally used by end users. If the camera or LCD is not being used then these lines are potentially up for grabs. In particular there’s a GPIO that turns the camera on or off that’s relatively easy to solder a wire to, and it was this one that fed the PWM line.

There are of course a few other ways to find some more lines on a Pi and indeed almost any microcontroller, with one of the many types of GPIO expansion chips. This trick is a particularly simple one though. and perhaps unsurprisingly it has surfaced here before.

Helicopter Is Full Of Compressed Air

April 27, 2021 by Al Williams 14 Comments

[Tom] likes to build little helicopters and decided to build one that runs on compressed air. (Video, embedded below.) Turns out it was a little harder than he thought. Originally, he was trying for a compressed air quadcopter. He’d already worked with an air turbine, but putting on a vehicle that can lift itself into the air turns out to have a lot of hidden gotchas.

[Tom] went through a lot of design considerations to arrive at the helicopter design. He considered counter-rotating props, but there were a host of problems involved. He finally settled on a single prob with a tail rotor that resides on the far end of a long boom to allow the resulting lever arm to reduce the work required of the tail rotor.

Continue reading “Helicopter Is Full Of Compressed Air” →

Ooohhh, That Smell: Arduino Monitors Air Quality

April 23, 2021 by Al Williams 26 Comments

According to [Dr. Tom Lehrer’s] song Pollution, “Wear a gas mask and a veil. Then you can breathe, long as you don’t inhale!” While the air quality in most of the world hasn’t gotten that bad, there is a lot of concern about long-term exposure to particulates in the air causing health problems. [Ashish Choudhary] married an Arduino with a display and a pollution sensor to give readings of the PM2.5 and PM10 levels in the air.

The sensor uses a laser diode and a photodiode to detect and count particles, while a fan moves air through the system. If you aren’t up on pollution metrics, PM2.5 is a count of very fine particles (under 2.5 microns) and PM10 is a count of particles for 10 microns. You can find a datasheet for the device online.

Continue reading “Ooohhh, That Smell: Arduino Monitors Air Quality” →

Hacking An Air Assist For The Ortur Laser

April 21, 2021 by Al Williams 13 Comments

Getting great results from a laser cutter takes a bit of effort to make sure all of the settings are just right. But even then, if the air between the material and the laser source is full of smoke and debris it will interfere with the laser beam and throw off the results. The solution is to add air assist which continuously clears that area.

Earlier this year I bought an Ortur laser engraver/cutter and have been hacking on it to improve the stock capabilities. last month I talked about putting a board under the machine and making the laser move up and down easily. But I still didn’t have an air assist. Since then I found a great way to add it that will work for many laser cutter setups.

I didn’t design any of these modifications, but I did alter them to fit my particular circumstances. You can find my very simple modifications to other designs on Thingiverse. You’ll also find links to the original designs and you’ll need them for extra parts and instructions, too. It is great to be able to start with work from talented people and build on each other’s ideas.

Continue reading “Hacking An Air Assist For The Ortur Laser” →

Orphaned IoT Sleep Tracker Resurrected As An Air Quality Monitor

April 10, 2021 by Anool Mahidharia 9 Comments

If you have a Hello Sense sleep tracking device lying around somewhere in your drawer of discards, it can be brought back to life in a new avatar. Just follow [Alexander Gee]’s instructions to resurrect the Hello Sense as an IoT air quality data-logger.

In 2014, startup “Hello” introduced the Sense, an IoT sleep tracking device with a host of embedded sensors, all wrapped up in a slick, injection molded spherical enclosure. The device was quite nice, and by 2015, they had managed to raise $21M in funding. But their business model didn’t seem sustainable, and in 2017, Hello shut shop. Leaving all the Sense devices orphaned, sitting dormant in beautifully designed enclosures with no home to dial back to.

The original Sense included six sensors: illumination, humidity, temperature, sound, dust / particulate matter on the main device, and motion sensing via a separate Bluetooth dongle called the Pill. [Alexander] was interested in air quality measurements, so only needed to get data from the humidity/temperature and dust sensors. Thankfully for [Alexander], a detailed Hello Sense Teardown by [Lindsay Williams] was useful in getting started.

The hardware consisted of four separate PCB’s — power conditioning, LED ring, processor, and sensor board. This ensured that everything could be fit inside the orb shaped enclosure. Getting rid of the LED ring and processor board made space for a new NodeMCU ESP8266 brain which could be hooked up to the sensors. Connecting the NodeMCU to the I2C interface of the humidity/temperature sensor required some bodge wire artistry. Interfacing the PM sensor was a bit more easier since it already had a dedicated cable connected to the original processor board which could be reconnected to the new processor board. The NodeMCU board runs a simple Arduino sketch, available on his Git repo, to gather data and push it online.

For the online data display dashboard, [Alexander] found a nice solution by [Nilhcem] for home monitoring using MQTT, InfluxDB, and Grafana. It could be deployed via a docker compose file and have it up and running quickly. Unfortunately, such projects don’t usually succeed without causing some heartburn, so [Alexander] has got you covered with a bunch of troubleshooting tips and suggestions should you get entangled.

If you have an old Sense device lying around, then this would be a good way to put it some use. But If you’d rather build an air-quality monitor from scratch, then try “Building a Full-Fat Air-Quality Monitor” or “An Air-quality Monitor That Leverages the Cloud“.