Crystal Oscillator Circuit

Another great crystal oscillator circuit with BB139, a 2-nd harmonic quartz crystal and one BF214 transistor. So, the Q quartz is half of the desired transmitter frequency, L1 has 24 turns, 0.08mm Ø built on a 455kHz carcase. L2 has 8-9 turns / 0.8mm Ø / 5mm Ø. This oscillator circuit has a great frequency stability, I’ve build it.

crystal oscillator circuit components

R1 = 10K
R2 = 100K
R3 = 8.2K
R4 = R6 = 820Ω
R5 = 15K
C1 = 330nF
C2 = 1nF
C3 = 1.5pF
C4 = 15pF
C5 = 2.2nF
C6 = 6 – 25pF trimmer
C7 = 4.7pF
D1 = BB139
D2 = 5.6v zenner diode
T = BF214
Q = half frequency quartz crystal

Crystal Oscillator Circuit Schematic

Crystal oscillator circuit schematic

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