The 27MHz quartz crystal oscillator circuit is as shown in figure 1. The biasing circuit is composed of the R1, R2 and R3, C6 is the bypass capacitor. The partial voltage circuit is composed of the C1, C2, C3 and C4 to control the strength of oscillation. L1 is the high-frequency choke coil, it has the role of filtering. Figure 1 The 27MHz quartz crystal os..