PTT

PTT may refer to:

Chemistry and medicine

Communication and technology

Switch

In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The mechanism of a switch may be operated directly by a human operator to control a circuit (for example, a light switch or a keyboard button), may be operated by a moving object such as a door-operated switch, or may be operated by some sensing element for pressure, temperature or flow. A relay is a switch that is operated by electricity. Switches are made to handle a wide range of voltages and currents; very large switches may be used to isolate high-voltage circuits in electrical substations.

Description

The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts, which are connected to external circuits. Each set of contacts can be in one of two states: either "closed" meaning the contacts are touching and electricity can flow between them, or "open", meaning the contacts are separated and the switch is nonconducting. The mechanism actuating the transition between these two states (open or closed) can be either a "toggle" (flip switch for continuous "on" or "off") or "momentary" (push-for "on" or push-for "off") type.

PTT (Turkey)

Ptt, abbreviation for Turkish: Posta Telgraf Teşkilatı, is the national post and telegraph directorate of Turkey. Formerly, the organization was named (Turkish: Posta Telgraf Telefon). After the privatization of the telephone telecommunications service business, the directorate was renamed, keeping its acronym. It is headquartered in Ankara. It is known as TURKISH POST internationally.

History

On October 23, 1840, Ottoman Ministry of Posts was established. In 1855, first telegraph service and in 1909 first telephone service were put into use. In the same year the name of the ministry was changed to Posta Telgraf Telefon ("Posts, Telegraph and Telephone" or PTT for short) a name which was used for 86 years. After Turkish Republic replaced the Ottoman Empire in 1923, the ministry became a general directorate of the Republic. In 1995 the telephone and other telecommunication services were transferred to newly founded Turk Telecom (which was soon privatized). Accordingly, the directorate was renamed as "Organization of Post and Telegraph" (Turkish: Posta Telgraf Teşkilatı). Thus the former acronym PTT is kept.