How to test contact vibration sensors

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kokkoplus Associate Join Date: Jul 2006 Location: Austin, Texas Posts: 45	How to test contact vibration sensors 12/08/2021 2:10 PM
	Hi all. I wonder if anybody can help me figure out a system to test the frequency response of an electro-dynamic contact vibration sensor. Shape:cylindrical Diameter 15 mm - Height 13 mm Impedance: 500 ohm. Mass; 6 grams Frequency range: 60 Hz to 12 kHz. Relative small amplitude of vibrations. I would like to avoid a commercial shaker. So far I have been using a speaker playing a sine sweep with the sensor glued to the cone. I get a frequency response but how do I calibrate the rig? Thank you all in advance!
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	Pathfinder Tags: Sensors calibration response

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SimpleMind Guru Join Date: Sep 2009 Posts: 1032 Good Answers: 86	#1 Re: How to test contact vibration sensors 12/08/2021 5:41 PM
	Use a flat response mike in a sound pressure feedback servo loop to stabilize cone sound volume output and make your sweeps slow. Speaker should NOT be on an enclosure but on a relatively heavy flat panel and arrange for as anechoick conditions as possible on both sides. You can then make comparative measurements of sensor output. S.M. __________________ Life is complex. It has a real part and an imaginary part.
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kokkoplus Associate Join Date: Jul 2006 Location: Austin, Texas Posts: 45	#2 In reply to #1 Re: How to test contact vibration sensors 12/08/2021 9:45 PM
	Ok thanks. Yes, the speaker in not in an enclosure just like you said and I am using a flat diaphragm speaker from Tectonic. https://www.parts-express.com/Tectonic-TEBM46C20N-4B-BMR-3-Full-Range-Speaker-4-297-2157 I have few mics around but I think I should buy a tiny condenser capsule from Primo. Few questions: Should I get a directional capsule? How far from the diaphragm would you place it? Could you explain the servo loop? Can I just build one that can controls the amplitude of the (slow) sweep going to the amplifier? Thank you so much.
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