In electronics, a battery is two or more electrochemical cells[1] connected in series which store chemical energy and make it available as electrical energy. Common usage has evolved to include a single electrical cell in the definition.[2] There are many types of electrochemical cells, including galvanic cells, electrolytic cells, fuel cells, flow cells and voltaic piles.[3] A battery’s characteristics may vary due to many factors including internal chemistry, current drain and temperature.
One common division of batteries distinguishes two types: primary (disposable) and secondary (rechargeable). Primary batteries are designed to be used once only because they use up their chemicals in an effectively irreversible reaction. Secondary batteries can be recharged because the chemical reactions they use are reversible; they are recharged by running a charging current through the battery, but in an opposite direction to the discharge current. Secondary, also called rechargeable batteries can be charged and discharged many times before wearing out. After wearing out some batteries can be recycled. Laptop Battery
Although an early form of battery may have been used in antiquity, the modern development of batteries started with the Voltaic pile, invented by the Italian physicist Alessandro Volta in 1800. Since then, batteries have gained popularity as they became portable and useful for many purposes.[6] The widespread use of batteries has created many environmental concerns, such as toxic metal pollution.[7] Many reclamation companies recycle batteries to reduce the number of batteries going into landfills.
A camera is a device used to capture images, either as still photographs or as sequences of moving images (movies or videos). The term comes from the Latin camera obscura for “dark chamber” for an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura.
Cameras may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum. A camera generally consists of an enclosed hollow with an opening (aperture) at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. Most cameras have a lens positioned in front of the camera’s opening to gather the incoming light and focus all or part of the image on the recording surface. The diameter of the aperture is often controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture. Camera Battery
The Dreambox is a Linux-powered DVB satellite, terrestrial and cable digital television decoder (set-top box), produced by German multimedia vendor Dream Multimedia. Its firmware is officially user-upgradable, since it is a Linux-based computer, as opposed to third-party “patching” of alternate receivers. All units support Dream’s own DreamCrypt conditional access (CA) system, with software-emulated CA Modules (CAMs) available for many alternate CA systems. The Dreambox is based on the DBox2 units that were distributed by Kirch Media for its pay-TV services before its bankruptcy; it uses the same Linux-based software originally developed for the DBox2. The built-in Ethernet interface allows networked computers to access the recordings on the internal hard disks on some Dreambox models. It also enables the receiver to store digital copies of DVB transport streams on networked filesystems or broadcast the streams as IPTV to VideoLAN clients. Unlike many PC based PVR systems that use free-to-air type of DVB receiver cards, the built-in conditional access allows receiving and storing encrypted content.
The combination of third-party developers and network connectivity which facilitates card sharing, makes Dreambox use particularly common among enthusiasts and those who intend to obtain services without payment. Third-party software for this purpose is neither officially endorsed nor supported by Dream Multimedia and voids the official warranty; however, unofficial web sites support a very large community of enthusiasts.
In 2007, Dream Multimedia also introduced a non-Linux based Dreambox receiver, the DM100, their sole to date, running on unspecified hardware, but still featuring an Ethernet port and a USB port. [1] The speed of the USB port is not specified, the manufacturer only says it is of “B” type, the one found on peripherals connected to PCs.