Headphone

 Headphones are a pair of small loudspeakers that are designed to be held in place close to a user's ears. Headphones either have wires for connection to a signal source such as an audio amplifier, radio, CD player, portable media player or mobile phone, or have a wireless receiver, which is used to pick up signal without using a cable. They are sometimes known as earspeakers or, colloquially, cans.^[2] The in-ear versions are also known as earphones or earbuds. In the context of telecommunication, a headset is a combination of headphone and microphone.

Headphones originated from the earpiece, and were the only way to listen to electrical audio signals before amplifiers were developed. The first truly successful set was developed by Nathaniel Baldwin, who made them by hand in his kitchen and sold them to the United States Navy.^[3][4]
Some very sensitive headphones such as those manufactured by Brandes around 1919 were commonly used for early radio work. These early headphones used moving iron drivers, either single ended or balanced armature. The requirement for high sensitivity meant no damping was used, thus the sound quality was crude. They also had very poor comfort compared to modern types, usually having no padding and too often having excessive clamping force to the head. Their impedance varied; headphones used in telegraph and telephone work had an impedance of 75 ohms. Those used with early wireless radio had to be more sensitive and were made with more turns of finer wire; impedance of 1,000 to 2,000 ohms was common, which suited both crystal sets and triode receivers.
In early powered radios, the headphone was part of the vacuum tube's plate circuit and had dangerous voltages on it. It was normally connected directly to the positive high voltage battery terminal, and the other battery terminal was securely grounded. The use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset.

sumber data: http://en.wikipedia.org/wiki/Headphones
Nama: Sherly Amri Ilyasha
No: 22
Kelas: 9a

RAM

 

RAM (Random Acces Memory) adalah salah satu memory dalam komputer yang bersifat sementara (apabila komputer dimatikan, maka semua instruksi maupun data yang ada di memori akan hilang) yang digunakan untuk menampung instruksi atau program, untuk memproses data-data yang telah diproses dan menunggu untuk dikirim ke output device, secondary storage atau juga communication device. Sebagai contohdi dalam task manager di bagian processes ada memory usage, nah program-program itu disimpan sementara di dalam ram. HARD DISK merupakan salah satu media penyimpan data pada komputer yang terdiri dari kumpulan piringan magnetis yang keras dan berputar, serta komponen-komponen elektronik lainnya. Hard Disk menggunakan piringan datar yang disebut dengan platter yang pada kedua sisinya dilapisi dengan suatu material yang dirancang agar bisa menyimpan informasi secara magnetis.

Sumber data: Wikipedia
Nama          : Rivaldy Ahmad N
Absent         :20
Kelas           :9A

WEBCAM

WebCam adalah :
- Kamera video sederhana berukuran relatif kecil. sering digunakan untuk konferensi video jarak jauh atau sebagai kamera pemantau. WebCam pada umumnya tidak membutuhkan kaset atau tempat penyimpanan data, data hasil perekaman yang didapat langsung ditransfer ke komputer.
- Sebuah periferal berupa kamera sebagai pengambil citra/gambar dan mikropon ( optional ) sebagai pengambil suara/audio yang dikendalikan oleh sebuah komputer atau oleh jaringan komputer. Gambar yang diambil oleh WebCam ditampilkan ke layar monitor, karena dikendalikan oleh komputer maka ada interface atau port yang digunakan untuk menghubungkan WebCam dengan komputer atau jaringan. Ada beberapa orang mengartikan WebCam sebagai Web pages + Cam era, karena dengan menggunakan WebCam untuk mengambil gambar video secara aktual bisa langsung di upload bila komputer yang mengendalikan terkoneksi internet. Gambar Webcam merk Dlink
- Webcam (singkatan dari web camera ), merupakan sebutan bagi kamera real-time (bermakna keadaan pada saat ini juga) yang gambarnya bisa diakses atau dilihat melalui internet , program instant messaging seperti Yahoo Messenger , AOL Instant Messenger (AIM), Windows Live Messenger , dan Skype .Istilah "webcam" mengarah pada jenis kamera yang digunakan untuk kebutuhan layanan berbasis web.

- Sumber : http://soerya.surabaya.go.id/AuP/e-DU.KONTEN/edukasi.net/SMK/TIK/Webcam

- Nama    : Zanu Ramdan Dwi Saputra
- No        : 29
- Kelas    : 9A 

HEADPHONE

Headphones are a pair of small loudspeakers that are designed to be held in place close to a user's ears. Headphones either have wires for connection to a signal source such as an audio amplifier, radio, CD player, portable media player or mobile phone, or have a wireless receiver, which is used to pick up signal without using a cable. They are sometimes known as earspeakers or, colloquially, cans.The in-ear versions are also known as earphones or earbuds. In the context of telecommunication, a headset is a combination of headphone and microphone.
Headphones originated from the earpiece, and were the only way to listen to electrical audio signals before amplifiers were developed. The first truly successful set was developed by Nathaniel Baldwin, who made them by hand in his kitchen and sold them to the United States Navy.
Some very sensitive headphones such as those manufactured by Brandes around 1919 were commonly used for early radio work. These early headphones used moving iron drivers, either single ended or balanced armature. The requirement for high sensitivity meant no damping was used, thus the sound quality was crude. They also had very poor comfort compared to modern types, usually having no padding and too often having excessive clamping force to the head. Their impedance varied; headphones used in telegraph and telephone work had an impedance of 75 ohms. Those used with early wireless radio had to be more sensitive and were made with more turns of finer wire; impedance of 1,000 to 2,000 ohms was common, which suited both crystal sets and triode receivers.
In early powered radios, the headphone was part of the vacuum tube's plate circuit and had dangerous voltages on it. It was normally connected directly to the positive high voltage battery terminal, and the other battery terminal was securely grounded. The use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset.

sumber : http://en.wikipedia.org/wiki/Headphones

CRT MONITOR

 

The cathode ray tube (CRT) is a vacuum tube containing an electron gun (a source of electrons or electron emitter) and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others. CRTs have also been used as memory devices, in which case the visible light emitted from the fluoresecent material (if any) is not intended to have significant meaning to a visual observer (though the visible pattern on the tube face may cryptically represent the stored data).

The CRT uses an evacuated glass envelope which is large, deep (i.e. long from front screen face to rear end), fairly heavy, and relatively fragile. As a matter of safety, the face is typically made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions, particularly if the CRT is used in a consumer product.

CRTs have largely been superseded by more modern display technologies such as LCD, plasma display, and OLED, which as of 2012 offer lower manufacturing and distribution costs.

The vacuum level inside the tube is ultra-high vacuum on the order of 0.01 Pa^[1] to 133 nPa.^[2]

A cathode ray tube is a vacuum tube which consists of one or more electron guns, possibly internal electrostatic deflection plates, and a phosphor target.^[3] In television sets and computer monitors, the entire front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster. An image is produced by controlling the intensity of each of the three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference.^[4] In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is commonly used in oscilloscopes, a type of diagnostic instrument.^[4]

^{http://en.wikipedia.org/wiki/Cathode_ray_tube}

^{Carina Maya Rismawati}

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^9A