Hacklet 75 – Guitar Projects

Some things just go hand in hand. Hacking and guitars are one perfect example. A huge number of hackers, makers, and engineers have at least dabbled in playing the guitar. Even those who don’t play have heard the swan song of the wayward guitarist “Bro, you fix amps?”. Seriously, once your guitar toting friends find out you tinker in electronics, you’ll never be left wanting for pizza or beer. This week’s Hacklet is about some of the best guitar projects on Hackaday.io!

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Hackaday Links: August 23, 2015

Dutch security conference! It’s called hardwear.io, it’ll be in The Hague during the last week of September, and they have the CTO of Silent Circle/Blackphone giving the keynote.

Baltimore’s awesome despite what the majority of the population says, and they have a few hackerspaces. One of them has an Indiegogo going right now to save the space. Want a tour of the space? Here you go.

[Fran Blanche] made it on to the Amp Hour. Included in this episode are discussions about the boutique guitar pedal market and the realities of discarded technology that took us to the moon.

Speaking of electronics podcasts, SolderSmoke is 10 years old now.

TARDIS-shaped guitars are nothing new, but [Gary] from the LVL1 hackerspace in Louisville, KY is making an acoustic one. The neck is, of course, taken from another guitar but the entire TARDIS-shaped body is custom-made. Now do resonance calculations on something that’s bigger on the inside.

Think German-made means German quality? [AvE], [Chris], or whatever we call him did a teardown of a Festool Track Saw. It’s a thousand dollar tool that will start to stink in a few years and has bearings that don’t make any sense.

Love 8-bit? There’s a Kickstarter from 8-bit generation for a documentary about the love, loss, resurrection and continuation of old computers. Dozens of very interesting interviews including one from our own [Bil Herd]

Hackaday Prize Entry: DIY Guitar Multieffects

Guitar effects and other musical circuits are a great introduction to electronics. There’s a reason for this: with audio circuits you’re dealing with analog signals and not just the ones and zeros of blinking a LED. Add in the DSP aspects of audio effects, and you have several classes of an EE degree wrapped up in one project.

For his Hackaday Prize entry, [randy.day] is building a guitar multieffect. Instead of just a single distortion, fuzz, or chorus circuit, this tiny little PCB is going to have several flavors of pitch shifting, a flanger, chorus, echo, harmony, and stranger ‘digital-ish’ effects like bitcrushing.

This effects unit is built around a PIC32 and a TI audio codec which processes the audio at 64k 32-bit samples/second. This takes care of all the audio processing, but the hard work for a guitar pedal is actually the enclosure and mechanicals – it’s a hard life for stage equipment. For the foot pedal input, [randy] is using a magnetic position sensor, but there’s no word if he’ll be using a fancy die-cast enclosure or a plastic injection molded unit.

The 2015 Hackaday Prize is sponsored by:

Ghost Guitar Plays Hendrix

Purple Haze all in my brain,
lately guitars they don’t seem the same,
[Josh] is playin’ funny but I don’t know why
‘scuse me while he electrifies.

[Josh] wanted to experiment with playing a guitar by different means. We’ve seen a few guitar hacks that use servos to play, and Arduino-based guitars that replace the strings with membrane potentiometers, but he decided to try a different approach. He’s using a permanent magnet and the electromagnetic effect to play the string.

Purple Haze all around,
all those amps are runnin’ up or down.
Are my strings all goin’ left or right?
Whatever it is, electromagnetism is pushin’ me outta sight.

To do this, he put a large permanent magnet next to the string and ran an alternating current through the string itself. When the current and the magnetic field interact, the string is pushed, like the bearing of a motor.  When the current goes the other way, the string is pushed in the opposite direction. Because he is using an alternating current (driven through a MOSFET tied into a frequency generator), he was able to control the frequency of this, and find the frequencies that made the string resonate, including the harmonics that give guitars their unique sound. It’s a pretty neat hack, but don’t forget that he is dealing with quite a lot of juice: if you were to inadvertantly touch the string and ground it to earth, there is enough current in the circuit to kill you.

Yeah, [Josh’s] hack is all about the right hand rule,
I know that he’s no hacking fool,
you’ve got my E string resonating, resonating so fine
just don’t touch it, or you’ll end your time
Help me, yeah, Purple Haze!

(with apologies to the ghost of [Jimi Hendrix], guitar hacker supreme)

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Mad Max Inspired Flamethrower Ukulele

The new Mad Max movie is getting a lot of buzz, and a few people are calling it a modern classic. There’s a flamethrower guitar in the movie, which means it’s time for cosplay accouterments. Our ‘ol buddy [Caleb] loves flamethrowers and poofers, so hacking together a Doof Warrior inspired flamethrowing ukulele was natural for him.

The fuel for this uke is a can of butane actuated with a caulking gun. This setup is actually pretty clever; by removing the locking tab on the caulking gun, butane is released when the gun’s trigger is squeezed, but stops when the trigger is released. The igniter is a simple grill igniter is used to light the gas.

[Caleb] is rather famous for his flamethrowing creations. His life-size fire-breathing piranha plant uses a similar setup to shoot fire.

Video below.

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Router Fixture for Radiusing Guitar Fretboards

Unless you’ve been up close and personal with a guitar, it’s easy to miss that the fretboard (where a guitar player presses on the strings) is not flat. There is a slight curve, the amount of which varies with the type and brand of guitar. There are even guitars with fretboards that have a compound radius that changes from one end to the other.

finger board radius cutter

[Mike] is a guitar builder and needed a way to radius his own fretboards. He did what any other DIYer would, he designed and built a tool to do exactly what he needed. The fretboard radius cutting fixture consists of a new large router base that has a curved bottom. This base rests on two metal pipes and can slide both back and forth in addition to along the new base’s curve. The flat fretboard blank is secured to the fixture below the router and is slowly nibbled away at using a standard straight flute router bit. A little sanding later and [Mike] will be able to keep moving forward on his guitar builds.

Homemade 3D Carving Duplicator

[Frank] is a guitar builder and has to make a quantity of acoustic guitar bridges that wouldn’t make sense to do manually by hand each time. He wanted a way of duplicating bridges quickly and precisely but he didn’t want to go to a CNC machine. Instead, he build a 3D duplicating machine.

The machine has 3 perpendicular axes, just like a milling machine. Mounted to the Z Axis is an air powered spindle that can reach 40,000 RPM. All 3 axes are moved by the operators hands. Normally, free-hand cutting something like this would be very difficult. [Frank’s] solved this in his machine by using a stylus that is offset from the cutting bit. The stylus is the same effective length and diameter of the cutting bit and is guided over a finished bridge pattern. While the stylus is tracing the pattern, the spindle and bit are removing material from a bridge blank. The stylus is continually moved over the entire pattern bridge until the spindle is finished carving out a new bridge out of the blank.

To aid in lifting the heavy Z Axis and spindle, [Frank] added a counter balance to make tracing the pattern extremely easy. Once the new bridge is carved, it only requires minor sanding to remove the tool marks before being installed on a guitar! [Frank] admits his linear bearings and rails are very rigid but also very expensive. If you’re interested in a less-expensive 3D duplicator, check out this project.