Probably The Simplest Sequencing Synth

March 15, 2025 by 31 Comments

With inexpensive microntrollers capable of the most impressive feats of sound synthesis, it’s not so often we see projects that return to an earlier style of electronic music project. The 1-bit synth from [Electroagenda] takes us firmly into that territory, employing that most trusty of circuits, a 555.

It’s a time-honored circuit, a 555 provides a note clock that drives a 4017 that functions as a sequencer. This switches in a set of voltage dividers, which in turn control another 555 oscillator that produces the notes. It’s a fun toy straight from the 1970s, right down to the protoboard and hookup wire construction. There’s a demo video with some lovely beeps below, and we think most of you should have what it takes to make your own.

If you’re seeking more inspiration, may we introduce you to our Logic Noise series?

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Piezo Buzzer Makes A Drum

January 15, 2025 by 6 Comments

The humble piezo disc buzzer is much more than something that makes tinny beeps in retro electronic equipment, it can also be used as a sensor. Tapping a piezo buzzer gives an interesting waveform, with a voltage spike followed by an envelope, and then a negative rebound voltage. It’s something [Igor Brichkov] is using, to make a simple but effective electronic drum.

First of all, the output of the buzzer must be tamed, which he does by giving it a little impedance to dissipate any voltage spikes. There follows some simple signal conditioning with passive components, to arrive at an envelope for the final drum sound. How to turn a voltage into a sound? Using a voltage controlled amplifier working on a noise source. The result is recognizably the drum sound, entirely in electronics.

In a world of digital music it’s easy to forget the simpler end of sound synthesis, using circuits rather than software. If you hanker for the Good Old Days, we have an entire series on logic noise, doing the job with 4000 series CMOS logic.

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Hackaday Podcast Episode 259: Twin-T, Three-D, And Driving To A Tee

February 23, 2024 by 4 Comments

Hackaday Editors Elliot Williams and Al Williams sat down to compare notes on their favorite Hackaday posts of the week. You can listen in on this week’s podcast. The guys talked about the latest Hackaday contest and plans for Hackaday Europe. Plus, there’s a what’s that sound to try. Your guess can’t be worse than Al’s, so take a shot. You could win a limited-edition T-shirt.

In technical articles, Elliot spent the week reading about brushless motor design, twin-t oscillators, and a truly wondrous hack to reverse map a Nintendo Switch PCB. Al was more nostalgic, looking at the 555 and an old Radio Shack kit renewed. He also talked about a method to use SQL to retrieve information from Web APIs.

Quick hacks were a decided mix with everything from homemade potentiometers to waterproof 3D printing. Finally, the guys talked about Hackaday originals. Why don’t we teach teens to drive with simulators? And why would you want to run CP/M — the decades-old operating system — under Linux?

Download the file suitable for listening, burning on CDs, or pressing on vinyl.

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Hackaday Podcast 159: Zombie Killer Or Rug Maker, 3D Printed Rims, 1950s Drum Machines, And Batteries On Wheels

March 11, 2022 by No comments

Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi as they look back on the best hacks and stories of the previous week. There’s plenty in the news to talk about, though between faulty altimeters and the ongoing conflict in Ukraine, it isn’t exactly of the positive variety. But things brighten up quickly as discussion moves on to 3D printed car wheels, a fantastically complex drum machine from 1958, a unique take on the seven-segment flip display, and a meticulously designed (and documented) coffee machine upgrade. Somewhere in there a guy also recreates a rare German anti-air rocket launcher from WWII, but it’s all in the name of history. We’ll also tackle two very different forms of electric propulsion, from the massive wheeled batteries popping up in garages and driveways all over the world to high-efficiency thrusters for deep space missions.

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A CMOS Ring Modulator Pedal

December 24, 2021 by 9 Comments

Earlier this year, we featured an unusual radio receiver that took the very traditional superhetrodyne design and implemented it in an unexpected fashion without any inductors, using instead a combination of 74HC logic chips and op-amps. Its designer [acidbourbon] remarks that the circuit bears a striking resemblance to a ring modulator,so has taken it down that path by producing a 74HC based ring modulator guitar pedal.

In both circuits, a 74HC4046 phase-locked loop chip serves as an oscillator, driving a 74HC4051 analogue switch chip that performs the mixer task. The extra-op-amp filter and demodulator circuitry from the radio is omitted, and the oscillator frequency moved down to the audio range. The result can be heard in the video, and we probably agree with him that it’s not quite the same as a classic ring modulator. This lies in the type of mixer, the diodes used in a traditional circuit have a forward voltage to overcome before they start or end conducting, while the CMOS switch chip does so immediately on command.

The 4000 series CMOS and their descendants are a fascinating family with many unexpected properties that our colleague Elliot Williams has gone into detail with for his Logic Noise series. Meanwhile take a look at our coverage of the original radio.

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A Superheterodyne Receiver With A 74xx Twist

April 19, 2021 by 31 Comments

In a world with software-defined radios and single-chip receivers, a superheterodyne shortwave radio might not exactly score high on the pizzazz scale. After all, people have been mixing, filtering, and demodulating RF signals for more than a century now, and the circuits that do the job best are pretty well characterized. But building the same receiver using none of the traditional superhet trappings? Now that’s something new.

In what [Micha] half-jokingly calls a “74xx-Defined Radio”, easily obtained discrete logic chips, along with some op-amps and a handful of simple components, take the place of the tuned LC circuits and ganged variable capacitors that grace a typical superhet receiver. [Micha] started by building an RF mixer out of a 74HC4051 analog multiplexer, which with the help of a 2N3904 phase splitter forms a switching mixer. The local oscillator relies on the voltage-controlled oscillator (VCO) in a 74HC4046 PLL, a chip that we’ve seen before in [Elliot Williams]’ excellent “Logic Noise” series. The IF filter is a simple op-amp bandpass filter; the demodulator features an op-amp too, set up as an active half-wave rectifier. No coils to wind, no capacitors to tune, no diodes with mysterious properties — and judging by the video below, it works pretty well.

It may not be the most conventional way to tune in the shortwave bands, but we always love the results of projects that are artificially constrained like this one. Hats off to [Micha] for the interesting trip down the design road less travelled.

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Hackaday Podcast 113: Python Switching To Match, A Magnetic Dyno, A Flying Dino, And A Spinning Sequencer

April 9, 2021 by 2 Comments

Hackaday editors Mike Szczys and Elliot Williams recap a week of great hacks. You won’t want to miss the dynamometer Leo Fernekes built to measure the power output of his Sterling engine, which is also DIY. In this age of lithium-powered multirotors, it’s nice to step back and appreciate a hand-built rubberband-powered ornithopter.

We have a surprising amount to say about Python’s addition of the match statement (not be be confused with switch statements). And when it comes to electromechanical synth gear, it’s hard to beat a spinning tape-head sequencer.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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