Stereo Microphone Preamplifier
For MP3 equipment
Published in issue 362, February 2007
There are still a lot of hobbyists who enjoy making high-quality live audio recordings of concerts, interviews, radio broadcasts, natural sounds, and so on. Professional equipment such as Nagra and the like is simply too expensive. We can thus be thankful that many MP3 players are equipped with an analogue input and a high-performance MP3 or WMA encoder.
Resistors
R1,R12,R23,R34 = 470Ω
R2,R24 = 100Ω
R3,R33 = 4MΩ7
R4,R5,R25,R26 = 3kΩ3
R6,R11,R27,R32 = 6kΩ8
R7,R10,R28,R31,R45,R46 = 47kΩ
R8,R9,R29,R30 = 2kΩ
R13,R35 = 33Ω
R14,R22,R36,R44 = 220kΩ
R15,R37 = 2kΩ2
R16 à R19,R38-R41 = 22Ω
R20,R21,R42,R43 = 10kΩ
P1,P2 = potentiometer 10kΩ B Alps type RK09K11310KB (Farnell # 119-1725)
Capacitors
(all SMD):
C1,C4,C6,C7,C8,C10,C13,C15,C16,C17,C19-C22 = 10µF 16 V tantalum, Vishay Sprague 595D106X9016B2T (Farnell # 392-8895)
C2,C3,C5,C9,C11,C12,C14,C18 = 470nF/25 V tantalum, Vishay Sprague 595D474X9025T2T (Farnell # 116-6814)
Semiconductors
D1 = LED, 3mm, red
T1-T8 = BC856ALT1G, SMD, SOT-23, ON Semiconductor (Farnell # 114-7782)
T9,T10 = 2N7002, MOSFET, SMD, SOIC, Texas Instruments (Farnell # 102-1754)
IC1,IC2 = TL071CD, SMD, SOIC, Texas Instruments (Farnell # 958-9449)
Miscellaneous
K1,K2,K3 = 3.5mm jack socket with 3 contacts, Schurter R36310000 (Farnell # 149-933)
S1,S2 = SPST switch, angled pins, PCB mount, height = 12.7mm, C&K 7103MD9 AV2BE (Farnell # 957-5510)
BT1 = 9V battery with clip-on lead
K4 = 2-way PCB pinheader
Case with battery compartment, e.g. BC2, Farnell # 223-554
PCB, ref. 060237-I from ThePCBShop
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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