piezoelectric ceramic plate used for guitar pickup

Experimental principle
This experiment utilizes the positive piezoelectric effect of piezoelectric ceramics. Using the piezoelectric ceramics installed in the guitar resonance box, the seven sounds from the center C to B (including B) in the C major scale are plucked by the player, and the electric signal from the piezoelectric ceramic is measured by an oscilloscope. Waveform, and the frequency corresponding to each tone is measured by an oscilloscope, and compared with the scale frequency of the international common standard pitch frequency conversion table. By analyzing the degree of coincidence and the allowable error range, it is judged whether the piezoelectric ceramic can realize the recognition of common instruments. The tone of the tone function in the experimental device.In this experiment, a PZT5H piezoelectric ceramic sheet having a length of about 2 cm and a width of about 0.7 cm and four thin wires were used. The piezo ceramics plates piezoelectric ceramic sheet is divided into three layers, the white outer layer on both sides is a positive electrode, and the middle layer is a negative electrode. Two of the wires are about 30 cm and the other two are about 70 cm.

In this experiment, six strings on the acoustic guitar are used as the sound source of the tones, and the player obtains the tones of different tones by plucking the strings. The selected sound source has been precisely tuned to accurately emit seven tones from the center C to B (including B) in the C major scale.

Two wires of about 30 cm in length are welded to the two poles of the piezoelectric ceramics plates transducer , and the piezoelectric ceramic is pasted into the resonance box of the guitar with "good brother" glue to make full contact with the resonance box, waiting for a day or so. The glue dries. (The reason why the sound is collected in the resonance box is that if you want to use the piezoelectric ceramic piece to get a clear waveform that can be used for analysis, the sound to be collected has a certain loudness. The resonance box uses the resonance principle to make the sound phase with the same frequency. Superimposed to enhance the original sound)

Two 30cm wires on the piezoelectric ceramic are extended from the resonator, respectively welded to one end of the two small iron pieces, and then the two long wires of 70cm are respectively welded to the other ends of the two small pieces of iron, and Connect the oscilloscope. (The two internal wires are connected to the piezo ceramic plates pickup. If it is too long, it will easily wrap and fall off when carrying the guitar. Once it falls off, it is very difficult to re-weld the piezoelectric ceramic inside the resonance box to prevent this. In this experiment, two long wires are used to extend the two inner parts.

Waveform acquisition

 Overview of Acquisition Waveforms
This experiment collects the piezoelectric ceramic electrical signal waveform displayed by the oscilloscope when playing the C major scale (CDEFGAB) on a string. During the experiment, each tone is played twice, and the oscilloscope is frozen immediately after each play. In the process of collecting the waveform of the electrical signal, each waveform exhibits regularity or periodicity, and the observer selects one cycle to record the frequency data.

Data collection analysis

The following images and annotations of piezoelectric plates piezoelectric sensor are the waveforms acquired by the oscilloscope when the guitar plays seven of the major scales. Each of the tones in this experiment was played three times, and each time the game was played, two different cycles were measured, so two waveform images were taken for each play. In this section, each tone only shows the waveform picture played twice, one picture at a time.Each waveform has two vertical yellow lines, the beginning and end of the period selected by the observer. The yellow fourth line of data (1/Δt) in the upper right corner of the oscilloscope is the frequency of this cycle.