DIY Mini-Amp Goes To Eleven

March 30, 2018 by James Hobson 26 Comments

On the day mini-amps were invented, electric guitar players the world over rejoiced. No longer would they be house-bound when jamming out on their favourite guitar. It is a doubly wondrous day indeed when an electric guitar-inclined maker realizes they can make their own.

[Frank Olson Music] took apart an old pair of headphones and salvaged the speakers — perhaps intending to replicate a vintage sound — and set them aside. Relying on the incisive application of an X-Acto knife, [Olson] made swift work cutting some basswood planks into pieces of the amp before gluing them together — sizing it to be only just bigger than the speakers. A tie was also shown no mercy and used as a dapper grille screen. Both the head and speaker cabinets were sanded and stained for a matching finish.

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Learn What Did And Didn’t Work In This Prototyping Post-Mortem

March 30, 2018 by Donald Papp 16 Comments

[Tommy] is a one-man-shop making electronic musical things, but that’s not what this post is about. This post is about the outstanding prototyping post-mortem he wrote up about his attempt to turn his Four-Step Octaved Sequencer into a viable product. [Tommy] had originally made a hand-soldered one-off whose performance belied its simple innards, and decided to try to turn it into a product. Short version: he says that someday there will be some kind of sequencer product like it available from him, “[B]ut it won’t be this one. This one will go on my shelf as a reminder of how far I’ve come.”

The unit works, looks great, has a simple parts list, and the bill of materials is low in cost. So what’s the problem? What happened is that through prototyping, [Tommy] learned that his design will need many changes before it can be used to create a product, and he wrote up everything he learned during the process. Embedded below is a demo of the prototype that shows off how it works and what it can do, and it helps give context to the lessons [Tommy] shares.

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This Is How The Fonz Would Play MP3s

March 30, 2018 by Dan Maloney 10 Comments

Here at Hackaday, we love to see old hardware treated with respect. A lovingly restored radio or TV that’s part of our electronic heritage is a joy to behold, and while we understand the desire to stream media from a funky retro case, it really grates when someone throws away the original guts to make room for new electronics.

Luckily, this Seeburg jukebox wall remote repurposing is not one of those projects. [Scott M. Baker] seems to have an appreciation for the finer things, and when he scored this classic piece of Mid-Century Americana, he knew just what to do. These remotes were situated around diners and other hangouts in the 50s and 60s and allowed patrons to cue up some music without ever leaving their seats. They were real money makers back in the day, and companies put a lot of effort into making them robust and reliable.

[Scott]’s first video below shows the teardown of this unit; you can practically smell the old transformer and motor windings. His goal in the second video was to use the remote to control his Raspberry Pi jukebox; he wisely decided to leave everything intact and use the original electromechanically generated pulses to make selections. His analysis led to a nicely executed shield for his Pi which conditions the pulses and imitates coin drops; happily, the coin mechanism still works too, so you can still drop a quarter for a tune.

The remote is working well now, but [Scott] still needs to finish up a few odds and ends to bring this one home. But we love the look and the respect for tradition here, as we did when this juke got a Raspberry Pi upgrade to imitate a missing wall remote.

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Building A Plate Reverb On The Cheap

March 23, 2018 by Tom Nardi 18 Comments

For those who don’t spend their free time creating music with experimental audio effects, a plate reverb is essentially a speaker. It just happens to be, by design, a rather poor one. Rather than using a paper cone for a diaphragm like a traditional speaker, the plate reverb uses as you might guess, a metal plate. As the plate vibrates along with the source audio, a set of piezoelectric pickups convert that to an output. The end result is that audio fed into the plate reverb comes out with a nice echo effect.

But despite their relative simplicity, a plate reverb costs thousands of dollars. They’re so expensive that the majority of people just emulate the effect in software. But it doesn’t have to be that way. [Sammartino] and an audio engineer friend recently came up with a detailed guide for building a plate reverb that cost about 10% of commercially available models.

The construction is fairly simple. A wooden frame is built, and eight hooks are installed around the edges. The plate is suspended between these hooks using guitar strings, which holds it tight but with enough give to vibrate along with the tunes. Another board is attached across the center of the frame to support the electronics: a transducer to vibrate the plate, and two piezo pickups to convert that to an audio signal, and a couple jacks and some wiring to tie it all together.

For a different take on the DIY plate reverb, check out this one we covered all the way back in 2013. If you’re in the market for something a bit larger, we’ve got you covered there as well.

Servos Do The Plucking In This MIDI Music Box

March 23, 2018 by Dan Maloney 18 Comments

It started with a cheap, punch-card programmable manual music box. Thirty-one hobby servos later, it ended as an automated MIDI music box, with a short pit stop as a keyboard-driven MIDI device.

If you think you’ve seen the music box in [Mitxela]’s video below before, you’re right. [Martin], musician, inventor, and father of the marvelous marble music machine, took an interest in these music boxes and their programming a while back. Like [Martin], [Mitxela] started his music box project with punch card programming, but he quickly grew tired of the bothersome process, even after automating production with a laser cutter. He decided to do away with the punch cards completely and devised a method to pluck all 30 notes using a few large handfuls of hobby servos. One servo, converted to continuous rotation, spins the drum, with the rest linked to small laser-cut acrylic plectrums via stiff brass wire. The fingers imitate the punched holes passing over the drum and pluck the notes according to MIDI messages. The whole thing can draw quite a bit of current, so in addition to a beefy power supply, [Mitxela] optimized the code to minimize power requirements. This had the happy consequence of reducing the latency enough to allow the music box to be played from a MIDI keyboard in real time.

A lot of work went into this one, but [Mitxela] isn’t resting on his laurels; he has a full slate of improvements that he wants to tackle, not least of which is SD card support for MIDI files to turn this into a jukebox. We’re looking forward to the updates.

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NES Controller Slider-Based Light Theremin

March 20, 2018 by Kristina Panos 1 Comment

Having never use a 555 before, [lonesoulsurfer] decided that his first foray into the world’s most popular and versatile IC would be to use a 555 to make beautiful chiptunes. For that, we commend him. He found [Dean Segovis]’ Slidersynth light-based Theremin and got to work building his own version it and stuffing it into a (knockoff!) NES controller.

For the uninitiated, a Theremin is a touch-less synthesizer that uses human capacitance and a pair of antennae to control oscillation and amplitude. In a light-based Theremin such as this one, the oscillation is controlled by the intensity of photons from a white LED and their interaction with a light-dependent resistor, also known as a photocell or ‘squiggly resistor’.

The oscillations themselves are created by wiring up the 555 as an astable oscillator, and the pitch is controlled with a potentiometer mounted on the back. It has a small built-in speaker, but [lonesoulsurfer] replaced the B button with a 3.5 mm audio jack so he can plug it into a powered speaker and really rock out. We’ve got his demo tape queued up after the break.

We love pocket instruments around here. If you prefer brass and woodwinds, this pocket woodwind MIDI controller just might draw your lips into an O.

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Pipe Your Way Through The Jams

March 18, 2018 by Jenny List 15 Comments

Playing the bagpipes is an art that takes a significant effort to master, both in keeping a constant air supply through balancing blowstick and bag and in learning the finger positions on the chanter. This last task we are told requires constant finger practice, and a favorite place for this is on the steering wheel as a would-be piper drives. [DZL] therefore took this to the next level, placing touch sensors round a car steering wheel that could be interpreted by an Arduino Pro Mini to produce a passable facsimile of a set of bagpipes via an in-car FM transmitter. It lacks the drone pipes of the real thing, but how many other Škodas feature inbuilt piping?

We’ve covered an unexpected number of bagpipe projects over the years, but never had a close look at this rather fascinating musical instrument. If you are curious, the US Coast Guard pipe band has a short guide to its parts, and we’ve brought you a set of homemade pipes built from duct tape and PVC pipe. They may once have been claimed as an instrument of war, but they seem to also be a favorite instrument of hardware hackers.

Thanks [Sophi] for the tip.