- on Audio/Video/Photography
- Published in issue 7/2012 on page 118
Universal Measurement Amplifier / Attenuator
For laptop or PC
A computer is very suitable for making (audio) measurements thanks to the sound card that is usually built in.
Unfortunately, the audio input on laptops is usually too sensitive to measure somewhat larger AC voltages. A small amplifier/attenuator circuit then comes in very handy.If you build or repair audio equipment yourself, you don’t always need an oscilloscope.
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CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.
R1–R4 = 1.8MOhm
R5,R9 = 1kOhm
R6,R7,R8,R10 = 1MOhm
R11,R13 = 10kOhm
R12,R14 = 4.7kOhm
R15 = 3.9kOhm
P1,P2 = 100kOhm potentiometer, logarithmic law
P3,P4 = 100kOhm potentiometer, linear law
C1,C2 = 100nF MKT, pitch 5mm
C3,C4 = 10µF 16V, 6mm diam., pitch 2.5mm
D1–D9 = BAT48 (DO-35 case)
IC1 = TS922IN (dual opamp, DIP-8 case)
LED1,LED2 = LED, green, 5mm
K1 = 3.5mm stereo socket (e.g. Lumberg 1503-09)
K2,K3 = BNC connector, right angled pins, PCB mount (e.g. TE connectivity 1-1337543-0)
BT1 = 9V battery clip
PCB # 120272-1