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Polar Cap and Non Polar Cap?

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weeyndha

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non polarized capacitors back to back

Hi all,

What is the difference between polar capacitor and non polar capacitor ?

Regards, Weeyndha
 

House_Cat

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A polarized capacitor forms the dielectric between the conducting plates electrochemically. Voltage must be applied in one direction only across the conducting plates to form the dielectric insulating film. The applied voltage across the capacitor must always be in a particular direction, and the capacitor is externally marked to indicate the proper voltage polarity. Reversing the applied voltage can cause the insulating film to rapidly fail, and can cause the capacitor to actually explode from rapid production of gas within the shell of the capacitor.

A non-polarized capacitor uses a dielectric material with uniform insulating properties (such as mylar, mica, glass, etc.), and can be installed in a circuit without regard for the polarity of the applied voltage.
 

Analyzer

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Hi,

Also polarized capacitors have big capacity in small size (above 1 microf), non-polarized capacitors can have big capacity but sizes are very big.(So they are unuseful in most projects)

Analyzer.
 

weeyndha

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Hi all,

Can I paralell 2 polar cap to form a non-polar cap ?
 

pool_77

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Dielectric of polarized capacitor is Al2O3 for Aluminium and TaO2 (if I remember clearly) for tantalum capacitors.

Polarized cap. must be under minimal 2V DC otherwise is dielectric resolved.
It is possible to form this cap. on a higher voltage
 

Borber

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series

No you can't. You must connect them antiserial. That means + polarity connected together and - and - used externally. Or viceversa. Voltage rating is as for single capacitor.
 

pool_77

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in some applications you can use serial pol. cap (+--+ or -++-) with parallel diodes (CAAC or ACCA)
 

Borber

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I saw many applications without diodes but connection made with electrolytic capacitors of same value.
 

sigint

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You can use caps back to back for non-critical applications, it is better to use them in conjunction with the diodes, but their characteristics will never be exactly the same as a true non-polarized cap.
 

flatulent

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now pleantiful

At one time these tricks with polar ones were necessary. Now the nonpolar ones are so common that Digikey and other mail order sources sell them for modest prices. In years gone by, these were used in audio power amplifiers which were powered from one polarity of supply.
 

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