What Does The Bat Say? Tune In With This Heterodyne Detector

Bats are fascinating animals, and despite all the myth and creepiness surrounding them, they really remind one more of a drunk bird lost in the night sky than the blood-sucking creature they’re often made out to be. Of course, some really fall into that category, and unlike actual birds, bats don’t tend to grace us with their singsong — at least not in ways audible for us humans. But thanks to bat detectors, we can still pick up on it, and [Marcel] recently built a heterodyne bat detector himself.

Bat Detector in its enclosure
The bat detector (and an insight to the beauty of German language, where a bat is a flutter mouse)

The detector is made with a 555, an MCP6004 op amp, and a 4066 analog switch — along with a bunch of passives — and is neatly packed into a 3D-printed case with a potentiometer to set the volume and center frequency for the detection. The bat signal itself is picked up by a MEMS microphone with a frequency range [Marcel] found suitable for the task. His write-up also goes in all the mathematics details regarding heterodyning, and how each component plays into that. The resulting audio can be listened to through a headphone output, and after putting together an adapter, can also be recorded from his smartphone. A sample of how that sounds is added in his write-up, which you can also check out after the break.

In case you want to give it a try yourself, [Marcel] put all the design files and some LTSpice simulations on the project’s GitHub page. If you are curious about bat detectors in general and want to read more about them, follow [Pat Whetman] down that rabbit hole, or have a look at this one made in Python for something more software-focused.

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Synthesizing Mother Nature’s Sounds Like You’ve Never Seen Before

We’ve all heard the range of sounds to be made electronically from mostly discrete components, but what [Kelly Heaton] has achieved with her many experiments is a whole other world, the world of nature to be exact. Her seemingly chaotic circuits create a nighttime symphony of frogs, crickets, and katydids, and a pleasant stroll through her Hackaday.io logs makes how she does it crystal clear and is surely as delightful as taking a nocturnal stroll through her Virginia countryside.

Homemade piezo buzzer with amplifierThe visual and aural sensations of the video below will surely tempt you further, but in case it doesn’t, here’s a taste. When Radio Shack went out of business, she lost her source of very specific piezo buzzers and so had to reverse engineers theirs to build her own, right down to making her own amplifiers on circular circuit boards and vacuum forming and laser cutting the housings. For the sounds, she starts out with a simple astable multivibrator circuit, demonstrating how to create asymmetry by changing capacitors, and then combining two of the circuits to get something which sounds just like a cricket. She then shows how to add katydids which enhance the nighttime symphony with percussive sounds much like a snare drum or hi-hat. It’s all tied together with her Mother Nature Board built up from a white noise generator, Schmitt trigger, and shift registers to turn on and off the different sound circuits, providing a more unpredictable and realistic nighttime soundscape. The video below shows the combined result, though she admits she’ll never really be finished. And be sure to check out even more photos and videos of her amazing work in the gallery on her Hackaday.io page.

For the more familiar range of sounds, though no less varied, check out our own [Elliot William’s] series, Logic Noise, where he takes us through an extensive exploration of a less Mother Naturely soundscape.

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Biomimicry Challenge: Hack Like Mother Nature, Win $100k

Hot on the heels of the 2015 Hackaday prize, with its theme of “Build stuff that matters”, comes another opportunity for hackers to make a difference. But you’ve got to think like Mother Nature for the 2016 Biomimicry Global Design Challenge.

wind chillThe aim of this challenge is to transform the global food system using sustainable approaches that emulate natural process. Entries must address a problem somewhere in the food supply chain, a term that could apply to anything from soil modification to crop optimization to harvest and storage technologies. Indeed, the 2015 winner in the Student category was for a passive refrigeration system to preserve food in undeveloped areas. It’s a clever two-stage system that uses an evaporative cooling loop inspired by the way an elephant’s ears cool the giant beast, and by use of a wind-capturing funnel that mimics how animals as diverse as termites and meerkats cool their nests.

In addition to the Student category, the challenge has an Open category for teams of any composition. Up to 10 teams will be selected from the Open category to proceed to the Accelerator phase, where they’ll receive support for a six to nine month development of their design into a marketable product. The winner will be awarded the $100,000USD Ray of Hope prize, endowed by the Ray C. Anderson Foundation.

We’d love to see someone from the Hackaday community take home the 2016 prize, and there are plenty of 2015 Hackaday Prize entries that may be eligible. The deadline for submissions is 11 May 2016, so get a team together and get to work.

Animate Your Artichoke With A Lathe And Camera

Spirals, fractals, and even bone length proportions whisper of a consistent ratio woven into the universe. Math is hidden in the fabric of things, and when this fact is observed in art, magic happens. Professor, artist, and inventor [John Edmark] draws inspiration from geometric patterns found in nature and builds sculptures using the golden ratio as a standard for design. In this project, he expresses these characteristics through animated biomorphic zoetropes.

goldenratio2[John] modeled several 3D sculptures in Rhino containing similar geometric properties to those found in pinecones and palm tree fronds. As the segments grow from those objects in nature, they do so in approximately 137.5 degree intervals. This spacing produces a particular spiral appearance which [John] was aiming to recreate. To do so, he used a Python script which calculated a web of quads stretched over the surface of a sphere. From each of the divisions, stalk-like protrusions extend from the top center outward. Once these figures were 3D printed, they were mounted one at a time to the center of a spinning base and set to rotate at 550 RPM. A camera then films the shape as it’s in motion at a 1/2000 sec frame rate which captures stills of the object in just the right set of positions to produce the illusion that the tendrils are blooming from the top and pouring down the sides. The same effect could also be achieved with a strobe light instead of a camera.

[John] has more information on his instructables page. He also provides a video of this trick working with an actual artichoke; one of the living examples of the golden ratio which this project was inspired by. Thank you, [Charlie Nordstrom] for helping him document these awesome sculptures and for telling us about them!

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