Author Topic: Polarized capacitors  (Read 2136 times)

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Offline paul18frTopic starter

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Polarized capacitors
« on: August 25, 2014, 12:31:07 pm »
Dear

Does polyester film capacitors are polarized ? I'm looking for 1nF to 100nF ones (to play with my breadboard and/or my new Arduino i.e. from 3V up to 12V max) and they seems not being electrolitic ones ...

Thanks

Paul
 

Offline Pedram

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Re: Polarized capacitors
« Reply #1 on: August 25, 2014, 12:32:40 pm »
no they are not
 

Offline paul18frTopic starter

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[solved] Polarized capacitors
« Reply #2 on: August 25, 2014, 01:37:32 pm »
thanks for the quick answer,

Effectively and after a "hard" search on internet, such polarized capacitor does not exist for 1nF; I understand (nut am I right ?) that "polarized" feature comes from the manufacturing process (and absolutely not from any design consideration) ; for such low capacity it's better to use ceramic capacitors.

Paul
 

Offline DanielS

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Re: Polarized capacitors
« Reply #3 on: August 25, 2014, 05:37:29 pm »
The "polarized feature" is because high-capacity capacitors use electrolyte to increase their energy density. Biasing them the wrong way causes electrolysis and fairly rapid failure.

Small-value capacitors do not require electrolytics' density since value requirements can often be met by straight electrostatic potential such as the very common multi-layer chip capacitors.

Over a decade ago, a 1µF ceramic capacitor used to be impractically large so 1uF electrolytics were still somewhat common but today, you can get over 10µF in 1210 MLCC format and this made sub-10µF electrolytics almost history.
 

Offline David Hess

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Re: Polarized capacitors
« Reply #4 on: August 25, 2014, 05:45:02 pm »
Polarization comes from the process by which the capacitor works.  Polarized capacitors rely on an electrochemical reaction which produces the insulating dielectric layer.
 


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