FM Stereo Test Transmitter
VHF FM and audio test signals
Published in issue 355, June 2006
This small signal generator uses an ingenious technique to generate a sine wave with very low distortion, a mono (L+R) baseband signal and an FM stereo signal.
Resistors
R1 = 1k
R2 = 1M
R3 = 470k
R4 = 180k
R5 = 15k
R6,R27 = 100k
R7 = 39k
R8 = 2k4 (or 2k43 from E96 series)
R9,R10,R25,R26,R28,R29 = 10k
R11 = 5k1 (or 5k11 from E96 series)
R12,R13 = 120k
R14 = 47k
R15 = 1k8
R16, R18 = 22k
R17 = 1k5
R19 = 33
R20 = 2k2
R21 = 4k7
R22 = 68
R23 = 470
R24 = 56
R30 = 5k6
R31 = 330
R32 = 100
R33 = 820
P1 = 25k preset
P2 = 4k7 preset
Capacitors
C1 = 47pF
C2 = 56pF
C3 = 22nF MKT, lead pitch 5mm
C4,C9,C13,C15,C26-C30,C32 = 100nF ceramic, lead pitch 5mm
C5,C10 = 47µF 6V3 tantalum or radial electrolytic
C6,C12 = 68pF
C7 = 4nF7 MKT lead pitch 5mm
C8,C16,C17,C21-C25 = 1nF, lead pitch 5mm
C11 = 4µF7 16V tantalum or radial electrolytic
C14 = 220µF 10V radial
C18 = 18pF
C19 = 100pF
C20 = 22pF PTFE trimmer capacitor
C31 = 4µF7 16V radial
Inductor
L1 = 6 turns 0.8mm ECW or CuAg, internal diameter 5mm
Semiconductors
D1,D2,D5 = 1N4148
D3,D4 = BB405 (alternatives: BB205, BB505, BB208-03)
D6 = LED, red, low current
T1 = BF199
IC1 = 74HC4060
IC2,IC3 = 74HC86
IC4 = TLC277 (TS922IN)
IC5 = 74HC4066
IC6 = 78L05
Miscellaneous:
JP1 = 2-way pinheader w. jumper
S1 = on/off switch (and/or 2-way pinheader w. jumper)
S2 = 1-pole, 3-way switch (and/or 3-way pinheader w. jumper)
S3, S4 = changeover switch (and/or 3-way pinheader w. jumper)
X1 = 9.728MHz quartz crystal, HC-49/U, fundamental frequency, parallel resonance, load capacitance 30 pF, ±10 ppm, (see text)
BT1 = 9V battery with clip-on leads
BNC socket 50 Ohm (optional)
PCB, order code 050268-1
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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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