Hi-fi Wireless Headset
2.4 GHz digital audio link
Published in issue 384, December 2008
Although they’ve been on the shelves of audio and video equipment retailers for quite a few years now, wireless headsets have been conspicuously absent from hobby electronics magazines. It has to be said that building this sort of headset, especially if we set ourselves a certain level of quality, is far from simple — or rather, was far from simple, until some recently-brought-out modules came along to help us out.
transmitter
Resistors
0.5 or 0.25 watt, metal film, 5%
R1 = 220O (270O for 2.4 module)
R2 = 360O (E96: 357O) (820O for 2.4 module)
R3 = 820O (1kO5 for 2.4. module)
R4,R6 = 20kO0
R5,R7 = 30kO0 (E96: 30kO1)
Capacitors
C1 = 470µF 25V radial, lead pitch 5mm
C2,C3 = 100 nF ceramic, lead pitch 5mm
C4 = 100µF 25V radial, lead pitch 2.5 mm
C5 = 10 nF ceramic, lead pitch 5mm
C6,C7 = 2µF2 MKT, lead pitch 5 or 7.5mm
Semiconductors
D1 = 1N4004
D2 = LED, red, low current
IC1 = LM317 (TO220)
Miscellaneous
K1 = PCB screw terminal block, lead pitch 5mm
K2 = 3-way pinheader
K3 = 2-way pinheader
S1 = DIL switch block, 10 contacts
S2 = pushbutton, 1 contact
Module1 = TX AUDIO 2.4/AE (Aurel.) + 2 x 8 pin connector with 2.0 mm lead pitch (e.g. Molex type 872641652, Farnell # 856-0145)
PCB, no. 080647-1
receiver
Resistors
0.5 or 0.25 watt, metal film, 5%
R1 = 270
R2 = 22
R3 = 820
R4,R23 = 1kO5
R5,R13 = 47k
R6,R7,R14,R15 = 8kO2
R8,R16 = 2kO2
R9,R17 = 100k
R10,R18 = 1k
R11,R19 = 10k
R12,R20 = 100
R21,R22 = 4kO7
P1 = 50O preset
P2 = 10kO potentiometer, dual linear (Vishay-Sfernice type P9A2RFISX1BB2103MAE3)
P3 = 10kO potentiometer, dual logarithmic (Vishay-Sfernice type P9A2RFISX1BB2103MLE3)
Capacitors
C1,C4 = 470µF 25V, radial, lead pitch 5mm
C2,C3,C9,C10,C15,C16 = 100nF, ceramic, lead pitch 5mm
C5,C8,C11,C14 = 2µF2, MKT, lead pitch 5 or 7.5mm
C6,C12 = 820pF
C7,C13 = 560pF
C17 = 10nF ceramic, lead pitch 5mm
Semiconductors
D1 = 1N4004
D2,D3 = LED red, low current
T1 = BC547B
IC1 = LM317 (TO220)
IC2,IC3 = OPA2134PA (DIP8)
Miscellaneous
K1 = 2-way pinheader
K2 = 3-way pinheader
J1 = 3-way pinheader with jumper
S1 = DIL switch block, 10 contacts
S2 = pushbutton, 1 contact
BT1,BT2 = 9V PP3 battery with clip-on lead (optionally with double-pole switch)
Module1 = RX AUDIO 2.4 (Aurel) + 2 off 2 x 8 contacts with 2.0mm lead pitch (e.g. Molex type 872641652, Farnell # 856-0145)
PCB no. 080647-2
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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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