Electronic Drum Toy Built From Scratch

January 11, 2022 by Lewin Day 9 Comments

Drum kits used to be key to any serious band, however, these days, much of our music is created on computer or using a drum machine instead. [spanceac] has built a simple example of the latter, using a microcontroller to build a basic sample-based drum toy.

The brains of the operation is the STM32F100VET6B, which comes complete with a 12-bit DAC for outputting sound. It’s also got a healthy 512 KB of flash, enabling it to store the drum samples onboard without the need for extra parts. Samples are stored at a sample rate of 22,050 Hz in 16-bit resolution – decent quality for a tiny little build, even if the DAC chops that back down to 12-bits later.

[spanceac] was sure to code proper mixing into the drum machine, so that triggering a second sample doesn’t stop the first one playing. With a kick, snare, two toms, and crash and ride samples onboard, there’s plenty to get a solid beat going on the kit. It’s all built up on a small PCB with tactile buttons to activate each sound.

The demo video shows the kit performing ably; it’s not clear if there’s an issue with latency on the samples or that’s just from the difficulty of [spanceac] playing one-handed. If the former, likely some code tweaks or simply trimming silence at the start of samples would be all that was needed. Overall, it’s a neat little groovebox, and the kind of thing that’s great fun to use when jamming with other musicians. Video after the break.

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The Atari Punk Console, Now With More Vacuum Tubes

January 11, 2022 by Dan Maloney 7 Comments

Most of us have beheld the sonic glory of an Atari Punk Console, that lo-fi synth whose classic incarnation is a pair of 555 timers set up to warble and bleep in interesting ways. Very few of us, however, have likely seen an APC built from 555s that are made from vacuum tubes.

It’s little surprise to regular readers that this one comes to us by way of [David] at Usagi Electric, who hasn’t met a circuit that couldn’t be improved by realizing it in vacuum tubes. His “hollow-state” Atari Punk Console began with the 18-tube version of the 555 that he built just for fun a while back, which proved popular enough that he’s working on a kit version, the prototype of which served as the second timer for the synth. With 32 tubes aglow amid a rats-nest of jumpers, the console managed to make the requisites sounds, but lacked a certain elegance. [David] then vastly simplified the design, reducing the BOM to just four dual-triode tubes. Housed on a CNC milled PCB in a custom wood box, the synth does a respectable job and looks good doing it. The video below shows both versions in action, as well as detailing their construction.

As cool as a vacuum tube synth may be, we realize that not everyone goes for the hot glass approach. No worries — plenty of silicon Atari Punk Consoles to choose from here. There’s one built into a joystick, a circuit sculpture version complete with mini-CRT, or even eight APCs teamed up with MIDI control.

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Portable PI Powered Music Player

January 9, 2022 by Matthew Carlson 13 Comments

There was a brief time in the early 2000s when we carried cellphones, wallets, keys, and a bespoke digital media player loaded with a small selection of our music libraries. Devices like iPods, Zunes, Sandisk Sansa, and iRiver. Then as cell phones gained more storage and processing power, the two devices became one, and audio players slipped to obscurity as sports accessories. Perhaps in that vein, [BalderDragonSlayer] made his own Raspberry Pi-powered media player.

The device was cobbled together using a Raspberry Pi Zero, an Adafruit OLED bonnet, a LiPo charger, and a cheap USB DAC. The interface software is written in python, which has all your usual player controls, using the directional joystick and two pushbuttons on the bonnet. DietPi is a slimmed-down Linux that offers an impressively fast boot time, which is why it was picked for this project. The case was a simple project case with some holes dremeled into the face for the screen and buttons.

It is a wonderful little project that seems wonderful for walks in the park. This isn’t the first Pi-powered media player we’ve seen before. But we’re hoping we see more in the future.

A CMOS Ring Modulator Pedal

December 24, 2021 by Jenny List 9 Comments

Earlier this year, we featured an unusual radio receiver that took the very traditional superhetrodyne design and implemented it in an unexpected fashion without any inductors, using instead a combination of 74HC logic chips and op-amps. Its designer [acidbourbon] remarks that the circuit bears a striking resemblance to a ring modulator,so has taken it down that path by producing a 74HC based ring modulator guitar pedal.

In both circuits, a 74HC4046 phase-locked loop chip serves as an oscillator, driving a 74HC4051 analogue switch chip that performs the mixer task. The extra-op-amp filter and demodulator circuitry from the radio is omitted, and the oscillator frequency moved down to the audio range. The result can be heard in the video, and we probably agree with him that it’s not quite the same as a classic ring modulator. This lies in the type of mixer, the diodes used in a traditional circuit have a forward voltage to overcome before they start or end conducting, while the CMOS switch chip does so immediately on command.

The 4000 series CMOS and their descendants are a fascinating family with many unexpected properties that our colleague Elliot Williams has gone into detail with for his Logic Noise series. Meanwhile take a look at our coverage of the original radio.

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DIY bagpipe made from a latex glove and some straws.

Ring In The New Year With DIY Bagpipes

December 23, 2021 by Kristina Panos 14 Comments

Remember early on in the pandemic when people would don protection just short of a full hazmat suit to go out, and wore rubber gloves to the grocery store? Was that just us? The point is, we are surely not alone in having an excess of latex gloves left over, and pitifully few uses for them aside from the usual — gross jobs around the house, and making hand-shaped ice cubes.

Well, here’s something a little more fun: DIY bagpipes. No matter how you feel about the sounds they produce, the way that bagpipes work is pretty interesting. In the video embedded after the break, [Charlie Engelman] shows us how they work and compares them to saxophonist Kenny G’s little jazz mouth.

See, Mr. G can circular breathe, which means he can hold a note for as long as he wants. Basically, he is able to keep a reserve of air in his mouth for playing the thing, while at the same time inhaling new air.

If we bring this back around to bagpipes, the bladder is akin to Kenny G’s mouth. It always contains air, so it perpetually releases air through the sound pipes that stick up. In the case of the glove pipe, the glove is the bladder, and the pipes are made of drinking straws. Check it out after the break — we think the sound is far more tolerable than real bagpipes.

We’ve seen bagpipes made from common household items before (if you consider a couple of plastic recorders to be common household items), and we’ve also seen real bagpipes go electromechanical.

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Active Pickguard Makes For A Great Guitar Mod

December 13, 2021 by Lewin Day 6 Comments

Much discussion goes on in the guitar world about the best hardware to use. Whether its pickups, how they’re positioned, or even the specific breed of wood on the fretboard, it’s all up for debate. [Eli Hughes] put much of that to one side, however, with his innovative “Active Pickguard” project.

The project reimagines the electronics of an electric guitar from the ground up. Instead of typical electromagnetic pickups, six individual piezo pickups are built into the bridge – one for each individual string. The outputs of these pickups is conditioned and then read by the analog-to-digital converter of a Freescale Kinetis K40. The DSP-capable chip can then be used to apply all manner of effects. [Eli] demonstrates the guitar providing an uncanny imitation of an acoustic guitar, before demonstrating jazz and overdrive tones as well.

The Kinetis chip also features touch-sensitive inputs, which [Eli] put to good use. All the hardware is built into a pickguard-shaped PCB, complete with touch controls for things like volume, tone, and choosing different DSP patches.

Unlike a regular guitar, this one needs a power supply, which it gets via a CAT 6 cable, in place of the usual 1/4″ guitar cable. The CAT 6 also carries audio out to a converter box which allows the audio to be output to a regular guitar amplifier.

It’s a neat build, and one that shows just how modern technology can reimagine a simple 20th-century instrument. DSP really is magic, after all. Video after the break.

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DIY Analog Synth Looks Like Fun

December 10, 2021 by Rich Hawkes 11 Comments

The relative ease of building the individual components that make up an analog synth make it very tempting to DIY your own. That’s what [Albert Nyström] did and the result is this great looking, and great sounding, analog synth.

The VCOs in his monosynth are based around the AS3340 VCO chip, which is a clone of the Curtis Electromusic Specialties‘ CEM3340 chip (used in machines such as the Oberheim OB-Xa, the Roland Jupiter-6, and the Sequential Circuits Prophet-5 among others.) The voltage controlled filters are based on Moritz Klein’s VACTROL based VCF circuits, and the envelopes based on Thomas Henry’s 555 envelope circuits (Google searches will dig those up pretty quickly, as well as schematics for builds using the CEM chip.) Finally, the keyboard is a donor from an Arturia Keystep. While there are no step-by-step build instructions, or a schematic, we do have some info about the instrument. As you can see from some of the gut shots, it should be fairly easy to figure how [Albert] has put everything together. Or not.

Even if the internals are a bit wild, the end result is a great looking monophonic synth that does pretty much everything you’d need. If you feel the itch to wire a bunch of components together and make one yourself, there are messier ways to go about it. Or maybe you’d prefer to go the digital route? Either way, synths are a ton of fun to build and to play.

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