Piezo Element Amplifier for Guitar and Violin

  • Rajkumar Sharma
  • 67 Views
  • easy
  • Tested
  • SKU: EL122204
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The board presented here is a preamplifier for contact microphones that are used for amplifying the sound of musical instruments which do not contain electrical pickups, such as guitar and violins. Most contact microphones use a piezo element to convert vibration in the body of the musical instrument to a voltage. The circuit is built using OPA1678 OPAMP. The low noise and low input bias current of the OPA1678 makes the device an excellent choice for high impedance preamplifiers for piezo elements. This preamplifier circuit provides high input impedance for the piezo element but has low output impedance for driving long cable runs. It provides a balanced audio output that can be fed to a balanced microphone pre-amplifier. The circuit has also the option for phantom power input. Install R3=1.2K Ohms, R2=1.2K Ohm and Zener diode 24V.

The project can be interfaced with “Phantom Powered Microphone Pre-Amplifier using SSM2019” published on our website.

Features

  • Supply 24V DC @ 5mA
  • –3-dB Bandwidth: 20 Hz to 20 kHz
  • Gain: 20 dB (10 V/V)
  • Balanced Output
  • Screw Terminal for Output Connection
  • Screw Terminal for Piezo Element Connection
  • Male Header Connector for Supply Input
  • Optional Phantom Power Input
  • PCB Dimensions 56.20 x 22.54 mm

Schematic

Parts List

NO.QNTY.REF.DESCMANUFACTURERSUPPLIERPART NO
11CN14 PIN MALE HEADER PITCH 2.54MMWURTHDIGIKEY732-5317-ND
21CN23 PIN SCREW TERMINAL PITCH 5.08MMPHOENIXDIGIKEY277-1248-ND
31C1100uF/35VRUBYCONDIGIKEY1189-2268-ND
41C20.1uf/50V SMD SIZE 0805MUARATA/YAGEODIGIKEY
52C3,C622uF/50VNICHICONDIGIKEY493-10491-1-ND
62C4,C5390PF/50V SMD SIZE 0805MUARATA/YAGEODIGIKEY
73D1,R2,R3DNP
81D2DIODE TVS TPD1E1B04 TIDIGIKEY296-46892-2-ND
91PT1 2PIN SCREW TERMINAL PITCH 5.08MM PIEZO DISCPHOENIXDIGIKEY277-1247-ND
104R1,R5,R14,R15100E 5% SMD SIZE 0805MUARATA/YAGEODIGIKEY
112R4,R131M 5% SMD SIZE 0805MUARATA/YAGEODIGIKEY
124R6,R7,R10,R12100K 5% SMD SIZE 0805MUARATA/YAGEODIGIKEY
132R8,R112K 1% SMD SIZE 0805MUARATA/YAGEODIGIKEY
141R9442E 1% SMD SIZE 0805MUARATA/YAGEODIGIKEY
151U1OPA1678 SOIC8TIDIGIKEY296-47347-1-ND

Connections



Gerber View

Photos

Video


OPA1678 Datasheet

opa1678

PCB

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