I Measure the Capacitance of a condenser

AI Thread Summary
The capacitance of a self-made capacitor varies with the distance between its aluminum plates, which can be influenced by sound waves. A De Sauty Bridge was considered for measurement but deemed unsuitable for the requirements. The relationship between capacitance (C), permittivity (ε0), area (A), and distance (d) is relevant, with ε0 and A remaining constant. To measure the variation in capacitance, one can charge the capacitor to a DC voltage, disconnect the source, and then measure the AC voltage as the plate separation changes. Utilizing a FET follower as a voltage buffer is recommended for accurate readings.
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I built a condenser and I want to measure the capacitance of it when reduce the distance between the two plate

when the distance between the two piece of aluminum variate, the capacitance of this self-made capacitor also variate, and I would like the measure the variation of the capacitance caused by a sound wave. If I thought about a De Sauty Bridge but it doesn't fit my requirements. The is this relation between C and ε0 *A/d where ε0 and A are fixed in my case.
 

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If you charge the capacitor to a DC voltage, then disconnect the source of charge. Measure the AC voltage as the separation of the plates change, due to sound waves.
Use a FET follower as a voltage buffer.
https://en.wikipedia.org/wiki/Microphone#Condenser
 
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