Today, the manufacturer of Vibratory Finishing Machine will share what is a piezoelectric sensor?

The piezoelectric sensor can sense the vibration frequency and ultrasonic noise generated by the roller. The piezoelectric sensing circuit is internally buffered by the MOSFET, while the current driving the MOSFET comes from the constant current source of A4 and is internally connected to the filter through AC coupling. A1, A2 and A3 amplifiers form a 6-pole low pass filter and provide 41.9dB gain. The sampling rate is a 200kHz ADC121S021 analog-to-digital converter responsible for converting amplified and filtered signals into digital signals. The software of the microprocessor can obtain the data about the signal frequency and amplitude through fast Fourier transform (FFT).

The sensor starts to roll off at about 30Hz, and its frequency response amplitude is relatively flat until it rises to the resonance frequency of 65kHz, at which time the flat response changes, after which the frequency response drops rapidly. The peak-to-peak amplitude of this flat band is about 32mVp-p, and then the amplitude will be amplified to 4 VP-p.

A gain of 125 times is used to leave more margin. Taking 40kHz, the highest signal frequency, as an example, the sampling rate has become a worrying problem. To avoid aliasing signal frequencies higher than the Nyquist frequency, half of the sampling rate is filtered, and then the amplitude is suppressed below 1LSB of the analog-to-digital converter.

To provide a practical filter for the Sampled data system, the highest frequency to be measured must be separated from the Nyquist frequency of the analog-to-digital converter to some extent. Although this may cause oversampling of the signal, the filter can suppress or completely eliminate spurious signals.

information about vibratory finishing machine : https://www.zhongyun-machine.com