When it comes to guitar effects pedals, the industry looks both back and forward in time. Back to the 50’s and 60’s when vacuum tubes and germanium transistors started to define the sound of the modern guitar, and forward as the expense and rarity of parts from decades ago becomes too expensive, to digital reproductions and effects. Rarely does an effects company look back to the turn of the 19th century for its technological innovations, but Zvex Effects’ “Mad Scientist,” [Zachary Vex], did just that when he created the Candela Vibrophase.
At the heart of the Candela is the lowly tea light. Available for next to nothing in bags of a hundred at your local Scandinavian furniture store, the tea light powers the Zvex pedal in three ways: First, the light from the candle powers the circuit by way of solar cells, second, the heat from the candle powers a Stirling engine, a heat engine which powers a rotating disk. This disc has a pattern on it which, when rotated, modifies the amount of light that reaches the third part of the engine – photoelectric cells. These modulate the input signal to create the effects that give the pedal its name, vibrato and phase.
Controls on the engine adjust the amount of the each effect. At one end, the effect is full phasor, at the other, full vibrato. In between a blend of the two. A ball magnet on a pivot is used to control the speed of the rotating disk by slowing the Stirling engine’s flywheel as it is moved closer.
While more of a work of art than a practical guitar effect, if you happen to be part of a steam punk inspired band, this might be right up your alley. For more information on Stirling engines, take a look at this post. Also take a look at this horizontal Stirling engine.
Winter NAMM is the world’s largest trade show for musical instrument makers. It is a gear head’s paradise, filled to the brim with guitars, synths, amps, MIDI controllers, an impossibly loud section filled with drums, ukuleles, and all sorts of electronic noisemakers that generate bleeps and bloops. Think of it as CES, only with products people want to buy. We’re reporting no one has yet stuffed Alexa into a guitar pedal, by the way.
As with all trade shows, the newest gear is out, and it’s full of tech that will make your head spin. NAMM is the expression of an entire industry, and with that comes technical innovation. What was the coolest, newest stuff at NAMM? And what can hackers learn from big industry? There’s some cool stuff here, and a surprising amount we can use.
Guitar pedals are a great way to experiment with the sound of your instrument. However, they require electricity, and when you’re using more than a couple, it can get messy. Some will run on batteries, while others are thirstier for more current and will only work with a plugback. There are a great many solutions out there, but most people with more than a few pedals to power will end up going to some kind of mains powered solution. [Don] is here to show us that it’s not the only way.
Mains power is great for some things, but where pedals are concerned, it’s not always perfect. There are issues with noise, both from cheap power supplies and poorly designed pedals, and it means you’re always hunting for a power socket, which is limiting for buskers.
[Don] realised that the common drill battery is a compact source of clean, DC power, and decided to use that to power his rig. By slapping together a drill battery with a pre-assembled buck converter and a 3D printed adapter, he was able to build a portable power supply for his pedals. Thanks to the fact that the vast majority of pedals use 9V DC with the same input jack design, it’s a cinch to wire up. With an appropriately sized buck converter, a drill battery could supply even a hefty pedalboard for a significant period of time.
Starting a new project is fun, and often involves great times spent playing with breadboards and protoboards, and doing whatever it takes to get things working. It can often seem like a huge time investment just getting a project to that functional point. But what if you want to take it to the next level, and take your project from a prototype to a production-ready form? This is the story of how I achieved just that with the Grav-A distortion pedal.
Why build a pedal, anyway?
A long time ago, I found myself faced with a choice. With graduation looming on the horizon, I needed to decide what I was going to do with my life once my engineering degree was squared away. At the time, the idea of walking straight into a 9-5 wasn’t particularly attractive, and I felt like getting back into a band and playing shows again. However, I worried about the impact an extended break would have on my potential career. It was then that I came up with a solution. I would start my own electronics company, making products for musicians. Continue reading “Taking a Guitar Pedal From Concept Into Production”→
For several years, [Ray] and [Anna], the team behind ElectroSmash, have been smashing audio electronics and churning out some sweet DIY audio gear. This time around, they’ve built Pedal-Pi — a simple programmable guitar pedal based around the Raspberry-Pi Zero. It is aimed at hackers, programmers and musicians who want to experiment with sounds and learn about digital audio. A lot of effort has gone in to documenting the whole project. Circuit analysis, a detailed BoM, programming, assembly and background information on related topics are all covered on their Forum.
The hardware is split in to three parts. On the input, a MCP6002 rail-to-rail op-amp amplifies and filters the analog waveform and then a MCP3202 ADC digitizes it to a 12-bit signal. The Pi-Zero then does all of the DSP, creating effects such as distortion, fuzz, delay, echo and tremolo among others. The Pi-Zero generates a dual PWM signal, which is combined and filtered before being presented at the output. The design is all through hole and the handy assembly guide can be useful for novices during assembly. The code examples include a large number of pedal effects, and if you are familiar with C, then there’s enough information available to help you write your own effects.
[Alex Lynham] has been creating digital guitar pedals for a while and after releasing the Atom Smasher, a glitchy lo-fi digital delay pedal, he had people start asking him how he designed digital effects pedals rather than analog effects. In fact, he had enough interest, that he wrote an article on it.
The article starts with some background on [Alex], the pedals he’s built and why he chose not to work on pedals full-time. Eventually, the article gets to the how [Alex] designed the Atom Smasher. He starts by describing the chip he used, the same one that many hobbyists, as well as commercial builders, use for delay based effects – the SpinSemi FV-1.
The FV-1 is a SMD chip used for digital delays and other effects that require a delay line – reverbs, choruses, flangers, etc. It’s programmed with an assembly-style language called SpinASM. [Alex] goes over some of the tools and references he used when designing for the pedal. He also has a list of tips for would-be effect pedal designers which work whether you’re designing digital or analogue effects.
A lot of people around here got their start in electronics with guitar pedals. This means soldering crappy old transistors to crappy old diodes and fawning over your tonez, d00d. Prototyping guitar pedals isn’t easy, though, and now there’s a CrowdSupply project to make it easier The FX Development Board is just that — a few 1/4″ jacks, knobs, pots, power supply, and a gigantic footswitch to make prototyping guitar pedals and other musical paraphernalia easy. Think of it as a much more feature-packed Beavis Board that’s still significantly cheaper.
How do Communicators in Star Trek work? Nobody knows. Why don’t the crew always have to tap their badge before using it? Nobody knows. How can the com badge hear, ‘Geordi to Worf’, and have Worf instantly respond? Oh, we’ve argued about this on IRC for years now. Over on Hackaday.io, [Joe] is building a Star Trek com badge. The electronics are certainly possible with modern microcontrollers, but for the enclosure, we’ll have to review a few scenes from Time’s Arrow and The Enemy.
[Alois] was working with an Intel Edison on a breadboard. He was generating a signal, and sending it through a little tiny breadboard wire to an oscilloscope. The expected waveform should have been a nice square wave at 440MHz. What he got out of this wire was a mess. You shouldn’t use long wires when probing circuits. That little breadboard wire was a perfect radiator for 440MHz, and the entire setup turned into an antenna.
[Douglas] is running a Kenwood TM-D710A as his amateur radio rig. This radio does APRS stuff, but it requires an external GPS and power source to do it right. GPS receivers are now very small and very cheap, so [Douglas] just stuffed a GPS module inside his radio. The module itself is a GP-20U7, a tiny GPS module the size of a postage stamp, and wired it up to a few pads on the radio PCB.