For the
hackerspace, I send out a lot of emails. Most of them get ignored, but some of them stick. One of the ones that got a reply was a request to tour a museum collection of rare and antique musical instruments that the university's music school owns. In one of the conversations we had with the outreach director of the collection, we decided that co-hosting an educational event that melds technology and music into a workshop for kids and their parents would be an excellent idea. This is what is referred to as a Make and Take, particpants register, pay a fee for parts, come and get taught how to make stuff, and then get to take it home with them afterwards.
So, like a good
engineer scientist (hacker?), I started thinking about what kinds of musical/technology projects we could conceivably build in a few hours. A while ago,
Abel Pharmboy, a fellow science blogger, scientist, and musician linked me to the trailer of
"It Might Get Loud" which showed Jack White of The White Stripes making a primitive electric instrument out of a 2x4 plank. This got me thinking about what sort of materials an instrument pickup could be made out of with the eventual thought of making a plank guitar. The potential for a Make and Take with the music museum gave that notion impetus, so tonight I built a 2 string electric slide guitar.
Figure 1: It's not exactly science, but it does make noise! I used a 1"x4" plank, the voice coil of an old telephone (has lots of 42G copper wire), some nails, a set of nickelwound guitar strings, 6 screws, and a glass bottle of Nantucket Nectar juice which was quite tasty.
Humbucker construction:
A humbucker is a type of electric guitar pickup that transforms the vibrations in the strings into an electronic signal. It is an electromagnet that projects a magnetic field perpendicular to axis through which the guitar strings vibrate when plucked, which induces a current. Some commerical pickups have a separate magnet for each string, and some have 1 rectangular magnet stretching under all the strings at once. I chose the latter option, and since most commercially used hardware is ferromagnetic, I figured I could use the dry-wall screws as the core of my pickup.
I began by trying to solder the 4 screws together. Turns out that silver-core solder doesn't stick very well to cold hard metal alloys regardless of how much I'd have liked it to. So I used some 20G copper wire on hand in the hackerspace to bundle the screws together. Next I tried to solder (stubborn-ness) the bundle of screws to an improvised Dremel bit to help me wind the 42G copper wire from the telephone voice coil around my ferromagnetic core more easily. This also didn't work. I wound up making a handle out of hemostats and hanging the voice coil like a spool from my soldering helping hands and winding it by hand. I got sick of this after 2h and decided the thick belt of copper wire now girdling the screws would suffice. Finally I soldered leads to the ends of copper wire (the trailing end and the beginning end that I left sticking out) and soldered that to the leads on a 1/4" audio jack someone gave to me. When I plugged it into my amp, it made clicking buzzy sounds, but this was expected since there weren't any vibrating metal objects nearby. I tried to simulate one by banging a stainless steel bowl around near it, but this doesn't work as stainless steel is a crappy magnet and it was annoying the other people present.
The guitar:
When I embarked on this phase of the project, I immediately regretted that the hackerspace doesn't have a T-square yet so I don't know if my lines are even close to even. Nonetheless, I began by plotting out a point near one end of the plank and nailing an E and D string through their winding holes to the board with skinny nails. Then I played with the placement of the glass juice bottle as an acoustic resonator and bridge and decided that about 4.5" was good for tension. I used 4 nails to create a little cradle/fence that keeps the bottle in place while also laying it flush against the plank.
Creating functional tuners was more difficult. I found 2 wood screws and tried to tie the strings around them to no success, hoping to be able to tune the guitar with a screwdriver. None of the knots stuck, they just rotated. I had expected about as much. So I hauled out the metal cutting bit of my Dremel and deepened one of the notches on the screw's head to be flush (made lots of pretty sparks that didn't start any fires). Then I filled the screw hole with molten solder and poked the end of the string into it and held it steady until it cooled, then used needlenose pliers to bend the string down to loop around the screw. This worked well, but since I had filled the screwdriver holes with solder, I had to use the needlenose pliers to tune, but tune I eventually did, with the supposed E string winding up tuned to a D2 and the supposed D string winding up as a C3.
The humbucker is stood up near the tuning pegs by 2 small nails.
Sound:
It's quiet. At least, it's quiet when it's plugged in inasmuch as it has a very low signal to noise ratio. Acoustically, it is surprisingly loud and was causing loose screws and nails to bounce about on the table surface when laid flat. I had to run it through a pre-amp with the volume boosts, EQ boost, and gain all the way up to get an appreciable signal out of it. But once I did it was loud and gritty with a very steely twang. It is a bit awkward to play, but that's part of what makes it cool. I quickly found the sweet tonal spots on the neck of the guitar and began to bang out simple rock and roll chord processions.
The signal is loaded with tones of natural distortion, so much so that hooking up my Boss Bass Distortion pedal didn't impact the tone or intelligibility of its done much at all.
What I Would Do Differently Next Time:
1) Use an actual magnet for the pickup core.
2) Find a way to wind the copper wire around the core mechanically instead of by hand.
3) Wax the wound wire around the pickup to give it some insulation from outside interference.
4) Mill tuner screws with holes through them to thread the strings through. Find a kind-of-flattened bottle to use for the resonator to decrease the necessary height of the strings from the board so I can also make a flatter pickup.