Oh Baby, Baby10 – Build a Classic Analog Music Sequencer

Recently I’ve been learning more about classic analog music synthesizers and sequencers. This has led me to the Baby10, a classic and simple analog sequencer design. In this article I’ll introduce its basic operation, and the builds of some awesome hackers based on this design.

Sequencers produce, a sequence of varying voltages. These control voltages (CV) can then be use to control other components. Often this is a simple tone generator. While the concept is simple, it can produce awesome results:

A basic sequencer is a great beginners project. It’s easy to understand the basic operation of the circuit and produces a satisfyingly entertaining result. The Baby 10 was originally published in a column called “Captain’s Analog”, but has now been widely shared online.

baby10
The original Baby10 article.

The circuit uses the 4017, a simple CMOS decade counter. The 4017 takes an input clock signal then sequentially outputs a high pulse on each of 10 output pins. As such, the 4017 does almost everything we need from a sequencer in a single IC! However, we want our sequencer to output a varying voltage which we can then use to generate differing tones.

To accomplish this variable resistors are connected to each of the output pins. A diode in series with the variable resistor stops the outputs fighting against each other (in layman’s terms).

To make the sequencer more visually attractive (and give some feedback) LEDs are often also added to the output of the 4017. A complete Baby 10 sequencer is shown in the schematic below. The original circuit used 1N917s, these are no longer available but the part has been replaced by the 1N4148.

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Second Skin Synth Fits Like a Glove

California textiles artist and musician [push_reset] challenged herself to make a wearable, gesture-based synth without using flex-sensing resistors. In the end, she designed almost every bit of it from the ground up using conductive fabric, resistive paint, and 3-D printed parts.

A couple of fingers do double duty in this glove. Each of the four fingertips have a sensor made from polyurethane, conductive paint, and conductive fabric that is connected to wires using small rivets. These sensors trigger different samples on an Edison that are generated with Timbre.js. The index and middle fingers also have knuckle actuators made from 3-D printed pin-and-slot mechanisms that turn trimmer pots. Bending one knuckle changes the delay timing while the other manipulates a triangle wave.

On the back of the glove are two sensors made from conductive fabric. Touching one up and down the length will alter the reverb. Sliding up and down the other alters the frequency of a sine wave. [push_reset] has kindly provided everything necessary to re-create this build from the glove pattern to the STL files for the knuckle actuators. Check out a short demonstration of the glove after the break. If you love a parade, here’s a wearable synth that emulates a marching band.

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Hackaday Links: October 11, 2015

[Kratz] just turned into a rock hound and has a bunch of rocks from Montana that need tumbling. This requires a rock tumbler, and why build a rock tumbler when you can just rip apart an old inkjet printer? It’s one of those builds that document themselves, with the only other necessary parts being a Pizza Hut thermos from the 80s and a bunch of grit.

Boot a Raspberry Pi from a USB stick. You can’t actually do that. On every Raspberry Pi, there needs to be a boot partition on the SD card. However, there’s no limitation on where the OS resides,  and [Jonathan] has all the steps to replicate this build spelled out.

Some guys in Norway built a 3D printer controller based on the BeagleBone. The Replicape is now in its second hardware revision, and they’re doing some interesting things this time around. The stepper drivers are the ‘quiet’ Trinamic chips, and there’s support for inductive sensors, more fans, and servo control.

Looking for one of those ‘router chipsets on a single board’? Here you go. It’s the NixCoreX1, and it’s pretty much a small WiFi router on a single board.

[Mowry] designed a synthesizer. This synth has four-voice polyphony, 12 waveforms, ADSR envelopes, a rudimentary sequencer, and fits inside an Altoids tin. The software is based on The Synth, but [Mowry] did come up with a pretty cool project here.

Hackaday Links: September 20, 2015

Here’s an offer from Intel and the guy behind all of reality TV [Mark Burnett]: win a million dollars for making something. Pitch an idea for wearable electronics to the producers by October 2, and you might be on a reality TV show about building electronics which they’re calling America’s Greatest Makers. With this, Intel is promoting the Curie module a tiny, tiny SoC with Bluetooth, IMU, and DSP functions. We’re of the opinion that a Hackaday reader should win this contest, or at the very least be featured prominently in the show. No, it’s not Junkyard Wars, but it’s still a million dollar prize.

[Jeremy] builds bombs clocks, and he has a Kickstarter for an interesting Nixie clock. Most Nixie tubes have digits, but [Jeremy] is using the IN-9 ‘bar’ tubes for the hour and minute hand.

The Luka EV is a semifinalist for the Hackaday Prize, and a completely open, road legal electric vehicle powered by hub motors. It also looks really, really cool.  Now, they’re selling them. It’s €20,000 for a complete car. Did I mention how cool it looks?

Boca Bearings is having a ‘Show Us Your Workshop’ contest, with the best (or should it be worst?) workshop winning tool cabinets, tool kits, a work mat, and calipers.

The EMU Drumulator is a classic drum machine that featured dirty 12-bit drum sounds in ROM. Now, it’s a single chip thanks to [Jan]. He’s done a lot of great work putting synths in single chips, and it’s great to see him move on to classic drum machines.

Offered without comment, here’s a ride through a PCB.

The Ubiquitous Atari Punk Console

The Atari Punk Console (APC) is a dual 555 (or single 556) based synth. Designed by the famous (and somewhat infamous) Forrest Mims in 1980 and originally simply named “Sound Synthesizer”, the circuit gained it’s more recent popularity when re-dubbed the “Atari Punk Console” by Kaustic Machines. The circuit however doesn’t bear much relation to the Atari 2600 which didn’t contain a 555 timer chip. However we assume the 2600 produced a similarly glitchy square wave audio output.

a2The circuits operation is easy to grasp and uses only 9 components. This ease of design and construction has allowed builders to focus more on the aesthetics of its construction, hacking it into interesting, and often unlikely enclosures and systems. One such hack is the “Atari Punk Bucket” (shown here) where the APC along with a simple amp was hacked into an old rusted bucket. The APC was built up on strip-board along with a simple amp and reclaimed speakers. [Farmer glitch] has used this as a prop in live sets and it both looks and sounds awesome. Continue reading “The Ubiquitous Atari Punk Console”

The Kraakdoos — Musical Abuser of an Ancient OpAmp

A friend from the newly founded Yeovil Hackerspace introduced me to a device known as “The Kraakdoos” or cracklebox.

The cracklebox is an early electronic instrument produced by STEIM in the 1970s. The instrument consists of a single PCB with a number of copper pads exposed on one side. The player touches the pads and the instrument emits… sounds which can perhaps best be described as squeeze and squeals.

While the cracklebox was original sold as a complete instrument, the device has been reverse engineered, and the schematic documented. What lies inside is quite fascinating.

The heart of the cracklebox is an ancient opamp, the LM709. The LM709 is the predecessor to the famous LM741. Unlike the 741 the 709 had no internal frequency compensation. Frequency compensation is used to intentionally limit the bandwidth of an opamp. As input frequency increases, the phase shift of the opamp also increases. This can result in undesirable oscillation, as the feedback network forms an unintentional phase-shift oscillator.

Most modern opamps have internal frequency compensation, but the 709 doesn’t. Let’s see how this is used in the cracklebox:

krackdoos_schRather than using the frequency compensation pins as intended the cracklebox just routes them out to pads. In fact the cracklebox routes almost all the pins on the opamp out to pads, including the inverting and non-inverting inputs. A single 1MOhm feedback resistor is used in a non-inverting configuration. However reports suggest the instrument can work without a feedback resistor at all!

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Hackaday Links: July 19, 2015

Everybody needs an external USB drive at some time or another. If you’re looking for something with the nerd cred you so desperately need, build a 5 1/4″ half height external drive. That’s a mod to an old Quantum Bigfoot drive, and also serves as a pretty good teardown video for this piece of old tech.

The Woxun KG-UV2D and KG-UV3D are pretty good radios, but a lot of amateur radio operators have found these little handheld radios eventually wear out. The faulty part is always a 24C64 Flash chip, and [Shane] is here to show you the repair.

Last year there was a hackathon to build a breast pump that doesn’t suck in both the literal and figurative sense. The winner of the hackathon created a compression-based pump that is completely different from the traditional suction-based mechanism. Now they’re ready for clinical trials, and that means money. A lot of money. For that, they’re turning to Kickstarter.

What you really need is head mounted controls for Battlefield 4. According to [outgoingbot] it’s a hacked Dualshock 4 controller taped to a bike helmet. The helmet-mounted controller has a few leads going to another Dualshock 4 controller with analog sticks. This video starts off by showing the setup.

[Jan] built a modeling MIDI synth around a tiny 8-pin ARM microcontroller.  Despite the low part count, it sounds pretty good. Now he’s turned his attention to the Arduino. This is a much harder programming problem, but it’s still possible to build a good synth with no DAC or PWM.