- on Audio/Video/Photography
- Published in issue 7/2010 on page 96
(Summer Circuits 2010 article)
This circuit is a revised version of the Audio Limiter published in the 2002 Summer Circuits edition, which is intended to limit the (possibly excessive) dynamic range of the audio signal from a TV set or DVD player (for example). The original circuit is based on attenuating an excessively strong source signal. Here we take the opposite approach of amplifying the quieter passages. To minimise the typical ‘breathing’ effect of compressors, the control range is limited to only 24 dB.
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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.
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R1,R5,R6,R10,R14,R18 = 10kOhm
R2,R7 = 13.7kOhm 1%
R3,R8 = 22.6kOhm 1%
R4,R9 = 49.9kOhm 1%
R11,R15 = 1.24kOhm 1%
R12,R16 = 2.94kOhm 1%
R13,R17 = 9.09kOhm 1%
R19,R20 = 100Ohm
R21,R22 = 3.3kOhm
R23,R24 = 18kOhm
R25 = 270kOhm
R26 = 100kOhm
R27,R28,R29 = 1MOhm
R30,R31 = 270Ohm
P1 = 5kOhm trimpot,horizontal
C1,C2,C5–C8,C15–C18 = 100nF ceramic, lead pitch 5mm
C3,C4,C13,C14 = 220µF 25V radial, lead pitch 3mm
C9 = 10nF , lead pitch 5 or 7.5 mm
C10 = 470nF, lead pitch 5 or 7.5 mm
C11 = 2.2µF, lead pitch 5 or 7.5 mm
C12 = 220 n, lead pitch 5 or 7.5 mm
D1,D2 = zener diode 8.2V /1.3W (e.g. NXP BZV85-C8V2)
IC1,IC2 = TL082CN
IC3,IC4 = 4052
IC5 = LM339D
IC6 = 4538
IC7 = 4093
IC8 = 4516
K1,K2,K3,K4 = cinch socket, right angled, PCB mount, type JB0115-B-G (Conrad Electroncis # 736899)
PCB # 090944