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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An Arduino Watch Without A Clock

When you show up at a party wearing this bare PCB watch, there are effectively two possible reactions you might receive from the other people there. Either they are going to snicker at the nerd who’s wearing a blinking circuit board on their wrist in public, or they are going to marvel at the ridiculously low part count. We’ll give you one guess as to which reaction you’d likely get at any event Hackaday is involved in.

Designed and built by [Electronoobs], this extremely simple watch consists of a ATmega328P microcontroller, a dozen LEDs with their associated 200 Ω resistors, and a battery. There’s also a single push button on the front which is used to not only set the watch, but turn the LEDs on when you want to check the time. Short of dropping down to one LED and blinking out the time, it’s hard to imagine a timepiece with fewer components than this.

You’re probably wondering how [Electronoobs] pulled this off without an external clock source for the ATmega328P chip. The chip actually has an internal 8 MHz oscillator that can be used, but you need to flash the appropriate bootloader to it first. Accordingly, the backside of the PCB has both SPI and a UART solder pads for external bootloader and firmware programming.

As you might expect, there’s a downside to using the internal oscillator: it’s not very good. The ATmega328P spec sheet claims a factory calibrated accuracy of ±10%, and [Electronoobs] has found that equates to a clock drift of around 15 seconds per day. Not exactly great, but considering the battery only lasts for two days anyway, it doesn’t have much of an impact in this case.

Compared to other “analog” LED watches we’ve seen, the simplicity of this build is really quite remarkable. The closest competitor we’ve seen so far is this slick binary watch.

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A Crystal Oscillator For A Stable Bench Reference

[Paul] likes a precise oscillator. His recent video shows a crystal oscillator with a “watch crystal” and a CMOS counter, the CD4060. Using such a circuit can produce very stable frequencies and since the 32.768 kHz crystal is a power of 2, you get nice divisions out of the counter.

We’ve seen the same trick done with decade counters (like the 4518B) to divide by 10 instead of powers of two to make frequency standards. A 1 MHz crystal can easily generate 100 kHz, 10 kHz, etc.

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A Graph Plotting Metal Detector

Metal detectors can be a great source of fun, and occasionally even found wealth. They allow the detection of metal objects at a distance, enabling hidden treasures to be discovered. They’re also highly critical to the work of minesweepers and unexploded ordnance disposal teams. [Andrius] wanted to add such a device to his kit when motorcycling through the woods of Lithuania, and thus decided to undertake a build of his own.

The detector is a thoroughly modern one – fans of the 555 may want to look away now. A Collpits oscillator, built from two transistors, is used to generate a frequency that is passed through the detection coil. This frequency is measured by an Arduino that plots a graph of the received frequency on an OLED display. As the coil is passed near metal objects, the oscillator frequency changes, and this is visible on the frequency plot on-screen.

Not only is it a quick and easy build that is achievable from what are now junkdraw components, it’s also one that would be readily usable by the hearing-impaired, too. It’s a great project to tackle if you’re looking to get to grips with basic oscillators, frequency measurement, or just microcontroller programming in general.

Still need more inspiration? We’ve seen a similar concept executed before.

The Colpitts Oscillator Explained

The Colpitts oscillator is a time-tested design — from 1918. [The Offset Volt] has a few videos covering the design of these circuits including an op-amp and a transistor version. You can find the videos below.

You can tell a Colpitts oscillator by the two capacitors in the feedback circuit. The capacitors form an effective capacitance for the circuit (assuming you have C1 and C2) of the product of C1 and C2 divided by the sum of the two capacitors. The effective capacitance and the inductance form a bandpass filter that is very sharp at the frequency of interest, allowing the amplifier to build up oscillations at that frequency.

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Dive Inside This Old Quartz Watch

In an age of smartwatches, an analog watch might seem a little old-fashioned. Whether it’s powered by springs or a battery, though, the machinery that spins those little hands is pretty fascinating. Trouble is, taking one apart usually doesn’t reveal too much about their tiny workings, unless you get up close and personal like with this microscopic tour of an analog watch.

This one might seem like a bit of a departure from [electronupdate]’s usual explorations of the dies within various chips, but fear not, for this watch has an electronic movement. The gross anatomy is simple: a battery, a coil for a tiny stepper motor, and the gears needed to rotate the hands. But the driver chip is where the action is. With some beautiful die shots, [electronupdate] walks us through the various areas of the chip – the oscillator, the 15-stage divider cascade that changes the 32.768 kHz signal to a 1 Hz pulse, and a remarkably tiny H-bridge for running the stepper. We found that last section particularly lovely, and always enjoy seeing the structures traced out. There are even some great tips about using GIMP for image processing. Check out the video after the break.

[electronupdate] knows his way around a die, and he’s a great silicon tour guide, whether it’s the guts of an SMT inductor or a Neopixel close-up. He’s also looking to improve his teardowns with a lapping machine, but there are a few problems with that one so far.

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GPS Disciplined Oscillators

[Martin Lorton] acquired a GPS-disciplined oscillator. He wasn’t quite sure what to do with it, so he did a little research and experimentation. If you have about two hours to spare, you can watch his videos where he shares his results (see below).

The unit he mainly looks at is a Symmetricom TrueTime XL-DC, and even on eBay it ran over $500. However, [Martin] also looks at a smaller unit that is much more affordable.

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