JENSEN Jensen NOS Aluminium foil Руководство по эксплуатации онлайн [19/23] 778569

The capacitor also works as a

filtering/attenuation circuit

The four pole electrolytic capacitors have

other additional advantages, which are

especially useful for reservoir capacitors in

high-end amplifiers. If you use a two

terminal, two pole capacitor the entire AC

and all noises coming from the power

supply appear on the capacitor and sent

toward to the high frequency signal path,

disturbing the load because of the common

resistive and inductive parts which force the

input and the output together electrically.

(Figure 2.).

Figure 2. Figure 3.

All these disturbances can be avoided by

using four terminal capacitor constructions,

where the AC on the input terminal is

decoupled from the load. The inductances

and resistances coming from the lead to foil

connections (tab foils) form and

advantageous filter circuit which

attenuation increases with frequency.

(Figure 3.)

As a consequence of the

damping/suppressive effect of this inherent

LR filtering, often a single four-pole

capacitor can replace a complicated filter

arrangement.

Complex construction inside

The filter capability (the measure and the frequency dependence of the attenuation) and the transfer

impedance of a capacitor is determined by the inside construction and different geometrical factors of the

capacitor winding itself. As these factors depends on the dimension of the can, the length and width of

the used capacitor and tab foil, and are different from type to type, the optimisation process must be

accomplished for every single capacitance/voltage/dimension combination.

The manufacturing of the four-pole capacitor is also more complex then the traditional one.

As the yield capacitance value of the electrolytic capacitor foils (anode- and cathode-) can vary up to

20%, the length of the foil should also be adjusted accordingly to achieve the needed nominal

capacitance.

On the other hand this adjustment will destroy the hair-fine geometrical balance optimised for best

filtering and impedance so you either need to re-optimise the capacitor with the new foil length or use

raw materials, which have always the same features. It’s a really technical and economical challenge.