PURPOSE: To enable testing without being masked by noise by applying oscillation to a sample, picking up the oscillation of a sample with a microphone, passing the output of the microphone through a filter and conducting the same to a display device.
CONSTITUTION: Pulse current S1 is conducted to a coil 1b from a pulse oscillator C to oscillate a sample 1. The sample is attached atop an oscillating table R which is formed with a hollow by the legs R2 fixed to four corners of a resonance plate R1 consisting of rigid plastic or the like in order to resonate mechanically the oscillation of the sample 1 and pulse current is fed from the oscillator C to the coil 1b to oscillate the coil. The oscillation of the sample is picked up with a microphone 2 attached to the end of the oscillating diaphragm. An amplifier A is connected, if necessary, to the output terminal of the microphone to amplify the output S2 of the microphone. The output thereof is conducted through a BPF3 to a display device such as a synchroscope 4 or the like. The above-mentioned BPF3 shuts off the low frequency obtd. from the microphone and shuts off the high frequency corresponding to noise, etc.
TAKAHASHI TAMOTSU
HASEGAWA SHIROU
