Circuit for the self-excitation of a mechanical oscillation system to its characteristic resonant frequency

摘要

PCT No. PCT DE89/00281 Sec. 371 Date Dec. 27, 1989 Sec. 102(e) Date Dec. 27, 1989 PCT Filed May 3, 1989 PCT Pub. No. WO89/10802 PCT Pub. Date Nov. 16, 1989.The circuit arrangement for self-excitation of a mechanical oscillation system to natural resonant oscillations includes an electromechanical transducer system which is arranged in the feedback circuit of an electronic amplifier circuit so that it is stimulated by the output AC voltage of the amplifier circuit to mechanical oscillations and furnishes an AC voltage with the frequency of the mechanical oscillations to the input of the amplifier circuit. The amplifier circuit has a non-linear gain characteristic which at small values of the input signal gives a greater amplification than at lower values of the input signal. As a result a reliable oscillation start is ensured even under unfavorable operating conditions while on the other hand the danger of erroneous indications of the oscillation state, for example due to external vibrations, is reduced.