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Interesting research on ceramic capacitors

2017-12-21 01:17  
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I found interesting article about capacitance of ceramic capacitors may depend on voltage applied.

It seems to be that in some designs you can face a problem when ceramic capacitor capacitance may strongly depend on voltage. Few tests were done with various capacitors using following circuit:

keramic_C_measurement.PNG

In the circuit CXa€“ tested capacitor; C0 a€“known capacitor. Voltage vas regulated from 0 to 50V using potentiometer R1. 50V is taken as nominal voltage of ceramic capacitor. Because Two capacitors are connected in series the total capacitance is C=CXC0/(CXC0) then we find capacitance of tested capacitor CX=CC0/(C0-C); C0a€“ is about 10 % of CXvalue.

There were several capacitors tested and stunning results were found. – Some of capacitors lost capacitance from 10 to 15 times due to increase of voltage up to 50V. Even when 10% of voltage were applied the capacitance was only about 35 a€“ 40% of nominal value.

One and only explanation may be that low quality dielectric material is used in (no-name) ceramic capacitors. Of course not all capacitors gave following results. But be ready for this when using unknown producer ceramic capacitors.


Reprinted Url Of This Article:
http://www.scienceprog.com/interesting-research-on-ceramic-capacitors/