what are the uses of coupling capacitors? decoupling capacitors? smoothing capacitors? and its use as a timing element? and other attributes of capacitor..

A trimmer or preset is a miniatur adjustable electrical component. It is meant to be ordered aright when installed in whatever device, and never seen or keyed by the device’s user. Trimmers can be potentiometers or varco (variable capacitors – trimmable inductors subsist but are rattling uncommon). They are ordinary in exactitude circuitry similar to  A/V components, and may need to be adjusted when the equipment is serviced. Unlike some another variable controls, trimmers are mounted direct on circuit boards, overturned with a small screwdriver and rated for some less adjustments over their lifetime.

Trimmers become in a difference of sizes and levels of precision; for example, multi-turn cut potentiometers exist, in which it takes individual turns of the fitting propellor to accomplish the modify value, allowing for rattling broad degrees of accuracy.

AC adapter basics:
It seems that the world now revolves around AC Adapters or ‘Wall Warts’ as they tend to be called. There are several basic types. Despite the fact that the plugs to the equipment may be identical THESE CAN GENERALLY NOT BE INTERCHANGED. The type (AC or DC), voltage, current capacity, and polarity are all critical to proper operation of the equipment. Use of an improper adapter or even just reverse polarity can permanently damage or destroy the device. Most equipment is protected against stupidity to a greater or lessor degree but don’t count on it. The most common problems are due to failure of the output cable due to flexing at either the adapter or output plug end. See section below on repair procedure.

1. AC Transformer. All wall warts are often called transformers. However, only if the output is stated to be ‘AC’ is the device simply a transformer. These typically put out anywhere from 3 to 20 VAC or more at 50 mA to 3 A or more. The most common range from 6-15 VAC at less than an Amp.

Loudspeaker anatomy:
In this document, we use the terms ‘loudspeaker’ or ‘speaker system’ to denote a unit consisting of one or more drivers in an acoustic enclosure perhaps along with a frequency selective crossover, tone controls and switches, fuses or circuit breakers. Connections to the amplifier or receiver are via terminals on the rear.

The front is covered with an (optically) opaque or semitransparent grille which provides protection and improves the appearance (depending on your point of view).

A ‘driver’ is the actual unit that converts electrical energy into sound energy. Most drivers use voice coil technology: a very low mass coil wound on a light rigid tube is suspended within a powerful magnetic field and attached to a paper, plastic, or composite cone. The audio signal causes the coil to move back and forth and this motion causes the cone to move which causes the air to move which we perceive as sound.

In this reading we are going to talk about capacitance. I have to make a distinction here between capacitor and capacitance. A capacitor is a device, whereas capacitance is an electrical property. First we will discuss the capacitor and then the property of capacitance.
We will avoid mathematics where possible.
Construction

As you can see a capacitor is a two terminal device. There is always an insulator between the plates of a capacitor. This should suggest to you that current never flows through a capacitor.