Pre-emphasis for FM Transmitter

This circuit was specially designed to be used with the FM Audio Transmitter found elsewhere in the Summer Circuits 2009 issue, but it can also be useful as an addition to other transmitters. The circuit uses a dual opamp.

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Materials

090305-PCB.pdf

Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD 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.

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PCB

Download Gerber file: 090305-1-V20

Extra info / Update

Specifications

* Correction network for FM Transmitter # 080727
* Also includes a 19-kHz filter
* Current consumption of 3 mA

Component list

Resistors (all SMD 0805)
R1,R2 = 22k
R3 = 10k
R4 = 100
R5,R7 = 15kO (24kO for 75 µs)
R6 = 3kO3 (3kO6 for 75 µs)
R8, R9 = 100k
Capacitors
C1,C7 = 4µF7 10V
C2,C8 = 100nF
C3,C6 = 47pF
C4 = 2nF2
C5 = 2nF7
Inductors
L1 = 33mH, e.g. 22R336C Murata Power Solutions (Farnell # 1077046)
Semiconductors
IC1 = TLC082CD SO8 (Farnell # 8453713)