The Ultramicrometer as a Vibration Meter
J. C. Hubbard, Philip Newton Hambleton · The Journal of the Acoustical Society of America · 1941
The L, C circuit of a radiofrequency oscillator of high frequency stability includes as part of its capacity a separate unit containing a reed condenser of variable inertia and resistance characteristics. When the oscillator is tuned to zero beat with another, preferably a Pierce oscillator, any shock or vibration reaching the reed throws the electrical tuning off zero beat. The resultant disturbance may be picked up by a tuned radiofrequency receiver and the output measured or heard by loudspeaker. The device has been used in the laboratory for testing the effectiveness of vibration insulation and “vibration free” mountings. The apparatus will be demonstrated.