Close up shot of a mechanical sequencer for 555 based synthesizers

Kinetic Synth-Kebab Sculpture Plays Punk Sequentially

October 4, 2021 by Ryan Flowers 12 Comments

What’s better than an Atari Punk Console synthesizer? How about four Atari Punk Console synthesizers. And what better way to present them but as brass wire art sculptures. We’d have forgiven [iSax] if he’d stopped at four brass wire synths, but he took things to another level with his kinetic sculpture that does double duty as a mechanical sequencer. Called the Cyclotone – The Mechanical Punk Console Sequencer, it features wood, brass, brushes, and 555 timers. You can see the demonstration in the video below the break.

If you’re not familiar with the Atari Punk Console, it’s a circuit first described as a “Sound Synthesizer” in Forest Mims’ “Engineer’s Notebook: Integrated Circuit Applications” first published in 1980. It utilized two 555 timers in a single chip, the 556. Later dubbed the “Atari Punk Console”, the circuit has stood the test of time and is still quite popular among hackers of all sorts.

[iSax]’s build adds a sequencing element that allows the synths to be played automatically. The synthesizers are skewered 90 degrees from each other on a square dowel, which is turned at a variable RPM by a stepper motor controlled by a knob at the base of the sculpture.

On either side of each synth is a commutator that contacts salvaged rotary tool brushes which provide power through the hexagonal brass supports. Each synth retains its own speaker and controls and has its own segmented numeral displayed with discrete LED’s that light up when each synth is played.

We applaud [iSax] for a well executed and imaginative build that successfully meshes circuit scultpure, kinetic sculpture, classic electronics and even blinkenlights. If you enjoyed this build, you should also go have a look at a free form Atari Punk Console build and another one built into a joystick. If you come across a project of any kind that catches your fancy, be sure you let us know about it via the Tip Line!

Continue reading “Kinetic Synth-Kebab Sculpture Plays Punk Sequentially” →

Classic Chip Line-Up Powers This Fun Dub Siren Synth

September 24, 2021 by Dan Maloney 8 Comments

There’s a certain elite set of chips that fall into the “cold, dead hands” category, and they tend to be parts that have proven their worth over decades, not years. Chief among these is the ubiquitous 555 timer chip, which nearly 50 years after its release still finds its way into the strangest places. Add in other silicon stalwarts like the 741 op-amp and the LM386 audio amp, and you’ve got a Hall of Fame lineup for almost any project.

That’s exactly the complement of chips that powers this fun little dub siren. As [lonesoulsurfer] explains, dub sirens started out as actual sirens from police cars and the like that were used as part of musical performances. The ear-splitting versions were eventually replaced with sampled or synthesized siren effects for recording studio and DJ use, which leads us to the current project. The video below starts with a demo, and it’s hard to believe that the diversity of sounds this box produces comes from just a pair of 555s coupled by a 741 buffer. Five pots on the main PCB control the effects, while a second commercial reverb module — modified to support echo effects too — adds depth and presence. I built-in speaker and a nice-looking wood enclosure complete the build, which honestly sounds better than any 555-based synth has a right to.

Interested in more about the chips behind this build? We’ve talked about the 555 and how it came to be, taken a look inside the 741, and gotten a lesson in LM386 loyalty.

Continue reading “Classic Chip Line-Up Powers This Fun Dub Siren Synth” →

3D Printed Synth Kit Shares Product Design Insights

September 4, 2021 by Donald Papp 1 Comment

We’ve always been delighted with the thoughtful and detailed write-ups that accompany each of [Tommy]’s synth products, and the background of his newest instrument, the Scout, is no exception. The Scout is specifically designed to be beginner-friendly, hackable, and uses 3D printed parts and components as much as possible. But there is much more to effectively using 3D printing as a production method than simply churning out parts. Everything needed to be carefully designed and tested, including the 3D printed battery holder, which we happen to think is a great idea.

3d printed battery holder, showing inserted spring contacts — 3D printed battery holder, with spring contacts inserted by hand.

[Tommy] also spends some time explaining how he decided which features and design elements to include and which to leave out, contrasting the Scout with his POLY555 synth. Since the Scout is designed to be affordable and beginner-friendly, too many features can in fact be a drawback. Component costs go up, assembly becomes less straightforward, and more complex parts means additional failure points when 3D printing.

[Tommy] opted to keep the Scout tightly focused, but since it’s entirely open-sourced with a hackable design, adding features is made as easy as can be. [Tommy] designed the PCB in KiCad and used OpenSCAD for everything else. The Scout uses the ATmega328, and can be easily modified using the Arduino IDE.

STL files can be downloaded here and all source files are on the project’s GitHub repository, which also contains detailed assembly and modification guides. Watch it in action in the video, embedded below.

Continue reading “3D Printed Synth Kit Shares Product Design Insights” →

Touchscreen Makes For A Neat Wavetable Synth

August 15, 2021 by Lewin Day 8 Comments

A popular tool in chiptune software like LSDJ allows the user to draw a waveform and use it as the basis for a wavetable synth. It’s fun and it can produce some great bleeps and bloops. [Kevin] has created a similar tool using an Arduino and a touchscreen.

The build is based on the Arduino Uno, the humble mainstay of the Arduino line. It’s hooked up to an ILI9488 color touchscreen display, which acts as the primary user interface. Using a stylus, or presumably a finger, the user can draw directly on the screen to specify the desired waveform for the synth to produce. The Arduino reads the step-by-step amplitude values of the drawn waveform and uses them to synthesize audio according to MIDI messages received over its serial port. Audio output is via PWM, as is common in low-cost microcontroller projects.

It’s a fun build and we’re sure [Kevin] learned plenty about wavetable synthesis along the way. We’ve seen his work on other Arduino synthesis projects before, too! Video after the break.

Continue reading “Touchscreen Makes For A Neat Wavetable Synth” →

Synth Gains Plug And Play Analog MUX

May 4, 2021 by Chris Lott 3 Comments

High school computer engineering teacher [Andy Birch] kept losing track of I/O pins on his home-built synth, so he made a custom plug and play addressable MUX system to solve the problem. [Andy]’s synth is based on the Teensy microcontroller, and he was already using CMOS analog 8:1 multiplexer chips (CD4051) to give him more I/O pins. But I/O pin expansion means that now there are more I/O pins to forget. Did I hook up that pitch potentiometer on U3 pin 13 or was it U10 pin 2?

He proceeds to design an addressing system for each I/O card using three bits (expandable to four) supporting eight cards, with a maximum of 16 possible in the future. Since each card may not use all eight signals, each card can tell the Teensy how many signals it has. [Andy] does his address decoding on each card using OR and XOR gates. We would have considered using a single 74HC85 four-bit magnitude comparator instead. That would require only one chip instead of two, but would deprive his students of the opportunity to learn gate level address decoding.

When seeing the term “I/O card”, you may be fooled like we were into thinking this was using PCBs and some kind of motherboard. [Andy]’s I/O cards are actually solderless breadboards mounted on the back of the synth control panel. We really like his bus technique — he removes the power strip sections from several breadboards and repurposes them as address and data buses. Check out the thorough documentation that [Andy] has prepared, and let us know if you have ever designed your own plug and play method for a project in the comments below.

[Ed Note: We love us some muxes!]

I/O Cards — Note the use of Power Strip Bars as Data / Address Buses

Music Production Studio In A Box

April 5, 2021 by Stephen Ogier 5 Comments

[Emil Smith] is an electronic music producer in the Greater London area. He spent a lot of time commuting in and out of central London, so he decided to put together COVERT-19, a portable music production studio. After making a couple of prototypes, [Emil] settled on what he needed from his portable studio: a sampler, a sequencer, a synthesizer, a mixer, and a way to record his work.

[Emil] didn’t overlook any details with his mechanical design. Taking the beautiful London weather into account, he designed a laser-cut plywood case that has a neoprene foam gasket to keep water out when closed and put all of the inputs and outputs on the interior of the case. Inside the case, he opted for machine screws with threaded inserts so he could disassemble and reassemble his creation as often as he liked, and he included gas springs to keep the studio open while he’s making music. [Emil] even thought to include ventilation slots to keep the built-in PC cool!

A portable studio is useless without a power supply, so [Emil] taught himself some circuit theory and bought his first soldering iron in order to create the custom power delivery system. Power is supplied by a battery of twelve 18650 cells with switching converters to supply the three different voltages his studio needs. Even with all of his music-making gear, he manages to get about four hours of battery life!

The music-making gear consists of a sequencer and synthesizer as well as a touch-screen NUC PC running Xubuntu. The built-in PC runs software that allows him to mix the audio, apply extra effects, record his creations, and save his patches when he’s done working. The system even has an extra MIDI output and audio input to allow it to incorporate an external synthesizer.

If you’re interested in getting started with MIDI synthesizers, but you’re more interested in building than buying, check out the KELPIE.

Homebrew Grain Synth Has A Rad Step Sequencer

March 19, 2021 by Lewin Day 8 Comments

In the world of homebrew synthesizers, there are plenty of noiseboxes and grooveboxes that make all kinds of wacky and wild noises. However, common projects like the Auduino and Atari Punk Console are often limited in that they can’t readily be programmed to play multiple notes or any sort of discernable rhythm. [Nick Poole] changes this with his Auduino step sequencer build.

The build takes the Auduino grain synthesizer, and modifies it by adding a step sequencer. This is possible as the Auduino code, which runs on the old-school ATMEGA-based Arduinos, is incredibly fast, leaving plenty of processing time for extra features to be added. [Nick] adds eight LEDs and eight buttons to the build, allowing the user to select one of eight steps to modify. Then, the sound parameters for the step can be altered with the standard Auduino controls. This lets the user quickly and easily build up 8-step melodies, something that was previously impossible with the Auduino.

It’s a fun build, and one that makes a great intro into the world of DIY synth builds. The techniques learned here will serve any aspiring maker well if they dive further into the world of modular synthesis and associated arcana. Video after the break.

Continue reading “Homebrew Grain Synth Has A Rad Step Sequencer” →