The function of capacitors is to store electric charge. They are used with resistors in timing circuits, for it takes time for a capacitor to fill with charge. Acting as a reservoir of charge, they can smooth varying DC supplies. Furthermore, because capacitors can easily pass changing signals (AC) but block constant signals (DC) at the same time, they are applied to filter circuits. Formerly known as condenser, capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator).
Tantalum Bead Capacitors
Tantalum capacitor is polarised and has low voltage ratings like electrolytic capacitor. It is expensive but very small; therefore, it is useful in circumstances that large capacitance is needed in a small size. The low leakage and high capacity of tantalum capacitors favors their use in sample and hold circuits to achieve long hold duration, and some long duration timing circuits where precise timing is not critical. They are also often used for power supply rail decoupling in parallel with film or ceramic capacitors which provide low ESR and low reactance at high frequency.
Trimmer Capacitor
Trimmer capacitor is one the the miniature variable capacitors. It is designed to be mounted directly onto the circuit board and adjusted only when the circuit is built. A small screwdriver or similar tool is required to adjust trimmers. The process of adjusting them requires patience because the presence of your hand and the tool will slightly change the capacitance of the circuit in the region of the trimmer! And trimmer capacitor is only available with very small capacitances.
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