PDP-8 Plays Period Popcorn Piece

December 11, 2022 by Chris Lott 18 Comments

[Kyle Owen], collector of antique tech, decided to try his hand at music arrangement — for the PDP-8 computer, that is (listen to the video below the break). He’s using a program submitted by Richard Wilson to the Digital Equipment Corporation Users Society (DECUS) in 1976, appropriately named MUSIC. It runs on OS/8 and is written in the PDP-8 assembly language PAL8. Using the syntax of MUSIC, [Kyle] arranged Gershon Kingsley’s famous Moog synthesizer hit “Popcorn” (the Hot Butter version from 1972).

You might notice the lack of a disk or tape drive in his setup. That’s because [Kyle] is using an RK05 disk emulator he wrote back in 2014. It’s running on a Raspberry Pi and connects over serial, which he says is slower than an RK05 but faster than a tape drive. He has connected up a Cordovox amplifier cabinet for this demonstration, but the original means of listening to the MUSIC output was an AM radio held near the computer (hear the second video below the break). This worked by executing the PDP-8 CAF instruction at a desired frequency, say 440 Hz.

Thus, when this instruction is executed, logic all over the computer goes “zap”, clearing out various registers. Now, if a radio is held close to the computer, it will pick up some of this energy, and at 440 times a second, will deliver a pulse to the speaker. The result is that you will hear a tone from the radio — as a matter of fact, you will hear an A.

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I’ve Got Two Turntables And A Laser Engraver

November 27, 2022 by Bryan Cockfield 29 Comments

Digital media provides us with a lot of advantages. For something like recording and playing back music, digital copies don’t degrade, they can have arbitrarily high quality, and they can be played in a number of different ways including through digital streaming services. That being said, a number of people don’t feel like the digital experience is as faithful to the original sound as it could be and opt for analog methods instead. Creating analog copies of music is a much tougher matter though, as [Marco] demonstrates by using a laser engraver to produce vinyl records.

[Marco] started this month-long project by assembling and calibrating the laser engraver. It has fine enough resolution to encode analog data onto a piece of vinyl, but he had to create the software. The first step was to generate the audio sample, then process it through a filter to remove some of the unwanted frequencies. From there, the waveform gets made into a spiral, accounting for the changing speed of the needle on the record as it moves to the center. Then the data is finally ready to be sent to the laser engraver.

[Marco] did practice a few times using wood with excellent success before moving on to vinyl, and after some calibration of the laser engraver he has a nearly flawless 45 rpm record ready to hit the turntable. It’s an excellent watch if not for anything than seeing a working wood record. We’ve actually seen a similar project before (without the wood prototyping), and one to play records from an image, but it’s been quite a while.

Thanks to [ZioTibia81] for the tip!

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A baguette sits diagonally across a wooden cutting board. Above it sits an Arduino and an electronics breadboard.

Theremin Baguette Brings New Meaning To Breadboarding

October 25, 2022 by Navarre Bartz 5 Comments

Theremins are a bit of an odd instrument to begin with, but [AphexHenry] decided to put one where no theremin has gone before: into a baguette.

The “baguetophone” is a theremin and piezo-percussion instrument inside a hollowed-out baguette. Starting with a DIY theremin tutorial from Academy of Media Arts Cologne, [AphexHenry] added some spice with a piezo pickup inside the baguette to function as a percussion instrument. One noted downside of squeezing the instrument into such an unusual enclosure is that the antenna doesn’t respond as well as it might with a more conventional arrangement. Outputs from the piezo and antenna are run through Max/MSP on a computer to turn the bread into a MIDI controller. Like many DIY theremins, it appears that this build neglects the volume antenna, but there’s no reason you couldn’t add one. Maybe disguised as a piece of cheese?

Outside smuggling an instrument into a French café for a flash mob performance, this could also prove handy if you’re someone who gets hungry while playing music. We don’t recommend snacking on the Arduino even if it is ROHS compliant though.

If you want to learn more about how theremins work, check out Theremin in Detail. After that, you might want to browse all of our theremin articles or look at this project where they used a 555 instead.

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Arduino Lo-Fi Orchestra closeup thumbnail

Lo-Fi Orchestra Learns Tubular Bells

October 14, 2022 by Dave Walker 4 Comments

Hardware projects often fall into three categories: Those that flash lights, those that make sounds and those that move. This virtuoso performance by [Kevin]’s “Lo-Fi Orchestra” manages all three, whilst doing an excellent job of reproducing the 1973 musical classic Tubular Bells by Mike Oldfield.

Producing decent polyphonic sounds of different timbres simultaneously is a challenge for simple microcontroller boards like Arduinos, so [Kevin] has embraced the “More is more” philosophy and split up the job of sound generation in much the same way as a traditional orchestra might. Altogether, 11 Arduino Nanos, 6 Arduino Unos, an Arduino Pro Mini, an Adafruit Feather 32u4, and a Raspberry Pi running MT32-Pi make up this electronic ensemble.

Arduino servo drumkit — Arduino Servo & Relay Drumkit

The servo & relay drumkit is a particular highlight, providing some physical sounds to go along with the otherwise solid-state generation.

The whole project is “conducted” over MIDI and the flashing sequencer in the middle gives a visual indication of the music that is almost hypnotic. The performance is split into two videos (after the break), and will be familiar to fans of 70’s music and classic horror movies alike. We’re astonished how accurately [Kevin] has captured the mood of the original recording.

If this all looks slightly familiar, it may be because we have covered the Lo-Fi Orchestra before, when it entertained us with a rousing rendition of Gustav Holst’s Planets Suite. If you’re more interested in real Tubular Bells than synthesized ones, then check out this MIDI-controlled set from 2013. Continue reading “Lo-Fi Orchestra Learns Tubular Bells“ →

Building An Old Guitar From A New One

September 27, 2022 by Bryan Cockfield 3 Comments

Anyone who’s ever played guitar to at least the skill level required to form a terrible garage band knows the names of the most legendary guitars. The driving sound of the Gibson Les Paul played by Jimmy Page, the upside-down and smooth Fender Stratocaster from Jimi Hendrix, or the twangy Rickenbacker made famous by George Harrison are all lusted-after models. The guitar that [Frank] really wanted was a Danelectro DC59 and since they’ve been steadily creeping up in price, he decided to build his own.

The body of the clone guitar is hollow and made from effectively scrap wood, in this case plywood. As the original guitars were in fact famous for using the least expensive materials possible, this makes it a great choice for a clone. [Frank] made the guitar using almost exclusively hand tools and glued everything together, but did use a few donor parts from a modern Stratocaster-type guitar. With most of the rough shape of the guitar finished, it was time to add the parts that make the guitar sound the way that a real Danelectro should: the lipstick-style pickups. He purchased these completely separately as they are the most important part to get right to emulate the tone and feel of the original.

With everything finally soldered and assembled, [Frank] got right to work recording a sample audio track which is included at the end of the video. It certainly sounds like the original to our untrained ears, and for around $100 it’s not a bad value either. If you’d like to see a guitar built from the ground up without using another as a clone, take a look at this build which brings a completely original guitar into existence, entirely from scratch.

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Making A Tape Echo The Traditional Way

September 14, 2022 by Dave Walker 12 Comments

[Juan Nicola] has taken inspiration from the musician hackers of old and re-purposed a reel-to-reel tape recorder into a tape-echo for his guitar with a built-in valve amplifier (video in Spanish).

The principle is to record the sound of the guitar onto a piece of moving magnetic tape, then to read it back again a short time later. This signal is mixed with the live input and re-recorded back onto the tape further back. The effect is heard as an echo, and this approach was very popular before digital effects became readily available.

[Juan] installed a new read-head onto his Grundig TK40 and managed to find a suitable mechanical arrangement to keep it all in place. He has since updated the project by moving to a tape loop, allowing an infinite play-time by re-using the same piece of tape over and over.

Turning tape machines into echo effects is not a new idea, and we’ve shown a few of them over the years, but every one is slightly different!

Both versions are shown after the break. YouTube closed-caption auto-translate might come in handy here for non-Spanish speakers.

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Touch Tone MIDI Phone And Vocoder Covers Daft Punk

September 6, 2022 by Donald Papp 3 Comments

[poprhythm]’s Touch Tone MIDI Phone is a fantastic conversion of an old touch tone phone into a MIDI instrument complete with intact microphone, but this project isn’t just about showing off the result. [poprhythm] details everything about how he interfaced to the keypad, how he used that with an Arduino to create a working MIDI interface, and exactly how he decided — musically speaking — what each button should do. The LEDs on the phone are even repurposed to blink happily depending on what is going on, which is a nice touch.

Of course, it doesn’t end there. [poprhythm] also makes use of the microphone in the phone’s handset. Since the phone is now a MIDI instrument with both a microphone and note inputs, it’s possible to use them together as the inputs to vocoder software, which he demonstrates by covering Around the World by Daft Punk (video).

We love how [poprhythm] explains how he interfaced to everything because hardware work is all about such details, and finding the right resources. Here’s the GitHub repository for the Arduino code and a few links to other resources.

We have seen MIDI phone projects before, and each one is always unique in its own way: here’s a different approach to converting a keypad phone to MIDI, and this rotary pulse-dial phone went in a completely different direction with the phone itself completely unmodified, using only external interfacing.

You can admire [poprhythm]’s Touch Tone MIDI Phone in action in the short videos embedded below, with each one showing off a different aspect of the build. It’s great work!

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