Mechanical Tremolo Does Things The Old-School Way

June 12, 2019 by Lewin Day 21 Comments

The word “tremolo” has a wide variety of meanings in the musical lexicon. A tremolo effect, in the guitar community at least, refers to a periodic variation in amplitude. This is often achieved with solid state electronics, but also recalls the sounds created by Hammond organs of years past with their rotating Leslie speakers. [HackaweekTV] decided to do things the old fashioned way, building a mechanical tremolo effect of his own (Youtube link, embedded below).

Electronically, the signal is simply passed through a linear audio potentiometer. The effect is generated by rapidly cycling this potentiometer up and down. The motion is achieved through a geared motor salvaged from a Roomba, which turns a cam. A sprung follower sits on top of the cam, and is attached to the potentiometer.

There were some challenges in development. Rigidity of the frame was an issue, and the follower had issues with snagging on the cam. However, with some careful iteration they were able to get everything up and running. The final project sounds great, and with the amplifier turned up, there’s no need to worry about the sound of the moving parts.

Naturally, you can always build a tremolo with a 555 instead. Video after the break.

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The Pianist Octopus

June 12, 2019 by Brian Benchoff 13 Comments

MIDI has been around for nearly forty years, but what do you do if you have an old ‘toy’ keyboard without MIDI? Or really any way to make it sound good? You could turn it into a player piano, and that’s exactly what [Alessandro] did with an old toy keyboard. It’s The Pianist Octopus, and it is perhaps the coolest, neatest pianist you’ve ever seen.

This build uses 24 individual 9 gram hobby servos, which of course means you need to drive those servos somehow. There are plenty of ways to attach a few servos to an Arduino board, but when you need to drive 24 servos, your options become somewhat limited. The electronics consist mostly of a Fishino Octopus, an Arduino shield that can drive sixteen individual servos. Slap two of these shields on an Arduino and you have something that will drive twenty four servos.

The mechanical part of the build consists of a 3D printed frame that allows the servos to be mounted across an arc, something like a harp. Metal rods connect the servos to tentacle-shaped actuators. These were designed in Google SketchUp and printed in PLA.

Attached to these servos and Arduino is a character LCD and a few buttons that allow the user to cycle through a few functions. The play button plays the current melody (based on old Nokia ringtones, by the way), a few more buttons adjust the position of the individual servos, and there’s another button to stop playing. Since this is a complete electronic-to-mechanical interface for a toy piano, a MIDI-in port isn’t out of the question; all a MIDI implementation would need to do is move a servo down on a note on event and move it back up on the note off event.

Hack My Wired Heart

June 12, 2019 by Helen Leigh 3 Comments

Liner notes? Passé. In Berlin, the release of a special edition synth-wave record came with an accompanying experimental synthesizer called Wired Heart.

At the core of this adorable heart-shaped synth, designed by music technology enthusiast [tobi tubbutec], is the classic 74HCT14 chip with six Schmitt trigger oscillators. The bright red PCB has eight gold touch and humidity sensing pads that activate and modulate these oscillators. As well as changing the sounds by playing with pressure and conductive liquids you can use the six sets of header pins on board to plug in your own components for noisy experimentation. Wired Heart ships with LEDs, photoresistors and a potentiometer, but we’ve also plugged our own DIY fabric pressure sensors into this synth to make some excellent electronic sounds.

In the Hackaday.io post linked above, [tobi tubbutec] walks us through a number of the circuit design decisions he made while prototyping his “cardiotronic human-touch hexoscillatric stereo esoteric snythespacer”. We enjoyed his creative and sometimes unconventional designs, from his inclusion of non-functioning traces for aesthetic reasons to his chosen method of hard syncing — injecting a small pulse of one oscillator into the other. If you want to examine his layout in more detail, [tobi tubbutec] has helpfully included the KiCad schematic file in his write up.

This adorable, hackable synth caught our eye at this year’s SuperBooth — an annual indie electronic music conference in Berlin that’s well worth checking out if odd noises and handmade electronics are your thing — but it’s recently been listed on Tindie too. To listen to the upbeat synth-wave record Wired Heart originally shipped with, visit the artist Hyboid’s bandcamp.

If you’re interested in experimental musical instruments and synthy chip tune you’ll also love [jarek319]’s Sega Genesis synthesiser.

Check out a demo of the Wired Heart synth in the video after the break.

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Vintage Speech Synthesizer Croons The Oldies

June 11, 2019 by Dan Maloney 33 Comments

If you listened to the National Weather Service Weather Radio in the US about 25 years ago, you’ll no doubt remember [Perfect Paul], one of the synthesized voices used to read current conditions and weather forecasts. The voice came from a DECtalk DTC01, a not inexpensive voice synthesizer first made in 1984 that also gave voice to [Stephen Hawking] for many years.

Long obsolete, the DECtalk boxes have a devoted following with hobbyists who like to stretch what the device can do. Some even like to make it sing, after a fashion, and [Michael] decided that making a DECtalk sing “Xanadu”, the theme song from the 1980 [Olivia Newton-John] musical extravaganza, was a good idea. Whether it actually was is debatable, and we’ll take exception with having that particular ditty stuck in our head as a result, but we don’t judge except on the merits of the hack.

It’s actually easy if you have a DECtalk; the song is a straight ASCII file with remarkably concise instructions on which phonemes the box needs to generate. Along with inflection, tone, and timing instructions, the text file looks almost completely unlike English while still somehow being readable. The DECtalk accepts the file over RS-232, which would be easy enough to do with a modern computer, but [Michael] upped his game a bit by using a TRS-80 Model 100 computer as a serial terminal. The synthesized song is in the video below, with the original included for reference by those who didn’t ~~experience~~ endure the late disco-era glory days.

DECtalks seem pretty rare in the wild, so we appreciate this glimpse at what they can do. There are other retro speech synthesizer hacks, though: the simulated walnut goodness of the Votrax and the MicroVox come to mind, as does the venerable TI Speak and Spell.

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Circuit Bending Those Adorable Voices

June 8, 2019 by Mike Szczys 8 Comments

Leapfrog make some pretty awesome kids electronics. Especially admirable is the low cost, the battery life, and the audio quality of these devices. This circuit bending hack takes advantage of those audio circuits by turning the Alphabet Pal into your lead vocalist. The performance in the demo video begins with some impressive tricks, but just wait for it because by the end the little purple caterpillar proves itself an instrument worthy of a position beside that fancy Eurorack you’ve been assembling.

The image above provides a great look inside the beastie. [Jason Hotchkiss] mentions he’s impressed by the build quality, and we have to agree. Plus, look at all of those inputs — this is begging to leave toyland and join the band. With an intuitive sense that can only be gained through lots of circuit-bending experience, he guessed that the single through-hole resistor on the PCB was used to dial in the clock speed. That made it easy to throw in a trimpot for pitch-bending and he moved on to figure out individual note control.

All of those caterpillar feet are arranged in a keyboard matrix to detect button presses. After pulling out the oscilloscope for a bit of reverse engineering, [Jason] grabbed a PIC microcontroller and added it to the same solder points as the stock ribbon connector. The result is that the buttons on the feet still work, but now the Alphabet Pal also has MIDI control.

Take a look at the writeup for full details, and the video after the break to hear it in action. If you’re a fan of circuit-bent toys, this pretty pink keyboard hack always impressed us, especially the spring reverb that was added!

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Play To The Beat Of This Robotic Drummer In A Box

June 8, 2019 by Dan Maloney 1 Comment

No drummer? No problem! With a little ingenuity, you can stuff the essentials of a drum kit into a box, and automate your rhythm section.

Mind you, [Franco Molina]’s “DrumCube” doesn’t quite have the flash of a human drummer, but it does keep a steady beat and has a charm of its own. The drum machine is mostly mechanical, reminding us somewhat of the Wintergatan Marble Machine which is as captivating to watch as it is to hear. The DrumCube has a snare drum played by two servo-controlled sticks, a kick drum using foam waggled back and forth between two piezo transducers hooked to a low-pass filter, and a reverse-biased transistor white noise generator used for the hi-hat. Sadly, the large gear appears to be just for show. An Arduino runs everything and makes sure the mechanical drum hits are synced to the electronic cymbals, which was no mean feat.

The video below shows it in action accompanying [Franco] on his guitar, and it looks as good as it sounds. Prefer a more compact, all-electronic drum kit? Here’s one that fits in your pocket.

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Moped Turn Signals, Now With More Cowbell

June 7, 2019 by Dan Maloney 14 Comments

Cue up the [Christopher Walken] memes, it’s time for moped turn signals with more cowbell. Because moped turn signals with less cowbell are clearly the inferior among moped turn signals.

It seems that [Joel Creates] suffers from the same rhythm recognition disorder that we do. The slightest similarity between a rhythmic sound such as turn signals, and any song in our seemingly infinite intracranial playlist cues up that song for the rest of the day. [Joel] heard “(Don’t Fear) The Reaper” in his turn signals, and that naturally led to a need for More Cowbell. So with a car door lock actuator, a relay, an improvised clapper, and a lot of hot glue and cable ties, the front of his scooter is now adorned with a cowbell that’s synchronized to the turn signals. The video below shows that it’s of somewhat limited appeal in traffic, but at least [Joel’s dad] was tickled pink by it.

Kudos to [Joel] for marching to the beat of his own [Gene Frenkle] on this one. It may be a little weird, but not as weird as an Internet of Cowbells.

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