One hertz is one cycle per second, meaning repeating cycle as an event. For example, hertz is applied physics measuring the number of times for a second wave (either acoustic or electromagnetic) is repeated or can be applied, among other uses, to ocean waves that reach the Beach vibrations per second or a solid. The quantity that measures the frequency hertz is called,in this regard, the inverse of the period. One hertz is an oscillation frequency of suffering a particle over a period of one second.

TOSLINK (Toshiba Link) is a standard fiber optic connection created by Toshiba 1983, which is based on the use of optical signals instead of electrical signals. It is generally used for interconnecting audio equipment, but supports different formats, both physical and data. 1 (in the image) Toslink Connector 2 (pictured) Connector Mini Toslink

VDC would be the abbreviation for Volt Direct Current which translated would volts direct current. The idea of ??this type is unidirectional current to the load. Direct current is normally produced by batteries, thermocouples, solar cells and a dynamo electric machine type. The direct current can flow in conductors such as wires, but may also flow through semiconductors, insulators ... In the image: 1 - current per pulse 2 - Direct Current (DC) 3 - Alternating Current (AC) 4 - Variable Current

The RCA (Radio Corporation of America) connector is a connector used to send video signals or audio.
This is a circular two-contact connector; signal and ground, used with coaxial cables. Each signal uses a single cable and to differentiate color coded RCA connector on the set.
(1) Analog Audio:
Audio Left (White)
Audio Right (Red)

(2) Videoanalogical:
Video (Yellow)

(3) Composite Video:
Audio Left (White)
Audio Right (Red)
Video (Yellow)

(4) Video Component (YPbPr):
Y (Green)
Pb (Blue)
Pr (Red)

(5) Video components (RGB):
R (Red)
G (Green)
B (Blue)

(6) Digital Audio:
S/PDIF (Orange/Gold)