Oscillating bar frequency measuring device - uses change of magnetisation caused by change of length and length of bar may be adjusted

摘要

The bar (1) may be part of an oscillator or an electro-mechanical frequency filter. The bar is placed in free oscillation in a constant magnetic field and is exposed to an external exciting force so that the resulting frequency of oscillation can be measured. Oscillation of the bar may be by a mechanical impact at one end or by means of an electric shock. The length of the bar may be adjusted to control the frequency by means of a material removing tool controlled automatically with feedback from the oscillation frequency. Air may be blown through a channel with a right angled bend (51), to excite the oscillation.