Find all your DIY electronics in the MakerShed. 3D Printing, Kits, Arduino, Raspberry Pi, Books & more!

MAKE: Intern's Corner
Every other week, MAKE’s awesome interns tell about the projects they’re building in the Make: Labs, the trouble they’ve gotten into, and what they’ll make next.

By Meara O’Reilly, projects intern

I’ve been working on winding coils and testing out a cool new electromagnetic guitar pickup for the upcoming issue of MAKE, so I thought I’d share a modification I did a while ago on the old piezoelectric pickup that was featured on the quick and easy Cigar Box Guitar in MAKE Volume 04.

oldCBGpickup.jpg
Here’s the piezo buzzer used for a pickup in MAKE’s original Cigar Box Guitar, still encased in black plastic.

Piezoelectric transducer discs often come in protective plastic casings, but they’re actually much more sensitive without them! I’ve spent many an hour with needlenose pliers cracking them open like steamed lobsters to get at the ceramic and metal underneath, and I’ve found the difference in amplification to be definitely worth it.

The original design had the plastic-encased piezo element (a piezo buzzer) inside the cigar box, and it worked fine, but I’ve learned that it works even better without the plastic case.

One of our old CBGs even had the piezo buzzer mounted directly under the strings, sort of propping them up into alignment with the fretboard, in order to show off the pickup. This was failing for two reasons: first, the point of contact was too broad, causing a buzzing sound as the strings hit the long, flat surface of the plastic, and second, because the piezo disc was oriented at the bottom of the plastic casing, it was protected from some of the most important vibrating bodies on the guitar — the strings!

I decided to build something where a narrower contact point (or bridge) could directly conduct the vibration from the strings to the disc.

Meara'sPick-up.jpg
Here’s my modified piezo pickup, naked, in direct contact with the bridge, and sounding great.

I cut a small block of balsa wood (about the width of the fretboard and long enough for the disc to rest comfortably upon) to prop up the whole setup. I placed placed the piezo on top of this balsa base, then cut a small piece of a wooden barbeque skewer we had lying around and placed that on top of the piezo as a bridge.

The strings, once wound on, will normally hold the bridge in place (in fact, many types of acoustic guitars have some sort of free-standing bridge like this), but for extra security, I cut both of the rounded ends off a popsicle stick and glued them flush with the balsa block to provide a sort of “baby gate” for the skewer, to keep it from rolling too much.

Voilà! The smaller contact point, applied directly to the piezo disc and held in place by the strings, conveys the string sound wonderfully.

What pickup modifications have you discovered?

Keith Hammond

I’m projects editor of MAKE magazine.


Related

Comments

  1. RocketGuy says:

    My buddy and I in High School used one of these bare for a violin pickup (earthquake putty seemed to work okay to attach it, but you might be better off with another approach to preserve the high end).

    Then, being slightly nutty teens, we decided to find out what a train sounds like from the track’s point of view.

    We got some really interesting bell/chime like tones from the approaching train, but then it turned into a bunch of really loud noise. We tried to compensate with the portable mixer, but it was just too much until the train had passed.

    Those bits at the start and end were really cool though.

    If you’re inspired to try it, make sure to be really paying attention in both directions, lots of folks die messing around near trains. Pick someplace where you’ve got about a mile straight in both directions so you can see it coming.

    We put the pickup on the side of the rail, about halfway down the side, on the outside, and then put a good long cable on it to the recorder. And we kept our distance until the train was gone. You have to fade it really fast when the train is getting close to the rail you put on.

  2. myxbyx says:

    I would recommend you use either steel strings, or nylon. The strings in the picture look like cotton and it will be difficult to tighten high enough to drive a small soundbox.

    I use piezo pickups from broken childrens toys, they are free and work well. You can cut the piezo from the round shape as long as you do not cut between the wires.

    You can also get great piezo pickups using the microphones and speakers from dead cell phones and again, you are recycling and reducing waste.

    The other point I wanted to make is simply a construction detail, usually the neck is mounted inside the cigar box, traveling under the top, with the bridge on the top. This aids in both the acoustic sound and the electric with a piezo.

    Your construction seems more like an Appalachan Dulcimer construction, and it works for them because of a larger sound box with a longer contact with the neck.

    If you are building a 3 string version, a brass decorative hinge makes a nice tailpiece, (as it has three screwholes in it for the strings), and an empty rifle shell makes a nice brass bridge, sharper tones than a spruce or pine bridge, and more recycling. You could also use a piece of an old piano key, the ebony one, as a source for a bridge, or glue some ivory, from the same source, between some hardwood for a bridge. The nut should also be a hard material, hardwood or metal.

    You can also use bone for the nut and saddle, I make them from old beef bones after the dog has cleaned them for me.

    Interesting experiment with the train….

In the Maker Shed