| 摘要 |
PURPOSE:To ensure a control of the oscillation frequency, by providing a variable attenuator to the feedback path of an oscillator using an electromechanical filter and thus controlling the quantity of feedback. CONSTITUTION:The transistor 15, forming an emitter-earthed amplifier, drives the lead filter 19 with the signal extracted from the load resistance 14 via the DC blocking capacitor 18. The signal passed through the filter 19 is applied to the capacitor 21 forming a phase shifter and then applied to the base of the transistor 25. The output signal is extracted from the collector side of the transistor 25; and the feedback signal reaching the base of the transistor 15 is extracted from the emitter side. The variable attenuator 30 is provided to the feedback path to ensure a control of the exciting level to the filter 19. As a result, the equivalent admittance of the filter 19 varies to change the oscillation frequency. |
