Electrolytic capacitor

Electrolytic capacitors are made differently to other types and are widely used throughtout the industry. They provide more capacitance for their size than any types but there not suitable for all applications.

When manufactured the plates are subjected to an electrolytic process which oxidises one of the plates. Aluminium oxided is a very effective dielectric, being ten times better then air. The oxide dielelectric is also very thin which helps to reduces the physical size of the electrolytics when compared with other types.

Where an electrolyic capacitor is clearly marked + and - it must always be connected to a D.C supply and the polarity must not be reversed as this will reverse the electrolytic process which deposited the oxide layer on the plates and the capacitor will be destroyed!!!!!!!!!!!

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Just one question... Where did you get the cool picture of Bender?

Tolerance of the Electrolytic capacitor is not so good.

For the Electrolytic capacitor to function properly DC voltage is essential. My question is how much (minimum) voltage is required? e.g if working voltage of the capacitor is 100 V, is it expected to work as effectively when used with 5 volts?

Where an electrolyic capacitor is clearly marked + and - it must always be connected to a D.C supply and the polarity must not be reversed as this will reverse the electrolytic process which deposited the oxide layer on the plates and the capacitor will be destroyed!!!!!!!!!!!

There is personal experience to back this up. A 5000µF 16V capacitor that had been inadvertently connected incorrectly to a 12VDC power source for smoothing purposes exploded after several seconds, spraying off-white powdered filaments across a wide area, including the individual's clothing, with the release of a fair amount of heat and smoke. Luckily no-one was hurt on that occasion.

I had this happen with a 500µF electrolytic at 450 Volts. Though no one was hurt, we never did find the can!

They sometimes use boric acid soaked paper as an insulator and the plates are usually carbon. They are usually polarized too.

Always Google first. In this case: Electrolytic capacitor Wikipedia