If you are an electronic hobbyst, you are of course very familiar with this part. This part usually used on PCB, to make the circuit “portable”, easy connect and disconnect to another circuit modul safely without soldering the connector.

A screw terminal is a type of electrical connector where a wire is clamped down to metal by a screw.Screw terminals are commonly used to connect a chassis ground, such as on a record player or surge protector. Most public address systems in buildings also use them for speakers, and sometimes for other outputs and inputs.

In some case, a fuse is very important for your electronic circuit and device. With this very cheap component, you will protect your expensive circuit/device from damage (or explosion.. ). Here the little explanation about fuse.

In electronics and electrical engineering a fuse (from the Latin “fusus” meaning to melt) is a type of sacrificial overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows, which interrupts the circuit in which it is connected. Short circuit, overload or device failure is often the reason for excessive current.

A fuse interrupts excessive current (blows) so that further damage by overheating or fire is prevented. Wiring regulations often define a maximum fuse current rating for particular circuits. Overcurrent protection devices are essential in electrical systems to limit threats to human life and property damage. Fuses are selected to allow passage of normal current and of excessive current only for short periods.

A fuse was patented by Thomas Edison in 1890 as part of his successful electric distribution system.

This is the explanation about “Voltage”

Voltage is commonly used as a short name for electrical potential difference. Its corresponding SI unit is the volt (not italicized). Electric potential is a hypothetically measurable physical dimension, and is denoted by the algebraic variable V (italicized )

The voltage between two (electron) positions “A” and “B”, inside a solid electrical conductor (or inside two electrically-connected, solid electrical conductors), is denoted by (V_A − V_B). This voltage is the electrical driving force that drives a conventional electric current in the direction A to B. Voltage can be directly measured by an “ideal voltmeter”. Well-constructed, correctly used, real voltmeters approximate very well to ideal voltmeters. For non-scientists, an analogy involving the flow of water is sometimes helpful in understanding the concept of voltage (see below).

Precise modern and historic definitions of voltage exist, but (due to the development of the electron theory of metal conduction in the period 1897 to 1933, and to developments in theoretical surface science from about 1910 to about 1950, particularly the theory of local work function) some older definitions are not now regarded as strictly correct. This is because they neglect the existence of “chemical” effects and surface effects. A particular lesson from surface science is that, to get consistency and universality, formal definitions must relate to positions or (better) electron states inside conductors.

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.