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Acoustic Guitar Pickup

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Step 1: Making the Pickup

Parts you will need:
1. Piezo Buzzer Element
2. about 1 foot of shielded audio cable
3. a 1/4" audio jack (that can be mounted on the guitar body)
4. a small amount of medium density foam. (just a couple square inches)
5. soldering iron, solder, wire strippers, hot glue gun, and hot glue

  • The first step is to design and create your pickup. The heart of the pickup is a piezo buzzer element. You can find these for just a couple dollars at your local parts store. (Radio Shack) Sometimes the Piezo Buzzer packages don't have that much information on them, but you want to find things as close as possible to the information listed on the "Specs:" page. In other words, they are pretty cheap so go for a good one. Also note that you do not need a fully functional buzzer device... just the Piezo element.
  • A word about Piezo Elements. Piezo elements are made from two conductors separated by a layer of piezo crystals. When a voltage is applied across the crystal layer, the crystals pull on one side and push on the other. This in turn bends the metal conductor layers. When a sinusoidal signal (audio) is applied, the conductors are pushed and pulled very quickly, creating sound waves. The beauty of the Piezo element is that it also can be applied reversely. If sound waves push and pull on the conductors, an electrical signal is created and can be output to an amplifier or recording device. This is exactly how we will use the Piezo Buzzer element in this project. It will be attached to the inside of the guitar body, and, as the body vibrates, the sound will be turned into an electric signal by the Piezo buzzer element.
  • Now that you have the Piezo Buzzer, you need to carefully break it open and get out the piezo element. Be careful not to hurt the metal device inside. Bending the element may cause it to break or lose some of it's sensitivity.
  • You are now ready to solder the device together. Strip the ends of the shielded audio cable. On one end connect the signal wire to the center of the Piezo element and the ground/shielding to the metal/brass surface of the piezo element. On the other end of the shielded wire, connect the signal wire to the signal tab on the 1/4" audio jack and connect the shielding to the ground tab.
  • We have found that a small piece of medium density foam improves the performance of the pickup over a large number of frequencies.(If you are familiar with circuitry, feel free to experiment with combinations of capacitors and resistors to cut undesired frequencies) Cut a piece of foam the same size of your piezo element and about 3/8" tall. Place a large drop of hot glue on the back side of the piezo element (where the wires connect) and then press the foam on until the glue cools.
  • Your piezo pickup device should now be ready to install. You may want to make sure it is working by plugging it into an amp and lightly tapping on it.
 
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khurlxen3 years ago
wow...its nice......the question is.....can i also use a microphone to be acoustic guitar pick up..........? need advice.....
In a venue, sound from the PA or monitors can feedback into a microphone, even if it's mounted inside an acoustic guitar. A piezo won't feedback.

Bobbily: The ground is usually the sheath of the cable. This is more for consistency's sake. GROUND IS A CONCEPT, NOT AN ABSOLUTE. A piezo creates a signal across two contacts. The only difference between the two choices for connection is the phase of the signal.
As an aside, if you make one of these to be installed in a ukulele, you can skip the length of extra audio cable and solder the signal wire directly to the signal pin and the ground wire directly to the ground pin.
levi19954 years ago
any way to put a volume pot with this to change volumes instantly? 
Bobbily4 years ago
Hi there,
My piezo element already has two small wires soldered to it, should I use them, or solder the audio cable directly to the piezo element? 
Also, how do I know which is ground of audio cable? 
And Will any shielded audio cable do, say for instance, mic cable vs. instrument cable?  I'm basically cutting up an old cable with a busted jack cuz I can't find a place that will sell me one foot of audio cable.
Thanks for the help.
asimmonds5 years ago
WHERE CAN I FIND MEDIUM DENSITY FOAM?!?!
i am a little confused on what the final product should be? in the picture it looks as if there is a stand that holds the pickup above the strings, it looks like it would interfere with your strumming hand. can this setup be used with a stereo that has a mic input jack if I dont have a amp?
heres a link to a few of them.. in case you cant open the pages for some reason im attaching 2 of the schems as pics.. so im def. gonna try 'preamp schem 2' and 'preamp schem 3' i might try the other one once i get more money cuz that one has more parts than the others
preamp schem 2.gifpreamp schem 3.gifpiezo preamp schem.JPG
ps where it says 'electret microphone' it just means thats the input.
sort of.. i did something like this and i use a set of computer speakers with it (because i dont have an amp) then i tried it with a different set of computer speakers and it didnt work.. then i did some research and figured out that: -the impedance of the piezo is to high for most amps to handle -and, technically, you are supposed to have a preamp in there to act as an impedance buffer. these preamps can be made fairly easily with minimal parts for cheap. i found 2 great schematics for some mad simple ones that ill attach if i can find them again.. i think i know where they are though so it should only be a few minutes.
StabbyJack6 years ago
thats the coolest thing ever. If you can remember I'd like to know how much do the parts cost
Radio Shack part number 273-073a is the piezo @ $1.99 ,. i don't bother removing the plastic case,. i just remove the sticker from the back side, clean it off and use hot glue to stick it inside the guitar top,. my personal preference is about 3 below the bridge and about halfway to the side of the guitar on the bass side,. sound tends to be fairly balanced at this location for a typical dreadnaught,. tweak sound futher with your P.A. Shack part number 274-252 is a package of (2) 1/4" mono jacks for $2.99. yo.
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