Electrolytic Capacitor types/ uses?

About electrolytic (aluminium) capacitors..... what do the low ESR ones do that normal ones don't? And how come they have these capacitors in bipolar types, but not all are bipolar? Is it because of the size/cost? And lastly, can you make an LC circuit with any electrolytic capacitor?

                                                                                                            Many thanks

P.S: In which frequency range are LC resonant ciruits best used? Cos I heard that lower/higher than a specific point, they become impractical or something....

A low Equivalent Series Capacitor has a low resistance compared to a normal cap - I bet you didn't know capacitors HAD resistance did you ?

Low ESR ones are used where power dissipation IN THE CAPACITOR is significant  - that happens in high frequency power supplies for example.

Bipolar electrolytics are piddling things, which are quite delicate electrically, and only really used in audio designs. The way the DIELECTRIC in the capacitor is made means that bipolar designs are weak and low valued.

I really wouldn't make an LC resonant circuit with an electrolytic, in most of my work, the frequency characteristic is very important. An electrolytic will give crap performance with temperature, time, atmospheric pressure.... avoid.

Steve
.Unknown. (author)  steveastrouk7 years ago
Woa....I always thought the resisistance had another name.
bwrussell7 years ago
Lower ESR (equivalent series resistance) electrolytics are used in power supplies for efficiency purposes but in a LC circuit you can sometimes get catastrophic voltage spikes.

The voltage applied to most electrolytics must be polarized, meaning the unlike normal caps these have terminals for +/- and cannot be used with normal AC. If you hook one up backwards or to AC it could burst, injuring someone. If you need a electrolytic for AC get a NP (non-polarized) type. The difference is how they are constructed and that when using an NP electrolytic for DC you should get twice the capacitance of the same electrolytic in an AC circuit.

Not sure on the range of the LC circuit, sorry. Hopes this helps.