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Piezo Element Amplifier for Guitar and Violin
- Rajkumar Sharma
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- 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. | DESC | MANUFACTURER | SUPPLIER | PART NO |
|---|---|---|---|---|---|---|
| 1 | 1 | CN1 | 4 PIN MALE HEADER PITCH 2.54MM | WURTH | DIGIKEY | 732-5317-ND |
| 2 | 1 | CN2 | 3 PIN SCREW TERMINAL PITCH 5.08MM | PHOENIX | DIGIKEY | 277-1248-ND |
| 3 | 1 | C1 | 100uF/35V | RUBYCON | DIGIKEY | 1189-2268-ND |
| 4 | 1 | C2 | 0.1uf/50V SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 5 | 2 | C3,C6 | 22uF/50V | NICHICON | DIGIKEY | 493-10491-1-ND |
| 6 | 2 | C4,C5 | 390PF/50V SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 7 | 3 | D1,R2,R3 | DNP | |||
| 8 | 1 | D2 | DIODE TVS TPD1E1B04 | TI | DIGIKEY | 296-46892-2-ND |
| 9 | 1 | PT1 | 2PIN SCREW TERMINAL PITCH 5.08MM PIEZO DISC | PHOENIX | DIGIKEY | 277-1247-ND |
| 10 | 4 | R1,R5,R14,R15 | 100E 5% SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 11 | 2 | R4,R13 | 1M 5% SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 12 | 4 | R6,R7,R10,R12 | 100K 5% SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 13 | 2 | R8,R11 | 2K 1% SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 14 | 1 | R9 | 442E 1% SMD SIZE 0805 | MUARATA/YAGEO | DIGIKEY | |
| 15 | 1 | U1 | OPA1678 SOIC8 | TI | DIGIKEY | 296-47347-1-ND |
Connections
Gerber View
Photos
Video
OPA1678 Datasheet
PCB
