# What Are Different Types Of Capacitors?

For example, in this model, if the pressure on the left side of the piston is greater than that on the right, the piston shifts to the right. One apparently receives a “current flow” through the condenser, because on the left just as much (water) flows into it as flows out on the right side. Although not the same water particles, since the two half-chambers are isolated from each other, but in quantitative terms, despite the piston as a separation layer, one can observe a transport of water particles “through” the condenser.

If the piston is deflected out of its rest position by the incoming water, a (mechanical) opposing tension builds up in the coil springs. The piston is displaced until the counter tension in the springs compensates for the overpressure applied to one side. If there is no one-sided overpressure, the piston returns to the idle state, which in turn leads to the charge transport “through” the capacitor (Safety Certified Capacitors).

## Capacitors in the DC circuit

To charge a capacitor completely, depending on the capacity of the capacitor and the strength of the charging current often only a few seconds or even fractions of seconds needed. By charging the capacitor and thereby building up voltage between the capacitor plates, the charging process is initially fast and then progressively slower.

The charging process comes to a standstill when the voltage U _ {\ mathrm {C}}between the two capacitor plates is equal to the charging voltage U_0; the capacitor is then charged and no further current can flow through the capacitor.

## Capacitors in the AC circuit

If an alternating voltage is applied to a capacitor, a charging or discharging current alternately flows. A capacitor acts like a resistor in an AC circuit.

During the charging processes, electrical energy is transferred to the capacitor, which is discharged again from the capacitor during the discharging processes; in the time average, therefore, the mean value of the occurring electrical power to an (ideal) capacitor is zero. One speaks in this context of “reactive power”; The capacitor is referred to in an AC circuit as a “reactance” or “capacitive impedance” (Safety Certified Capacitors).

The capacitive impedance depends on the capacitance of the capacitor and the frequency of the alternating current; the larger the capacitance C and the higher the frequency of f the alternating current, the lower the capacitive impedance of the capacitor.

## Trim capacitors

Trim capacitors (also called rotary capacitor or short “Drehko”) refers to a capacitor with an adjustable capacitance; this ranges from zero to the specified maximum value.

The capacitance value of variable capacitors can usually be adjusted by means of a rotary knob. Since there is air between the capacitor plates in most variable capacitors, the maximum capacitance values ​​are usually less \ Unit [500] {pf}. Such capacitors are used for example in radios to adjust the receiver to different transmitter frequencies can.

## Electrolytic capacitors

Electrolytic capacitors (“Elkos”) usually have high capacity values ​​of about \ unit [0,1] {\ mu F}to \ unit [1000] {\ mu F}, or even more. However, electrolytic capacitors are polarized, so they each have a plus and a minus connection, which must not be interchanged. The connections are clearly marked, mostly by printed minus signs at the minus connection. With new Elkos one can recognize the plus pole additionally at the longer connecting wire.

When using electrolytic capacitors, not only must one pay attention to correct polarity, but also consider that their capacity may decrease considerably over time. Electrolytic capacitors should therefore only be installed in places where a deviation of the capacitance value for the circuit does not play too great a role.