Recognising Bird Sounds With A Microcontroller

Machine learning is an incredible tool for conservation research, especially for scenarios like long term observation, and sifting through massive amounts of data. While the average Hackaday reader might not be able to take part in data gathering in an isolated wilderness somewhere, we are all surrounded by bird life. Using an Arduino Nano 33 BLE Sense and an online machine learning tool, a team made up of [Errol Joshua], [Ajith KJ], [Mahesh Nayak], and [Supriya Nickam] demonstrate how to set up an automated bird call classifier.

The Arduino Nano 33 BLE Sense  is a fully featured little dev board that features the very capable NRF52840 microcontroller with Bluetooth Low Energy, and a variety of onboard sensors, including a microphone. Training a machine learning model might seem daunting to many people, but online services like Edge Impulse makes the process very beginner-friendly. Once you start training your own models for specific applications, you quickly learn that building and maintaining a high quality dataset is often the most time-consuming part of machine learning. Fortunately for this use case, a massive online library of bird calls from all over the world is available on Xeno-Canto. This can be augmented with background noise from the area where the device will be deployed to reduce false-positives. Edge Impulse will train the model using the provided dataset, and generate a library that can be used on the Arduino with one of the provided sample sketches to log and send the collected data to a server. Then comes the never ending process of iteratively testing and improving the recognition model. Edge Impulse is also compatible with more powerful devices such as the Raspberry Pi and Jetson Nano if you want more intensive machine learning models.

We’ve also seen the exact same setup get used for smart baby monitor. If you want to learn more, be sure to watch at [Shawn Hymel]’s talk from the 2020 Remoticon about machine learning on microcontrollers. Continue reading “Recognising Bird Sounds With A Microcontroller”

Evan Doorbell’s Telephone World

Ah, phone phreaking. Some of us are just old enough to remember the ubiquity of land lines, but just young enough to have missed out on the golden years of phreaking. There’s something nostalgic about the analog sounds of the telephone, and doubly so when you understand what each click and chunk sound means. If this wistful feeling sounds familiar, then you too will appreciate [Evan Doorbell] and his recordings of 1970s telephone sounds. He’s been slowly working through his old recordings, and compiling them into a series of narrated tours of the phreak subculture.

[Evan]’s introduction to exploring the phone system started from a misdialed number, and an odd message. He describes that recorded “wrong number” message as being very different from the normal Ma Bell messages — this one was almost sultry. What number did he have to dial to hear that unique recording again? What follows is a youth spent in pursuit of playing with the phone system, though it would be more accurate to say the “phone systems”, as discovering the differences between the various local phone exchanges is a big part of the collection. Check out the first tape in the series after the break.
Continue reading “Evan Doorbell’s Telephone World”

See-Through Carburetor Gives A Clear Demonstration

Carburetors have been largely phased out on most automobiles, but for a century they were the standard, and still are on many smaller engines. Armed with a high-speed camera and with the help of his father, [Smarter Every Day] investigates these devices by experimenting with a DIY see-through carburetor connected to a real engine.

The purpose of a carburetor is to mix gasoline and oxygen to the correct ratio for combustion inside the engine. Gasoline flow from the tank to the bowl, from where gets sucked into the venturi. The choke valve adjusts the amount of air entering the carb, while the throttle controls the amount of air-fuel mixture entering the engine. It appears that the carburetor was made from a resin 3D printed body and manifold, with an acrylic cover and PLA throttle and choke valves. It was attached to a single-cylinder engine.

The high-speed footage is incredible, and clearly shows the operation of the carburetor and makes it incredibly easy to understand. If you’re interested, he also uploaded a second video with almost 80 minutes of detailed footage.

[Smarter Every Day]’s infectious curiosity has led to numerous fascinating projects, including a supersonic baseball canon and the backward bicycle.

Continue reading “See-Through Carburetor Gives A Clear Demonstration”

E-Paper Pocket Map Goes Where Your Phone Can’t

It’s easy to take for granted the constantly-connected, GPS-equipped, navigation device most of us now carry in our pockets. Want to know how to get to that new restaurant you heard about? A few quick taps in Google Maps, and the optimal route given your chosen transportation method will be calculated in seconds. But if you ever find yourself lost in the woods, you might be in for a rude awakening. With no cell signal and a rapidly dwindling battery, that fancy smartphone can quickly end up being about as useful as a rock.

Enter the IndiaNavi, a modernization of the classic paper map that’s specifically designed to avoid the pitfalls that keeps your garden variety smartphone from being a reliable bushcraft tool. The color electronic paper display not only keeps the energy consumption low, but has unbeatable daylight readability. No signal? No problem, as the relevant maps are pre-loaded on the device.

Besides the 5.65 inch e-paper display from Waveshare, the India Navi features a L96 M33 GPS receiver and ESP32-WROOM-32 microcontroller. The 3D printed enclosure that holds the electronics and the lithium pouch battery that powers them is still in the early stages, but we like the book-style design. The focus on simplicity and reliability doesn’t end with the hardware, either. The software is about a straightforward as it gets: just boot the IndiaNavi and you’re presented with a map that shows your current position.

With the rise of easily hackable e-paper displays, we’re excited to see more concepts like the IndiaNavi which challenge our ideas on how modern electronics have to function and be used.

USB Power Bank’s Auto-Off Becomes Useful Feature In Garage Door Remote

For devices that are destined for momentary and infrequent use as well as battery power, some kind of power saving is pretty much a required feature. For example, when [PJ Allen] turned two ESP8266-based NodeMCU development boards into a replacement wireless remote garage door opener, a handy USB power bank ended up serving as a bit of a cheat when migrating the remote away from the workbench. Instead of moving the board from USB to battery power and implementing some kind of sleep mode or auto-off, [PJ Allen] simply plugged in a USB power bank and let it do all the work.

This is how the feature works: some USB power banks turn themselves off unless they detect a meaningful current draw. That means that if the power bank is charging a phone, it stays on, but if it’s only lighting up a few LEDs, it’ll turn itself off. This feature can be a frustrating one, but [PJ Allen] realized that it could actually be useful for a device like his garage door remote. Turning on the power bank delivers 5 V to the NodeMCU board and allows it to work, but after about fifteen seconds, the power bank turns itself off. Sure, strapping a power bank to the remote makes the whole thing bigger than it needs to be, but it’s a pretty clever use of the minimum load as an effortless auto-off feature.

The NodeMCU boards in [PJ Allen]’s DIY remote use ESP-NOW for their wireless communications, a nifty connectionless protocol from Espressif that we’ve seen used in other projects as well, such as this ESP32-based walkie-talkie.

Linux Fu: PDF For Penguins

PostScript started out as a programming language for printers. While PostScript printers are still a thing, there are many other ways to send data to a printer. But PostScript also spawned the Portable Document Format or PDF and that has been crazy successful. Hardly a day goes by that you don’t see some kind of PDF document come across your computer screen. Sure, there are other competing formats but they hold a sliver of market share compared to PDF. Viewing PDFs under Linux is no problem. But what about editing them? Turns out, that’s easy, too, if you know how.

GUI Tools

You can use lots of tools to edit PDF files, but the trick is how good the results will look. Anything will work for this: LibreOffice Draw, Inkscape, or even GIMP. If all you want to do is remove something with a white box or make an annotation, these tools are usually great, but for more complicated changes, or pixel-perfect output, they may not be the right tool.

The biggest problem is that most of these tools deal with the PDF as an image or, at least, a collection of objects. For example, columns of text will probably turn into a collection of discrete lines. Changing something that causes a line to wrap will require you to change all the other lines to match. Sometimes text isn’t even text at all, but images. It largely depends on how the creator made the PDF to begin with. Continue reading “Linux Fu: PDF For Penguins”

Lightwave Multimeter Teardown

You tend to think of test equipment in fairly basic terms: a multimeter, a power supply, a signal generator, and an oscilloscope. However, there are tons of highly-specialized test equipment for very specific purposes. One of these is the 8163A “lightwave multimeter” and [Signal Path] tears one part for repair in a recent video that you can see below.

If you’ve never heard of a lightwave multimeter, don’t feel bad. The instrument is a measuring system for fiber optics and, depending on the plugins installed, can manage a few tests that you’d usually use an optical power meter, a laser or light source, and some dedicated test jigs to perform. Continue reading “Lightwave Multimeter Teardown”